Timers

[AndrewB]

Could somebody help me with timers.

I am trying to make an intervalometer for my camera . Only for my usage.

I have tried to work out how to use timers but having problems.

I need an output that can be triggered every so many min/secs with an exposure of secs/10th of secs

Thanks

[David John Barker]

what problems are you having?

[AndrewB]

Just getting my head round it

The example shows a sub with timers set and also similar timers triggered on the main.

Not sure how that works as there is no way to determine which one is which?

I want to have a timer that repeats every set time by vaiable that can be started and stopped.

That first timer also triggers another timer of a set time by variable at its finished event.
This one only triggered by the first.

Sorry but I'm in and out of programming. I bounce around firewing,Picbasic,Venom etc so forget a fair bit.

[AndrewB]

Any chance of some help please.

[Jerry Messina]

Not sure which examples you're looking at, but hardware timers are good for short intervals... they can't typically be used for minutes without extra code to extend them.

If you're having a hard time understanding how they work then maybe just use delay loops?

Code: Select all

dim seconds as ulong          // time to repeat, in seconds
dim exposure as uinteger      // time output is active, in msecs (65535 msecs = 65.535 secs) 

sub WaitSeconds(secs as ulong)
   while (secs <> 0)
      delayms(1000)
      secs = secs - 1
   end while
end sub

Sub Main()
seconds = (5*60) + 30            // repeat every 5 mins, 30 seconds
exposure = (2*1000) + (25*10)   // output high for 2secs, 25 tenths (in msecs)
 
while (true)
   WaitSeconds(seconds)
   high(PORTB.0)
   delayms(exposure)
   low(PORTB.0)
end while
End Sub


[AndrewB]

Thanks Jerry.

How would I be able to abort the waitseconds with a button?

[Jerry Messina]

Change WaitSeconds to something like....

Code: Select all

dim Button as PORTB.1

sub WaitSeconds(secs as ulong)
   dim msecs as uInteger
   while (secs > 0)
      msecs = 1000                 // wait 1 sec (1000msec)...
      while (msecs > 0)
         delayms(1)
         if (Button = 0) then    // leave if button pressed (PORTB.1 to GND)
            exit sub
         end if
         msecs = msecs - 1
      end while
      secs = secs - 1
   end while
end sub


[AndrewB]

Thanks for your help

[AndrewB]

Hi Jerry I dont think that routine is aborting the subroutine.

I have a lcd shield

[AndrewB]

Ok I have rewired the reset to portb.1 and it works ok.

I had tried using the keypress but that bounced the programme and would never stop. I guess its a something to do with making it public?