In this project we will use a LED as a notification when an obstacle is too close to our sensor.
We will learn how the standard I/O works with a GPIO in Android Things.
Requirements
We use a Raspberry Pi 3 with pre-installed Android Things Developer Preview(version 1).
I have a cheap Obstacle Avoidance Sensor and a Dual-color Common Cathode LED for this project.You can use any LED what you want, I had only this at home.
Setup
Google has a really good tutorial how to prepare your Raspberry Pi 3 for Android Things development, so I don’t want to describe it again.
Please follow the steps here:
Raspberry Pi 3 | Android Things_Raspberry Pi 3 Model B is the latest iteration of the world's most popular single board computer. It provides a quad…_developer.android.com
Wiring
So, let’s see our sensors.
The Obstacle Avoidance Sensor has 4 pins, we use only 3 of them. The 4th (Null), the top one is not in use.
As you see in the picture, the bottom one needs to be connected to a Ground (GND) pin on the Pi, the 5V obviously to a 5V power pin, and the Digital Output pin needs to be connected to a GPIO.
The Digital Output pin sends the signals to our development board if an obstacle is too close.
The LED module is a bit simpler.
It has only 3 pins, we will use 2 of them, but of course, you can connect all the 3 to your Pi for testing.
The GND connects to a Ground pin on your Pi, and the Yellow (or Green on some modules) and the Red input pins need to be connected to a GPIO (1 pin - 1 GPIO) on your board. (For this project one Input pin is enough to be connected.)
(If you have a simple LED, you have only 2 pins, 1 Ground and 1 Input pin.)
Here is how I connected the Obstacle Avoidance Sensor pins with the Raspberry Pi:
- Null →
- Digital Output → GPIO 21 (BCM21, Pin 40)
- 5V → 5V (Pin 4)
- GND → GND (Pin 20)
And here is how the LED pins connect to the Pi:
- GND → GND (Pin 34)
- Yellow → GPIO 16 (BCM16, Pin 36)
- Red → GPIO 20 (BCM20, Pin 38)
And this it how it looks together:(On the left side you can see a pinout diagram which illustrates the locations of the available ports exposed by the breakout connectors of the Raspberry Pi 3 board)
Software
Google also has a good tutorial how to configure your Android Things project in Android Studio.
Please follow the steps here:
Create an Android Things Project | Android Things_Things apps use the same structure as those designed for phones and tablets. This similarity means you can modify your…_developer.android.com
Now you have a basic, compilable, working Android Things application, so we can start adding the necessary code.
In our main Activity we can setup our GPIO pins:
Then we initialize the pin (BCM21) for the Obstacle Avoidance Sensor as an input (we read from this pin):
Configure the LED pins (BCM16, BCM20) as an output (we write to those pins):
And our GpioCallback(), which does the magic: (blinks the led, when the obstacle is too close)
And don’t forget to close the resources if you don’t need them:
That’s it! And the end result:
I hope you enjoyed the Raspberry Pi hacking with Android.
The full project is available on Github:
Danesz/AndroidThings-ObstacleAvoidanceSensor_Contribute to AndroidThings-ObstacleAvoidanceSensor development by creating an account on GitHub._github.com