It should be a piece of cake if you program your Attiny85 chip (not Digispark) using your existing Arduino IDE with the help of one “USB tiny ISP (v2.0)” programmer. The software/Arduino sketch /* * ...

Using motion detectors and an Arduino you can trigger lights, fans, ... } } Here is the circuit for the Sparkfun Active Low style sensor. PIR Pin “+” connects to Arduino +5.