Using a pre-loved Telechron 6-digit 7-segment clock, controlled by a MAX7219 IC…
On power up.. clock to display 00 00 00
if Digital I/O xx is HIGH (pulled to 5v) (requires external pull-up-resistor)
counter = 1 hour. ** Closed contact closed, or button pushed..
Counter is always counting down
When clock gets to 00 00 00, stop counting.
Closed contact from Brightsign Relay box, when clip starts – timecode 00h00m00s00f for 2 seconds.. tells clock to start counting down.
Code: https://github.com/dargs/timer
Parts:
1x ATMega168
1x 16MHZ Crystal
2x 22pF Caps
10k resistor (reset pullup)
10uF cap (decoupling)