It's only 100 Hz, but every pulse has a width with a 14 bit resolution. So a
simple pulse counter won't do. I have to have the start and stop time of
that pulse, in as high a resolution as possible. I want to use timer0
without prescaler and it's a 20 Mhz PIC, so that's a 5 Mhz counter. That's
why I have to do it in an interrupt, if it's in the main code, i can't do
anything else.

So the sport is to clear the int check flag and get a poll of the port as
close together as possible, check the isr flag again on my way out of the
isr and just hope for the best :) That way, only an interrupt in two or
three instruction cycles could be lost.

Regards,
Claudio

-----Oorspronkelijk bericht-----
Van: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]Namens Bob Ammerman
Verzonden: Thursday, April 11, 2002 12:52 PM
Aan: PICLIST@MITVMA.MIT.EDU
Onderwerp: Re: [PIC] Interrupt on change


> So I think I just have to take a possible collision into account when
> processing the numbers. And at 100 Hz I have some measurements
> to spare, so that's ok :)

Ah... if this is really only 100Hz then I would definitely handle it by
polling in a timer interrupt.

Bob Ammerman
RAm Systems

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