3 PWM for 16F877A

suchinthaka · Joined: 07 Dec 2016 Posts: 1

Hi guys,
I want to turn on a RGB LED, but i want to to give 3 pwm for change the brightness of it to get different colours. But in 16F877A has only two pwm pins. What can i do? Some said me use multiplexing to generate 3rd one(code wise) but i don't know how to do that? Sad

temtronic · Posted: Wed Dec 07, 2016 9:44 am

1st check the code library here... there's a few RGB LED programs

2nd LEDs aren't fuzzy about speed, so a software PWM will work fine.

3rd if nothing in the code library , just search 'PWM LED' on this forum...you aren't the first to use a 20 year old PIC for RGB LEDs !

Jay

Gabriel · Joined: 03 Aug 2009 Posts: 1067 Location: Panama

I once wrote a little piece of code that did some operation, i believe XOR on both hardware PWMs and the resulting value was output as the 3rd PWM line...

the 2 hardware PWM were set as oposites... and by controling these 2 lines you could get any color desired from the RGB

I lost said code and never tried it again... but this is hardly a problem that cant be solved with Software PWM or a little operations on the 2 hardware lines.

G.
_________________
CCS PCM 5.078 & CCS PCH 5.093

Mike Walne · Joined: 19 Feb 2004 Posts: 1785 Location: Boston Spa UK

A simple search on this forum yielded several links including this 10 year old one.

http://www.ccsinfo.com/forum/viewtopic.php?t=27913&start=0&postdays=0&postorder=asc&highlight=pwm+877

Should give you a start.

Mike