You're on the right track, however, it's one timer tick per instruction
cycle. In the PIC the instruction frequency is xtal/4. So your numbers
should be divided by four.

You also should read the FAQ at http://www.piclist.com about posting
with topic tags - that way more people will be able to see your message
and help you out.

Welcome to PICs!

Josh
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Rob Stockley wrote:
>
> Hi all. I'm new to pics so please excuse this relatively basic question.
>
> PIC:    16f648a with 20MHz xtal
> Aim:    To measure the charge time of an RC pair using the
>         comparator and timer1 modules.
> Issue:  What is the relationship between ticks and uC frequency? Or
>         more simply, how do I convert the tmr1 value to seconds?
>
> These are my ponderings :)
>
> Assuming no prescaling does one tick occur for every cycle?

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