code: function enableLuxometerNotifications(deviceHandle, configCharacteristic, dataCharacteristic)
  {
  	// Turn Luxometer ON.
  	evothings.ble.writeCharacteristic(
  		deviceHandle,
  		configCharacteristic.handle,
  		new Uint8Array([1]),
  		turnOnLuxometerSuccess,
  		turnOnLuxometerError)
  
  	// Enable notifications from the Luxometer.
  	evothings.ble.enableNotification(
  		deviceHandle,
  		dataCharacteristic.handle,
  		readLuxometerSuccess,
  		readLuxometerError)
  
  	function turnOnLuxometerSuccess()
  	{
  		showMessage('Luxometer is ON')
  
  	}
  	function turnOnLuxometerError(error)
  	{
  		showMessage('Write Luxometer error: ' + error)
  	}
  
  	// Called repeatedly until disableNotification is called.
  	function readLuxometerSuccess(data)
  	{
  		var lux = calculateLux(data)
  		showMessage('Luxometer value: ' + lux)
  	}
  
  	function readLuxometerError(error)
  	{
  		showMessage('Read Luxometer error: ' + error)
  	}
  }
docs: Use notifications to get the luxometer value.