Quote Originally Posted by cncmachineguy View Post
Hi Hank, not sure why you can't just poll the A/D, but heres an idea. If your chip has compare on the same pin(s) as A/D (like '877) set the comparater up to interupt when any switch is pressed. then switch to A/D on that pin and read the value. after switch back to comp and wait.

Re using a comparator - that's a mighty fine idea.

re polling ......not sure I've totally understood what you're getting at (I'm still a n00b at heart!), do you mean constantly poll the analogue pin connected to the nav switch to see if there's been a meaningful change in voltage? (thereby meaning a switch has been pressed) If so, my program already has a good few loops with 'pause' commands gratuitously used throughout.

I guess during the waiting periods (ie pauses), I could be checking the incoming switch potential divider level to check for a change in voltage ....maybe it's my poor programming approach, but I've always has snappier results with interrupts (vs polling)