BT Characteristic value change events don't associate per device

[earp123]

I have my Bangle.js 2 acting as Central, connected to two peripheral devices with identical firmware (differing only in MAC address). I am trying to sort which device a notification of a characteristicvaluechanged comes from by id. Unless I'm missing something, it seems like the event argument passed to the on('characteristicvaluechanged', function(event){}); handler are identical objects even when the characteristic handler and startNotifications() function is called from separate GATT Servers. I have the following sketch that connects to the devices (AR1 and AR2) one after another and assigns a handler to the characteristic notification but I will only ever see the event come from whichever GATT Server is instantiated last.

const pag_svc = "whatever UUID";
const pag_chrc = "whatever UUID+1";
var AR1chrc, AR2chrc;
let AR1 = {}, AR2 = {};
let AR1gatt = {
  connected: false,
  handle: undefined
};

let AR2gatt = {
  connected: false,
  handle:undefined
};

function initScan()
{
  getDevice();

  let scan = setInterval(function(){
    if (radioLock){
      getDevice();
      clearInterval(scan);
    }
  }, 200);
}

function getDevice(){
    radioLock = false; //print(radioLock);
    NRF.requestDevice({ filters:[]})//some filters
      .then(function(device) {
      print(AR1gatt.handle);
      if (AR1gatt.handle == undefined) {
        AR1 = device;
        AR1gatt = device.gatt;
        return AR1gatt.connect();
        }
      else if (AR2gatt.handle == undefined) {
        AR2 = device;
        AR2gatt = device.gatt;
        return AR2gatt.connect();
        }
    }).then(function(gatt){
      if(gatt == AR1gatt){
        AR1gatt.getPrimaryService(pag_svc).then(function(s){
        return s.getCharacteristic(pag_chrc).then(function(c){
          AR1chrc = c;
          AR1chrc.on('characteristicvaluechanged', function(event) {
            //This never runs
            print("This never runs");
            console.log("-> ",event);
            Bangle.buzz(3000, 1);
          });
          return AR1chrc.startNotifications();
        }).then(function(d) {
            console.log("Waiting for notifications");
            radioLock = true;
          }).catch(function() {
            console.log("Something's broken.");
            radioLock = true;
          });
        });
      }
      else if (gatt == AR2gatt){
        AR2gatt.getPrimaryService(pag_svc).then(function(s){
        return s.getCharacteristic(pag_chrc).then(function(k){
          AR2chrc = k;
          AR2chrc.on('characteristicvaluechanged', function(event) {
            //Reports the same event as if from the same device
            console.log("-> ", event);
            Bangle.buzz(3000, 1);
          });
          return AR2chrc.startNotifications();
        }).then(function(d) {
          console.log("Waiting for notifications");
          radioLock = true;
        }).catch(function() {
          console.log("Something's broken.");
          radioLock = true;
        });
        });
      }
    }).catch(function(f){print("No devices found");});
}

initScan();

Am I implementing this incorrectly?

[gfwilliams]

Interesting, thanks - what you're doing there looks ok.

I've just looked into this and there was a bug in the Bangle.js firmware (it was assuming that the handles received from the Bluetooth stack were unique, when they're only unique per-connection). Previously I'd been testing with different devices and those just happened to have their characteristics on different handle numbers and it was fine, but if you connect to identical devices you get identical handles.

If you install a cutting-edge build now I think you'll find it works correctly.

[earp123]

First try! Thank you sir! I'm sending an email to your [email protected], keep a lookout :)