On Apr 6, 2005, at 2:28 PM, V. T. wrote:

> Timing:
> AFAIK there are no PICs with internal 3 channel PWM circuitry, (since 
> I'm an
> old programmer recycling himself and a newbie to electronics), PWM 
> should be
> software driven A.K.A. a virtual instrument.

There's code for driving 4 channels of 6bit PWM from a 4MHz (internal
oscillator) 12f675, in C, here:

http://www.geocities.com/westfw/electronics/flames.c

IMO, you don't need more than 64 levels for driving LEDs, but IIRC this
code will do 7 bits relatively smoothly, and shouldn't have much trouble
with 8bits on a faster processor; the existing 64 levels have more to
do with how often I wanted things to change than the limits of PWM.
I think.

See also Big Clive's tri-color LED driver stuff here:
http://www.emanator.demon.co.uk/bigclive/rgb.htm
although I don't see source code.  Clive has a number of interesting
projects "up-url", as well...


> Pic should be programmed with accurate timing. So forget about loops.

Huh?

BillW
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist