microbit-bluetooth

This is an example of communicating via bluetooth between a web app and a BBC micro:bit device.

Wiring

1. Connect LED1:

• red wire from pin 1 -> resistor -> LED (positive leg)
• black wire from LED negative leg -> GND

3. Connect LED2, sharing the same GND

• red wire from pin 2 -> resistor -> LED (positive leg)
• black wire from LED negative leg -> GND

Setup and run Micro:bit program

1. Connect micro:bit device to computer with USB
2. Update the firmware to allow pairing (see https://support.microbit.org/support/solutions/articles/19000019131-upgrade-the-firmware-on-the-micro-bit)
3. Open the MakeCode editor (https://makecode.microbit.org/) and create a new project
4. Expand the Advanced section and click Extensions. Select bluetooth and click the Remove extensions(s) and add bluetooth button
5. Click the cog icon in the top right, then go to Project Settings. Enable No Pairing Required: Anyone can connect via Bluetooth
6. Click JavaScript at the top and paste in the code from microbit/microbit-bluetooth.js in this repo
7. Click the cog icon in the top right, then Pair Device and pair with the Microbit (note: requires latest firmware on the device for this to work).
8. Click Download to flash the program to the device. It should show a smiley face to show that it is ready.

Run the web app

This repo contains an example web app built with Angular.

The interesting part lives in src/microbit - this includes a component allowing the user to select a BPM either by dragging a slider or tapping a button 8 times (2 bars) in time with the music. This BPM will be used to set the speed at which the LEDs flash.

The src/app/microbit/microbit.service.ts file uses the Web Bluetooth API to connect to the micro:bit and send a message each time the BPM is updated.

1. Install Node and Yarn
2. In the web directory, run the following to install dependencies and start the app

   yarn
   yarn start
   

3. Go to http://localhost:4200/
4. Click the Connect button and select the microbit in the device pairing pop up. On the Microbit LED display you should see a tick to signify that the connection is active. The LEDs should start to flash.
5. Move the slider or press the "Tap" button 8 times in a row to change the speed. This transmits a bluetooth message for example 400: for 400ms delay between on/off states. The microbit reads until it sees a : character, parses the number to an int and sets the flash speed.