.Net Foundation .NET Conf 2018, 9 Oct 2018

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From YouTube: S314 - Have Your Pi and Eat It Too: .NET Core 2.1 on Raspberry Pi

Description

The open source, cross-platform design of .NET Core opens up all kinds of new possibilities for .NET developers. This talk teaches the attendee how to install the .NET Core runtime on the ultimate IoT platform, Raspberry Pi and unlock the potential of IoT devices for .NET developers!

A

Hey everyone we're back with that Netcom, so we did a little troubleshooting and it seems like Miguel just muted us. He was all the way down that we couldn't hear us well.

B

I would probably mute me myself. Do.

A

You know what I mean yeah.

B

I know fine, it's true. That's true.

A

But the content was so good and I would talk it with cam. So for our next speaker was right here say: hey, say: hi cam, hey everybody, so we were like talking behind the scenes like well. Let me go I'll do Miguel stuff and then we'll come back and go about it. But anyway, now we've got cam. I'm hearing down and calm talking about half your raspberry. Have your pie, I! Need it too. Let's talk about that camp.

A

C

So before we start hey Miguel, if you're watching man I'm so sorry, I had to cut you off, I was really digging your talk. So one of the most exciting features of dotnet core is its cross-platform compatibility. So this applies not just the server and desktop environments, but also to IOT devices. Raspberry pi is arguably the ultimate IOT platform because it packs a very broad range of functionality into a credit card size device, that's affordable for students, hobbyists and professionals.

C

So what we're going to cover in this talk? Let me share this.

C

Where's my display hey there, we go.

C

What we're gonna cover is we're gonna talk about the basics where's my slide there. It is so we're going to talk about developing, deploying and debugging dotnet core code on the Raspberry Pi. There's a lot less that goes into it. Then you would think this is actually gonna seem kind of 100 level stuff. Then we're gonna talk about GPIO GPIO stands for general purpose, input and output. It refers to this header here on the motherboard. It's a collection of pins that we can use for all kinds of input and output purposes.

C

What we're going to use it for today are some pretty simple demonstrations: we're going to control an LED and we're going to control a reversible motor, we're going to turn a motor on and we're going to be able to make it go forward or backward, and then, after we played with the GPIO pins a little bit we're gonna. Take it a step further and use our IOT device on the internet, we're going to integrate a few components with some cloud services.

C

We've got a sensor that we're going to use to alert us when a door is open or closed, and the final thing we're going to do is we're going to control an array of LEDs using Cortana here on my desktop. So with that, let's start at the very beginning: hey.

A

Cam really question mine, quick question: Jen wants to know what version of the Raspberry Pi you're using so.

C

I'm using a Raspberry Pi 3 model B, not the B+, although the B+ is a very incremental upgrade over the B. It just has at it's like a rev on Bluetooth and it adds a power over ethernet header. Oh wow,.

D

C

Yeah we're using yeah so we're using the three B, but the demos that I have out on github and I'll share that link in a little bit should work on should work on the two. The three the freebie I, don't know about. The zero I haven't tried it on the zero, but I'd be I'd, be interested in hearing what what what your experience is with that awesome.

A

C

So sure so, I'm gonna jump right into a demo. I'm gonna show you how easy it is to get dotnet code running on the Raspberry Pi. Now I'm not gonna, go through. You know where to get the Raspberry Pi and the operating system and all that it's out there on the internet. It's easy to find we're. Gonna start where I've got a Raspberry Pi device sitting here on my desk, it's connected to my network and it's running the raspbian OS with SSH and abled. So all we need to do is write some code.

C

So, let's get to it so I'm, just gonna pop open, a new visual studio window here and we're just going to file new project.

C

Asp.Net core web application and I'm gonna call it PI demo ah I already have a PI demo folder how about PI demo 2, that's creative.

C

I'm just going to take all the defaults, so it's going to be an asp.net core, 2.1 razor web application.

C

All right, so that's done. There's really no need to review this boilerplate I'm sure anybody who's done an asp.net core applications seen it all I think I will go ahead and we'll just change some text on the index razor page. Just so we can say that we changed it.

C

There we go and let's run it locally, real quick to make sure it works and that I didn't somehow break anything.

C

All right, so that's it's working, that's fine! Now we need to get it on to the Raspberry Pi well to get it on the Raspberry Pi I need to package it up as a deployment. First, there are two ways we can do deployments in dotnet core, there's a framework dependent deployment that expects the framework to be installed on the operating system or there's a self-contained deployment that has all the dependencies, along with the executable I'm going to go with the self-contained deployment. So I don't have to worry about getting the dotnet framework.

C

The dotnet core of runtime and framework installed on on my device.

C

Now I could package that we are in PI demo. 2 I could publish that rather dotnet publish are for to make it a self-contained deployment targeting Linux arm and that that will work that that will do exactly what I want it to. But since I use a Visual Studio to build the application, it seems to me, like I, should probably use Visual Studio to at least publish it before I before I FTP it out to the device. So, let's take a look at how to do that.

C

Really quick, just like publishing to Azure we're going to right click on the project and go down to publish but I'm, going to publish to a folder I'm going to put this folder I'm gonna put it in the root I'm just going to call it a PI demo pub and then we're going to set a few Advanced Options I'm gonna go with the debug configuration because I'm gonna be showing you debugging here in a minute target framework. Is that is net core app one deployment mode is not going to be framework dependent.

C

It's going to be self-contained and target run time when you'll notice, Linux arm isn't in the list. That's okay, I gotcha, we're gonna pick Linux x64 save the profile and create it I'm going to go ahead and rename it just so. I I know what the file name for the profile is: we're gonna, rename it a PI profile.

C

Now, before I click publish I'm going to come over here to the by properties node under the project and there's a folder for published profiles. If we look in there there's my PI profile- and this is the profile and there's the Linux x64 runtime identifier, I'm- going to change that to Linux arm, save it and now I can come back over here then I can click publish and it's going to do its thing.

C

All right, so it's done. Let's see what we've got. I've learned a code and I put it in C pi demo to pub. So there we go. We've got a whole bunch of files in here. We've actually got 355 files in there, but that's that's everything that our application needs to run on the device.

D

C

Ftp that out there, because it's gonna take a few seconds to transfer and before we look at the files, hey.

A

Cam yeah there's a couple questions in here that we were wondering Skullcrusher for life. It's asking: if you're self-contained will it package the required dependencies there in saving space on the Raspberry Pi.

C

You know I, don't know of all the deployments I've done it does seem to grow if I'm doing asp.net versus say a console. So I'm inclined to say yes, but to be honest, I haven't looked that closely: I I. It is a bigger transfer from asp.net, so I'm inclined to say yes and I'm, hoping that somebody has a more definitive answer. Gotcha.

A

C

Just blow up when someone's.

A

Saying is there performance difference between publishing a self-contained framework independent, so I.

C

Would assume that framework.

A

Independent II bigger, though, would you.

C

Well, I wouldn't assume, there's any type of a performance difference. It's the same. It's the same binaries that are being read in at runtime, it's just whether they're located in the same directory, as has the the assembly or whether, whether they're off somewhere in like a global. You know like in a path, location, somewhere, perfect.

A

C

Right well, I see another question just popped up who wants to know which of us is running on the Raspberry Pi and that is I'm running the latest version of raspbian Linux, so yeah, so we're gonna grab this publish location. Where was it? Where did I call I probably need to refresh locally there? It is PI demo pub and I'm going to connect to my raspberry pi over SFTP and FileZilla. Filezilla is an open source file. Transfer client I actually have a profile already set up. Sftp uses the same username and credentials as SSH.

C

So when you set up your PI and you go into the configuration tool to turn on like Wi-Fi and things, you'll also want to turn on the SSH service. Let's make a little location, so you see we're in our home directory for the PI user. I'm gonna make a location to store that will just call it PI demo, actually PI demo.

C

There we go and I'll come over here, ctrl a drag and drop and let it go- and this will take a couple of seconds it's about ninety three Meg's total with all the dependencies a while.

C

That's doing that, I want to come over and I want to actually look in that folder, and we see a lot of things that you would see in a typical asp.net core deployment right like your app settings, dot, JSON files and we go down and there's a whole bunch of dll's and pieces of the framework and compatibility shims for linux and all kinds of things, and then we get down- and we see like we have PI demo, DOL and PI demo views DOL.

C

Those are also what we would expect to see in a razor app, but we also have this file right here. This file that has no extension, PI demo, no extension, that's actually the executable file, that's actually what we're going to run in Linux, there's, probably a term for that I'm, really more of a windows guy anyway. So I. If there's a terminology terminology there that I'm not aware of I'd love.

C

For somebody to tell me, but all right, so our file transfer is done, so we should in theory, be able to SSH out to the shell on my Raspberry Pi.

C

C

Should be able to run it right? Well, not so fast, here's, let me go ahead and type in the command. Pi demo permission denied if you're not familiar with Linux Linux has a mechanism whereby we don't just run any file willy-nilly. We have to give files permission to run the way we do. That is the chmod command, so I'm going to give it permissions.

C

So now it should be able to run.

C

Give it a few seconds to jet.

C

All right, it's running now, I can't look at the website yet, though, because we're running as a as a Kestrel applicant whoops wrong wrong zoom it we're running as a Kestrel application and Kestrel by default. If you don't tell it otherwise is only listening on the loopback adapter localhost port 5000. So we can change that right. You can change it in code.

C

We can go to you, know the the programs dot CS and come in here and when we're creating our web host, we can add a dot use, URLs right, for example, but what we can also do is just at the command line when a ctrl C to end the program and I'm going to run it again. But this time I'm going to pass in a switch URLs, HTTP, HTTP colon, slash, slash star, so every adapter port 5,000.

C

Alright, so now we're running and we're listening on all the network adapters on the device, so we should be able to go to my browser and I should be able to go HTTP colon, slash, slash, Raspberry, Pi, port 5,000.

C

Well, that wasn't what I wanted.

C

Why are you searching edge? You should not be searching. You didn't search earlier.

C

There it goes, it's loading this time.

C

All right so there's our website running on the device. So that's really all there was to it. I mean dotnet core is cross-platform. We really should be able to pick up an application and run it on any platform without any significant changes.

C

Now debugging the application is where it gets just a tiny bit trickier, but it's still not that difficult I'm going to leave the application running. I'm gonna come back over to Visual Studio I'm gonna get rid of this little change. I made.

C

There we go and we're going to go to debug and attach to process and in the connection type, when you come in here, it's usually gonna say default. It's going to list all your local processes, but we're going to select SSH in the connection target is going to be your username at the network. Address and.

C

It'll prompt you for a password, it's not gonna prompt me because it's got my credentials. Cached already, but I'll hit enter and there's my list of running processes on on the Raspberry Pi, there's PI demo 2. So we can just attach right to him.

C

It asks it's asking us what type of code we're debugging. So this is managed code.

C

I'm looking at the while, it's attaching I'm looking at the chat, yeah I do have like a foot tall, Deadpool characters standing here on my desk by the way, all right. So it's running, let's set a breakpoint real, quick I'm gonna go into the razor page and when I set a breakpoint where it drops out of the on get method. So in theory we should be able to come back over here to our browser, refresh the page and hit the breakpoint.

C

So it's gonna take a couple seconds this first time because there's a little warm-up involved, but pretty quickly we do hit the breakpoint all right. So let's continue I'm gonna hit refresh again.

C

You notice it hits the breakpoint much quicker that time. So that's how we debug in Visual Studio. You can debug in Visual Studio code too, but there's a little bit more involved. There's a dependency that you have to install on the PI and I've got a link to a walkthrough to that on the github page. For this talk, I'll be sharing that URL later alright.

C

So that's pretty much all we need to do to get an asp.net core app running now. I want to talk about some of the device, specific features of of the Raspberry Pi, specifically GPIO. Right now, before we start talking about GPIO, we have to talk a little bit about just a tiny bit about Electrical Engineering. Now let me preface this I am NOT an electrical engineer. There are probably plenty of you in the audience who have way more experience in electrical engineering than I.

C

Do I'm, probably going to mess up terminology and for that I sincerely apologize feel free to correct me in the chat or Twitter or whatever.

C

So the hello world app when it comes to GPIO, is blinking an LED to do that. I'm using a few devices here that I want to make you familiar with the first one. Is this little blue thing right here on my device? It's black on one I, think it's green on another one, but it's it's called a cobbler or a breakout board. The idea behind this cobbler or breakout board is that I can hook on the Raspberry Pi itself.

C

A ribbon cable that connects the GPIO header to the header on this cobbler and then plug the cobbler into a breadboard which makes it easy to connect wires to these various pins on the Raspberry Pi and have a visual representation of what I'm connecting to now the breadboard itself. If you've never used a breadboard and breadboards were new to me until recently, the breadboard itself is a device. That's used for prototyping circuits without doing any soldering, which is really handy for me, because I'm awful at soldering.

C

So the way it works is all these ports on the breadboard are connected to other ports on the edge we've got ports running down the length of the device and in the middle we've got ports that run on either side of the median.

C

And what this allows us to do, like I said, is to plug our cobbler into the breadboard and then use jumper, wires and kind of play operator. You remember the old cartoons where the operators would plug in the the plugs into the switchboard, and it's kind of like that again I'm not going to go into the circuit or why the LED works or why there's a resistor there or anything like that. But what's important is to know that to turn on the LED I need to turn on GPIO 17.

C

That's pin, 17 I, just arbitrarily picked, pin 17, there's no reason to pick it over any other. One I just arbitrarily picked that one and it feeds power to this rail down here on the bottom, which feeds power to the resistor which feeds power to the LED, which is connected. The cathode the out, pin on the LED is connected to this row right here, which goes back to the ground pin on the header.

C

So that's the circuit now before I show you the code. That's going to run this circuit I need to show you a feature of the raspbian operating system, that's fundamental to how the code works. So, let's drop out of the slide here and I'm gonna go back over to my shell and what I want to show. You is a virtual file system, location on the raspbian operating system, so this slash class, slash GPIO and what this file system location allows us to do. Is it allows us to control our GPIO pins directly through the shell?

C

Let me let me demonstrate so. If I look at the contents of this directory, we have a few different locations, we locations and export and export, and we have three representing GPIO chips. We're just concerned with export and unexplored at this moment now to open, pin 17 I'm, going to write the text 17 and I'm going to pipe it to that export location.

C

So now, if I look at the directory contents notice that I have right here, a GPIO 17 location.

C

So if we change our directory to GPIO 17 and look at the contents, we have a few other locations and what we're concerned with here are direction and value. So whenever we open a pin, we need to set a direction. We need to tell the device whether to it's whether to generate current or expect current coming in to the pin like a ground pin the way we do. That is we write again.

C

We just write a text value and in this case out, we want the pendant generator current echo out to direction alright, so Direction is out and then we can turn on the LED turn it off and on by writing, 1 or 0 to the value location. To show you an actual breadboard with the LED I've got a low camera rig here. I actually had to do a little bit of a Rube Goldberg contract' contraption, where I'm remoting into another machine driving the camera, because Skype does not like this camera, and you can see that this.

C

This circuit is exactly the same as it was on. The schematic. I showed you a second ago: I mean I've, got it plugged into pin 17 the blue wire right now to the wire color. I really wanted to make it. So you could reconstruct this at home without too much effort, so so yeah. We should be able to just write, 1/2 the value and it should be able to should turn the LED on. Let's, let's try it echo 1/2 value.

C

There we go, we turned on an LED now, let's turn it off.

C

There we go and then we can close the pin by echoing 17 to unexpecting.

C

17 has been closed, so how do we do this in dotnet? Well, there are api's to do it.

C

Certainly now I did not use any of the other api's that are out there and we're going to talk about that later near the end of the talk I actually rolled my own and this GPR GPIO dotnet project in the demos folder on the github repository for this talk has a GPIO pin class, but in that class we just have three properties, number direction and value, and we'll come back to the getters and setters for value here in a second, when we initialize the object, we are requiring a pin number in a direction in the constructor right and we're setting those right off the bat and we're writing those out to that location.

C

So we're opening the pin then later on we're setting the direction and then we're setting a default value right. So we have an optional parameter on the constructor that that sets a default value of pin valued low wait-wait-wait low. What's that mean we talked 1 & 0 well in in in GPIO terms. High is one low. Is zero I? Don't know why all right! This goes back to me, saying I'm, not an electrical engineer. I'm sure somebody in the audience can probably tell us why.

C

But, but that's that's the terminology, so that's what I went with the other thing that this class does is in the event that we set pen Direction in, in other words, we're expecting current, so we're gonna watch to see if the circuit is broken. I kick off a task, asynchronous tasks that I call pin watcher just actually polls the value, every 10, milliseconds and fires off an event. If, if the value changes to either high or low, why am I polling there?

C

Why didn't I use like a filesystemwatcher, well I tried using the filesystemwatcher, and it doesn't like that virtual file system thing so I had to use kind of this hacky clootie method. There is an API out there that will do it kind of the right way directly in memory, but it's not quite baked yet and we'll get to that.

C

So my hello world led program. Where was the code for that there? It is all it does when we run the code. Is it's going to new up my GPIO pin class with pin 17 Direction out and we're gonna loop five times we're gonna turn it on wait. A second turn. It off wait a second! That's all we're gonna do now: GPIO pin it implements I disposable, because I made it I wrote it in such a way that it is considerate and closes the pins that it opens.

C

So we want to use the using pattern to make sure that we dispose of it properly. So with that I've already got it built, I've already got it deployed. Let's just go ahead and run it.

C

Let me get the breadboard up where we can see it there we go.

C

And sure enough, it works alright. So on one hand that's pretty cool. We can control an LED through hardware that you know kind of like low level on the metal hardware, but on another level big deal, we turned on an LED right, well, that little piece of functionality being able to open and close a pin, open and close a circuit like that gives opens up a whole world of possibilities for us. Let me illustrate.

C

The next demo I'm going to show you is this circuit now I realize this circuit looks kind of nasty. He has lots of wires and relays, and things like that. It's really not that bad I'm actually switching out my breadboards, while I'm talking so I've got to relay modules attached to attached to my breadboard, and what we need to take away from this is that the first relay module the one on the top there. It's only using one of its two relays, because these are dual relay modules.

C

It's connected to, pin, 21 and all it does is open and close. The circuit turn this motor on and off. That's all it does now the other one. The the second relay module has two relays on it and we are actually using both of those. But what I want to point out is that they are both hooked up to the same pin. In fact, let's zoom in a little bit there you can see those are both hooked up to pin 27 both of them. Now. Why would I do that?

C

Well, the reason I did that is because I wired this circuit in such a way that, when these two relays on the second relay module are turned off power flows, one way through the circuit and then when we have turned them both on. At the same time, we use a different set of wires and power flows. The other way reversing the polarity of the motor okay.

C

So we're going to I see somebody likes my zooming. Oh, it's Scott, hey Scott! You, like my zooming skills, huh so I'm going to switch out. Let me plug in this breadboard.

C

Really quick this again, this breadboard is exactly what's on the schematic. I showed you right down to the wire color I paid a lot of attention to detail. I 3d printed a little bushing to hold my motor, so we can make it more visible for you and I put a little spinner on the on the shaft. So when the motors spinning, you have a visual representation of it, so let's take a look at the dotnet code that goes along with that real quick before we run it.

C

This is the motor project in the demo solution, we'll start with the motor class. The motor class is actually really simple when we knew it up. We pass in in the constructor a power pin number and a polarity pin number, and we knew up those GPIO pins and notice. We set a default value of pin value hi. Why on earth? Would we do that? Well, it has to do with the way the relays are expecting current from the device.

C

It turns out that my relay modules expect pin value high to be on and pin value low to be off. It's just how the how the relay modules were designed so I'm, just rolling with it. So when we call on we set, pin value to low turns the motor on when we call off, we set high, turns motor off and then I just arbitrarily chose high and low for forward and reverse the program code that launches that motor class I just made a little command-line interpreter right.

C

So it news up the motor using the the using high disposable pattern again and sits in a loop looking for commands, on/off, reverse forward and exit and those are all pretty self-explanatory. So let's go ahead and run it need to put the breadboard where you can see it there. We go.

C

I know it's a directory executable! Please there we go all right, valid commands, on/off forward, reverse and exit. So let's try on motors spinning. Alright, let's reverse it.

C

Alright, it's going the other way. Let's go ahead and just turn the motor off so you'll notice. It's still reversed and the the relay that controls reverse and forward is it works independently of the relay that controls on or off so we can set it back forward again. Turn it on again.

C

So that's a practical application beyond just turning a light on and off. We can actually turn like physical things on and off motors. You could connect relays to lamps to you these relays actually support up to 15 amps on a 110 volt circuit, so you could control your your your your household lighting with one of these, if you were so inclined alright, so we've put the things in Internet of Things.

C

We've been looking at the GPIO pins, but this is all everything we've done so far has been constrained locally to my Raspberry Pi right here on my desk. What I want to do now is I want to show you a few projects that I did to give you some ideas of things that you can do with this using some services out in the cloud and to start I'm gonna dive right in with that door. Alert sensor, I told you about now. Let me switch out. My breadboards bear with me for a few seconds.

C

All right, hey, cam, so what I've got now.

A

C

A

Loving you, this is amazing,.

A

C

Appreciate that you never know how a talk is going to be received until you do it, and this is a brand new talk, gentlemen.

A

C

Appreciate that alright, so what I'm gonna show you now is we're actually gonna use, pin direction in right, we're gonna, Mott we're going to watch a circuit to see if it gets, you know see if it's opened or closed and what I'm using are these little magnetic this little magnetic Reed switch. So the whole idea behind a reed switch is when the magnet is present. The switch is closed. So the circuit is connected and when the magnet is not present, the switch is open.

C

So the circuit is disconnected and let me zoom in a little bit here so I can show you. You can't really make out the text on the breadboard, but the blue wire is three volt power and that's going to the read, switch and then pin twenty right. There is that's going to be in that's going to be what's watching to see if the power is coming into the pin or not and firing off events in our code.

C

So let's look at that code. Real quick, so we understand what's going on. This is the door watcher program.

C

So I'm gonna skip right down here to main and all I'm doing is I'm mooing up that pin on port 20 direction in and I'm wiring up a couple of events, contacts which high in contacts which low. If we go look at those two events, they both do practically the same thing. They pass a message off to a method called post status and what post status does? Is it kicks off an asynchronous tasks that serializes a message and if you're wondering what that, what the what that looks like there's not much to it.

C

It's just a single property on that class. It serializes that message to JSON and it posts it to an azure logic. App now I chose an azure logic app for this because they are dead, simple to set up. We can go look at it real quick. This is the logic app it has. It has a single trigger and a single action.

C

The trigger is just an HTTP web hook, so you saw back in back in the code, I'm I'm posting to a HTTP location and there's the the schema for the message that Matt matches the class in my in my project and then what it does with that message. There's a billion different connectors that we can choose from in in logic. Apps I chose slack in this case, just because it would be easy to show here on the screen share, but you could use something like Twilio. You could log it in an Excel spreadsheet.

C

If you want to know who came and left your office all day, you could set that up and I'm not who, but what time people came and left and I have one the doors open you could you could rig up a home systems? You could do stuff like that and make it go to your phone, go wherever that's kind of kind of the magic of something like logic apps.

C

So, let's look you can see where I was I was actually trying this earlier, I meant to reset this. This is my. This is my slack room right here and go back to the GPIO. Let's move this over here I exit, my motor program, whoops.

C

There we go and let's run the door watcher program all right. So now it's waiting for the switch, so you can see up in the breadboard I'm going to put the magnet next to the switch. It's gonna take a few seconds to wake up the logic app the first time, but after that it's basically sub-second.

C

So there we go, there's a a a home security system made with a Raspberry Pi and a $5 reed switch.

C

Okay, now, for my final demonstration of cloud integrations that we can do I want to actually use Cortana to drive like I said: I have an array of LEDs that I want to be able to instruct Cortana to turn these LEDs on and off. There's a problem with this, however, and I've got a slide to illustrate that the problem is that the way this is going to work is I'm actually going to do this with the Cortana integration on IFFT. If this than that, it's a it's a service, it's a lot like logic, apps!

C

It's it's a lot simpler though it has a single trigger and a single action. If a happens, then B and Cortana actually has some actions out there that are pretty robust. That are really easy to use. I'm going to show you that here in a second, so my thought was well, we could trigger Cortana. We could invoke Cortana dotnet Bhatt is gonna. Help me with that.

C

If I can there, we go we're gonna invoke Cortana and that's gonna set off the trigger in IFFT right and then, if could maybe fire off a web hook to hit a web api on my Raspberry Pi right I mean that seems to make sense. The problem is we're here in my home office, we're behind my firewall. I could open a port on my firewall, but I'm not gonna.

C

Do that and what, if I, was in a location where I couldn't open a port on my firewall, so there traffic's not gonna, get through and that's not going to work. So we have to come up with another solution. So the way what this is going to work is we're going to use a couple. Other services we're gonna, use an azure logic app and an azure service bus message queue and the way it's gonna go is when we first start the application.

C

It's going to make an outbound connection from behind my firewall to the message: queue where it's gonna watch the queue and it's going to wait for new messages. Then, at some future time we can invoke Cortana, which will fire off the trigger on. If this than that, which will send a we use a web hook and post the post that web hook on another Azure logic app, which that logic app will in turn, create a service bus message and put it on the queue where it's immediately picked up and acted on by our application.

C

All right, so I'm gonna walk through all the code on that and then we're actually going to demo. It.

C

Close that so, let's start with the service bus queue, there's actually nothing to the service bus queue. I already have a service bus, namespace, I created, there's no I I just took all the defaults and then there's two queues I put in there. I had one for another demo that I'm not that I I am NOT going to be doing and I have this one here called Cortana. There's all default. I made no changes whatsoever, just a file new. Basically now the logic app. Let's check out that logic, app.

C

That logic, app again, is pretty simple. It's pretty much the same as the other one. We've got a web hook here right with a simple schema: that's expecting a single property called color and the action that that logic app is going to take. Is it's going to send a message to a service bus queue named Cortana and I've already done all the wiring up and it walks you through it the first time you you set it up?

C

Okay, so that's the that's the add the to Azure components, that's the service, bus queue and the logic app. Let's go. Look at the dotnet code, really quick.

C

Don't don't do this by the way? Don't don't hard-code your connection, strings I was rushed. I was rushed. You put your connection strings someplace where they belong. Please.

C

So what we do is we open up these three pins and then we connect to the service bus queue and we watch it. We register some handlers to handle the handle the messages as they're posted and then we, we just say: okay, we're waiting for kirtanam. Now the handlers are actually pretty simple, they're, very similar to the to the door watcher app. Actually, the same kind of thing where all we're doing is we're.

C

Looking at that message right and we're looking we're doing when we get down to the process color text, it has to go through several levels of of process messages and handlers and so forth, but when it gets down to process color text we're just looking if it's red, we turn on the red light. If it's yellow, we turn on the yellow. If it's green, we turn on the green again.

C

You're gonna say okay, but why is this pin value low and not pin value high I'm gonna explain that in just a second, this one's actually pretty easy to understand for me anyway, and then, if, if it's not red, yellow or green we're gonna blink, all the LEDs is kind of an error state to say hey this: isn't this isn't a color? You asked for purple and we don't have purple.

C

So the final thing that we need to do to get this all wired up is we need to set up Cortana and if she thinks I'm talking to her hold on it there we go so I've logged into my IFFT account. We're gonna make a new applet, I'm gonna say if this- and this is going to be Cortana.

C

We're going to say a phrase with text: what do you want to say I'm going to say turn on the, and then you see it says down here that says down here that the dollar sign is the token for the for the text ingredient. They call it so the text that we want to pass on to the to our action, so we're gonna, say turn on the dollar sign light. Also just add dollar sign light. Please is another option and what do I want Cortana to say in response? How about? We have her say sure.

C

I'll send a message to turn on the dollar sign light.

C

So there's our trigger yeah I, see out in the chat they're asking where's the device integration this this is. This is poor man's Cortana integration you're! Absolutely right. We can. We could write Cortana code to live on a PI device using the Windows IOT, but this is more I'm going to use some some integrations from my desktop here to automate stuff like in my house or office or whatever so the trigger was Cortana, and then that is going to be a in this case. Another webhook.

C

We're gonna make a web request and I have my web hook URL over here. My notes.

C

Authentication is baked into that. Url has a believe, an OAuth token in it going to posts, application JSON and then what we're going to post the shape of that message is whoops wrong copy and paste there we go. That's the shape of the message. Just a single property called color.

C

And I don't want notifications.

C

So there we go, we made a new applet, it's all wired up and ready to go. The only other thing we need to do is we need to hook up the breadboard that has the LEDs. So let me do that very quickly.

C

There we go now, I told you that the reason that there's a very easy to understand, reason why we're using low, instead of high to turn on these LEDs and that that reason is the what's the hotkey for a line. So the 3.3 volt wire here is going to this rail, which is providing power to all these resistors, which are in turn providing power to the LEDs. And then the cathodes from the LEDs are connected to their respective ports. Since the cathodes, the outputs from the LEDs are connected to the ports.

C

The ports are going to be blocking the connection when they're high and when they're set to one but they're going to be allowing the connection when they're set to zero. So that's why low is going to turn them on and high is going to turn them off. You'll notice, also the red and the yellow happen to be glowing a little and I think the green is to is just not coming through on the camera. That's because we haven't opened the pins and there's just a little bit of background voltage flowing across the pins.

C

Yet when we open the pins in the raspbian operating system, you'll see that those that little glow will go away. So let's just go ahead and run it. It should all be Y up and ready to go now.

C

Alright, so let's try this hey Cortana turn on the green light.

D

To turn on the green light, there.

C

We go it was that quick, let's try it again: hey Cortana, oh yeah, sorry I've got I clicked when I shouldn't I've, hey Cortana I'll, just click turn on the yellow light. Well, now, I've gone and confused her.

D

Message to turn on.

C

The yellow light: alright, let's try a color that we don't have hey Cortana turn on the purple light.

D

Message to turn on the purple light.

C

Well, I, don't know how the I don't know how good the frame rate on the frame rate on skype is, but you should have seen all the lights blinking in quick succession to show that we don't have a purple light. One more thing: I want to try: hey cortana, a cortana. Oh she heard me say: hey Cortana twice.

C

My poor little surface is I. Can just hear the CPU burning, I'm, just gonna click, the mic. You don't have to put on the red light.

C

For those of you, young uns, that was a joke about the police. They were a really cool band in the 80s and you should go check them out on Spotify alright. So that is it for our integration, demos, which leaves us one more point of discussion, and that point of discussion is what now well I encourage you to go check out my github at that address right there github.com slash camp, so / / have your pie. There you'll find my notes with everything you need to know.

C

I've got links to where you can get the operating systems and some some advice about which devices to buy and and which components to buy, to build. These I've got all my schematics all my demos, including some demos that I didn't use, and all these slides I'll also put a link to this talk on that github. So you can refer to it in the future.

C

The other thing I wanted to talk about is you should go. Take a look at system, dot devices that GPIO. That is a package that is currently in pre-release. It is targeted for dotnet core 3. Oh, it is very early in development and the API surface is very likely to change before release. It's designed for all kinds of IOT platforms that use GPIO, Raspberry, Pi included, and it's kind of an easy one to feature because it's so ubiquitous.

C

There's a few there's actually a reason why I didn't use system dot devices that GPIO it mostly works, but the demo that I had where we were watching the read sensor. It locked up my Raspberry Pi, pretty consistently every time, I demoed it so I ended up not using it, but it is like I, said early pre-release, and it doesn't use that kind of hacky mechanism that I used in the file system. It does support pulse width, modulator pulse width, modulation.

C

So that's the ability to kind of ramp up and ramp down power on a pin, so you can make a make a make LEDs for, for example, you could make LEDs brighter or dimmer, and it also supports SPI and i2c, which are serial interfaces for talking to things like temperature, sensors and humidity sensors.

C

Finally, the team has asked me to point out to you guys that they're looking for contributors, if you're, if this is something that you're really interested in- and this is in your wheelhouse by all means- go check out their github and and send them a few pull requests. So with that I'd like to see if we have any other questions.

A

Hey cam, I think everybody's afraid of asking questions. You just literally drop the Mike here everybody's loving. Yet the vistas demo was on point like Hanselman.

B

Like literally, if I'm a little bit bro crushing on you, my friend just FYI just just have that in the back your mind while I'm saying this but like IOT demos are hard because I'm literally sweating bullets that things will not work. But everything worked amazing for you. But.

C

If there aren't any more questions, I just want to say I hope everyone found this informative and enjoyable and I really hope. You found yourself inspired with some ideas to go implement in your own Raspberry Pi projects. You can again check out my github check out my Twitter. You can always hit me up and I'll, try to help you out and and do check out the system, dot devices GPIO project, because that is going to be the official dotnet course support in the future. Nice.

B

C

B

I'm cam spired.

B

And I heard I'm too loud, so I will.

A

Keep it down thanks for taking the time talking to us, everybody, we're gonna, go to a quick break, I, learn about of functions in Azure and then we'll be right back with Jeremy our next presenter. Thank you. So much.