Hi,

On Sun, 21 Apr 1996, Todd Peterson wrote:

> One possible solution...
> >Could anyone help me with a means of deriving a delay of between 5 seconds &
> >5 minutes.
> >I'd like to use a 16c56..is this possible?
>
> Short of using a VERY slow clock, how about putting a 555 timer pulsing once
> every, say, 5 seconds onto the RTCC input pin?  A 555 with a period of 5
> seconds is not extremely accurate, but I assume that when you are timing
> something to 5 minutes extreme accuracy is not critical.  You might want to
> use one of the new CMOS versions of the 555 timer (the original 555 design
> tends to be noisy on the power lines).  If you do use a 555, be sure to put
> a bypass capacitor at its power terminals.
>
> Todd Peterson

I also needed to measure a long delay (using the 16c54). I did it by
counting the timer overflow. for example, if you have an RC oscilator
running the PIC at about 70KHz then the timer is driven by FOsc/4 which
can be passed through 1:256 prescale which brings the timer overflow to
about 85/Sec. If you count this in a 16 bits counter, you can reach
minutes (but then you might want to have a better oscilator).


chaipi


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! Chaipi Wijnbergen                                                           !
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