Multiple PWMs, how? - Electronic Circuits Projects Diagrams Free

johankj · 9th May 2008, 06:53 PM

I've seen various projects that have programmed a PIC to have multiple independent(maybe?) PWM outputs, even thought the chips only have one in hardware (did I see one with none?).

Does anyone know how this is done?

blueroomelectronics · 9th May 2008, 06:56 PM

How many do you need?

johankj · 9th May 2008, 07:00 PM

Erch... I dunno... At least 3 for an RGB idea I have (moodlight-thing), but the more the merrier.

BTW, that was hella-fast!

blueroomelectronics · 9th May 2008, 07:03 PM

For LEDs a simple software PWM is plenty.

johankj · 9th May 2008, 07:05 PM

Yarh, but how? Does it have nothing to do with the hardware PWM then? And doesn't it tie up all the processing time?

blueroomelectronics · 9th May 2008, 07:07 PM

It can be all interrupt driven. Lots of code samples on the net I'm sure.

johankj · 9th May 2008, 07:09 PM

AAAHH!! I find it, I find it! No worry.

There is a technical document from Microchip themselves. AN1074 - Software PWM Generation for LED Dimming and RGB Color Applications.

johankj · 9th May 2008, 07:09 PM

Looks like I answered my own question...

blueroomelectronics · 9th May 2008, 07:32 PM

The App notes are really handy.

**3v0** · 9th May 2008, 08:15 PM

If you want several hardware PWM's look at one of my favorites the 18F1330. It also has a PLL that works with the internal 8MHz clock that bumps it up to 32MHz.

9th May 2008, 06:53 PM	#1 (permalink)
johankj Experienced Member Join Date: Jan 2007 Location: Norway Posts: 110	Multiple PWMs, how? I've seen various projects that have programmed a PIC to have multiple independent(maybe?) PWM outputs, even thought the chips only have one in hardware (did I see one with none?). Does anyone know how this is done?

9th May 2008, 06:56 PM	#2 (permalink)
blueroomelectronics Experienced Member Join Date: Jan 2007 Location: Toronto, Canada Posts: 4,121	How many do you need? __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

9th May 2008, 07:03 PM	#4 (permalink)
blueroomelectronics Experienced Member Join Date: Jan 2007 Location: Toronto, Canada Posts: 4,121	For LEDs a simple software PWM is plenty. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

9th May 2008, 07:07 PM	#6 (permalink)
blueroomelectronics Experienced Member Join Date: Jan 2007 Location: Toronto, Canada Posts: 4,121	It can be all interrupt driven. Lots of code samples on the net I'm sure. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

9th May 2008, 07:32 PM	#9 (permalink)
blueroomelectronics Experienced Member Join Date: Jan 2007 Location: Toronto, Canada Posts: 4,121	The App notes are really handy. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

9th May 2008, 07:00 PM	#3 (permalink)
johankj Experienced Member Join Date: Jan 2007 Location: Norway Posts: 110	Erch... I dunno... At least 3 for an RGB idea I have (moodlight-thing), but the more the merrier. BTW, that was hella-fast!

9th May 2008, 07:05 PM	#5 (permalink)
johankj Experienced Member Join Date: Jan 2007 Location: Norway Posts: 110	Yarh, but how? Does it have nothing to do with the hardware PWM then? And doesn't it tie up all the processing time?

9th May 2008, 07:09 PM	#7 (permalink)
johankj Experienced Member Join Date: Jan 2007 Location: Norway Posts: 110	AAAHH!! I find it, I find it! No worry. There is a technical document from Microchip themselves. AN1074 - Software PWM Generation for LED Dimming and RGB Color Applications.

9th May 2008, 07:09 PM	#8 (permalink)
johankj Experienced Member Join Date: Jan 2007 Location: Norway Posts: 110	Looks like I answered my own question...

9th May 2008, 08:15 PM	#10 (permalink)
3v0 Moderator Join Date: Jul 2006 Location: USA Posts: 2,568	If you want several hardware PWM's look at one of my favorites the 18F1330. It also has a PLL that works with the internal 8MHz clock that bumps it up to 32MHz. __________________ To control the world from your PC with USB I suggest USB Bit Wacker 3v0's Tutorials for ABSOLUTE BEGINNER C, PIC 18F, MPLAB® and MCC18 Compiler

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