Android Things GPIO Callbacks

Following the blog post to get you up and running with Android Things, Visual Studio and Xamarin.  http://explorationspace.co.za/2017/02/26/using-xamarin-and-visual-studio-with-android-things/

 

Android Things has GPIO callbacks which are triggered on certain trigger events.    This is great for event handling.    I’ve added a sample to Xamarin bindings which illustrates this by means of a Grove PIR (Passive InfraRed) sensor much like what’s in your home alarm system.   If we use that in conjunction with a buzzer, you have a primitive alarm system.

 

The source can be found here:   https://github.com/apead/Xamarin-Android-Things

 

Intel Edison with PIR and Buzzer

 

 

Gpio callbacks are classes implemented inheriting from the abstract class Gpio Callback.    This call back is triggered on certain trigger types.   This are set on the gpio pin with the settriggertype method.

  • EDGE_NONE: No interrupt events. This is the default value.
  • EDGE_RISING: Interrupt on a transition from low to high
  • EDGE_FALLING: Interrupt on a transition from high to low
  • EDGE_BOTH: Interrupt on all state transitions

 

 public class AlarmCallback : Com.Google.Android.Things.Pio.GpioCallback
 {
 public Gpio BuzzerPin { get; set; }

 public override bool OnGpioEdge(Gpio p0)
 {
 if (p0.Value)
 {
 if (!BuzzerPin.Value)
 {
 BuzzerPin.Value = true;
 Thread.Sleep(1000);
 BuzzerPin.Value = false;
 }
 }

 return true;
 }

 public override void OnGpioError(Gpio p0, int p1)
 {
 Log.Info("Alarmcallback", "Error");
 }
 }

 

The class has two methods to override.   OnGpioEdge and OnGpioError.     The OnGpioEdge method is called on a trigger event.     The OnGpioError is called on an error.

 

This class is registered on the actual input gpio pin.


_callback = new AlarmCallback {BuzzerPin = _buzzerGpio};

_alarm1Gpio.RegisterGpioCallback(_callback);

 

Happy Android Things development with Xamarin!

 

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Using Xamarin and Visual Studio with Android Things

Android Things is Google’s new IOT Android based platform.    In essence it’s a slightly altered version of Android which can run on Iot type devices such as the Intel Edison and the Raspberry Pi3.

 

“Android Things lets you build professional, mass-market products on a trusted platform, without previous knowledge of embedded system design.”

 

Personally I’m not yet too impressed with Android Things.   It is still very new and very raw and is lacking a lot of what you’d expect from an Iot platform.   However, having finally a standard Android implementation officially from Google running on these devices has to be a good thing.    The platform should just get better from here.

 

 

 

Running in Visual Studio using Xamarin

 

Of course being Android, Android Things works with Xamarin too.     Using Xamarin will also be a benefit for all those awesome cross platform benefits it offers, like sharing your Iot code with your backend services, Android, Ios, Windows Phone, Windows 10, OSX, XBox and whatever other devices you’d like to be supporting in your solution.

 

Getting the devices to appear in Visual Studio is exactly as you’d expect.    The devices will use the standard Android Debugging Bridge (ADB).      Plugging in an Intel Edison via USB will be reflected as “Unknown Iot_Edison”.    You can obviously also use the network debugging features of ADB.   eg.   adb connect <ip address>   The device will then also be detected in Visual Studio.   A Raspberry Pi will appear as “Unknown iot_rpi3”.

 

Using Xamarin is very simple.    All we need to do is bind to the Android Things API Jar to be able to make use of all the features provided by the Android Things SDK.   At this moment in time there isn’t an official release Nuget package from Xamarin to do this.   It is however very simple to do this yourself.     In this sample (and I’ve shared the code on GitHub) I’m binding to the new Dev Preview 2 API for Android Things (androidthings-0.2-devpreview.jar).    Once the binding project is referenced from your Android Things project, everything will work as expected.   Just of course with the benefit of using C# and not Java!

 

I’ve created some samples based on the Standard Android Things Samples

 

Samples:   https://github.com/apead/Xamarin-Android-Things

Blink Led

No Iot sample and demo is complete without a blinking LED.   This sample is a conversion of the Android Things sample.

 

 

Simple UI

This sample is a simple illustration of using a UI on an Android Things device.   It also illustrates GPIO pins and how to set the high/low values of the pins.

 

Simple UI Android Things Sample

 

 

 

Learning Resources:

 

SDK Samples:  https://developer.android.com/things/sdk/samples.html

How to install Android Things on your Device:   https://developer.android.com/things/preview/index.html

A great article on the basics of electronics and hardware:  https://riggaroo.co.za/android-things-hardware-basics/

 

Happy Android Things Development with Xamarin!

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Windows 10 IOT Remote Display Experience

With Microsoft Build 2016 complete, there are so many things to be looking at and trying out.   One of the more useful features for me right now is the new remoting functionality in Windows 10 IoT Insider Preview 10.0.14295.   I have this running on a Raspberry Pi 3 and I am busy with some work using an array of sensor telemetry.  Being able to see what is happening remotely make life far easier when building Universal Apps.

To configure this is very simple.    There is a new menu option added to the administration console called “Remote”.  This is accessible via the URL:  http://[ipaddress of pi]:8080.   If you haven’t changed the password the login should be:  “Administrator” and “p@ssw0rd”

IoT Remoting

Enable the Windows IoT Remote Server by ticking the box presented.

 

To access the Raspberry Pi remotely you need a client.   This is available in the Windows Store either by following the provided link, or just by searching for “Windows IoT” in the store.  https://www.microsoft.com/store/apps/9nblggh5mnxz

 

remote client

 

This will run on any Windows 10 device.   Just something to note: on a Windows 10 Mobile device (Lumia 950 XL in my case) you may have to set the device color scheme to light for the application text to be legible.  I’m sure this will be corrected in later builds.

iot client

Fill in the IP address of the Raspberry PI in the “Enter an IP address” text box and click / tap “Connect”.  You should now be seeing what the Raspberry Pi is displaying.

WP_20160403_16_42_25_Pro_LI
Remoting to a Windows 10 PC / Tablet
WIN_20160403_17_10_17_Pro
Remoting to a Lumia 950 XL

 

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