I’m using capacitor-community ble plugin to integrate with a raspberry trough bluetooh.

Basically that model 3B is running a a script that expose a notification charactetistic that keep reading bytes from serial port and exporting it to bluetooth (every 8 bytes send one bluetooth value using notifications)

My Ionic app start and stop notifications many times and almost 95% works properly

But, sometimes we call startNotifications but we never receive the data back (sometimes we get a low voltage warn in rasp but we are using a 33w energy charger..)

Any clues on whats going on?

import { BleClient, BleDevice } from '@capacitor-community/bluetooth-le';


await BleClient.initialize();

await BleClient.getConnectedDevices(BALANCE_SERVICES)
        .then(async (devices: BleDevice[]) => {
          if (devices.length > 0) {
            this.connectedDevice = devices[0];
          }
          this.ngZone.run(() => this.isBluetoothConnected = devices.length > 0);
        });

await BleClient.startNotifications(
        this.connectedDevice.deviceId,
        this.moduleService.serviceUuid(),
        this.moduleService.characteristicUuid(),
        (data: DataView) => {
          let weight = this.moduleService.parseWeight(data);
          this.ngZone.run(() => {
            this.lastReadingReceived = weight;
          });
        }
      );

Python script ( just get_data section of )

def get_data(self):
        value = []
        firstRead = []
        secondRead = []
        isFirstRead = True

        print('Initing get_data')

        try:
            ser = serial.Serial('/dev/ttyS0', 
                baudrate = 9600,
                parity=serial.PARITY_NONE,
                stopbits=serial.STOPBITS_ONE,
                bytesize=serial.EIGHTBITS,
                timeout=1
            )
        except Exception as e:
            print('Failed to connect to serial %s', str(e))
            return value

        print('Connected to Serial')

        while True:
            try:
                received = ser.read()
                #print(received)

                if isFirstRead is True:
                    firstRead.append(dbus.Byte(received))
                else:
                    secondRead.append(dbus.Byte(received))

                if b'r' in received and isFirstRead is False:
                    if firstRead == secondRead:
                        value = firstRead
                        break
                    else:
                        value = []
                        isFirstRead = True
                        firstRead = []
                        secondRead = []
                        pass
                else:
                    if b'r' in received and isFirstRead is True:
                        isFirstRead = False    
                        pass           
            except:
                pass

        print('Buffer received successfully')

        ser.close()

        print('Serial closed')

        #print("%s" % ''.join([str(v) for v in value]))

        length = len(value)

        #Change that after development of LAN port reading
        missingBytes = 16 - length

        for x in range(missingBytes):
            value.append(dbus.Byte(32))

        return value