Robin Clarke – Life and Tech

Getting into PIC programming, I thought I’d start small: our fridge sometimes jams open leaking cold air out, and heating up the compressor in the back, burning electricity without end.  I could just be really careful when putting milk in, and always push the door shut, but being lazy, I like reminders – but gentle ones!

So – a little bit of C code, a little bit of soldering, and hey presto: a fridge alarm.

How it works

When the door is opened, the magnet moves away from the reed switch, it opens, and the door_open flag is set.  As time goes by, the LED first blinks slowly, then more frequently… after 30 seconds it is accompanied by an intermittent chirp from the buzzer, and if the door hasn’t closed after a minute, the buzzing and flashing gets really intense.  I don’t think I’ll be able to forget the door open any more!

Want one for yourself?  Get the code and schematics here.

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