Unleash The Raspberry Pi Through Physical Computing

1. Welcome to Class: - welcome to unleash the raspberry pi through physical computing. - First of all, - I want to tell you how much I truly appreciate you enrolling in this class. - If it any point during this class, - you don't understand something or need some help. - The best place to go is the community tab on the class page. - You're also welcome to email me or reach out on Twitter. - I'm happy to help. - So first of all, - what is physical computing Wikipedia describes. - It is building physical systems by the use of software and hardware that consents and - respond to the analog world. - In the last five years, - there's been an explosion in the hardware hacking space. - Some amazing low cost tools have been created that have allowed hobbyists to start creating - serious hardware projects. - That, - combined with the fact that writing a blob with the latest shiny software tool just isn't - cutting it anymore for the basement hackers out there. - There's a huge desire to write software that leaves the room of our PC and the Internet and - actually starts interacting with the physical world around this, - making your toaster tweet, - getting feedback from your car sensors locking your house from the Beach. - These are all examples of physical computing. - There are a lot of hardware tools available for physical computing, - but the raspberry pi has gained a lot of traction not only because of the price but also - because it can run software that many people already have experience with. - Unlike microcontrollers, - which predominantly require you to write in C or assembly the raspberry pilots, - you create hardware projects using things like python or even know J s. - So what exactly will we cover in this class? - We'll start by setting up and configuring the raspberry pi. - We'll cover in detail the basic digital input output capabilities it provides. - Next, - we'll introduce you to the purple capabilities exposed to be the Pies GP I Ho header and - cover each one in detail. - We'll do this by building a simple home monitoring device. - We'll wrap things up by connecting our device to the Internet so we can check the status - remotely. - We'll throw in some tips and tricks along the way and also cover some electron ICS - principles to help you in your own projects. - There are some things that won't be covered in this class, - however, - while we will cover some basic electron ICS knowledge along the way. - This class isn't meant to teach electron ICS in depth. - I wouldn't even consider it an intro to electron ICS, - as we will gloss over some topics who also be using python to write the code for our device - but won't be covering python in depth. - Most of the code, - however, - will be very simple and will not require deep knowledge of the python language. - Even so, - I've included some links for learning python in the resource section. - Going through some of those first will definitely help but isn't required. - It's not required that you follow the class project exactly, - but it would help to ensure that you are reaching the learning milestones. - List of materials needed to follow along can be found on the info tab for this class. - It can also be found in the resource section for this unit. - I tried to keep the Costas lowest possible. - The most important objective of this class is for you to have fun. - As we go through the various units. - I hope that your imagination will take over as you think of ideas to try and projects to - create. - I encourage you to act on those desires and share them with the class by creating your own - student project. - All right, - let's get started. 2. Prepare the SD Card (Steps 1-3): - Welcome back in this unit will go over setting up our raspberry pie with an operating - system and getting it ready to start a project. - As always. - If you have any questions, - feel free to submit them on the skill share class page, - where you can send me an email or try and find me on Twitter. - So before we can boot up our raspberry pi need to give it some sort of base operating - system. - Unlike a conventional computer, - the pie doesn't have a traditional hard drive. - It's hard drive is the SD card we put in it. - But just like a normal computer, - the pie needs something to boot up. - Traditionally, - that would be something like Windows OS 10 or a form of Lennox. - But even if the hardware were compatible, - the pie would have no hope of running something like Windows or OS 10. - But it turned down version of Lennox will do just fine, - and that's exactly what we're going to install. - The pilot doesn't use a normal CPU like an Intel I seven, - so we can't just throw a bun two or red at Lenox on it. - We need a special distribution of clinics. - Unfortunately, - for us, - there are plenty to choose from. - Lots of smart people have modified various Lennix distributions to make them work on the - raspberry pi. - An exploration of all the available distributions is beyond the scope of this class, - but you can read more about them on the downloads page at raspberry pi dot board. - For our purposes, - we're going to stick with the recommended starter distribution known as Raz B in. - So let's go ahead and walk through it. - We'll start by going to the raspberry pi dot org's homepage Well appear to downloads Now. - In the early days of the raspberry pi, - you had to follow special steps just to get Raz b in onto your SD card. - News has changed all that and made it extremely easy to get started. - As you can see here, - we simply have to for madness D card and copy of the unzip nubes image onto it. - Let's go ahead and download that well. - That's downloading. - You'll notice that they recommend that we four matter SD card using the SD card - associations formatting tool. - So let's go ahead and get that tool now. - The downloads air over here on the left hand side, - and we'll just choose the SD four matter for dot over windows. - As usual, - we have to go through a license agreement. - So we'll go ahead and accept that and the down little start. - I'll go ahead and fast for the download is it takes just a minute. - Okay, - once that finishes downloading, - just go ahead out to that location where just downloaded on windows will unblock it before - we extract it. - We'll just extracted here. - Okay, - great. - Now let's go ahead into that folder and we will launch the set up the Senate for this tools - . - Really easy. - We're basically just gonna go ahead through and accept off defaults, - so I'll sort of fast forward and let it play through a little faster so you can see what's - going on. - Start by going to next. - Just accept the defaults here and hit Install. - Okay, - which this finches up. - We'll go ahead and click finish, - and that's all there is to sitting up that tool. - And you can see we have a little bit left to go on our nubes download so we'll go ahead and - fast forward. - That hasn't finishes. - No way we watch this formatting tool. - You'll see here that we have a drive dropped down. - This will be the drive that you have us that represent your SD card. - In my case, - that's G. - Now you want to make sure you verify this because if you select the wrong Dr here, - you could end up formatting your local hard drive or another are drive that as things like - pictures and things like that. - So, - as you can see here, - my ruble disk is my G drive. - You can also see the size is correct will come into the options you could just leave. - The format type is quick, - but you'll want to turn the format size adjustment toe on and then click. - OK, - Once we've done that, - we are already to format this drive, - so we will go ahead and we'll click format. - Once RST card is formatted, - we're ready to put the image on toe. - So it's come back to this image that we downloaded. - Go ahead and unblock it like we did before, - and we will extract it here. - Oh, - this will only take a minute. - All we need We don't want to copy the folder. - We want to copy the contents of the folder. - So let's go ahead and select all of this will, - right Click and we'll do a copy and then we want to put that onto our SD cards will come - over here to this window. - If you remember, - SD card is the G Dr will open that and we'll just paste our files here. - Now it's a lot of files, - so this will take a second. - So we'll go ahead and use the magic of video to speed this up. - I only take a few seconds. - All right, - that's it. - This SD card is now ready to be placed into our pie so that we can boot it up for the first - time, - which will allow us to install raspy in. - So let's go ahead and do that next. 3. Install Raspbian and Update (Steps 4-9): - Okay, - so now that we have our card here with nubes on it, - we're ready to hook everything up. - So I've got the raspberry pi out here. - You can install it in a case if you want to. - Just make sure that you leave access to these header pins because we'll need those later, - and all we're gonna do is hook all of this stuff up. - So first thing we're gonna do is insert the SD card. - Make sure it's nice and snug will go ahead in hook up our monitor. - I'm gonna start with wired Internet, - So go ahead and look that up. - And the last thing that will need is a keyboard, - so we'll go ahead and that it the U. - S B port. - Now, - I would wait to connect your power toe last. - That's just the way I normally do it. - Um, - another thing that you wanna be aware of is you don't want to lay this on a surface that - can conduct electricity, - so don't put it on anything metal. - You can actually leave it without a case. - It's fine if you don't want to use one. - Just make sure that it's sitting on something sturdy so that won't fall off. - And that won't connect electricity. - So the last thing will do is will connect our power. - And now we are ready to boot up for the first time. - I'd like to make just a quick note on the video quality in this unit. - It's really bad. - As I'm trying to record directly from another screen, - I promised. - The whole course won't be like this. - As soon as we get our pie installed, - I'll start to ssh in and screen record so everything will look much nicer than the first - time that you boot up your pie. - Now that you've got Nubes on your SD card, - this is a screen that it's going to boot to. - It is going to give you the choice to install bunch of distributions. - We want to stick with Raz B in, - which is the one that's highlighted by Deep all. - So if you just push space bar on your keyboard, - it'll put an X on that, - saying that it's highlighted. - And then, - if you notice you might not be able to see on the screen in the top left, - there's it, - says Install, - and there's an I in parentheses, - so If we just push I on our keyboard, - it's gonna give you a warning that it's going Teoh race everything on the SD card and be - overridden, - and so then we'll just hit. - Enter to say continue, - and it will start the installation. - This is a great time to grab a snack or a drink, - as this will take a while. - While Raz B is installing you, - compress L to set your language will bring up a drop down. - You can select the one that you want. - You can also choose your keyboard layout by pressing nine. - If you do it now, - while it's installing, - you won't have to worry about it later. - Once the install finishes, - you'll get this message box that says OS is installed successfully. - Just it entered to say OK, - that'll trigger a reboot of your pie. - And after the pie loads everything up, - you'll see this blue screen with the white dialog box on it. - This gives you some options to configure your raspberry pi. - The only thing I would recommend doing here is making sure that ssh is enabled. - To do that will go down the Option eight Advanced options hit, - enter and scroll down to ssh and hit Enter should be enabled by default. - But just check it and make sure and hit. - Enter. - It'll say ssh server enabled Had entered for Okay. - Once you've done that, - if you hit the right arrow key, - it will take you down to the bottom and highlight the select. - If you do one more right arrow, - it will take you to finish and hit. - Enter. - It's off screen here, - but that will bring you up to your first prompt. - What you want to do from this command line here, - the very first test you want to do is an Internet connectivity test. - I recommend just doing ping space google dot com, - and you can see that I'm getting responses, - which means my Internet is up and running. - Just that control. - See, - to cancel out of that. - Now that your raspberry pi has raz being installed and is connected to the Internet, - we're ready to move on. - One thing I like to do right after getting Raz being installed is to configure it for ssh. - I just want to clarify that this is not required for the class. - If you want to continue using the keyboard and monitor. - That's just fine. - Ssh stands for secure show and will allow us to log into our pie from another machine on - our network. - In my case for my desktop computer, - this allows me to get rid of the monitor and keyboard connected to the pie. - The way I like to do this is to have my router reserve a static i p address for my - raspberry pi based on its Mac address. - Is there so many possible network configurations and router types? - I won't cover how to do this, - but there are plenty of resource is online. - If you do a little searching on Google, - all we really need for ssh is the I. - P address of rpai. - If you're using Lennix, - you can simply open a terminal window in type ssh, - followed by a space and then the i P address on windows. - I like to use putty. - So for my desktop, - I will launch putty and you'll see that I need to fill in some information the port in - connection type default. - Ssh. - So all I need to enter is the I. - P. - Address of my pie, - which I've configured in my router to be 10.0 dot 0.17. - Once I've entered that, - I'll come down here and click open, - and it will launch a terminal window from here. - I will just log in with the default credentials that come with our Raz B and distribution. - The user name is pi P. - I in the password is raspberry all lower case, - and that will bring me to a terminal problem, - just as if I were right in front of the pie. - Just as a test, - I'll do an LS command, - which lists the directory contents, - and you can see that it works just fine. - I really like using ssh because it allows me to be on my desktop computer, - where I can easily look things up on the Internet while I'm working on my projects. - Another thing I like to do at this point is to install a USB WiFi adapter so I can unhook - my Ethernet cable again. - This is not something that I'll cover and is definitely not required for the class. - But if you intend to use WiFi, - I'd suggest that you set it up. - Now. - Make sure any WiFi adapter you purchase specifically list that it's compatible with the - raspberry Pi as many will not work with our pie booted up and razz being installed almost - ready to start working on our class project. - The last step of setting up our pie is making sure Raz being is up to date. - We do that with two commands pseudo after get update and sudo apt get upgrade. - The pseudo part of these commands is something we will use frequently throughout this class - . - Sudo is a program on Lennox that allows you to run commands his route. - If you're a Windows user, - think of it as allowing you to run commands with administrator privileges. - So in this case will run apt, - get update and after get upgrade with administrator privileges, - you will need Internet access for these two. - Run. - We'll do the update first, - followed by the upgrade. - These commands do take a while to run, - so it's a good time for another snack run with our pie updated. - We're ready to move on in the next unit. - I'll introduce you to the GP Io header on the raspberry pi 4. The GPIO Header: - in this unit were going to introduce you to the general purpose input output header on the - raspberry pi. - We'll talk about the capabilities it provides and cover a few do's and dont's having - followed the raspberry pi for a while now, - I've seen a lot of cool projects, - but many of them use the raspberry pi only is a very cheap Lennix machine, - things like print servers and file servers, - Minecraft, - consuls and beginning programming environments. - Those things are really cool. - Don't get me wrong. - But for me, - the real power of the raspberry pi comes when we start connecting hardware to it. - We do that through the GP Io header through the header. - We can achieve quite a bit because it gives us access to things like the S P I and I two c - protocol as well as general input and output. - Don't worry about what all that means right now, - because we're gonna cover all of it during this class. - What's important to know is that these things were we used to connect to the outside world - . - So instead of thinking of the SP I protocol, - we can think of a display and for general input and output. - We can connect things like motion sensors, - buttons, - switches. - And then when we talk about the eye to see protocol, - we can connect things like sensors and other components, - the concepts we're gonna cover in this class or general enough that you can use them to - connect almost anything to your raspberry pi. - So the first thing we need to do is locate the header. - Well, - it's pretty hard to miss, - as you can see whether you have a model A or model be raspberry pi the headers in the same - place. - It's just in the upper right hand corner if you're looking at it from this perspective, - so let's take a closer look. - To be able to correctly identify the pins, - we need to know how they're numbered. - We start by locating Pin One Now. - From this image, - it may seem like the P one label at the top left of the header is identifying Pin one, - but that's only a coincidence. - P one is just the name of this header. - As of the second revision of the Raspberry Pi board there, - six headers on the pie labeled P one through P six. - Now just to the right of that, - P one label was a little white box, - which is the actual indicator that this is indeed pin one. - The numbering then continues, - similar to how you would read a book left to right top to bottom with pin to here, - followed by pins three and four. - And then, - if you count all the way down, - you'll get to the bottom where there's pins 25 26. - So what do all of these pins do they provide us with? - All of the functionality will need to connect our pride external hardware. - We have power in the form of both 3.3 and five volts. - That's important to know that there's some limitations to how we can use power from the - header and we'll talk about those as we get further along. - For now, - I just know that we can only pull a limited amount of power from those pins and we have the - ground pins to complete the powers. - Then we have pins for the various protocols will be using as our project progresses, - things like S, - P, - I and I to see one aspect of the header. - We won't be covering this class is the you are. - As you can see, - the pins for that are located here. - Finally, - we have quite a few pens available for the basic digital input output. - Now, - unless you have a photographic memory, - there's no way you're going to remember what each of the pins is just by looking at the - header. - I mean, - I guess you could memorize them, - but I like to take an easier approach. - And there are a few ways to simplify working with the header and remembering what functions - the pins provide here. - Just a few. - The simplest and cheapest ways to just print out a pin diagram for your board revision. - There are different revisions of the header pin map, - and in just a minute we'll show you how to figure out what yours is in the middle. - Here is an ingenious concept called the raspberry leaf. - It was created by Simon Monk and is meant to be printed out and then installed on your pie - . - Just like this, - this is a really nice way to mark your header. - If you'll be using jumper wires to make your connections, - it takes a little bit of effort to create because you need to pre perforate the leaf before - sliding it onto the header, - but makes it so you don't have to constantly refer to a print out and count pins. - Finally, - there's the high end solution known as the pie cobbler from Ate a fruit. - You simply connect a ribbon cable to your header, - and the cobbler board has all of the pens marks. - This makes it really easy to connect to a bread board, - and it's what I'll be using for our project just to keep things clean. - Now, - if you don't want to spring for the pie cobbler, - don't worry about it. - Just haven't pronoun handy and use jumper wires. - And that worked just great. - So now that we know that there's different versions of the header, - we need to figure out what version we have on our pie, - and that's a really simple thing to do. - All we have to do is Buddha Bar pie to a command prompt. - Here we're gonna type in cat C A T space, - and then we'll do forward slash Prock ford slash CPU info. - Now, - if you're not familiar with Lennox operating system Cat is just a built in utility that - will allow us to display the contents of a file. - And in this case, - we're gonna display the contents of the CPU info file inside the Proctor folder. - So we hit. - Enter here. - It's gonna tell us a bunch of information and the one that we care about right now is this - revision down near the bottom 000 e. - In my case. - So what we do is we take that revision and we come over to this page here on the Lennix dot - org's. - And there's a hardware history table, - and what we'll do is just look up our revision number in this table, - As you can see for mine tells me that this model be already knew that. - But the important column is the PCB revision. - Here it's version two point. - Oh, - we can also get some other information like this. - Particular one was manufactured by Sony. - Now that's important because most sites that give you information about the pin out of the - header will have both versions available. - For instance, - we have this simple table here. - There's both versions, - and even the raspberry leaf has both versions that you can print out and install in your - pie. - Now that you've identified your vision and chosen a way to identify your pins. - Go ahead and set that up. - Now you go ahead and pause the video and do that. - Whether you're just printing out a sheet, - installing a raspberry leaf or using the pie cobbler, - now's a good time to set that up. - It's also a good time to get your bread board out, - because we're gonna be using that shortly. - If you are using the pie cobbler, - go ahead and hook it up. - Now, - if you plan to use jumper wires to follow along, - that's okay to just make sure bread board is nearby because we're gonna start filling it up - . - So here's what my set up looks like so far. - Before we go any farther, - I want to cover a few items regarding header safety, - otherwise known as how to not ruin your raspberry pi first. - If you plan to use jumper wires to make your connections, - do not use alligator clips. - It may look OK, - but they're likely to big and can cause a short. - The power and ground pins are right next to each other, - so if you inadvertently short them together, - you'll break your raspberry pi. - Instead, - I recommend using isolated jumper wires. - As you can see, - these create a much cleaner connection, - and there's no risk of shorting pins together. - Another way you can accidentally short pins together is by touching the header while the - pie is powered on as a general rule, - never touch or try to make any connections on the header. - While the raspberry pi has turned on. - Electrostatic discharge can also be a problem in touching the header, - even when the pie has turned off. - So be sure to ground yourself before touching anything or making connections. - So let's review never make connections, - while the pious powered on it only takes a minute to turn it off, - make the connections and booted back up. - It's not worth ruining a pie to save a minute, - even though there's a five vote pin on the header. - The peripheral pins on the pyre, - not five vote tolerant. - That means that if you connect a five volt source toe one of the input output pins, - you can ruin your pie. - If for some reason you need to interface with the system that delivers five bolts, - you'll need to use some sort of level shifting technique. - If you're going to use jumper wires, - use isolated female jumper wires to make connections to the header. - Or use a ribbon cable like you saw in my set up with pie cobbler. - Make sure you always verify which board revision you are working with to make sure your - connections air correct. - Chances are you have border vision to, - but it's best not to risk it, - especially since it's easy to figure out. - As we showed along that same note, - you probably heard the phrase measure twice. - Cut once. - When you're dealing with making connections, - verify the pin twice and connect once. - This is especially important when connecting jumper wires directly to the header. - Always double check the pin you're connecting. - Finally, - never, - ever touched the header while the unit is powered on. - That goes for other parts of the pie as well. - While it's on hands off and while it's off, - be sure to ground yourself before touching anything. - Well, - that's enough of theory and scary warnings. - Now it's time to start working on our project. - In the next unit will introduce you to the general input and output capabilities of the pie - and talk about how we will use them to start piecing together our class project as always. - If you need help or have questions, - the best place to go is on the Skill share website for this class under the community tab, - you can also reach him via email or find me on Twitter. 5. Setup Basic Input/Output: - welcome to Unit four of the class. - This unit will be covering the set up of the basic digital input output that a raspberry pi - header provides us. - So let's remind ourselves of a few things before we get started. - When dealing with the Iot header, - we need to remember that 3.3 volts is considered a digital one or the high state. - It actually needs to be greater than 1.3 bolts, - but we'll just say 3.3 bolts and ground or less than or equal 2.8 volts, - is considered a digital zero. - Our GP I opens can be configured to be an input or output, - but they can only do one job at a time. - It can't be an input and an output at the same time. - And finally, - we need to remember that while there is a five volt pin on the header, - the input out pins are only 3.3 vote tolerant. - So if we connect five votes to those, - we're gonna end up ruining our pie. - Now it's set up our pies that we can have access to this functionality, - the pipe on script. - Okay, - so we have our pie booted up here and we're ready to start working with the input and - output capabilities provided by the header. - Now, - as I stated in the introduction to the course, - we're gonna be using Python to do all of the code that we're going to need to write for our - monitoring device. - Raspberry by default, - comes with python installed, - and you can see that if you from your command line here just you python dash dash version. - You see, - the python 2.7 dot three is installed. - But for what we're gonna do, - we're gonna need a little bit more than just the basic python. - We're gonna need the developer tools and we're also gonna need something called the rpai - dot g p a library. - And so let's go ahead and install those. - We'll just do a pseudo after get install, - which is just if you're not familiar with Lennox, - that's just saying that this is a standard command. - To install new packages, - you will need to be connected to the Internet for this store. - That's what Do sudo Apt get install hi Thon Dev and we'll let that go ahead and install it - says it's gonna take up 42.2 megabytes of additional dicks space. - Is that okay? - Yes, - This might take a minute, - so we'll go ahead and skip ahead. - Okay, - Now that that's installed, - let's go ahead and install the, - uh, - raspberry pi GPO Python module will do that. - Very similar to how we did the python Dev modules do sudo after get install. - It's python Bashar pied a g p i o. - And when this model is going to do for us is that it's gonna make it really easy to access - the general purpose input output pins on the raspberry pi. - And as you can see, - the latest version of the Rpai GPO library is already included with the RAZ B and - distribution. - So if you remember from before when we needed to find out our border vision, - we did this we did cat slash Prock slash CPU info and we use this revision number to go - look up in a table. - What border vision we have. - Well, - now that we have the GPO library, - let's go ahead and launch a python environment. - We do need to use pseudo here because of the way that the GP I module access is the low - level hardware. - So you need to make sure you run. - This is ah, - administrator here and from the prompt here. - We're gonna go ahead and import our pied a g p i o as g p A. - That's just says that we're gonna import that module and we're gonna reference it as GP io - . - So go ahead and do that. - They will do GP ioo dot rpai underscore revision and you could see we get a to here, - which is correct. - We found out before from my specific raspberry pi that my board revision was too. - So this is another easy way you can tell after you've installed libraries to get your - border vision instead of having to look it up in a table. - This also tells us that everything looks like it's installed properly, - So we are ready to start trying to access the input and output and seeing what we could do - with it. - As always, - if you need help or have questions, - the best place to go is on the Skill share website For this class under the community tab, - you can also reach him via email or find me on Twitter 6. How to Hook up an LED (Step 1): - Now that we have our GP i o module working on our pie, - it's time to start connecting things to it. - Now, - a few of the things we're gonna cover involve electron ICS principles. - If you don't understand them, - try to look something's up online to get help. - If that doesn't work, - feel free to submit questions to the skill share class page. - I'd be happy to answer those there. - So when we talked about our header on rpai and the GP I opens, - we talked about how they could be configured as either an input or output. - We're gonna tackle the output side first. - So if you remember from our header section you have a pin here. - Multiple pins, - actually that connect to ground will destroy one of them. - And we also have a pin appear that connects to 3.3 volts. - And we'll draw our I open like this. - No. - So the first thing to understand is when you configure a pin to be an output, - what happens when we toggle? - It's setting in our python scripts, - so there's two ways to set this. - We can either set this to a one or two a zero high or low. - And when we set an output pin when a pince configure doesn't output to a one or high, - it's gonna try and drive it to 3.3 volts. - If we send it to a zero or connected low, - it's gonna connect it ground. - And so what we want to do first is we want to see how we can connect an led to turn the led - on and off. - That's sort of the hello World project in hardware. - So let's see. - How we might do this we're gonna do is if we could do this like this, - we could come out of our Iot pin come down. - We need to go through resistor now, - the resisters to limit the current to our led. - That's the symbol for it. - And this is the symbol for our led, - and we'll connect it back down to our ground pin here. - So what's gonna happen is when we drive this pin high, - we set it to 3.3 volts. - Current flows from a high potential to low potential, - so it will try and flow from 3.3 volts down through here into ground. - The resistor limits the amount of current. - But when that current flows to our led, - that's what's going to turn it on. - So that's one way to get our led to turn on. - Now we can also hook this up another way. - Strong other. - I open here. - This time we're gonna draw the line out of our 3.3 volts, - go through the resistor through our led and come down to our pin. - So remember, - there's two states to the pin, - 3.3 volts and zero volts. - Now, - if we set this high or to 3.3 volts, - no current is gonna flow from 3.3 volts to 3.3 boats so are led Will not turn on. - However, - if we set this toe low or connected to ground, - that's when the current will flow. - So it's the exact opposite. - In this case, - if we set our, - um, - are pinned to be high, - that turns the led on. - We set our pinned to be high in this case, - it turns it off. - Just something to remember when we're writing our scripts for it. - Um, - we can hook this up either way. - The way I prefer to do it is this way and I don't want to get too much into the details of - how the raspberry pi handles this, - but something to know when we hook it up this way, - the Penis said to source the current. - In other words, - when it turns to 3.3 volts, - it's trying to provide the current to flow to ground to turn the led on. - In this case, - the pin is sinking the current, - the current actually being supplied from the 3.3 supply on the pie down through the - resistor and into the output pin. - Um, - it's called sinking current. - Now the raspberry pi can Onley source so much current based on the drivers that air in it - when I mean when I say drivers, - I don't mean software drivers. - I'm talking about hardware drivers that drive the current, - um, - for how these input output pins work. - So you can hook this up either way for our purposes, - we're gonna be using this one. - We're gonna be setting it up so that the 3.3 supplies is driving the current through our - led. - And so we just need to remember that in our Python script later, - zero is going to be on one is gonna be off. - So now that we've seen how this looks on our white board and how we might draw this up, - let's move to our bread board and see how we might connect this up to get it working. 7. Intro to Fritzing and LED Hookup (Step 2-3): - all right. - Now that we've seen how our circuit will look on our white board, - it's time to put it on to our bread board. - And I just want to take a minute to show you a tool that I like to use when I'm planning - out circuits for different projects that I work on. - And it's called Fritz Ing. - The website, - for it is just fritz in dot org's and I'll put a link to it in the show notes here. - But this is what it looks like here. - And what we're gonna do is we're gonna download. - This will come to the download page and you can see that I am running windows. - But you can download it for Windows, - Mac or Lennox. - So I'm just gonna download the windows version of it here. - Well, - that's downloading. - What this is is a good way to visualize on a bread board your circuit before you actually - put the components on your bread board. - It's great for more complicated circuits to visualize how you're gonna connect things also - , - to see how you're doing on real estate on your bread board, - things like that, - we're gonna use it in our project to show the different phases. - As we connect things up, - I'll do these all inference sing, - and I will show you what they look like in that before we put him on the bread board. - Now that's finished. - I'll just pull this window over here. - That's just in a Zippo here. - Soldiers to extract all once that's extracted will just come into the folder here, - and we'll just double click on it to launch it and let me just go ahead and slide this over - here are screen resize it here. - Okay, - so it comes up to this nice welcome screen, - but we're gonna come right over here. - This is where we're gonna work most of our times in this bread board. - You and you could see this looks just like a real bread board. - This is one of the things I really like about spritzing is it has a very real life. - Look to it. - You just use the scroll wheel on your mouse to zoom in and zoom out, - and then all you do is you grab parts over here, - there's different libraries and you can download additional libraries and you just drag him - over onto your bread board, - example resistor. - And down here you can change the values. - You know, - just the color bands. - Just how it would look in a real resistor. - You can add things like switches that will get into later and and buttons things like that - now fit in there. - They're all the right size. - And when you want to connect things up, - you can just come down here. - There is a wire part, - and we can just, - ah, - click from here. - So we have to drag them on here. - Tatchell wire. - From here to here, - you can even use the control A control click that will kind of give you this curve. - Look to the wire seeking bend, - Um, - and kind of make it, - you know, - look a little more rial, - which is nice. - The other thing it has Ah, - that will be doing next. - Things like this weaken dragon led on and connect that up will show you how to do that in a - minute. - And even if you come to the microcontrollers, - I believe is the name of section here we can even drag on a raspberry pi the mountain You - could see you could move things around. - You can If you get down in the corner here, - you can You can rotate him and moving like that. - Anyway, - I just want to give you a brief introduction. - This is a tool that will be using you don't have to. - I just like it. - Like I said to plan my layouts on my bread board, - see what space is gonna be taken up and how I want a route wires and things like that. - So just something to be aware of. - I'll be showing you the fritz seeing images as we go along as we connect different parts - and it's a great tool. - If you want to download it and play with it, - check it out. - Okay, - so here is what are led circuit? - Looks like when we hooked it up to our bread board. - Inference sing. - This is just like we drew it up on the white board. - We come out of the 3.3 volts header pin through a resistor. - In this case, - it's 330 OEMs into our led and then are led. - Connects back to an input output pin. - In our case, - it's gonna be pinned 12. - Now, - in this diagram, - it's labeled 18. - That is the BCM reference number, - and we're gonna talk about it a little bit. - The difference between the board pin number, - which is this, - is literally pin 12 if you remember how he counted it in Unit three. - But it's also referred to has been 18 to the broad common chip. - We'll talk about that a little bit later, - but for now, - this is how we have it set up. - A couple things to note. - If you are not familiar with how bread boards work, - it's really easy along the top and bottom. - The pins connect horizontally. - If we're looking at it like this and then in the middle, - the pens connect vertically. - They do not cross the middle of the bread board. - So the pens on this side on the top side here are not connected to the pins on the bottom - side, - and the other thing to remember is your led has to be hooked up the right way. - You can hook it up backwards, - which will burn it out, - so make sure you're paying close attention to how you hook that up. - So this is how I intend to lay it out on our actual bread board. - Let's see what that would look like. - And that's what it looks like when I have hooked it up to my actual bread board. - Now, - for those that aren't using the pie cobbler, - that's okay. - I have the Fritzi image here, - uh, - connecting it straight to the raspberry pi. - You're also welcome to do that. - It will work just fine. 8. Use Python to Control an LED (Step 4-5): - with our led connected to our bread board. - We're ready to test it To do that, - we're gonna come back to our terminal here and we're going to launch a python show. - We're going to do that with pseudo python. - We need the pseudo because of how a library works. - The rpai g p a library works. - And so we're going to import that library just like we did in the last section. - Import rpai dot gp io as g p i. - O. - And then the very first thing that we're gonna need to do when we're using this library is - we need to set the mode. - When that does, - is sets the mode of how we're going to reference the pins through other various functions - that will use and their two options. - There's GP ioo dot board and GP ioo dot bcm board means we're going to refer to the pins by - their physical number. - When looking at the header, - we went over that, - um, - in section three, - where we talked about the GPO header how the pins are numbered. - The BCM mode means that we're gonna need to refer to the pin numbers based on how they're - numbered. - on the Broadcom chip that the raspberry pi runs on. - And so you can do this either way. - However, - if we use the board were guaranteed, - that are python code will work between revisions because the library is smart enough to - know what revision were using. - So I'm gonna recommend that we use the board mode. - Okay, - Now that we have that set, - we need to set up our pin whether as an input or is an output. - In the case of the led, - we're gonna set it up as an output. - So for that, - all we have to do is GPO dot set up reference the pin number. - We're connecting to pin 12. - If you remember from our bread board, - and we're going to set this to gp ioo dot out that sets it up is an output. - Soon as we hit, - enter on this, - you'll notice that the led will turn on. - That's because the default state of the output zero if you remember from when we drew this - up on our white board, - when we set the output pin to zero, - that's what's going to turn out. - Led on. - That's what happens here. - So to turn it off. - You remember. - All we have to do is set it high. - So we do that by saying, - gp ioo dot output Reference the pin number again, - and one when we hit Enter here, - you'll see that it turns off and we could just play around with this. - We can turn the led, - um, - back on. - We can turn it back off. - That's all there is to it. - We have successfully connected in led. - Now, - when we're done using this library before we exit, - you want to do a GP Io dock cleanup that just cleans up how the pins were set up. - If we don't do this next time we try to run a script, - it's gonna tell us that the pain is already configured and give us a warning. - It's not a huge deal, - but it's just a good idea to clean up when we're done, - and that's it. - We've got our led working. - Now that we've talked about how toe configure pin is an output, - let's move on to the input functionality in connecting are switching button as always, - if you need help or have questions, - the best place to go is on the Skill share website For this class under the community tab, - you can also reach him via email or find me on Twitter 9. Safety Reminder: - before we go connecting things, - start bread board. - There's just a couple of things I want to mention the first I already mentioned in the - header unit, - and that's whenever you're making connections to your raspberry pi. - Always unplug it. - Some of them you can make safely, - but it's best not to risk it. - Just unplug it. - It takes two seconds. - Make your connections. - The pie boots up very quickly. - It's not worth risking burning out your pie. - The second thing along the same lines is depending on where you live. - You might build up a lot of static electricity when you're moving around. - Right now, - we're just putting things on a bread board that are out in the open. - You can touch resistor legs and other things, - so you need to be careful when you're getting in there and pushing the button and moving - the switch. - And before you do that, - it's best to discharge the static electricity that builds up on you. - Touch something that's grounded to get that spark out of you. - That way we won't ruin anything. - This stuff is really pretty safe. - People get scared that don't know Ah lot about electricity. - They think I'm an electrocute myself. - I'm gonna burn my house down. - We're dealing with low voltages and low currents. - I'm not saying don't be safe. - I'm just saying Don't worry too much. - You might get a shock. - You might burn out your pyre, - your components. - That's really probably all that will happen. - So I want you to have fun, - but be safe when you're doing it. 10. Theory and Switch Hookup (Steps 1-2): - All right, - so now we've covered how to hook up and input output pin to be an output to driving led. - Now let's talk about how we can configure it to be an input to read this state of things - like switches and buttons. - So when a penance configured as an output, - it's actually driving the state. - It's saying be 3.3 bolts or be tied to ground when it's configured as an input pin. - It's going to read this state of the pin and decide. - Are you closer to 3.3 bolts? - Are you closer to zero volts now? - It's not so simple. - Listing which one's closer. - There's certain limits that determine what's high and what's low. - But that's the general idea. - And so we want took a circuit up to this so that when we, - uh, - flip a switch, - it'll give us one state. - And when we put the switch back in its original position, - it will give us another state. - So let's see how that how we might do that. - So we're gonna come off of the 3.3 vote pin up here. - We're gonna come down, - and we're gonna just leave this open and we'll pretend that this is our switch like this. - Come down and well connected ground. - And so this point, - the switches open, - and then we're gonna put our Iot pin out there. - Now, - this might look fine to start with. - So in this state that we have here, - if we sample this pin, - it's going to read ground, - cause this is open up here. - If we close this switch, - it's going to connect us up to 3.3 volts. - That might seem like an easy way to get a different state when the switch is in one - position, - as opposed to the other position. - However, - this would be a terrible idea because as soon as we flip this switch, - we're gonna connect are 3.3 volts to ground, - and that's when you kill your pie. - So how can we make this circuit a little better? - Well, - we can't have a short circuit. - So what we can dio is we can just put a resistor in here. - So now when we flip our switch, - the 3.3 volts isn't gonna be tied straight to ground. - It's gonna go through resistor first, - which will prevent that short circuit situation and so will read still ground when the - switches disconnected, - even though the resisters there that'll still read ground. - And then when we flip our switch, - it's gonna read 3.3 volts. - So this is pretty good. - We could connect this up and this would work just fine. - However, - there is one thing that we might want to consider. - What if we accidentally configure this pin to be an output? - Well, - in that case, - it's gonna try again to drive the state to 3.3 volts or ground. - Now, - if it's set to 3.3 volts and the switches closed, - nothing's gonna happen. - No currents gonna flow from 3.3 volts to 3.3 bolts. - But what happens if it's configured as an output and we try to drive it to ground? - So we set it to a zero. - If we do that and we flipped the switch, - we're back to the state where 3.3 volts is gonna connect straight through the ground and - we're gonna have a short circuit. - So now we could just be really careful and not miss configure our pin, - but nobody's perfect. - And we might make a mistake and so we can prevent a problem here by again using a resistor - so we'll have a resistor here. - Now again. - When the switch is open, - we're still going to read ground. - And when we close the switch, - we're still going to read. - 3.3 volts will have to choose the values of these so we don't drop. - Um, - too much voltage here. - But this will work just fine to read the two different states 3.3 volts when the switch is - closed and ground when the switch is open. - Now that's all there is to it. - So that's how we would do a switch. - Now let's take just a second to talk about a button. - Well, - turns out are we have to do is take out that symbol and replace it with our symbol for a - button. - We'll use that as our button because really, - a button is nothing more than a momentary switch. - When you press it, - it closes the circuit. - When you let go, - it opens the circuit back up. - Just how when you flip a switch, - it closes a circuit. - When you flip it back the other way, - it opens it back up so there's really nothing we need to do differently for a button than - we already did for a switch. - So we'll actually use the exact same layout for our button that we're gonna install that - we're going to use for our switch. - Let's take a look at how I've mocked this up in print. - Sing Now. - I changed a few things since the last view of just the led being connected. - You'll notice that I've taken the 3.3 bolt and ground connections off of the cobbler and - attached him up across the top. - And if you remember from the previous explanation, - the pins on the top of the bread board connect horizontally. - So by connecting the black and green wires here, - I get 3.3 bolts in ground all the way across and Aiken Branch off of those wherever I need - now, - a convention that I'll be using here, - and it helps me to stay organized and keep my connections right is that I'll use green - wires to represent ground, - and I use black wires to represent 3.3 bolts. - For me, - it's easy to remember Green and ground both start with G, - and it just helps me keep myself organized. - So now let's take a look at this switch connection here. - Well, - the very first thing that we need to know is, - how do we connect our switch? - It's got three pins on it, - but what did those pins mean? - And a common theme that you'll see as we go through this is that the data sheet will tell - you everything that you need to know when working with things from switches and buttons all - the way up to our display in temperature sensor. - So let's take a look at a section of the data sheet for the switch. - We can see that the switches three pins labeled 12 and three with to being in the middle - that if we look here on the left, - we can see the little circuit drawing, - which shows that, - too, - is the common in connects toe one in three, - depending on which position the switches in. - So if we switch the pin to the left when looking at it at this view, - it connects pins one in two. - If we switch it to the right, - it'll connect pins two and three. - Now we only need two of the pens, - so we'll leave Pin three unused for now. - So with the switch in the position to the right pins, - one and two will be disconnected. - And when we switch it left pins, - one and two will be connected, - and that's all we'll need to hook it up to our input pin. - So if we look at this connection, - we can see that we have 3.3 bolts coming down to pin one and then pin, - too. - If you remember, - we talked about having to protections one to protect the input output pin if we - accidentally configured it as an output and to prevent the short circuit to ground. - Now the values that we chose for these resistors Air one K in 10-K see the show notes for a - link that has a good explanation of how to hook switches up toward input output pins and a - deeper explanation of how he came up with those resistor values. - Another conventional use here is yellow wires to indicate a connection to an input or - output pin. - In this case, - we've connected our switch to pin 16 so we'll need to remember that when we start writing - our scripts now that we've mocked this up. - Inference sing. - Let's see what it looks like when we actually hook it up on our bread board. - Here's what mine looks like before starting the next video, - go ahead and take a minute to hook yours up a swell so you can follow along in the next - lesson again. - If you're not using the pie cobbler, - here's what it would look like if you're connecting it straight to your pie. 11. Switch Integration (Steps 3-5): - with our switch hooked up to our bread board, - we're ready to start testing it. - So we'll launch a python shell just like we've done before using pseudo, - and we'll follow the same pattern like we did when we set up our pin is an output we need - to import the rpai that GPO library. - And remember, - the very first thing that we need to do is a set mode, - and we'll continue to use the GPO dot board mode. - And this time, - when we do our set up, - we're gonna choose pin 16 because that's what we've connected to honor Header. - And instead of doing gp ioo dot out, - we're gonna do GPO dot in because we're configuring this pin to be an input. - And all we need to do to test this state of Arpin is G p i o dot input and pass the pin - number again. - 16 and you see here we have zero, - and that's because our switches in the right position so pins one and two on our switch or - not connected. - Now, - if we come over and move our switch to the left and try it again, - you'll see that we get a one this time and we could just test that again. - I still get a one. - Let's go ahead and switch it back and we get a zero again. - So this is working perfect, - just as we expected. - When the switch is in one position, - we get a zero. - When we flip it, - we get a one. - So far in the class, - we've been doing all of our python testing from the show. - I think it's a good time now to move into a file so we can start running this and not have - to re type in everything every time. - So to do that, - let's just from our command line here. - Let's make a directory using the Make dir command. - I'll just call mine skill share again. - We'll be using the Nano program to edit our file, - and I'll just call it monitor dot pie. - So in here we're gonna do the same thing that we did from the show. - We're gonna import rpai dot GPO as g p I. - O. - And then, - of course, - we have to set our mode, - which is board that we've been using, - And so to test our move to a file, - let's just do something with our led. - So I'm gonna put a comment in here to set up the only deep in. - And if you remember, - just like we did in the show, - we'll do gpu dot set up 12 is what are led is connected to and will do. - GP ioo dot out Now, - if you remember before when we did this set up the default state is zero, - which in our case, - turns are led on. - But what if we don't want the led to turn on when we configure our pin? - Well, - there's a nice little argument that we can add on to the end here called Initial, - and if we say initial equals g p i o dot high. - When it sets up the pin, - it will make the initial state high, - which in our case, - will turn the led off. - Then we'll just do a simple test. - Here will do GP ioo dot output 12 and then set the pin low, - which will turn are led on. - And then we'll just wait for a second and try to turn the led back on just a simple flash - test to make sure that our script is working as we expect and so toe weight that second, - we're going to need to import another python module. - So we'll come up here and we'll do from time import sleep. - And all that does is gives us access to this sleep function in the time module so that we - can call it here right after we turn our led on. - So just to asleep one which will hold us up for one second, - and I will do GPO dot output 12 and said it to gp ioo dot high, - which will turn are led back off. - And of course, - when we're done, - we want to do the cleanup like we talked about not exit out of Nano. - All you want to do is hit control X, - and it'll ask you save modified buffer. - And if you say yes to this since we already gave it a name, - it will follow up with the question file name to write monitored up I If you just hit enter - here, - it will save our file. - And if we do a directory listing, - you'll see. - Now we have this monitor dot pie file. - I forgot to change directories into the Skill share directory before I created this. - So let's go ahead and do a move monitor dot pi into the skill share boulder, - and you'll see that it's missing now. - So let's CD into the skill shareholder, - and you can see our files right there. - Justus we needed to use pseudo to launch. - The Python show will also need to use pseudo when we run our scripts. - So to run that monitored up I fall that we created. - We'll just do pseudo python and then give it the file name monitor dot pie and we'll go - ahead and hit. - Enter here and perfect There's are led. - It gave us one flash. - That's all it was supposed to do. - So we've successfully created the base for our script that we're gonna right. - So all the code that we write in the future now other than doing maybe quick tests will be - in this monitored up I and we'll just build this file up until we get all the functionality - that we're looking for. - Now that we've shown that we can write our code in our Python file, - we don't want it to flash our led. - That's not the functionality that we're looking for. - So let's write something a little bit more meaningful, - so we'll go back into our file here. - Well, - just come down here and follow the same pattern that we did with the led. - Penn will put in a little comment that we're setting up the switch pin well. - The gp ioo dot set up. - Remember, - it's been 16 this time is what are switches connected to. - We're configuring it as an input. - So the gp ioo dot in and let's go ahead and get rid of this code that we wrote to flash the - led Ah, - quick tip in Nano is if you get on a line that you want to delete the entire line. - If you just hit control K, - that will cut our entire line out. - So we'll just do that. - Get rid of those lines. - One thing that I found very handy when working with the raspberry pi in Python scripts is - to wrap on my code in a try except block. - Basically, - what that does is everything you put under the try. - It will run normally, - and then when it reaches an exception, - it will go into your except handling. - And the reason I do this is because when we run these from this show, - they will just run forever. - And the way you cancel those is by hitting control, - See which exits out and brings you back to the shell. - Prompt. - Well, - when you do that, - it could be anywhere within your main try block. - And so we want to make sure that things get cleaned up. - Remember, - we need to call that gp ioo dot cleanup. - So the handle that I do in except keyboard interrupt what that'll do is it'll hit that - except block when we do control. - See? - So let's come in here to our try. - And what we want this to do is just run forever. - Like I said, - until we hit control c So we'll just wrap everything in a wild, - true loop and we'll just test our switch. - So we'll say if GPO dot input 16 is high, - so they have flipped the switch to the left. - Then we want to go ahead and do GPO dot output 12 is our led will set it too low, - so we'll turn it on. - So what we're gonna do is we're going to set this up so that when we flip our switch are - led turns on. - And then when we flip it back to the right, - the led will turn off. - So this will come in here and sample if it's high turn are led off and we'll do else. - So the switches in the low reading or to the right We just want to do GPO dot output 12 and - then said it high, - which turns it off. - And then down here in the except Block, - is where we want to do the cleanup. - So put that here. - Then we'll clean up our line down there and then finally will just want to exit gracefully - . - So we'll do assist dot exit and given a code of one now to be able to use this system exit - , - we need to go ahead and import the module for that. - So we'll come back up to the top here. - We're just doing import cysts that way it won't throw an error when the script runs. - All right, - that's it. - Let's just give this a quick look. - And you see that I have a typo there. - I didn't put the tea on inter evidence where I like to give Dakota quick once overlooked - before I close it and save it. - So let's fix that and we will save an exit. - Okay, - let's run this again using pseudo, - and we'll come over here and flip our switch and you can see it turns are led on Perfect. - Just like we wanted. - Now that switches working as we want it to, - Let's move on and see how we're gonna hook up our button. 12. Button Integration (Steps 6-7): - remembering back to the first video in this unit, - we explain how a button is nothing more than a momentary switch. - So this is how I have it constructed, - influencing. - Now It may look different because I have the resisters oriented a little differently, - but if you look at the connections, - it's all the same. - In the case of our switch, - our 10-K resistor goes through the green wire up to ground, - where, - in the case of our button, - I've just attached it straight to ground without using the wire. - And then are 3.3. - Bolt connection comes down to the other side of the button, - and the one K resistor goes out to the GPO wire, - which is again yellow. - You'll notice that my button straddles the middle of the bread board. - Oftentimes you'll do this if it would be a problem to connect pins in the same row - vertically. - In our case, - our button doesn't have that problem. - I just felt like installing it this way for real estate purposes, - and the reason I know that it's not a problem is by looking at the data sheet again. - If you look at the dimensional drawing here in the lower right hand corner. - We have the terminal arrangement. - We can see that pins that share a side of the button aren't connected to each other. - In fact, - the connection goes from pins 2 to 4 and 123 Now you could arrange this anyway so you could - set it up. - So pin one and pin four connected when you push the switch or pins two and three. - But it's important to note that pins one and two are connected together and pins three and - four connected together again. - This is where the data sheet is so critical it shows the internal connections. - The only other way that you'd be able to figure this out would be to hook up a meter and - keep pressing the button to try and figure out which pins were connected when the button - was pushed in when it wasn't pushed. - This is how we haven't laid out. - Let's see what it looks like in my set up. - And for those not using the pie cobbler, - this is what we have so far. - So go ahead and take a minute and hook your button up so that we can test it. - Okay, - So now that we have our button installed, - let's go ahead and write some code to test it. - So it's open apart, - monitor Paul again and we'll do just the same thing that we've done before. - We'll go ahead and we will put comment in here about setting up the button pin. - And we'll set that up just a lot like the switch been if your call from when we talked - about the theory on this ah button is nothing more than a momentary switch. - So we'll set it up as an input. - And now all we need to dio is we're not going to interact with the led A to this point with - our button. - What we're gonna dio is going to come down here in our loop this while that just - continuously runs and we're gonna do some logic around the buttons, - so we'll see if gp iota input 18. - I remember that's the pin number that are Button is connected to the pool's. - Did she pay a high? - And for now, - we're just going to print something to the screen just like that. - So now we've set up our button isn't input. - We've We're gonna check in on while loop. - And if we press it, - we're just gonna print something out to the console to make sure that are set up is working - correctly. - So let's go ahead and give this shop. - We're gonna go ahead and exit. - We want to save our changes. - Okay, - so let's go ahead and run this pseudo python monitoring up. - I I should just be running there and then let's come over here and touch her button and see - what happens. - Okay? - We got a ton of pronounce here of you pressed me. - So what is going on? - Let's go ahead and cancel this hour. - It's obviously isn't working the way that we wanted to. - Let's go back in to our file here. - Now, - this while live this while true, - right down here is gonna be executing so fast, - and it's gonna be testing that input so fast that just the little bit of time that you have - that held down the button how down? - Even though it's a fraction of a second, - that logic is being executed. - Testing If it's high and it is high for those, - you know, - whatever. - 102 100 milliseconds. - And so it's gonna print that just as many times as it can in that amount of time. - So an easy way we can fix this the simplest way this just come down here and will say sleep - for a second. - So after you've printed out the message, - just hang out for a second before you do anything else, - and that gives us enough time to release the button and see if that changes things. - Let's go ahead with that. - CLECs it out will save. - And now let's go ahead and run this. - All right, - let's come back over to our set up here and push a button and see what happens. - Okay, - pressed it a couple times there and we only got one print out, - so that's working pretty good. - It's good and close this again. - So now what might be an issue with this? - We come back in here if you notice when this sleep executes here. - It's holding up our entire program, - so it's not checking this switch. - That's not doing anything else. - It is literally just staying right there until the one second is up, - and then the program will continue to execute. - Now there are ways to get around this the GP I O module has some things for event detection - , - and I played around with this quite a bit, - where you can create callback functions where the hardware will detect a change and call a - function that you write any time there's a rising edge, - which is what we're doing. - When we press the button that we're going from zero volts to 3.3 volts, - it will detect that rising edge and call your function. - However, - when I was missing around with that, - it was very sensitive to static electricity, - to the point where if I moved around in my chair, - it would set off interrupts, - as in it noticed that there was a change on the pin. - Now we can eliminate that. - We could do some things to D bounce our switch, - and we could shield the pie to make sure it's not picking up anything like that. - But it was really interesting to see how sensitive that was when we set up the edge, - detect. - So to keep things simple for now, - this sleep, - even though it is holding up our program some it's not really gonna hurt us in this - application, - so we're not gonna get much more complicated in this. - I'll put a link down below, - too. - Some of the resource is on the event detection, - so you can look at that If you'd like Teoh, - it is an option. - But for now, - we're just gonna keep it simple and just use this sleep. - We've covered a ton during this unit. - We have are switching our button connected and working and integrated into our python - script. - And that's great. - If you've made it this far, - you're doing an awesome job. - Now we're gonna get into the two communication protocols SP I and I two c But before we do - that, - we need to take care of a little bit of sauntering and that's up next in unit seven. - As always, - if you need help or have questions, - the best place to go is on the skill share website For this class under the community tab, - you can also reach him via email or find me on Twitter 13. Soldering Headers: - before we move on to talk about SP I and I, - two c, - we need to get our boards ready to attach to our bread board. - As you can see here, - we've got the display on the left and temperature sensor on the right. - Now these air on what are called breakout boards, - which means the pins are broken out to these little holes that you can see. - But there's no way for us to connect it to our bread board. - So we need to fix that by sauntering on some headers or wires. - Now, - the best way to do this is to take some header pins like you see here and use a pair of - pliers to break them down into the sizes that will need on the display. - Will need one of seven to cover the ground pin to the select been and then, - as you can see on the temperature sensor, - we're just gonna need four on the top two on the bottom. - So this is what they look like broken out. - This is what the header would look like if we held it in place on the display module. - Now, - one of the tricks that I used to make this easy to sauder. - Is it? - Just use a bread board as a jig. - And so we'll put our header in with the long portion actually installed in the board. - So the short ends air sticking up in such a way that we can layer module on top. - And it's just easy to Sauder. - So this is what it would look like for the display. - Now, - the two pin header you see here is just to keep our board level during sauntering. - We're not actually gonna sort of that. - In fact, - that would be a disaster because, - as you can see on the board here, - that's the negative and the positive. - So we would essentially be shorting it together when we tried to power it up. - And this is what the full jig looks like with the display and the temperature sensor - headers plugged in. - So we're gonna do is set our modules or a breakout boards on top of those header pins like - you can see here to get ready for soldering. - I wanted to make a video to show you how to sauder this. - Unfortunately, - my camera wasn't good enough to get a real tight shot. - There's lots of tutorials on the Internet for how to Sauder. - And this is probably one of the simplest things to Sauder. - So don't worry about this. - You can do this, - not a problem. - So here's a close up of our temperature sensor sitting on the jig. - So what we're gonna do when we saw her, - as you can see in this picture, - is you want to have your sauder on one side and your iron, - your hot iron on the other, - and what you'll do is you'll touch the iron to the pin and the pad on the breakout board - and then bring the sauder in from the opposite side. - So this is a pin after I've sorted it, - and here's the entire temperature sensor sauntered, - and we're just gonna repeat and do the same thing on the display. - This is what it will look like when it's done. - So now we've got our to breakout boards, - Stoddard, - and we're ready to install them on her bread board for a project again. - Don't let the sauntering freak you out, - even if you've never saw her before. - This is something that you can handle, - I promise. - If you don't have hitters. - That's all right, - too. - You can use just why you could just saw her wires directly in here. - It's a little harder because you have to hold the wire and, - um, - started at the same time, - but not impossible. - In fact, - here's a module that I've used before where I've done just that. - I didn't have headers, - and so I used regular wires that I had stripped. - I said, - It's a little hard to do but doable. - If you don't have headers, - I recommend headers. - If you can get a hold of some. - All right, - that's it. - Now that our boards air sodded, - we're ready to move on to the next unit. 14. Intro to SPI (Step 1): - Okay, - so the first protocol that we're gonna cover when connecting to our pie is the S P I - protocol. - Now, - with any communication protocol, - the goal is to connect two things together. - So in our case, - we've got a raspberry pi. - We want to connect that to our display an SP isa protocol that we can use to do that. - So when we're connecting anything together, - the first thing we need to take care of is the power. - Now, - the pie, - if you remember, - has 3.3 volts and five volts, - and it also has a ground. - Now it's important to remember when you're working with S P I or any protocol for that - matter where you're connecting to devices together, - that you're consistent with your power. - So you don't want to be sending five volts down to a device that can only handle 3.3 bolts - . - That's how you're gonna start breaking Things now are display is able to handle 3.3 volts. - So we're okay to share the power from the pie to power. - Now we do have to worry about doesn't have enough power, - cannot supply enough current, - and we'll look at that a little bit later, - but for right now, - let's just assume we can share it so we'll connect the power there in the ground here. - Now, - even if you have a scenario where the display is gonna have its own power, - you have to connect the grounds together. - That way, - when the lines are talking the signal wines, - they are referencing the same thing as ground. - Because if this has a different idea of what ground is than this, - when you start sending data across it, - it could get very confusing. - The data is gonna get jumbled. - It probably isn't gonna work out really well for you, - so make sure you connect the grounds. - So the next thing we need is how do they communicate together? - Well, - an SP I It's known as the three wire or four wire protocol, - and that's because it uses generally three or four lines and we'll draw each of those here - . - Now, - an important concept in S P. - I is an idea of master and slave that always has to be a master device, - which in this case is gonna be a raspberry pi and a slave device. - All communication in this protocol is driven by the master. - And just as a side note, - the raspberry pi actually can't be a slave. - So you couldn't hook to raspberry PiS together. - One is a master and was a slave because the only mode this can operate in is a master role - in the SP I protocol. - It's our first line is what's called Master Out slave in and this is always referenced from - the perspective of the master. - So on the display, - it's also gonna be called Mos Side because it's still master out Slavin because the display - is the sleeve. - And that's where data goes from our master towards our slave. - The next one is master in slave out, - which, - as you can guess, - it's just data coming back this way. - No, - the state is sent only when a clock is running. - A clock is what keeps the two devices in sync to make sure that they're sampling and - reading the data at the same time. - So that's the next line. - This is our clock line, - and it's gonna look something like this. - And remember, - this is always driven by the masters so the master will supply this clock, - so the display knows what speed to run out, - and then the final line is what's called Chip Select. - Now you'll see this sometimes with a bar over it like this. - That just means that it's active low. - Typically, - we think of Ah zero as being zero bolter ground and then hire one being 3.3 volts or five - volts, - or what's known as the supply voltage. - In this case, - the chip select is the exact opposite. - When it's pulled low or its pulled the ground, - that means it's enabled or it's turned on. - So these are the four lines that we need to communicate with now. - One of the unique parts about S P I is that data is transferred at the same time, - meaning as the master is sending data down to the slave. - The slave is always sending data back Now, - it may not be actually putting data on this line, - but the masters going to read it. - So on every clock edge that the master is sending data down this line. - It's also sampling this line to see if data is coming back. - So SP is not really a good protocol to send a bunch of data and then wait for a slave to - process it and then the slave decide to send it back because, - remember, - it's always driven by the master. - So to get data back from the display, - the pie has to be sending data. - And so the way this will happen sometimes is if the master needs to read from the slave. - It'll just send dummy data down. - That's the same length is the data that it needs to read back. - So one of the cons of this is it's a little tricky sometimes to get communication going - both ways. - It's really meant to be driven by the master. - Now, - one of the pros of this is that we can share these lines so you can see we have the display - here. - We could also have another module, - maybe something like a sensor down here that can share all of these lines. - So it's gonna take the master out slave in the master and slave out in the clock all shared - with these lines here. - So when you hook it up on a bread board, - they can all share those three lines, - and then it's gonna have its own chip select right here. - That can come up and connect to the pie and so it can share these three lines just with the - display and only needs one additional line. - So for each additional device, - you only need one additional pin on your raspberry pi. - So it's important to remember one of the great things about SP I is. - It's a standard meaning as long as the display or the sensor or whatever other module you - want to connect is SP I compliant, - meaning it knows how toe work on this protocol, - you can connect it in the exact same way that we've connected display in the center here. - You don't have to figure out or right special code to create a communication protocol. - It's just that is it s p I is the standard and they know how to talk to each other Now that - we understand how to connect to devices that are going to communicate with S P I. - Let's talk about the different modes. - You hear people talk about SPE mode zero or one, - there's actually four mode 012 and three. - Let's talk about what that means. - So I remember when I said that the data is driven by oclock line in a clock line is gonna - look something like this when it's transmitting data. - And if we think of this is zero bolts and this is 3.3 volts. - In our case with the pie, - this is what's known as clock polarity zero or C pole zero. - Now, - just like the Chip select line can be active low, - the clock can be active low as well, - so it might also look like this going from 3.3 volts down to zero. - So again, - this is 3.3 volts. - This is zero. - This is what's known as clock polarity one. - So those are the two different ways that you can drive the clock line. - Now data is going to be put on that master out and master in line during certain windows of - time while this clock line is running. - And so if we think about this, - if we think of the windows where the data can come in where maybe it's zero here or this is - a one and this is a one. - What's known as the clock phase determines when the master and slave or going to sample the - data lines to determine whether it's a one or a zero and so we can either sample on the - leading clock issue of the clock starts here on the left. - If we sample on the leading edge, - this is known as clock phase or C p h Not C p A c p h a of zero and so you'll see the data - will be sent in such a way that whether the clock is active, - higher, - active, - low, - the phase of the data is gonna sample so that it's sampled right in the middle of the data - on the leading edge. - Now, - clock phase one is the exact opposite. - It's gonna sample on this falling edge. - So if he's sample right here, - you can see that's gonna sample right in between the windows. - But on clock phase one, - the windows are actually gonna shift the phase of its gonna shift. - So look, - just something like this. - Where again, - this is a zero. - This is a one. - And if we did one more, - this would be a one that would be clock phase one. - So we've got CPJ zero cph a one. - Now The combination of these two things are what determine the mode and so if we look at it - clock polarity, - Clark fees and then mode. - This is a simple table. - We've got four options you've got 0001 10 and 11 of these Corp respond to the different - modes. - So if clock polarity is zero again like this and the phases zero So the data looks like - this. - That's mode zero. - Now we just got on the table, - would one to and three Now, - by default, - the pie operates in mode zero, - and so does our display, - so we're not gonna need to do anything special. - But it's good to know, - because you may have a slave device that says I use mode to and so you need to calibrate - the master so that it speaks that same language as it were so that the clock is in sync in - the day doesn't sink. - If all of this still seems a little confusing, - don't worry about it. - For now, - we're gonna connect things up. - You'll see how it works. - There's lots of resource is online that you can learn more about this. - You don't have to have a deep understanding of the different modes of SP I when the - polarity and the phase are to be able to connect devices and talk over this protocol. - I just wanted to give you a heads up so you could have a general idea of what we're talking - about when we refer to things like SP I mode zero or clock polarity and things like that. - So now that we've talked about the theory, - let's get in there and hook something's up. 15. Enable and Test SPI Protocol (Steps 2-6): - So now that we've talked about the theory of SP, - I let's get it working on our pie. - So we're gonna come to L A next out organ and there's a page dedicated to SP I on the by. - It's got a lot of different information here. - We're not gonna cover it. - All right? - Now, - we're gonna come down to this link for the loop back test because what we want to do is see - if RSP I module is working. - It says this could be used to test SP. - I send and receive. - Put a wire between Master Out Slavin and Master and slave out. - Okay, - so we're gonna come over to our set up here, - and you can see this blue wire just right here is connecting our master out slaving in our - master and slave out on our pie cobbler There. - So we have that connected just like it says in the directions in the next part. - Says we need to download a file here. - So I've got my terminal here where I'm ssh into my raspberry pi and were literally just - going to copy exactly what they've written there before. - We do that, - though, - I want to make a little directory here that we can work out of. - So we'll do. - Make sure S p I Then we'll CD into that and we'll just do this command. - Now, - don't worry about what w get is. - It's just a utility that's gonna allow us to download a file in this case, - the SP I Dev underscore test dot c file. - So let's just go ahead and do that. - Okay, - So that's gonna download if we just do an ls will see that it's there. - The next part of this is a GCC line. - Now, - if you don't know much about compiling files, - that's okay, - that's all we're gonna do here. - We need to compile this source file. - So we're going to GCC desh Oh sp I underscore test in the file that we're gonna compile is - the one that we just downloaded. - So this is going to do is it's gonna create an output file called SP I Devin or score test - . - Let's go ahead and hit Enter. - That only takes a second. - If we list the directory again, - you'll see we now have this SP I Devonish court test and we're just gonna run that just - like it says in the instructions. - Okay, - Now it says can't open device. - No such file or directory. - So what's going on here is that by default SP I is not enabled on our raspberry pi raz B - and distribution. - And we can see that by looking at a special file. - We'll just use this cat command again. - We've used it before. - We're gonna look in e t c mon proved dot de raspy blacklist dot com We had intern that - we'll see It says blacklist SP I and I two c by default. - Many users don't need them and then it hasn't blacklisted. - Well, - we do need them, - so we need to turn that off. - So we're gonna go pseudo nano. - Don't forget the pseudo because we need elevated privileges to change this file, - and we're just gonna go to that same file, - okay? - And in here, - all we're gonna dio is we're gonna put a pound symbol in front of the S P I line, - which basically turns that into a comment. - We'll save our changes now, - After we do that, - we need to reboot for the changes to take effect, - so we'll just go ahead and do a pseudo reboot and we'll wait for that to come back up. - Okay? - Our pies booted back up. - And now we're ready to try our test again. - So let's change directories back into that s p I directory that we created. - And if you remember, - we compiled that file. - So we're just going to run it again dot slash sp i dev Test Dash d. - Okay, - now we get this SP I mode bits per word, - Max Speed. - The important part is this block of characters this f f f the 40 line that tells us that - data is making it out of the master output pin and onto the master input pin. - Now, - we've confirmed that the ESPN module is actually working on our raspberry pi. - That means we're ready to connect our display, - and that's what will take care of next 16. Basic Setup and Test (Steps 1-4): - remembering back when we talked about SP I there were some things that we needed to know to - be able to use the protocol, - things like the clock mode, - how fast we could run it and what wines that we were going to use. - And so, - before we can hook up our display, - we need to know those pieces of information. - So for that, - we're gonna turn to the data sheet. - Now, - remember, - we've said this before the data. - She is your friend for these projects. - It will tell you the answer to most of the questions that you have. - Some data sheets are better than others. - And so we're gonna go ahead and look at the seven segment display data sheet that sparked - point is put together as far as data sheets go. - This is right there up at the top. - They have done a really nice job of laying it out, - making things very clear and easy to understand. - And the information is very accessible. - Let's come down here to the data sheet links section. - We're gonna go into this interface specifications link. - As you can see, - it's gonna tell us about the U. - R S P I and I two c communication protocols. - As you can guess, - since we've been talking about the SP I protocol, - that's the protocol that we're gonna use to talk to our display. - So if we come to this section here, - we can find all the information that we need to talk to our display. - We can see that we're going to use the slave data in also known as the master Out slave in - the slaves select, - or sometimes we call that the Chip Select and the clock line noticed that we're not gonna - use the master in slave out, - which would be the SD open on the display because we don't need to get any information back - from the display. - Were simply gonna be sending commands down to it. - The other thing that's important here is down here in bold. - It says the maximum speed of the SP I clock input is 250 killer herds. - That's gonna be important when we start talking to it from the pie to make sure that we're - not sending too fast of a clock signal that the display can understand. - And then finally it lists that the display is configured toe work with SP I mode zero and - you'll recall what that means from when we talked about the theory of SP I The nice thing - about this is SP I mode zero is what the pie operates in by default, - so we won't need to do anything special there. - All right, - that's all we need to know about the SP I protocol. - But there's one other thing I want to look at. - So let's go back to this main page here and I want to go into hardware specifications. - Every module that you connect to your raspberry pi should have information about the - electrical characteristics. - So if we scroll down here, - we'll have things like the physical dimensions. - But what we're really looking for are these operating characteristics. - If you recall when we talked about the header, - we can only draw so much power from the 3.3 volts power supply and the raspberry pi. - We need to make sure that as we're connecting modules that we're not over doing it on power - . - If we are, - we need to find an external power source. - As you can see from the table here, - it gives the supply current for different voltages. - We're gonna be using the one right here in the middle of 3.3 volts so you can see that the - minimum current draw will be 3.8 million amps and the maximum will be 7.9. - So right around eight milligrams. - So if we take the worst case scenario, - our display can dropped eight mil amps of current from our raspberry pi 3.3 volts power - supply. - So we just need to make a note of that to make sure that as we're connecting things, - we're not pulling too much power. - Eight mil amps is well below the 50 mil amp. - Limit. - So we're okay to use our raspberry pi to power the display. - Now, - before we actually connect our display to the board, - let's use Fritz seem to see what it'll look like. - So the first thing library didn't have an exact match on the display that we're gonna be - using. - But this was close enough in had the right number of pens across the top. - Let's go over each of the connections. - First and foremost, - we have to have power, - says you can see here we have our ground in our 3.3 bolt connection. - The display can run from his low as 2.4 bolts all the way up to five volts. - So 3.3 puts us right there in the middle. - We're sticking door conventions, - as we have before green, - representing ground in black, - representing 3.3 bolts. - Aside from that, - all we need to do is make the connections for the SP I protocol. - We have the clock line, - the master out, - which is how we're gonna send data down to the display in the chip Select line. - Last. - This is what's gonna tell the display that the raspberry pi is ready to send data to it. - And that's all there is to hooking up RSP. - I display toe a raspberry pi at this time you want to pause the video and make the - connections on your own bread board? - This is what my bread board looks like after I've connected my display. - It's not that we haven't hooked up. - We can go ahead and boot rpai back up and see if we can get this thing to point out some - characters To do that, - we're gonna go back to the data sheet. - We're gonna go back to the main page here and we're gonna go to this basic usage section. - This will describe to us how we can display numbers. - So the first thing they do is they give us an example. - Display one to a B and the data she describes. - How weaken send actual binary values to print out zero through nine and a through F, - or we can use the asking code for it. - So, - as it says right here, - we can send 01 0 to 0 a zero B, - or we can send them as 31 32 41 42 which the asking codes for all of those so we have to do - is send that data down the wire to our display module, - and it should show up on Scream Well, - a neat way that we contest this. - If we come back, - T Olynyk stud, - or go over here, - we can see that there's a way to test the SP I interface through this show, - and that's just by echoing straight to the device. - Let's go ahead and try this. - You bring my show window back over here. - My prize booted back up as I was trying to film the display. - I noticed that with lights on it in the camera on, - I was getting a refresh problem that was easily fixed by turning off the lights. - So the next few shots of video that you're going to see our with the lights turned off. - It's hard to see everything else on the bread board, - but the most important part, - which is the display, - is nice and easy to see. - We're gonna type it just exactly how it says it here at Go Dash any backslash x one x last - exit to back slash x 03 Now the backslash exorcist says we're passing a Hexi decimal value - here and then we're gonna pipe this out to Deb SP I 0.0 when we hit. - Enter. - Let's see what we get. - Awesome. - Get 123 right there on the display. - Okay, - so now that we have 12 300 display, - how do we get rid of it? - Well, - if we go back to the data sheet here, - we scroll down a little bit more, - says clearing. - The display says the clear display command bite is hex 76. - So go ahead and bring our consul back here and we'll dio echo, - dash any x 76 and we'll pipe it out just like we did before we hit Enter and we get a clear - display. - So this shows that our display is working. - We can send commands to it. - We get it to print out digits. - We can clear it. - Everything's ready to go so that we can start integrating this into our python script - pretty good. 17. Controlling the Display (Steps 5-11): - we obviously don't want to use the Terminal two controller display, - and we do need to integrate it into our python script. - And to do that, - we're gonna need a python module. - There are several available, - but the one that we're going to use is this one that we confined on Get hub called Pie Dash - S P I Dev, - this few files that we're gonna need our this sp i dev module dot c and set up dot pie, - which is how will install the module for python to use. - We can get this a couple of way if you want to install, - get and pull the repository down. - You can do that, - but this class isn't meant to go over getting detail. - So instead of using that, - we're just going to use w get again. - Get my terminal here and to get these two files. - First of all, - let's make a directory form. - Call it Python Dash s P I little CD into that can to get these were just gonna do w get - https and then raw, - get hub dot com and then we follow the rest of the path as we see it up in the address bar - . - That's how we get the set up dot pie. - And if you just use your up arrow key, - get the path back, - we'll just take off, - set up it up pie in the U. - S. - P i. - Deb, - underscore Montreuil dot c and you'll notice it's not quite like the URL, - as we have to add the branch in there. - The master part of the link and I include these links in the show notes so that you can - just copy him. - Okay, - so let's do a directory listing and you can see that we have both of them there. - And now to install this for python to use are we have to do is to a pseudo python the name - of the Python file and then doing install. - This will install the module so that will have access to it from our pipe on script. - Now, - before we added into our script, - let's test it. - Using the python show again, - I needed to turn the lights off so that the display was nice and clear. - So let's go ahead and do Sudo Python to bring up our python show, - and then we need to import S P I dead. - That's the module that we just installed. - So let's go ahead and do that. - Then we'll set a variable sp i equal to SPF dev dot s p I Deb like that. - Then we're gonna do SP I open and then the arguments to this. - If you remember when we were using this show, - we're piping it out to SP I Deb 0.0 There's also a 0.1 which will use the other chip select - pin on a raspberry pi And so the arguments are just that. - So for 0.0 will do zero zero like this to open it up just like that Now to write data. - All we do is we say sp I done expert to or transfer to And then we can send the data here - as a array of bytes. - If you remember before we sent, - we can do Hexi decimal in python like this As we sent 01 zero to 03 I think that's right, - Syntex. - Okay, - Perfect. - We got 123 on their display so that's working notice. - We had to put the zero before the X is where as in the show, - we just did. - The exit is that's just syntax difference between Python and Shell. - So if you also recall the way to clear the display was sending 76. - Let's see if that's working. - All right. - Perfect. - Okay, - so that means that we have successfully downloaded the Python module and we can use it now - we just need to add it to our scripts. - So let's exit from here. - Actually, - before we do that, - I want to do an SP. - I close just to clean that up, - and now it will have an exit. - You'll notice When we did these transfer commands, - we got an array of bytes back. - So we sent 12 and three. - We got back a list in Python of 000 when we sent the 76 We got bags. - Eras. - Well, - remember in the SP I protocol, - you have to send a bite to get a bite. - So what the library is doing is when it sends those bites, - even though we're not connected to the display to get information back, - it's still trying to read the master in slave out pin on the pie and telling you I read - back in this case all zeros and that would be the case because we don't have our display - talking back to the pie. - But just so you know, - when you're using this library when you do the transfer, - that return value that you see underneath is what it's reading back from the slave device. - All right, - this is going really well. - Now let's see d back into our skill share folder and will go back into our file our monitor - , - Dr Pie, - and we need to add our SP I Deb module. - So let's right here at the top. - The first thing that we needed to do, - if you remember, - is import SP i, - Dev, - and now we need to open it up so we'll do that just here the top. - Now this isn't right now. - Our Python script is very script e. - It's it's not. - If anybody's watching that has some experience of programming, - it's not object oriented. - All we're doing is we're taking baby steps here to get all of the functionality that we - need. - We can always come back later and re factor this, - but the purpose of the class isn't too right. - Perfect pipe on. - It's too. - Show you how we can use python to interact with that raspberry pi. - So let's come down here to another comment right here will open things up like we did, - so C s p I equals SP I Deb, - uh, - sp I dead. - Okay. - And we'll open it up just like we did in the shell. - If you're called from the data sheet, - there is a max speed on our display of 250 kilohertz, - so we can set that here. - You noticed we didn't have a problem when we used it in the show, - but it's still good practice to set the max speed. - If we know it, - we could just say Max speed hurts equals 250,000. - Just to make sure that we're not going too fast for display. - Okay, - so that opens it up. - Now it's ready to transfer. - Before we do that. - I want to come up here and I want to write a couple of functions, - and the 1st 1 is gonna be for sending data so we'll just call this SP. - I sinned. - I apologize for that blue font, - and I know it's kind of hard to read And what we're gonna pass it is the bus that we're - using and then the data that we want to send and we have to send an array to it. - So we call this the transfer list, - just create a list there, - and now we might want to send different things to this function. - We may want to pass it Hexi decimal value, - like we did in the show. - Or we may want to just pass a normal text or even just a imager. - And so we want to be able to handle all those. - What we're gonna do here is we're just gonna check the type, - so bring it will say, - if type of data now, - this will return the type of the variable that's passed in data. - So it might be a string. - It might be an imager. - It might be a list, - so we can just check that and we'll see if that equals the built in python type of stir. - What we want to do is looped through the data. - So for each character in that string, - we want to do a transfer list. - Stop upend. - Add to that, - we don't want to just depend the character we want to pass the asking value of the - character. - And for that, - there's a built in function python called Ward. - So it's a ward of see is what will pen to the list. - Okay, - then we'll just do some LFC here. - I left the type of data equals a list. - So if we send in a list of bites, - all we're gonna do in that case is a pendant to transfer list. - And we can just do this. - We just do plus equals data and python that will upend the to list together. - Okay. - And the last one that I want to handle here is if we pass an integer, - this isn't well, - say transfer list. - Not part Sequels that attend the uniter just like that. - Finally, - our else case here that will drop into it. - It's none of those types. - We'll just do a print se must be stir int or list. - Okay. - And then the last thing that will want to do after we've gone through that loop is we want - to do our bus dot Okay? - Remember, - the bus will have that sp I object transferred to. - We'll just send it our transfer list. - Okay, - so we have our SP I sinned. - Let's go ahead and test this. - So you've recall when we have had our button here and before we're just printing out that - you pressed me. - Why don't we go ahead and use this instead of printing? - Why don't we go ahead and try an SP I send of? - We'll just do it like we did in the show. - One to three. - I was trying just like that. - So if we press their button announced that it printing to the screen, - we will send 123 So let's go ahead and exit, - and we'll save that. - No, - let's go ahead and run this. - And if you remember, - we need to do pseudo. - So we'll do. - Pseudo python monitored up. - I Okay, - now it's telling us our max speed hurts isn't a bad file, - descriptor. - So let's go ahead and come back in to here. - What will do for now is well, - just comment that out. - I don't have to go back to the documentation to see what we have wrong there. - Okay, - let's try to run this again. - We're getting a warning here. - That is because on our previous run, - it opened up the GPO pin for 12. - We don't need to worry about this. - We can actually turn these up, - but for now, - our scripts still is running. - So let's come over here and see what happens when we push a button. - Okay? - This is why we test. - As you can see, - we got an air here, - says SPS and takes exactly two arguments in our script accidents. - So he forgot who's to pass our bus to our functions. - Let's come down here and we need to send S p. - I hear. - Okay, - let's hope third time's a charm. - All right. - Perfect. - Push a button we get 123 All right. - We've successfully integrated the SP I Dev module into our script. - So weaken start to write a bunch of helper functions to display the things that will need - for this project. - First thing I want to do is to display the time. - So the default state of our monitor, - I think it would be nice to shore show the current time on the display. - So that's what we'll go ahead and do next instead of making you watch me type all of this - into our python script. - I've gone ahead and made the changes so we can display the time. - And I just want to go over them since come back into our file. - Okay, - so the first thing I did was I imported local time in stir f time from the time module here - at the top. - That's going to allow us to get our time and four minute for display. - One thing I'd like to mention also while we're here is I did some more research on the - setting the max speed and I've changed that here you can see in my transfer to function. - We were just passing the list before we can pass a second argument, - which is the max speed that we want to transmit at which again was 250 kilohertz. - So I've made that change there. - I'm not sure why setting the member is not working because that is a member of the S P. - I object, - but this will work just fine for us. - I've added this clear display function which takes a bus is the argument. - And then we just do a send that hex 76 that you've seen before. - And then our display time function here, - we're gonna do is call stir F time in the documentation for this is readily available - online from pipe on. - But the percent h percent m here says give us the hours as a two digit number in the - minutes is a two digit number from our local time. - We just call local time there and then we're gonna call clear display, - just in case anything showing them will send that time String down to RSP. - I send function, - come down here a little bit more We can go ahead and cut out this max speed hurts line put - in just to keep things clean. - The first thing I do is I set our ah variable clock mode to true. - And then I do display time so right away When you turn this on when you start running the - script, - the time should display then down here in our loop for the button. - I just added an if else so if we're in clock mode, - if we're already displaying the time and we push a button, - we want to set the clock mode to false and clear the display later on will add our - temperature when we get that module connected. - If we're not in clock mode and we push the buttons. - That's the else we're gonna want to set clock mode to True, - and then we'll display our time. - So let's go ahead and exit out of here. - Save this, - All right, - so let's go ahead and run this and we'll see over under Borden we hit. - Enter the time shows up, - and if we come over to it, - we push our button. - The time turns off, - push it again. - He comes back on. - Now there's one problem with this and you'll notice that the time is in military time and - 17 04 would be 504 It's not 504 p m. - Where I'm at right now. - It's actually still in the morning. - So what's going on here? - We're gonna go ahead. - I don't like the display to be in the state where the screens on when we're working so - we'll go ahead and push the button again. - To turn that off, - we'll come back and exit from our script. - So this brings up an important point about the raspberry pi. - It doesn't have a real time clock that keeps track of time when it's unplugged. - When it's unplugged, - it loses all state information. - It does. - However, - when you boot it up, - try and pull the correct time. - If you're connected to the Internet, - it will go out and try and pull the correct local time. - But it will only pull the correct local time if you have your time zone select, - which we haven't done yet. - And so let me show you how to set this up really quick. - We just come to our command line here and we do TZ select. - This is gonna take us through some problems. - The last justice select a continent in the Americas so due to enter, - then get him in the United States and my time zone is actually mountains. - I'll do 18 okay? - And it's gonna say, - Is everything correct? - This is the local time. - That's right. - It is about 10 06 in the morning here and we will say yes, - that's fine. - Now, - an important part here it says here is that TZ value again, - this time on standard outputs that you can use the user been TZ slight commanded shell - scripts America slash Denver and then up above it says TZ equals American Denver. - Okay, - so what we need to do is we need to add this to our profile so that when we start up, - it'll automatically set the correct local time. - So to do that, - we're going Teoh, - change directories back up in your room here. - We're going to nano dot profile and what? - We'll do it The very bottom here. - Back up here, - you can see this line right here that says TZ equals American Denver Export TZ. - We just want to add that to our profile. - So we'll come down and will say TZ equals and you need to have the single quotes here - America slash Denver semi colon export TZ. - And when we do that, - when we boot up, - it'll set the time zone to mountain time. - So we're gonna go ahead and exit here will save this, - and then we're going to do a pseudo reboot. - All right? - My pie is booted back up and just real quick, - let's launch a python show. - We'll do from time in court, - local time. - Just a test that this worked local time. - Now you can see the TM Our is 10 in the minutes is 22 10 22 and that's what time it is here - right now. - So now we have the correct local time, - so exit and we'll CD back into our folder that we've been using Run our monitor again. - We hit enter. - You'll see that we get the correct local time. - Now the very last thing I want to do with the display before we move on is you'll notice - the time is showing 10 22 correctly, - but normally on oclock, - you'll have a colon in the middle of the tent between the 10 and the 22 we don't have that - are display is capable of showing that, - but we're not sure how to do that yet. - We haven't done that yet, - so let's figure that out. - Where we gonna go? - You guessed it data sheet. - So it's exit out of our program here. - OK, - but come up to the data sheet. - We're still in the basic usage apart, - so let's go back to the home. - Well, - the serial 17 display data sheet and we'll go down to special commands. - You can see here it has decimal colon apostrophe control will come down here, - So if we look at this, - we need to determine for the colon bit to be set. - What's the value we need to send to our device? - One easy way to do that. - You can kind of cheat. - I'm gonna grab my calculator over here. - We're gonna change the view to programmer, - and we could just enter the binary form of what it would be. - So digit one will be a zero digit two will be a zero. - Did you? - Three will be a zero digit four b zero, - but then the colon needs to be a one. - So let's just starting with the cones do one and then 000 z room the four zeros - representing bit zero through three, - which are also digit 13 digit for And then if we just change this to decimal, - we can see that 16 or if we want to descended as hex would send it as hex 10 Now, - if you remember from RSP I send function, - we could send it either way. - For now. - Let's just send it as 16. - Pull this back aside. - Bring a terminal back up to do Nano. - I will come back in here is part of our displaying time. - I will send the time down, - but then we'll do NSP I send now. - I said we're gonna send it as an imager, - but we need to send the special control bite first. - So let's send it as a list of hex again. - So we'll send zero x 77 which is that command bite. - And then we need to send dear X 10 Okay, - so after we've sent the time down, - this should go ahead and turn our Colin on. - Let's exit out, - seem it and run it and see what we get when we hit Enter. - All right, - that looks much better now, - our displays correctly showing the time it's got the colon. - It looks nice and pretty, - and that's pretty good. - So that is all I really want to cover for S P I. - We've covered a lot of ground here. - We've gotten some good functionality out. - Now, - let's go ahead and move on to the I to see protocol and see how we can get our temperature - sensor hooked up 18. I2C Basics (Step 1): - All right, - we've got SP I working on our pie. - Now it's time to talk about the second communication protocol that we're going to use in - our project, - which is I to see some people call it. - I i c I squared. - See, - It stands for Inter integrated circuit. - And what we're gonna do is we're gonna use this protocol to talk to the temperature sensor - that will be using you're gonna see a lot of similarities to the SP I protocol. - There's also gonna be some differences, - but we're gonna follow a very similar pattern that we followed before. - And that is we're gonna start with power. - How are we gonna power a temperature sensor? - Well, - we need to refer to the data sheet to see how much current it draws to see if the pies able - to provide power to it. - And we'll look at that a little bit later. - But I can tell you that the temperature sensor is very low power, - so we'll be okay to use the 3.3 volts supply from the pie again. - So let's go ahead and make those connections. - And I just want to make a quick note. - Um, - just like an SP I We need to make sure that our voltages agree when we're doing I to see - meaning the pie wants to speak in 3.3 volts. - So we need to make sure temperature sensors okay, - doing that as well. - We never want a sensor that's going to use five volts talking toe rpai even though we do - have five votes on the raspberry pi. - The input output pins or not, - what's called five boat tolerant meaning. - If you put five volts on an input pin, - it's going to burn it out. - You may ruin your pie, - so just keep in mind, - because remember, - this doesn't have to be a temperature sensor. - We're using a communication protocol to talkto a module. - This module could be a temperature sensor. - It could be a gas sensor. - It could be some other module. - But when you're buying these, - just make sure, - especially if you're using the pie that they speak the same voltage language. - In this case, - 3.3 bolts are temperature sensor does. - So we're okay Now, - let's see the lines that we're gonna need to connect this unlike SP I that requires three - or four I to see only requires to. - That's in addition to the power lines, - of course. - And they are SDA and s CEO SDA is the data line and SCL is the clock line So this will look - very similar like it did in SP I it's gonna send the clock signal now unlike SP I Though - there's not separate lines for sent and received, - the same line is used and that's the SDA line. - Another similarity to SP I is that there's this concept of a master and a slave. - The pie again will be our master device. - The temperature sensor will be our slave device. - The master will always drive the clock line which syncs up master and slave Now one of the - main differences between SP I and I to see is that how the master contacts the slave If you - remember with SP I we had a concept of a chip select line so we needed an extra pin for - each additional sp I device. - We wanted to connect to our pie so the pie could let it know it's ready to talk to it in - the eye to see protocol. - There's a concept known as ad dressing every single module that you'll connect has an - address. - And what happens is the pie. - The first thing it does before it talks. - It says all the devices connected to the line. - I want to speak to the device with this address. - Right now, - all of the devices that are connected will compare that to their internal address and - decide. - Is that me? - Yes. - Okay, - I'm gonna start listening. - It's not me. - I don't need to worry about it. - And so most modules will come with some form of address configuration. - In the case of our temperature sensor, - there's an extra pin that we can connect up to 3.3 volts or connect down to ground to - adjust the address because it comes with a base address. - But what if we wanted to stick three or four of these temperature sensors on the same eye - to see data lines? - Well, - they don't need to have different addresses, - and so there's always a way to do that. - I should say most of the time there's a way to do that with modules that we connect. - And so, - just like an S p I we can take, - we can share these lines we can come off of the data line here, - we can come off of the clock line and we can connect another module down here and you can - do this multiple times connected another module year running into each other and again, - there's no additional connection to the pie for those. - They'll all have a unique address that the pie will say. - I need to talk to this address now and the correct one will start to listen and we'll - understand what the pious saying. - So, - um, - that's one of the pros. - It uses less lines than SP I One of the cons to it, - though, - if you compared to S p I is that it's a little bit slower. - The maximum speed you can talkto tonight to see devices 3.4 megabits per second. - Whereas SP I can go upwards of. - There's really no defined upper limit, - but you can get up in the 2050 megabit transfer rates, - so that's our right to see protocol. - That's how we'll connect towards temperature sensor. - Let's go ahead and see what this looks like when we connect it and figure out all the - details 19. Configure Pi for I2C (Steps 2-5): - Before we hook up our temperature sensor, - we need to configure pie so that we can access the I two C bus. - If you recall from the SP I unit, - we needed to modify a few files and download some tools before we could communicate over - that protocol. - I two C has similar requirements, - so let's go through those briefly. - Let's start by modifying the modules file to tell our pie to load up the EITC modules at - boot time. - And to do that, - we'll do Pseudo Nano. - The file is in the E. - T. - C folder. - It's called modules. - Like it says, - this file contains the names of kernel modules that should be loaded at boot time. - That's what we'll do is we'll come down here Well, - had I to see Dash BCM 2708 as well as I to see Dashed Dev, - we'll go ahead and exit and save the other file that we need to modify is that blacklist - file. - If you remember from the SP I module, - so we'll do a pseudo Nano also in the E. - T. - C folder, - it's in. - The mob proved that d sub folder. - If you remember the name It's raspy. - Die raspy dash blacklist dot com, - and we'll comment out the line that blacklist the EITC module. - Finally, - we'll need to install a few tools that will need in the next unit. - Since we're using, - Python will need to install the python Dash s M bus package. - Let's do that with a sudo apt get install Python Dash s m bus and once that's finished will - install the I two c tools by doing a pseudo I have to get install I two c tools you know, - since says the EITC tools already on the newest version. - That's because the sm the python dash S m bus installed it right. - Those are all the things that will need to have installed crust access or i two c bus on a - raspberry pi. - Now, - for all of these changes to take effect will need to reboot. - So let's go ahead and do that and will continue on in the next unit 20. Datasheet Review and Hookup (Steps 1-2): - as we've done with everything that we've connected so far, - we're going to take a moment to review the data sheet for our temperature sensor because - there are a few questions we still need to answer before we can hook it up and start - communicating with it. - The temperature sensor data sheet weighs in at a light 19 pages, - but that can still seem pretty daunting if you're a beginner. - An important thing to remember is that reading a data sheet is just like anything else. - The more you do it, - the better you get. - At first, - you might stumble through them, - looking for the one piece of information you need. - But as you do it, - more and more becomes second nature. - Instead of scrolling around the 19 pages of this particular data sheet, - I just want to highlight the important stuff and, - as usual, - will start with power. - I mentioned earlier that the temperature sensor is very low power, - so we will be fined a steel power for it from the pie. - But the data sheet is the place that will tell us for sure. - This is the top of the very first page of the sensor data sheet and we can see first of all - , - that the supply range for this sensor is 1.4 volts to 3.6 volts. - We're planning to pull from the 3.3 boat line on the pie, - so that is within the allowable range. - The second thing we see right here on the first page is the quiescent current range of one - micro am to 10 micrograms. - Let's get a little more detail by looking at the electrical characteristic section of the - data sheet. - We could see the same information here about the power supply operating range being 1.4 to - 3.6 bolds. - But we see a little more information about the quietus and current question. - Current is the amount of current that the sensor will draw from the power supply. - Went inactive, - were just sitting there, - connected and not actively doing anything. - Remember, - though, - that this device may be connected to the same lines as other sensors, - so you'll see different values for when the bus is inactive and active with different clock - speeds. - In any case, - the values Aaron, - the microgram range and if you recall previously, - we mentioned that the 3.3 bolts apply on the pie in source a max of 50 milligram, - so we're just fine. - One thing to note is that the sensor does draw more current in very short bursts when - actively driving the data lines as seen here. - But three mil amps and very short bursts is still very low. - So now that we know we're OK on power, - let's talk about how we're going to address our sensor. - Remember that each device has a unique address that the pie will need to know so it can - talk to it. - Here's the section of the data sheet that explains how we can configure are temperature - sensors address. - It says here we can connect up to four of this particular sensor on a single bus, - and we configure the address based on how we connect the A zero pin. - Let's just use this first address in the table by connecting our A zero Pinder ground again - . - We can use our calculator to figure out that this binary number is the Samos Hex 48 or 72 - in decimal format. - That will come in handy when we start writing code to talk to our sensor. - The last thing you need to understand before you hook up your sensor is how to actually - talk to it and get a temperature reading. - Well, - we know that we'll be using the act to see protocol. - But just as we needed to know what data descend over SP I tore display. - We also need to know the things we need to say to our sensor. - So it will give us a temperature reading because the same SDA line is used for send and - receive. - We need to understand how data is exchanged between the two devices. - Essentially, - the pie is the master needs to say Hey, - sensor with address 72 please give me a temporary thing. - Then it will release the data line and drive the clock line for the sensor to respond with - temperature data. - For that, - we need to read about the pointer register. - As it says here, - The pointer register of the device is used to address a given internal data register. - As we can see from this table therefore different registers that we can read and or right - to inside of our TMP 10 to censor the one with the current temperature reading is at - address 00 So instead of saying please give me a temporary ting, - what we're really saying is please give me the contents of your internal register at - address 00 If this seems confusing, - that's perfectly normal. - Sometimes this stuff has to sink in after reading it multiple times in the data sheet. - Once we start getting into the python code, - you'll see that a lot of this is abstracted away for us. - And I promise it won't be that difficult to understand now that we know what registered to - read to to get the temperature data, - we need to understand how to interpret that data. - So for that we need to take a quick look at the temperature register section of the data - sheet. - As we see here, - the temp data comes back in two bites, - and it says one least significant bit equals 10.6 to 5 degrees Celsius. - We'll come back to this table later when we're writing our python code so we can properly - translate the data into a meaningful temperature reading. - All right, - now that I've melted your brain with the data sheet, - let's get it actually hooking this thing up and playing with it. - Here's how I intend to connect the sensor on our bread board. - I've pulled power from the top, - just as I've done with everything else. - Remember, - Green is ground and blackest 3.3 volts. - I've also connected the SDA in SCL lines over to the corresponding pins on the pie cobbler - . - The breakout board for the temp sensor has the pins clearly labelled, - so it is very easy to know which pins go where. - Finally, - to set her address correctly. - I have the A zero pin connected to ground. - This will give us that address of 72 that we mentioned earlier. - This is what it would look like connected directly to your pie. - And here's what it looks like hooked up on my board. - Now that we're all hooked up, - let's see how we can start communicating with our sensor 21. Add Sensor Code to Python File (Steps 3-6): - with our temperature sensor hooked up, - we're ready to start playing around with it so we can start getting temperature readings - from it. - So with our pride booted back up and everything connected, - the first thing we want to dio is to make sure that we have everything hooked up correctly - . - And we can use one of the utilities that we downloaded and installed called I two c detect - . - So just like with the python shell and with some of the other things we need to run, - this is pseudo So we'll do pseudo I to see detect dash y and the number of the eye to - seaport that we want to test now. - For most of you, - that will be I to seaport one. - However, - some of the early raspberry pies that were delivered used I to seaport zero. - So if you have an older pie, - you may need to you zero is this last argument. - In my case, - it will be a one no hit enter And what this does is tries to find any devices with an - address on the I two c bus. - And as you can see right here, - we have our temperature sensor with hex address 48. - These were all hex addresses, - and that's the Samos 72 like we showed before. - So if you run this and you don't see a 48 there, - it means you don't have something hooked up correctly or didn't install one of the tools - that we did in the previous video. - If you do see the 48 that means the Pichon C and is ready to talk to your temperature - sensor. - So let's do that next, - as we've done before will launch a python show, - and all we have to do is import the SM bus module. - And then we'll just say I two c equals a Simba Stop S M bus and then pass it the EITC port - . - We want to communicate over in our case one. - Now, - before we try to read the temperature. - Let's review the data sheet really quick. - Here's the section on the temperature register now, - As it says here, - two bites must be read to obtain data and are described in table three and four. - So when we ask for the temperature from our sensor, - we need to read two bites back to get the full temperature value so back here in our show - we want to do I two c dot reid word data. - Pass it. - An address in this case will pass the hex 48 and the address of the internal register that - we were on a read. - Remember that zero? - Now, - the SM bus module has a few functions that we can use in this case we're using Read word - data. - Ah, - Word is two bites, - which is what we need. - There's also a function called read bite data, - which will show you in a minute. - But this will give us the full temperature register value back from our temperature sensor - . - So if we hit enter, - you'll see we get this war. - Ginger 24,595. - That's coming from our temperature sensor. - Now you can do this. - Just is easily. - We use the hex value for the address, - but you can also use the image of value if it was 72 so Well, - read it again. - You see, - we get the same value back. - They're also functions on the EITC variable that we have here for writing data back to our - sensor. - We're not gonna get into that. - We're going to stick with just reading the temperature for now. - So as I mentioned, - we can also read just a single byte of data. - So instead of reading both bites of the temperature information, - we can just do read bite data, - which will read a single bite back. - You'll see we get 19 there. - So remembering back from our data sheet, - we know that the temperature data that we get back needs to be multiplied by 0.625 to give - us a temperature reading. - So let's see what happens if we do that. - So we multiply by 0.6 to 5, - and I forgot to assign Art Temple value there. - So do temp equals I to see that read Work data 72 0 Okay, - let's try that again. - Now what is this? - We're getting 1537 degrees Celsius. - It's definitely not that hot where I'm sitting right now, - so something's wrong. - This is where reading the data sheet and understanding what we're working with really comes - in handy and can be a little tricky if you've never done it before. - So let's bring our data sheet back up Now. - There's a couple of things that are important to note here, - right here, - it says. - Note that bite one is the most significant byte, - followed by bite, - too. - So from Table three and Table four, - we see bite. - One is the most significant bite, - and bite to is the least significant byte. - And that's how the temperature sensor is going to send the data back to us. - However, - the standard for I to see is to send data least significant byte first. - And so are temperature sensors actually going to send that data back bite, - too, - as the first bite and bite one of the temperature data as the second bite. - We can see that if we come back here and we do a binary on the value that we read that 24 5 - 95 and you'll notice the least significant byte, - which is here on the right ends in 10011 But if we come back to our data sheet will see - that bite to at least significant byte should have four zeros at the end, - so our bites air swamped. - That's our first problem. - The second problem that we have is you'll notice that this temperature data is shifted. - So the first bit of the temperature data is actually in the fifth bit of that least - significant byte. - We know that we're reading data from our temperature sensor, - and we know that we need a massage it a little bit. - So I think we can be done in the shell for now and make these changes right in our monitor - , - not pie file. - So let's go ahead and do that instead of having you watch me type. - These changes into are monitored out pipe. - I'll have gone ahead and made them, - and we'll walk through them together. - Feel free to pause the video as we go and make the changes in your file if you're following - along at home. - So if we come back into our monitored up I pile here, - the very first thing I did was an import SM bus, - just like we did in our shell. - We need to import that module so that we can use our I two c bus. - The next thing here, - right at the top, - is that I defined a new function called get underscore temp and I pass and I two c bus is - an argument to it. - Now we remember from our data sheet that are bites were coming back in the wrong order were - actually the right standard order for I to see but the wrong order for how we want to read - them. - And they needed to be shifted a little bit. - So with the data sheet is a guide here the changes that I made if you don't understand this - the first time through it might help the watch it a few times so that it can really sink - into how I accomplished this. - So from the data sheet, - it helps if we look at the bite side by side. - This is how we'd like to have gotten the bites back from our temperature sensor. - However, - this is how we actually got them back. - So the first thing that we need to do is isolate each bite and to do that, - we'll use something called a bit mask. - If you're not familiar with binary operations, - that's okay. - I'll put a link down in the resource is so you can learn more about it. - But basically what we're going to dio is we're going to on Lee, - take the bits that we want for each bite the high bite in the low bite. - Then we're free to move them around as we please. - So for that I have two masks bite one mask, - which takes the bottom eight bits from our return temperature reading and bite to mask, - which will isolate the top eight bits. - So this is the state that we're trying to get to all of the temperature bits, - right? - Aligned with t zero being all the way it bit zero in our temperature value. - So to do that will do a binary and of our temperature reading with the bite one mask which - isolates that bite one. - And then what will need to do is you can see that the first bid in that is actually the - fourth temperature bit. - So we'll shift it up by four. - That's what this symbol right here does. - And then we'll do something very similar for bite to will and our temperature value with - our bite to mask toe, - isolate those bits and then we need to shift them down. - You'll see. - We need t three t two t one and t zero. - We have to shift those down 12 bits so that they're all the way down to the right. - Once we do that, - our bites are in the right position. - All we have to do is or them together again, - another binary operation, - and that will give us the actual value that we want. - And one last thing to remember from the data sheet is that that value needs to be - multiplied by 10.625 to give us the temperature reading in Celsius. - So I just added a print statement for now, - Celsius like this. - And then I do the conversion to Fahrenheit and print that out as well. - And for those paying close attention, - Yes. - I just realized that I have spelled Fahrenheit incorrectly. - So let me go ahead and fix that. - Okay, - so that's the function. - Forgetting our temperature. - Now, - I just came down here and followed the same pattern that we've done before. - Right after RSP I module set up, - I set up the I tease the eye to see module by doing an SM bus. - That s m bus one. - If you remember earlier from our button testing, - we found that when we push the button without having asleep, - we got a lot of you pressed me output. - That's because that wild loop is executing so fast. - Well, - we don't want to read our temperature hundreds of times every second. - And so I put in this last temperate ing value that has the current time. - When we start up and down here in the wild loop, - I added some code that says, - if the current time minus the last temp reading is greater than or equal to five. - And so what that does is basically says, - Has it been five or more seconds since our last temperate ing? - If so, - will say the last temp reading is right now and then we'll get the temp. - So if we exit out and we run this, - we should see a temperature reading coming in every five seconds. - So let's go ahead and hit. - Enter. - The 1st 1 will take five seconds, - and there we go. - We get 69 degrees here, - and it will keep giving us temperature every five seconds. - So this is perfect. - Are temperature sensors working? - It's giving us a value, - and we figured out how to interpret that data. - It was a little more complicated than we would have liked, - but remember Using the data sheet is your guide. - You can figure this stuff out now that we have this working instead of printing our - temperature out to the console. - Why don't we put it on our display? - Let me show you how to do that again. - I've made the changes so you don't have to watch me tight. - So let's walk through those now. - The first thing I did was in our get tempt function here. - As I commented out the print lines cause we don't need to print those out of the council - anymore. - And I've added a return. - In my case, - I want to return the fair in high value. - If you live in a part of the world where you prefer Celsius, - you can return your Celsius value here. - Either way works just fine. - The next thing I did was created display function just like we display our time. - We also have a function to display our temperature again. - We need to pass the bus because we'll need that to talk to RSP. - I send function and the temperature that we want to display Now we need to modify the value - of our temperature before we can send it down to our display. - We only have so many characters on our little display, - so we need to format this in a way so that it will all fit. - And to do that I've just used some python formatting functions here. - Let's just walk through it real quick. - The corn four says. - I want the max width of this to be four characters wide, - including the decimal point, - and I want one decimal point precision and the F says it's afloat, - and the second F actually appends the literal character F two r string When we're done and - what we're formatting is the rounded value of our temperature with one decimal precision, - our temperature sensor can give us readings like 69.125 degrees Fahrenheit. - We can't display all of that. - And so what all of this does is wraps that down into 69.0 and then we want to display the F - on our display so that we can indicate that it is fair and height that we're showing if - you're doing Celsius, - all you would change. - Here is the second F to B A C that will give us back of value like 69.0 f. - Well, - if you remember when we configured our display, - we can't just send the period down to our display and have it displayed correctly. - We have to send down special characters so far, - display vow. - Here we're going to replace the period with nothing. - So basically, - we remove it from our string. - So what we're left with is 69 zero f in the case that it's 69.0 degrees. - And so, - just like before with the time we're gonna want to clear a display before we put anything - on it and then we'll sp I send that display vow After we've sent it, - we want to turn on the decimal in the apostrophe. - The apostrophe will kind of give us like the degree symbol, - and I think it looks pretty good. - So again, - we'll do sp I send 77 Is that special character saying we're going to send extra data about - turning on the decimal apostrophe? - And in this case, - I figured that to be hex 22 the other change I made was right When we set up our module, - I want to grab the current temperature right away. - So we added this call here and then if you remember from before where we were sitting our - mode, - we're displaying the temp. - But I've modified this loop where we're clearing for the temperature. - So not only do we get the temperature every five seconds, - but if we're not in the clock mode so we're displaying our temperature, - I want to update the display with the current temperature. - So that's what this if statement here, - does and then just isn't note. - I did add down here in our except for when we exit to clear our display. - I didn't like how when I was cancelling out of the script, - whatever was on the display would stay there. - So I just clear that before we close. - So if we exit out of here and then run our monitor, - remember, - the default is to display the time and yes and military time that his 12 28 in the morning - . - If we come over and we hit our button to display her temperature, - you'll see that we get 69.2 and it's Tata going there between 69.2 and 69.1 degrees - Fahrenheit. - Now I have another thermometer here next to it. - For comparison, - the 31 of the top is the outside temperature, - but the 71 at the bottom is the inside temperature. - I tested this with a few thermometers, - and as it turns out, - our TMP 10 to censor. - At least mine appears to consistently be about two degrees low. - I don't know if it's a defective sensor or what, - but that's what it seems to be. - It will always be about two degrees low anyway, - so that's it. - I think it's displaying really nice. - I think it looks nice with the apostrophe, - is kind of the degree symbol, - and it's updating in real time. - All right, - that wraps up our unit on interfacing with our temperature sensor. - Everything is going really well, - and we've almost got all of the functionality that we want in our little home monitoring - unit. - In the next unit will work on adding motion detection as always, - if you need help or have questions, - the best place to go is on the Skill share website for this class under the community tab, - you can also reach him via email or find me on Twitter 22. Datasheet Review and Hookup (Steps 1-2): - the last piece of hardware functionality that we want to add to our simple monitor is that - of motion detection. - We'd like to create the idea of, - in a way mode so that while we're gone, - are monitor can detect motion and let us know some of you may be thinking, - Why not use a webcam and some open source software to detect motion? - We could easily do that, - but then we wouldn't be using the GP Io header. - And besides, - it's way quarter. - Roll your own and show off your hardware hacking skills to detect motion. - We're going to use the passive infrared or P ir sensor from Parallax. - There are a lot of motion sensors available, - but I like this woman because of its simplicity and power supply range. - We'll go a little faster through this one, - since you're probably starting to get the hang of this. - So here's the data sheet for our sensor. - And what's the first thing that we need to check on? - That's right power. - And here on the first page we see the power requirements are 3.6 volts and the current - draws 130 micro amps. - When Idol and three milligrams. - While active and not driving a load, - the sensor was designed to be able to drive a load like an led or relay when it detects - motion. - So that's why up here, - it says it can source up to 12 million amps at three volts. - We won't need it to drive any load as we'll see in just a minute. - I want to pause here for just a moment to recap on our power usage. - I said in the very early stages of our project that we could only pull 50 million amps of - current from the 3.3 volts supply on rpai otherwise would need help from an external power - supply. - Well, - let's add up. - What we've got so far in a worst case scenario are led draws about four mil amps of current - when it's on our switch, - if we actually configure incorrectly as an output is when it will draw the most current and - that's around 3.3 milligrams, - same thing for our button. - Our display can pull a maximum of eight million amps in our attempt sensor three milligrams - and finally, - our motion sensor can draw up to three milligrams while it's active. - So in a worst case scenario where we've configured something's incorrectly and everything - is running all at once a peak current draw, - our worst case scenario would be about 25 million amps. - It's important to keep track of this when you're working on your own projects. - Now, - even though the pie can provide 50 milligrams, - you'll never want to push it right to the edge. - 90% is a good rule of thumb. - If you're gonna go over that, - you should look into adding external power. - Okay, - back to our motion sensor. - So how do we talk to this thing? - Well, - if we scroll down just a couple of pages, - we see that we have two pins for power. - In the third pin is the signal pin. - It says hi when it detects movement and low when it doesn't detect any movement. - Sounds like the perfect job for a Iot pin on our header configured as an input. - So, - as I was saying before, - we don't need to drive a load with the sensor output pin. - We just need to read it state, - and we'll just use this quick start circuit in the data sheet is our starting point, - we'll make one simple modification to it. - Remember, - we talked about hooking up are switching button. - And what would happen if we accidentally configured our pin to be an output and drove it to - ground or 3.3 bolts? - We could create a short circuit. - The same concept applies here. - What happens if we accidentally configure I open to be an output? - We know the default state is set to zero or ground. - Now, - when our sensor detects motion, - it's going to try to drive that pin high, - and we're back to having a short circuit. - So the only change will make is to add a one kill own protection resistor between our - sensor output pin and the eye open on the raspberry pi. - The only other thing of note here is the warm up time. - It says that it may take our sensor up to 40 seconds without any movement toe. - Learn the room it's in before it's ready to detect motion. - So let's see how well, - hook this up. - As you can see, - I've put my motion sensor on a separate bread board. - That's just to facilitate the overhead views I'm shooting, - and there's nothing to prevent you from hooking it up on the main board. - In fact, - I purposely left room here. - If you'd like to install it there, - there's nothing new here. - We have our ground and 3.3 bolt connections. - And then the output pin on the sensor goes through our one kill own protection resistor toe - . - I open 22. - That's all we'll need. - An important note is that Fritz and didn't have the Parallax motion sensor in the library. - So this is a substitute part with different pen orientation. - The pins are clearly labeled on the censor board, - so make sure you get the connections right. - This is what my overall set up looks like. - And here's a closer view of the sensor connection for those connecting straight to the pie - . - This is what I mocked up with our motion sensor install. - We've completed the hardware build out of the class project before starting the next video - . - Take a moment to hook up your sensor. - Remember to power down your pie First. - Next up, - we'll show you how easy it is to integrate the motion sensor into our pipe on script 23. Script and Test (Steps 3-4): - with our motion sensor connected, - we're ready to integrate it into our monitor script because we're using an eye open - configure. - It isn't input. - There is nothing new to learn here. - You should be a pro this after hooking up your switching button. - We don't really want the motion sensor doing anything while people are around, - because it will constantly detect emotion we don't care about. - We want to be able to arm our system. - For example, - when we leave our house or go to bed, - well, - we still have our switch lying around, - and right now all it does is turn on our led, - which isn't very useful. - So let's repurpose them by making the switch arm the system. - So when the switch is off, - the motion detector won't do anything. - When it's on will put our system into a mode where if it detects motion, - it will turn the led on. - If the led is on when we come back home, - we'll know that the system detected motion while we were gone. - That may seem a little lame, - but try to think about the big picture. - Remember that we have a small Internet connected device on our hands let your imagination - take over in a real application. - Instead of turning on an led, - we might sound an alarm, - send an email or even send a text. - All of those things are possibilities, - but to keep things simple will take the led approach. - For now. - Let's take a look at the changes we made and monitored out pie to integrate our motion - sensor. - It's really pretty simple. - My pies booted back up here. - I'm just going to use CD into the skill share folder and you Nano monitored up. - I I've added nothing new here. - The top. - We're actually going to scroll all the way down to where we set up things like our input - output pins and our protocols just below the eye to see module have this block of three - lines of code that says Set up motion sensor. - We configure the pin to be an input, - just as we've done before. - Using gp ioo dot set up. - It's connected to pin 22 we use gp ioo dot in to configure it as an input. - And then we just need to variables to track the state of our system system armed, - which could be true or false, - depending on our switch and the time it was armed and you'll see how we use that down below - here. - If you remember before this first, - if else block under our wild true was where we returning the led honor off based on the - state of our switch connected to input Pin 16 All we've done is changed the body of the - infidels. - So now, - instead of turning the led honor off if we detected the switches on or equals g p i o dot - high we're gonna check to see if the system is armed. - If it's not already armed, - we're gonna set the time than its armed to now and then Set system armed equals true in the - else block. - Or if the switches back in the off position, - we're gonna set time armed back to none and say that the system is no longer armed by - saying system arm equals false. - Lastly, - here the bottom. - We have just a few lines of code we're gonna check in our wild loop. - If the system is armed. - If it is armed, - we're gonna do this top. - If here now, - a lot of security systems will have a feature where you can arm it while you're in your - house and then gives you a little bit of time to get out. - Well, - we have the same concept here. - We're going to say if the current time, - minus the time that it was armed, - is greater than or equal to 10 or 10 seconds have passed, - then we're gonna monitor. - This will give you, - in this case 10 seconds to get out of the room without the motion detector firing. - You can set this value to anything you want. - If you want a minute or two. - Just change the 10 to 60. - That would be one minute or 120 for two minutes. - Whatever works for you now, - if that amount of time has passed, - we're gonna come to this inner If that says, - if g p i o dot Input on pin 22 is high or a motion detector has detected motion. - We're going to see a gp ioo dot output 12. - Remember, - that's the led and setting it too. - Low turns are led on. - That's all there is to it. - If it detects motion while its armed, - it'll turn. - That led on and leave it on. - That will be our indicator that the system detected motion while we were out. - Go ahead and make these changes. - Save it next. - It out. - All right. - All that's left is to test this out. - Let's do a pseudo python monitor dot pie. - Okay, - you see that? - Our monitor has initialized. - We have the time displaying, - and we can come over here and show how. - If we push our button, - we get the temperature 67 degrees, - and now you'll notice I have this switch in the off position. - It might be a little hard to see, - but it is off. - If we do some motion in front of the sensor, - the sensor will turn on. - You'll see that red light there that's just in led within the motion sensor that says it's - detected motion, - but you'll notice are led is still off. - Do it again. - That's because our system isn't armed now when we are Mitt. - If you remember, - I have 10 seconds where it still won't turn the led on because that's the time that it - allows me to get out of the room. - So let's go ahead and arm it, - and I'll go ahead and do motion in front of it. - Here. - You'll see that the sensors picking up motion but are led is not turning on. - And we'll just wait 10 seconds. - And now let's see what happens if we put some motion in front of it. - You can see are led. - Turned on working just as we hoped it would. - Right. - Let's go ahead and exit out. - That wraps up our unit on hooking up our motion sensor in our next unit. - We're gonna do something a little more interesting than just turn on an led when are - monitored a text motion. 24. Twitter Integration: - our monitor is now hardware complete, - and we're using almost every function the GP Io header provides. - This is my favorite part of a project because once the hardware is implemented and - functioning, - you can really start getting creative. - This is where the pie really shines over other development boards, - in my opinion, - because now we're just experimenting and Software Analytics computer. - Currently, - we're using an led to indicated intrusion when the system is armed and were displaying the - temperature on a tiny display. - We can do so much more. - We could have our hardware send texts or emails. - We could store historical temperature data, - but even better we can start interacting with the Internet. - The cloud is everyone loves to call it. - We could store data there or access our hardware vo website there. - So many possibilities. - I'm sure some of you watching this. - Our experience programmers and the wheels are already turning. - But this is a beginner's class, - and I want to show you a very simple way to get your monitor on the Internet that requires - only a few lines of code. - Let's see how we can get our device up and running on Twitter. - I'd be truly amazed if you were watching this class on skill share and had never heard of - Twitter before. - But just in case somebody out there hasn't Twitter is an online application. - I'm on the about page here, - it says. - Twitter helps you create and share ideas and information instantly, - without barriers. - Essentially, - it allows you to post micro content 140 characters or less. - You can also post images and links and things like that. - How we're going to use Twitter is to post some information about the temperature and to - alert us if motion is detected while we're away. - And to do that we're gonna use a library called twice on Over Here and get Hub, - it says actively maintained pure python rapper for the Twitter, - a p I. - And so we'll just scroll down here to the installation section and it says, - installed twice on via Pip. - And so let's pretend that we don't have any idea what that is. - Some of you may not. - We'll just bring our shell over here. - I'm logged into my raspberry pi and we'll just go ahead and type what they have here Star - that says Pip command not found So what we need to do is we need to install another Python - development tool. - And to do that, - we'll just use Sudo Apt get install like we've done before. - We'll do sudo. - I get install Python Dash Pip, - just a installation tool used for pipe on. - Once that's finished, - we can go ahead and run this command again when I've run this before, - I've had to use pseudo because when the Pip install twice on command runs, - it tries to install things on directories that, - um, - need privileges that we won't have if we run it normally. - So let's just go and do sudo have been stall. - Try it on. - All right, - Once that's finished now what do we do? - Well, - let's come back. - We'll slide this out of the way for a second. - We'll come back toward get home page here, - and there's a lot of information about authentication and a lot. - A lot of things that access this ap. - I interact with users, - and so there's a handshake process where you ask for credentials and things like that. - We're not going to do anything that complicated. - We're gonna scroll down to this basic usage section right here it says all we need to do in - our script is from twice on import wife on and then we set a variable Twitter in this case - equals twice on, - and then we need to pass it some information. - You have an app key, - an app secret and oh, - a token and off token secret To access Twitter from our python script, - we're gonna need to create an application on Twitter. - So to do that, - we're gonna come back over here to Twitter, - and we're gonna go to dev dot twitter dot com slash abs It's going to say, - signing with your Twitter account. - Now, - if you want your python script to post Twitter updates to your own Twitter account, - you can sign in with your account here. - What I've done is create a separate email just for our monitor to use, - So I'm gonna log in with that and create an application under that account, - you can do it Either way. - I have a domain that I own that I can add email addresses to. - But if you don't, - you can just create a Gmail account for your device and use that here so we'll log in these - air name is Pie Home Monitor what I created and I'll enter the password here. - And it will take you to this My applications page. - And you can see it says, - Looks like you haven't created any applications yet, - so we'll just come over here and we do create new application. - Just gonna give it the same name. - Give it a description. - Now the website here it says your applications publicly accessible home page. - It says you can use just a placeholder for now, - but remember to change it later. - I'll just do skill share and then the call back you are Oh, - we're just going to leave empty. - As with anything online, - there's an agreement that you should read and agree to. - We'll see. - Yes, - I agree. - And then everyone's favorite capture. - See if I get that right the first time. - Alright, - Awesome. - Okay, - so now we're in the page that talks about our application. - What we'll do is we'll scroll down now. - Important thing to notice. - Here is the access level, - as read only wanna have re write permissions. - But if you remember back over here and get hub We're talked about app, - key and app secret. - That's right, - here that's also known as our consumer key and our consumer secret. - And if we scroll down just a little bit more, - it says your access token. - Now, - before we create our access token, - which will be the other two pieces of information that we need. - Let's scroll back up and come to settings and will change that. - Permission to read write. - The other option is read, - write in access direct messages. - We don't need that. - We just need read right and we scroll down and we do update this with our application - settings. - Now, - one thing I've noticed in this user interfaces, - if we scroll back down to check, - still says read only that's just because they don't update it right. - If you hit a five here and reload the page, - you'll see that it actually has changed to read, - right. - Let's go back to details, - scroll down, - and now we'll create my access token. - When you create this access token, - sometimes you'll need toe weight even up to a couple of minutes for degenerate on display - on your page here. - As you scroll down, - you can see that it still isn't here, - so we'll just hit F five update. - And here we go. - It gives us our access token, - our access token secret, - and our access level is reading right now, - as it says on both the access token and the consumer, - there's a secret version of that. - These are things that you don't want to share. - So now that we have these four pieces of information, - we're ready to start integrating it into our python script. - So let's bring our console window back over here, - slide the Internet it for window over a little bit so we can kind of still see our keys. - Now, - this is what I really like about ssh ing into my raspberry pi when I'm working on it. - I've got my regular desktop here where I can look things up on the Internet really easily - copy things you can copy and paste through the windows here, - which we'll see in a moment which really makes this nice when we're copying these really - huge keys. - So let's go ahead and CD into are still share directory and open up our monitor file. - Now. - If you remember, - we need Teoh. - Go back and look at it real quick. - We need to do from twice on import oil on. - So actually, - let's go ahead and show this week just to control, - see here and come down. - And in Nano here, - if you just right click it pastes in. - So it's pretty nice, - all right, - and we'll just go down to where we set up everything else. - It's probably a good place to put it. - Just put in her comment, - but and we'll do the variable. - The same will say Twitter, - People's Now we just paste in our app key, - otherwise known as our consumer Keilar consumer secret and then the token and the token - secret. - One thing to note while you're doing this is that these should all be strings, - so you'll have to double quote them. - If you copy him in there without the quotes around them, - you'll get an air when you try to run it. - So let's go ahead and do that real quick, - all right, - that takes care of that. - Now let's just do a simple test. - So when we start our monitor, - let's just haven't update the status in our Twitter feed to say that it's starting up to do - that again, - we refer back to the get home page where it says updating status. - And again we'll just copy this right out of here and pasted in. - We'll do a status of I just powered up, - ready to monitor. - Okay, - so each time we run our script, - it should update the Twitter status to let us know that it's powered up and ready to go. - Let's exit out and see. - And before we run this, - open up another page here and do twitter dot com pie Home monitor. - You can see it's just an empty account here. - We don't have any tweets yet, - do you? - Pseudo python monitor dot pie. - Let's see what happens. - Care monitors running. - It's come back over to our page here. - Well hit F five to refresh. - And there we go. - I just powered up, - Ready to monitor? - Perfect. - As promised in the last video. - Let's use our Twitter account to do something a little more interesting than turning on an - led when our sensor detects motion. - Pull this back over here. - Let's go back into our file and something that I want to mention. - While I was testing this, - I learned something new about the twice on module and actually the Twitter a P I, - and it's that the a p I will look at your recent, - uh, - status updates. - And if you try to post a duplicate status, - the A P I will return a four or three forbidden air. - I don't know what recent means to Twitter, - so I don't know if that's after 20 minutes you can post a status that's the same as it was - 20 minutes ago, - or if that's an hour, - I'm not sure, - But within a few minutes, - if you try to post this, - I just powered up, - ready to monitor? - You'll get a four or three, - your script will exit. - And so we don't want this at the start and just something to be aware of. - As you're putting Twitter integration into your scripts, - make sure that the status is different. - We could leave this status here and give it a unique identify or like we could put - something associated with the date and time down to the second so that it's it's unique - every time it posts, - but just something to be aware of. - We're gonna go ahead and cut this line out altogether, - because what we really want to show is how weaken, - tweet when we detect motion in the system is armed. - So let's come down here to where we detect our motion Right now we're just setting the led - pin too low, - which turns are led on. - This is where we're gonna want to do our twitter integration. - So if the systems arm and we detect motion, - come down here and it seems like we could just add a status update right here. - So if we did twitter dot of dates status, - then we do status equals something. - The problem with this is that this runs is part of our wild That's executing superfast like - we've talked about before. - So right now in this, - when it gets down to this section of code, - it's trying to turn the led on over and over and over hundreds of times a second, - which doesn't matter with the led, - it's already on. - Trying to turn it on again doesn't hurt anything. - But in the case of our Twitter statement here, - we're gonna try and update the status on Twitter hundreds of times every second. - That's not what we want. - So we need some way to meet her that, - and do it on a time interval So what we'll do is what I have. - One more. - If here we got a lot of ifs, - we'll say if, - just like we did a above the current time minus blast Tweet is greater than or equal to 10 - seconds. - So it's been 10 seconds since we've last updated. - Then we'll go ahead and update our status and so that we don't have a repeat. - We'll reset the last tweet time to now and remember, - we need to make this tweet unique. - So let's create some text right here. - We'll say status text equals. - And let's just use the date to help make our status update uni. - So we'll do stir f time so form at the time. - If we use this percent Capital X, - that'll give us the military time, - including seconds. - And so that should be good enough. - We do that and we need to format the local time, - and then we'll just add right here. - I detected motion and then, - while we're at it, - what we go ahead and say by the way the current temp is, - and then what we'll do up the end here is we'll do a stir on our current temp variable - remember, - we're taking that every five seconds. - That's just above that. - Should work. - And then for the status will say, - just set this to the status text. - And because we use this last tweet variable, - we need to come up here right where we do our in our initialization. - We'll just set, - uh, - last tweet to right now. - Okay, - That should do it. - So let's go ahead and exit out of here. - Yes, - and let's redness. - We have to make sure system is armed. - So go ahead and do that, - then will wait 10 seconds. - And once the 10 seconds sir up, - we should be able to do a little bit of motion in front of the sensor and get a status - update on our Twitter account. - So I think that's been about 10 seconds. - Let's go ahead and try this. - Okay? - The led came on. - I have an error in there, - so it's go ahead back in. - I forget use local time is a function. - Let's come all the way back down here. - Oh, - no. - I did call this function. - I misspelled it. - Okay, - there we go. - Local time. - All right. - Save that now. - When we run this again we'll get that warning because I rescript ended prematurely last - time as it sets up the GPO channels. - I will see that there. - That's OK. - It's still running. - Uh, - it's still armed. - I left the switch in the armed position, - so we just need to wait that 10 seconds again. - Okay? - Early D came on and I'll go ahead and exit from our script here and now that's left is to - come over. - I'll move this out of the way and see if our Twitter feed updated. - Let's go ahead and reload this page here and here. - We have our tweet. - It's got the time in front of it. - The text that we put in there, - 68.45 degrees Fahrenheit. - We could have formed out of that a little better and put the F in there. - But you get the point here. - We have completely integrated with Twitter. - We can do lots of cool things now. - I mean, - use your imagination. - You could track the temperature and tweet every hour with the average temp Has been you - could do things like threshold monitoring. - You could say if it gets above 70 degrees, - send a tweet to my feet. - If it gets below 60 degrees, - send a tweet things like that. - So hopefully you find this interesting and that you've got some ideas now that you can - integrate into your own application. - As always, - if you need help or have questions, - the best place to go is on the skill share website For this class under the community tab, - you can also reach him via email or find me on Twitter. 25. Conclusion: - We've covered a lot in this class. - We've gone from having a raspberry pi right out of the box to having a device that can - detect temperature and motion and even communicate on Twitter. - I really hope you've enjoyed the class and have learned some things that will help you - create your own projects. - One thing I failed to mention is that once your hardware is finished, - you can clean up your bread board. - You may have noticed that we had wires everywhere. - Once things are working, - you can clean up the connections with wires, - cut the size or even do that along the way is your building. - I like to wait until the very end, - just in case I decide to relocate something. - Here's what my board looks like after cleaning things up. - I really hope that you apply the things you've learned in this class to make some amazing - projects for yourself. - I wanted to a quick recap of the different protocols we used and list some additional ideas - that you could implement with each. - We started off with the basic input output functionality of our header pins in the class - project. - We use that functionality to turn led on and off, - detect the state of a switch and button and even read the state of our motion sensor. - Basically, - anything that communicates an on off state or can be controlled with a simple on off state - is a good fit here. - Things like relays will allow us to turn big things on and off lights, - appliances and motors. - Just name a few. - You can actually control your home furnace and air conditioner with just a few pins - controlling on off states. - The two communication protocols we covered SP I and I two C will allow you to talk to just - about any module you can imagine. - We use them to talk to a display and temperature sensor, - but that barely scratches the surface. - Their sensors for humidity, - gas, - altitude pressure, - color, - light and many more. - And these protocols aren't just for traditional sensors, - either. - You can use them to talk to things like barcode and fingerprint scanners, - GPS modules and or, - if I D readers, - you can use the principles and patterns we followed in this class to connect almost - anything to your raspberry pi. - And whatever the project, - maybe I'd love to hear about it as a reminder the final code for this class project is up - on Get Hub at the link below. - I've also included the link in the resource section for this year to help you in your own - projects. - Have attached a simple cheat sheet of tips and reminders that you can download and have - handy when you work on your own projects. - If you have questions or just want to share an awesome project, - you're always welcome to contact me via email or Twitter. - But please also post on the community tab for this project on skill share so others can - benefit from your work again. - I want to thank you for enrolling in the class and I invite you to keep learning, - have fun and start creating.