code: function enableLuxometerNotifications(device, configCharacteristic, dataCharacteristic)
  {
  	// Turn Luxometer ON.
  	evothings.ble.writeCharacteristic(
  		device,
  		configCharacteristic,
  		new Uint8Array([1]),
  		onLuxometerActivated,
  		onLuxometerActivatedError)
  
  	function onLuxometerActivated()
  	{
  		showMessage('Luxometer is ON')
  
  		// Enable notifications from the Luxometer.
  		evothings.ble.enableNotification(
  			device,
  			dataCharacteristic,
  			onLuxometerNotification,
  			onLuxometerNotificationError)
  	}
  
  	function onLuxometerActivatedError(error)
  	{
  		showMessage('Luxometer activate error: ' + error)
  	}
  
  	// Called repeatedly until disableNotification is called.
  	function onLuxometerNotification(data)
  	{
  		var lux = calculateLux(data)
  		showMessage('Luxometer value: ' + lux)
  	}
  
  	function onLuxometerNotificationError(error)
  	{
  		showMessage('Luxometer notification error: ' + error)
  	}
  }
docs: Use notifications to get the luxometer value.