Struggling with react native and puck js

[espruino-discuss]

Posted at 2023-03-31 by user154849

Hi :)

Im working on integrating the Puck.js into my react native application using react-native-ble-plx
Everything is working fine, but when i try to write some data, i just get this message

[BleError: Characteristic 6e400002-b5a3-f393-e0a9-e50e24dcca9e notify change failed for device 1E986C85-8037-E56E-A18D-0F38826AAB12 and service 6e400001-b5a3-f393-e0a9-e50e24dcca9e]

Thats my code :)

return new Promise<string>((resolve, reject) => {
            return Ble.startDeviceScan(null, null, async (error, device) => {
                if (error) {
                    console.log(error.message);
                    if (typeof error.message === 'string') {
                        //show error
                    }
                    reject(false);
                    return;
                }

                console.log(device?.name);

                if (device?.name?.trim().startsWith('Puck.js')) {
                    try {
                        if (device) {
                            Ble.stopDeviceScan();
                            const connected = await device.isConnected();

                            if (!connected) {
                                await device.connect();
                                await device.discoverAllServicesAndCharacteristics();
                                const result2 = await device.services();
                                result2.forEach(async (service) => {
                                    const charLit = await service.characteristics();
                                    charLit.forEach(async (chari) => {
                                        console.log('carhi', chari);
                                        if (chari.uuid === '6e400002-b5a3-f393-e0a9-e50e24dcca9e') {
                                            chari.monitor((error, char) => {
                                                console.log('monitor,', error, char !== undefined);
                                            });

                                            const data = Buffer.from(['LED1.set();/n']).toString('base64');
                                            chari
                                                .writeWithResponse(data)
                                                .then((val) => console.log('val', val))
                                                .catch((reason) => console.log('reson', reason));
                                        }
                                    });
                                });
                            }

                            resolve(device.id);
                        }
                    } catch (err: any) {
                        console.log('errMessage', err);
                        if (typeof err.message === 'string') {
                            // show error
                        }

                        reject(err.message);
                    }
                }
            });
        });

I would be greatful for any help :)

[espruino-discuss]

Posted at 2023-03-31 by @gfwilliams

I think the issue is you're trying to read and write from characteristic 6e400002-b5a3-f393-e0a9-e50e24dcca9e

If you check other code that uses BLE at something like : https://www.espruino.com/Interfacing#node-js-javascript

It writes to "6e400002-b5a3-f393-e0a9-e50e24dcca9e" (as you're doing) but then reads from (notifies/monitors) "6e400003-b5a3-f393-e0a9-e50e24dcca9e"

So you need:

if (chari.uuid === '6e400003-b5a3-f393-e0a9-e50e24dcca9e') {
  chari.monitor((error, char) => {
      console.log('monitor,', error, char !== undefined);
  });
}
if (chari.uuid === '6e400002-b5a3-f393-e0a9-e50e24dcca9e') {
  const data = Buffer.from(['LED1.set();/n']).toString('base64');
  chari
      .writeWithResponse(data)

When you get this working, please could you paste up the final code? It'd be graet to have a full example of using react-native-ble-plx

---

Posted at 2023-03-31 by user154849

Hi, thanks, now it works :)

Here is the working code :)
I fixed the uuid part and also the command was wrong :)

  return new Promise<string>((resolve, reject) => {
            return Ble.startDeviceScan(null, null, async (error, device) => {
                if (error) {
                    console.log(error.message);
                    if (typeof error.message === 'string') {
                        //show error
                    }
                    reject(false);
                    return;
                }

                console.log(device?.name);

                if (device?.name?.trim().startsWith('Puck.js')) {
                    try {
                        if (device) {
                            Ble.stopDeviceScan();

                            const discoverAndWrite = async () => {
                                await device.discoverAllServicesAndCharacteristics();
                                const result2 = await device.services();
                                result2.forEach(async (service) => {
                                    const charList = await service.characteristics();
                                    charList.forEach(async (characteristic) => {
                                        if (characteristic.uuid === '6e400002-b5a3-f393-e0a9-e50e24dcca9e') {
                                            const data = Buffer.from('LED.toggle();\n').toString('base64');
                                            characteristic
                                                .writeWithResponse(data)
                                                .then((val) => console.log('value', val))
                                                .catch((reason) => console.log('reason', reason));
                                        }
                                        if (characteristic.uuid === '6e400003-b5a3-f393-e0a9-e50e24dcca9e') {
                                            characteristic.monitor((error, newCharacteristic) => {
                                                console.log('monitor', error, newCharacteristic);
                                            });
                                        }
                                    });
                                });
                            };

                            const connected = await device.isConnected();

                            if (!connected) {
                                await device.connect();
                            }

                            await discoverAndWrite();

                            resolve(device.id);
                        }
                    } catch (err: any) {
                        console.log('errMessage', err);
                        if (typeof err.message === 'string') {
                            // show error
                        }

                        reject(err.message);
                    }
                }
            });
        });