> -----Original Message-----
> From: Pic Dude [SMTP:picdude@AVN-TECH.COM]
> Sent: Wednesday, February 27, 2002 8:10 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      [PIC]:  LED brightness control thru PIC...
>
> I would like to control the brightness of some LEDs (directly attached to
> a port on a PIC) thru code.  Each LED would be at full bright or dim --
> just
> 2 intensities.  Here's what I thought...
>
> Assume as some point in the code, I want to set the output to
> 'ooBoDDBo' where 'o' is Off, 'B' is Bright, and 'D' is Dim.
>
> Let V1 = value of port for dim LED's.  In this case V1 = '00001100'
> Let V2 = value of port for bright LED's.  In this case V2 = '00100010'
>
> Then set V3 1 = V1 OR V2 = 00101110'
>
> Now in my code, every time I come around in the main loop, I would
> alternate the output between V1 and V3.  Bright LEDs would get set
> all the time (both times), and dim LED's would get set only on alternate
> cycles -- sort of like a pulse-width dimmer.
>
> Perhaps I may need to have 3 cycles with V1, V1, V3 depending on
> relative brightness level, etc.
>
> Is this reasonable?  Is there an easier/better way to do this?  I'll be
> using a 16F84 or 16F872 for this.
>
> Thanks,
> -Neil.
>
>
Neil,

Check the recent thread "Ultra fast low res PWM".  There are several code
examples for minimal software PWM routines that take only a few cycles.

Regards

Mike

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