Elapsed Timer Demo

[jmgelba]

Getting frustrated! :-) I've tried a bunch of things to get the counter to count down correctly.

There is a problem at rollover. Let's say the timer is set to 1 hour 1 minute zero seconds, it should start there and one second later change to 1:00:59. It doesn't, it stays at 1:01:00 for 1 second and then counts down from 1:01:59. Then when it gets to 1:00:00 it rolls over to 0:00:00 for 1 minute then the next second its at 0:59:59.
Not really sure what to try. What about a "first run through the interrupt" flag that automatically makes minutes = minutes - 1 and starts the seconds at 59?