For my AS Level Electronics coursework in 2001 I designed a simple burglar alarm system. The project uses a PIC 16C84 to monitor 4 NC alarm inputs that when triggered, activates an output relay. The first zone triggered is illuminated with a solid lit LED, while the second and subsequent zones are indicated with a flashing LED.
This project serves as a complete, although relatively basic introduction to digital electronics, PIC microprocessor programming and interfacing techniques.
Full source code, individual schematics and component values are detailed in the project report. Unfortunately I don't have a full schematic anymore, except an old except Crocodile Clips format which I no longer have a reader for. It should be possible to reverse the design from the board layout, this is the best photograph I have:
The preset pot in the RC oscillator (providing the PIC clock) is wired as a variable resistor rather than potentiometer, despite appearances. What you don't see is that the 3rd leg was cut off and the cap/mid leg joined with a wire bridge.
