Beret

Beret is an educational project to program the Rainbow HAT on Android Things using a visual language built on Blockly (which is a library from Google for building beginner-friendly block-based programming languages)

You can write the code directly on the Android Things device, or you can write it on an Android phone or tablet and send it over using Nearby

There are a few similarities between Beret and Micro:bit, both are great tools to introduce coding that interacts with hardware. Beret is intended to be an introduction to Android Things, but you can just use it as it is.

Using Beret

There are 2 main ways to use Beret: Directly on a developer kit or with a companion app

Using Beret directly

When you use Beret direclty you write the programs in the same device that runs them, which has certain appeal. For this you need an Android Things developer ket installed with Beret (see next section for options) and a way to interact with it.

For a Raspberry Pi a common use case is to attach an HDMI Monitor and a mouse (and optionally a keyboard).

For an iMX7D a common use case is to use the touchscreen included with the development kit.

Using Beret Editor

The other option is to have a developer kit withouth any screens and use a tablet with the Beret companion app to write the programs. When you press run the program is sent to the Android Things developer kit using a nearby connection. It takes a bit longer but it is handier.

Note that at the momnent you have no way to select the target developer kit, so if you have more than one it can be disconcerting.

Installing

You need to have an Android Things developer kit. You can use a monitor, keyboard and mouse connected to your dev kit, or you can use the companion app on a tablet to create your programs. You have a few options, I suggest you take the easy way.

The simple way

• Flash the Beret Android Things image for Raspberry Pi or i.MX7D into your developer kit using the setup tool
• Optional: Install the mobile app in yout tablet or phone via Google Play
• You are good to go

How to flash an Android Things image on a Raspberry Pi

The easy way

Prerequisites:

• Android Things developer kit setup
• Android SDK installed

Steps:

• Install the Beret things apk into your Android Things Developer Kit usig adb
• Optional: Install the mobile app in yout tablet or phone via Google Play
• You are good to go

The slightly harder way (if you like compiling things)

Prerequisites:

• Android Things developer kit setup
• Android Studio installed and configured

Steps

• Clone the repo
• Open it on Android Studio
• Compile and install the things module to your Dev Kit
• Optional: Compile and install the mobile module into a phone or tablet to be used as editor

Available Blocks

The list of currently available blocks for the Rainbow HAT is:

Buttons

• when [Button] is [pressed

  released

  changed]

• state of [Button] : Boolean

LEDs

• set [Red

  Green

  Blue] LED to [Boolean]

• state of [Red

  Green

  Blue] LED : Boolean

LCD display

• display text [text]
• display number [number]

Sensor

• temperature : Float
• pressure : Float

Piezo buzzer

• play frequency [Number] Hz
• stop playing

RGB LED Strip

• display colors [list]
• display colors [array of colors]
• display colors [array of colors as insets]

Functional blocks (hooks)

• when program starts
• repeat every [Number] milliseconds

Temporary removed due to misbehavior

• wait [Number] milliseconds

Code Samples

This is a list of suggested exercises for beginners. Proper project descriptions in the style of Code Club will be provided soon.

• Blink a LED
• Synchronize the LEDs with the buttons
• Three Tone Piano
• Display current temperature each second
• Marquee mode on the Alphanumeric display
• Display random array of colors on the LED Strip
• Knight Rider
• Control servo via Rainbow HAT (future example)
• Simon says game?

Future Work (soon to be moved into the issue tracker)

• Support for Servos via the PWM output
• Compile only completed blocks, ignore “headless”
• Allow multiple entries to an event
• Support for multiple save files
• Add a reset key combo to the app, to stop the JS and restart advertising
• Add animation to “compile” or “load” using the Rainbow HAT
• Add Rainbow HAT simulator to the mobile app to “test”
• All the API methods from the components as blocks
• Support for selected I2C or SPI peripherals (i.e. LED Matrix)
• Consider using Rhino instead of a WebView to execute the generated JavaScript
• Only allow remote code deploy on Android Things if there is no screen attached

Known issues

• Button drivers are not processing 2 buttons pressed at the same time: Move to Button Input Drivers
• Events are executed in the main thread, if an event takes long to run, new events get queued (button presses)
• Only one event of each type is allowed at the moment

References

• Official Android Things documentation
• Android Things driver for the Rainbow HAT
• Blockly homepage

If you want to get started on Android Things and the Rainbow HAT, I suggest to take a look at the book Android Things Quick Start Guide