bangle-microbit-temp

Use a BBC micro:bit as a remote temperature sensor for a BangleJS watch or other Espruino device

What it does

Put a simple MakeCode / Typescript program on a BBC micro:bit and it will transmit temperature data once a minute using the deprecated Eddystone beacon protocol over Bluetooth radio. Put the JavaScript code on your BangleJS watch or other Espruino device to view the temperature.

How to make it

micro:bit

The Eddystone protocol this uses is deprecated and when you add Bluetooth radio blocks to the Microsoft MakeCode editor for the micro:bit, you won't find the 'advertise url' block you need. The underlying code is still there, however, at the time of writing (25 Aug 2022).

So you have a few options:

download the HEX file in this repo and drop into in the MakeCode editor or flash it direct to a micro:bit
open this published project: https://makecode.microbit.org/_F48YvbPqdaqs
switch to JavaScript text mode, enter the Typescript code and switch back to blocks.

loops.everyInterval(60000, function () {
    basic.showIcon(IconNames.Heart)
    bluetooth.advertiseUrl(
    "https://microbit.org#" + convertToText(input.temperature()),
    7,
    false
    )
    basic.clearScreen()
})

BangleJS watch or other Espruino device

Open the IDE and send the bangle-code.js code in this repo to the device.

// List of eddystone devices
var eddystone = {};
var temp;

// Start scanning for devices
NRF.setScan(function(dev) {
  if (dev.serviceData && dev.serviceData.feaa)
    eddystone[dev.id] = dev;
});

setInterval(function() {
  for (var id in eddystone) {
    var dev = eddystone[id];
    if (!dev.age) dev.age=0;
    dev.age++;
    // only use data from devices we heard from recently
    if (dev.age < 40) {
      // if the URL contains a hash, the temperature is what comes after
      var url = E.toString(dev.serviceData.feaa).substr(3);
      var hash = url.lastIndexOf("#");
      if (hash) {
        temp = url.substr(hash+1);
        print(temp);
      }
    }
  }
  // now display on the screen
  g.clear();
  g.setFontVector(40);
  g.setFontAlign(0,0);
  g.drawString("Temp: ", g.getWidth()/2, (g.getHeight()/2)-20);
  if (temp) {
  g.drawString(temp+ "°C", g.getWidth()/2, (g.getHeight()/2)+20);
  }
  g.flip();  
}, 500);

Tell me more

The code is based on this micro:bit voting project: https://www.espruino.com/MicroBit+Voting