What would be a sensor that I could use to detect if my desktop's CD tray has opened?
There are so many sensors to choose from in the Digikey catalog.
Should I use a mechanical component?
A light beam interference component?
Which one would allow me to detect if my CD tray is open such that the information can be fed into a PIC MCU?
I know I can do a system call for this sort of question, but I would prefer some sort of external sensor.
Use a permanent magnet and a reed switch.
Fix the magnet on the moving part and put the reed switch on the fixed part. Then monitor the reed switch with the microcontroller.
If power consumption isn't an issue (compared to the reed switch), I think I would go with an IR LED and a phototransistor. You could either have it break the beam when it opens or when it's closed and read from the transistor on you digital in pin.
If you don't mind disassembling the drive you could look into the interlock or drive open switch, which should be fairly easy to wire in to. It may even have a pull-up, providing a logic signal directly to your device of choice.
