On 9/09/2011 2:53 PM, Josh Koffman wrote:
> Ok, I've been doing some math, and I'd love a double check of my thinking=
..
>
> I'm working on an 18F1320, and I'm looking to use TMR2 and TMR3 for
> servo stuff. The chip is running off the 8MHz internal oscillator.
>
> To generate the 20mS trigger, I'm looking at TMR2. If I setup the
> prescale at 1:16 and the postscale at 1:10, then I think I should be
> able to load the period register (PR2) with d'250' and get a 50Hz
> interrupt.
>
> Once I've got that going (I won't be able to try it until tomorrow)
> I'll be looking at TMR3 to generate the 1mS to 2mS variable pulse. If
> I setup TMR3 in 16 bit mode, with a prescale of 1:8, I think I can get
> an interrupt at 1mS if I preload the timer register with 65286, and an
> interrupt at 2mS if I load with 65031. So I should be able to take my
> control value (from whatever, analog pot, data in, etc), subtract it
> from 65286, and away I go.
>
> Does that sound plausible?
>

That sounds pretty much what I did, but with timers 0 and 1.  I was=20
using a PIC16F1934 running at 20MHz with DMX reception as well.
David...

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David Duffy        Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717      Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au
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