All About Circuits > Volume III > 3.12.3 Light-emitting diodes

A PICAXE 08M2 can be used to read the amount of IR (infrared) light falling on a phototransistor and respond by moving a servo to a predetermined position.

We've all been there - you've spent hours and hours trying to get that sketch working, but somehow, you're not reacting well to time critical events in your system. Maybe it's a wireless peripheral indicating when a packet is ready. Maybe it's an external Flash device signaling when data is ready to be read out. Maybe it's as simple as a button push that you need to react quickly to! But, try as you might, it seems the best way to see these sort of events is to just `digitalRead()` that pin over and over in your main `loop()` function until something interesting happens. ...or is it?

The month of April has brought us some truly unique crowd-funded toys in the form of some DIY speakers and two development boards with some great hardware features.