Project/Vetinari Clock: Difference between revisions

 

The random numbers are mapped to patterns such that there is a 10 in 16 chance of the regular pattern being used, a 3 in 16 chance of one irregular tick, a 2 in 16 chance of two irregular ticks and a 1 in 16 chance of three. So most of the time the clock works normally and occasionally it will tick abnormally. Timer 1 is used to count the period between ticks and during this period the PIC is put into a low power state. When the timers counter reaches zero the CPU wakes, loads the timer for the next period and generates a pulse to move the seconds hand before going back to sleep. This means the CPU is active for just over 50mSec during each tick. This should make the batteries last much longer than designs that run the CPU continuously.