Elapsed Timer Demo

[HenrikOlsson]

Hi,
A Pause (or any other command) will not interfere with the interrupt - it'll keep running in the background.
However, if you're interrupting at a high rate the context saving, interrupt code and context restore will take cycles from the main PBP program without it knowing so your pause may be a bit longer than what you specify. For non critical timings it's not a problem.

/Henrik.

EDIT: Obviosuly interrupting at ANY rate will take cycles away from the main program. What I mean is that the faster you interrupt the more cycles will "vanish" and any software timed routines like Pause, SERIN, Pulsin that you have in the main program will be affected.

[jmgelba]

No the pause length isnt critical. I'm trying to get one switch to start and stop the elapsed timer. So it needs a debounce and a wait period so that it doesnt immediately stop the timer again.

Here's what I have but it doesnt work to well:

loop1:

For A = 0 to 1000
     IF PORTB.7 = 1 and TimerRunning = 0 then 
     gosub StartTimer
   endif
next A

if SecondsChanged = 1 then
           LCDout $FE,2, dec2 Hours,":",dec2 Minutes,":",dec2 Seconds
           SecondsChanged = 0
        endif
        
For B = 0 to 1000
     If PORTB.7 = 1 and timerrunning = 1 then 
     gosub StopTimer
   endif
next B
goto loop1

This means the user has to press and hold the button for 1 second before the timer will start. However, if they press it for 1.5 seconds, then they only need to press it again for half a second and it stops. If they press it for 2.5 seconds, then timer has started, stopped and is half way to starting again.

I was wondering id something like this would work?

'If PORTB.7 = 1 then
'gosub StartTimer
'TimerRunning = 1
'pause 150
'endif

If SecondsChanged = 1 then
           LCDout $FE,2, dec2 Hours,":",dec2 Minutes,":",dec2 Seconds
           SecondsChanged = 0
        endif

If PORTB.7 = 1 AND TimerRunning = 1 then
'gosub StopTimer
'TimerRunning = 0
'pause 150
'endif

I think the problem with both of them is that there is no time between the on if then and the off if then, and there needs to be some sort of logic that says that if the timer is running and the button is still pressed, do not stop the timer until the button has been released and pressed again.