At 07:48 PM 15/02/99 -0500, you wrote:

VOILA!! I see what you mean.


Thanks to all for the suggestions.


Peter
>>
>> At 08:05 AM 15/02/99 -0500, you wrote:
>>
>> To translate, 0.5MHz means 0.5 microseconds. If I clocked a PIC at 10MHz
>> then I would have time to do about 1.25 instructions during this time. I do
>> not want to go above 10 MHz for my crystal. I am also doing a lot of other
>> things inthe micro and wish to be informed when the counts have finished
>> (another signal)
>
>Peter,
>
>By setting the counter to overflow, you'll only see an interrupt every 128 uS
>by using the TMR0 counter. As I said below it's a bit much to do in software
>but by using the timer hardware, it because doable if not easy.
>
>If the timer isn't available, you definitely need another external part.
>
>BAJ
>>
>> Thanks,
>>
>> Peter
>>
>> >>
>> >> I need to be able to count to 4,000,000 (24 bits) and when complete I wish
>> >> to address serially for the result. The counter is clocked at about 0.5MHz
>> >> which is a little fast for the PIC to keep up with. Can anyone suggest a
>> >> chip that would do this for me. I do not want a parallel output as it uses
>> >> too many pins. If this is not possible then perhaps a counter and shift
>> >> register??
>> >
>> >I'm a bit confused. While this may be a bit much for a PIC to count solely
>> >in software, using its hardware counter is an ideal application. The keep
>> >the software interaction down you can simply interrupt on rollover and have
>> >a short interrupt routine that bumps up the top two bytes.
>> >
>> >In short you're going to create a whole lot of extra hardware doing this
>> >with discretes.
>> >
>> >If you really feel you must have an extra piece of hardware, then I suggest
>> >using a second PIC whose sole purpose is to count and report the count
>> >serially to the master PIC. A 12C508 could give you the requested
functionality
>> >in an 8 pin package. a three line serial interface should be sufficient for
>> >both interrupting the master PIC, and commanding and reading the counter
PIC.
>> >
>> >This is the type of application where microcontrollers excell.
>> >
>> >BAJ
>> >>
>> >> TIA,
>> >>
>> >>
>> >> Peter Grey
>> >>
>> >
>> >
>>
>
>