That's exactly what I'm looking for :).  I wasn't sure what to search on
so I couldn't find any example code related to servo control.  By chance
do you have a link or some example code to show how to set this up?  Up
till now I have been using JAL to produce the asm files and then =
tweaking
them a bit here and their.  I haven't had any experience with setting up
the timer that you spoke of and for some reason all the data sheets I =
find
on the processor don't have the assembly command reference section in =
them.

Thanks again,
Jeremy Darling

-----Original Message-----
From: Dale Botkin [mailto:dale@BOTKIN.ORG]
Sent: Tuesday, July 01, 2003 10:24 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]:Another newbie question JAL & PWM related


On Tue, 1 Jul 2003, Jeremy Darling wrote:

> But I can't get it to work with the servos and speed controls as I
> can't figure out how to create a PWM.

I have not been following this thread that closely, so please pardon me =
if
I'm way off base here...  but which PWM, the servo control pulses?  Near
trivial.  Don't look at it as a PWM problem, look at it as just =
generating
a pulse of X width, where 900us < X < 1.5ms or so.  Different brands and
models of servos need different pulse widths, you'll need to experiment =
to
figure out the quirks of yours.  In all cases I have seen, though, 1.5ms
pulses will center the servo.

Once you can generate pulses of the correct width, just use a timer =
driven
interrupt to send the pulse every 20ms or so, maybe less.  The interval =
is
NOT that critical in my experience (several brands of servos), but you
probably dont' want a larger interval than 20ms.

I don't think you can get the hardware PWM to run with a large enough
interval with a useful clock speed.  Anyway, servo control is pretty =
well
trodden ground if that's what you're trying to figure out.

Dale
--
It's a thankless job, but I've got a lot of Karma to burn off.
Get a PicoKeyer: http://www.hamgadgets.com

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