Pause that's not interrupted

[Jeremy Leach]

This is a very simple idea, and demonstrates how useful Timer can be...

The SetInt command in the manual explains "After the interrupt code has executed, program execution continues at the next program line in the main program. In the case of the interrupted pause,wait, play or tune command, any remaining time delay is ignored and the program continues with the next program line."

So you might have a very quick interrupt routine, but that will mess up any long pauses in your program. To get round this you can have a special pause routine, which in pseudo-code might look like ...

TPause:
    Peek TimeValue 'the time you want to pause
    SetTimer <suitable preload value>
    Timer = 0
    Do
    Loop Until Timer > TimeValue
Return

So during the Do Loop, if the interrupt fires it will return to the do loop and if the Timer has exceed Timevalue will end, otherwise will carry on looping.

This whole idea will work most effectively when the interrupt routine is short compared to the Pause time. For instance my interrupt is 50ms and I want to pause for a second, or two seconds to keep LEDs lit.

 

[westaust55]

Have not yet had a program where timing has been crucial but a solution worth keeping in mind.

 

[Michael 2727]

Jeremy it may be worth putting this in the code snippets section, won't get lost there

 

[stocky]

Thanks Jeremy - that potentially solves a little problem I have!



Stocky

 

[Jeremy Leach]

ok, posting in snippets too ;-)

 

[matt2466]

If i'm using a for...next loop for example for b1 = 1 to 2000, how long will 2000 increments take?

 

[inglewoodpete]

Best to use a stopwatch to time it. Different PICAXE models take (slightly) different times to execute code.

 

[matt2466]

Best to use a stopwatch to time it. Different PICAXE models take (slightly) different times to execute code.

I'm using an 08M running at 8MHz...any ideas?

 

[Jeremy Leach]

Hi
b1 = 1 to 2000

Well b1 is a byte variable and can't have a value of 2000, only a value 0 to 255.
But apart from this, if you were using a word variable like w1 = 1 to 2000 it depends what other code you have in the loop.

But for an 08M I'd do like InglewoodPete says and just use a stopwatch. Set the count as high as possible/practical, and light an LED after the loop has finished. So you have the time for x iterations of the loop, so you can then work out the time for one.

I find timing code execution quite fascinating, and by understanding the timing it allows you to do clever things, making LEDs flashing at constant rates, but executing things in the meantime etc.