I'm plan to interface a atmel avr with my alarm system in home but the issue is DSC has a propriatary protocol between the keypad and the base. So has anyone messed with this before or can give me a few beginners tips on how to reverse engineer this protocol?
The wiring is simple: Vcc, GND, Data, Clock
The Vcc is +12 volts and the data/clk lines are between +8-10 but work just fine through a voltage divider to the logic analyzer.
The Clock line is confusing tho, its a 1kHz clock at 50% duty but only runs for 41.600ms then it goes high for 5.400ms and then starts over again.
The Data line appears to change on on either rising or falling edge of the clock
(0 is the Data line, 1 is the Clock line)