Can't monitor device

According to the docs, I’ve done the following:

• Scanned for devices
• Connected to device
• device.discoverAllServicesAndCharacteristics
• writeCharacteristicWithResponseForDevice

My problem lies in reading the response I get from sending my command.

RX characteristic is writable, but TX is only notifiable and not readable. Therefore I need to monitor the characteristic with monitorCharacteristicForDevice, however I can’t get this to function.

I never recieve neither “Monitor success” nor “monitorDevice called” in the code below. If I run the checkBattery() function after connection it returns “Not monitoring”.

How do I read the return?

monitorDevice = () => {
	console.log("monitorDevice called")
	this.manager.monitorCharacteristicForDevice(this.state.connectedTo, SERVICE_UUID, TX_CHARACTERISTIC, (error, characteristic) => {
		if (error) {
			console.error("Error at receiving data from device", error);
			return     
		}
		else{
			this.setState({monitoring:true})
			console.log("Monitor success")
			console.log("Monitor success " + characteristic.value);
			this.state.messagesRecieved.push(characteristic.value)
			return
		}
	})
}

connectAndFetchServicesAndCharacteristics = (device) => {
	this.manager.connectToDevice(device.id, null)
	.then(device => {
		this.setState({connectedTo:device.id})
		console.log('Connection successful\nScan stopped')
		this.manager.stopDeviceScan();
		this.setState({scan: false})
		return device.discoverAllServicesAndCharacteristics()
	})
	.then(device => {
		this.setState({servicesDiscovered: true})
		console.log("Services discovered")
		this.monitorDevice()
		return
	})
	.catch(err => {
		console.log(err)
	})
}
  
checkBattery = () => {
	if(this.state.monitoring){
		this.manager.writeCharacteristicWithResponseForDevice(this.state.connectedTo,
			SERVICE_UUID, 
			RX_CHARACTERISTIC,
			"YmF0dGVyeQ==")
		.then(characteristic => {
			console.log("Successfully sent: " + characteristic.value)
			return
		})
		.catch(err => {
			console.log(err)
		})
	}
	else{
		alert("Not monitoring")
	}
}

[WQvist]

Progress! Hooking the peripheral up to a serial monitor I can see that the received string is basically gibberish. “battery” is received as “m畫mz�”. Some type of encoding problem

Edit: Solved it by using base-64 library instead of sending a string that was already base64 encoded.

[dariuszseweryn]

I dunno. I want to check what is going on.

btw. you directly set the state this.state.connectedTo = device.id