topic Re: PWM on MCF51JM128 in ColdFire/68K Microcontrollers and Processors

PWM on MCF51JM128

b_rad — Tue, 19 Jul 2011 21:38:06 GMT

Hi There

I am trying to create a simple PWM signal on my MCF51JM128. Ive already tested the device with timer overflows and output compare mode which work perfectly. However, as soon as I set TPMxCnSC to operate in PWM mode I get nothing out. Its driving me mad.

My code is attached

Anyone got some advice?

Re: PWM on MCF51JM128

RichTestardi — Wed, 20 Jul 2011 01:12:07 GMT

I didn't see any code in the attachment, just an mcp file?

I run PWM on the 51JM128 and you can see the code in the StickOS skeleton project at the bottom of this page: http://www.cpustick.com/downloads.htm

The file you want to look at is sources/pin.c, and follow the 51JM128 #if''s -- sorry there's lots of noise in the file for other MCUs. The routine pin_declare_internal() sets up the pin for PWM mode (either servo or analog output) and pin_set() sets it to a specific value (in microseconds or millivolts) -- search for PIN_PTE3 for one of the pins with PWM capability.

-- Rich

Re: PWM on MCF51JM128

b_rad — Wed, 20 Jul 2011 14:04:04 GMT

Thanks for the help Rich!

It turned out that I was setting up the registers in the incorrect order. I had followed the same procedure that I had been using in programming a GT16 chip which simply did not work on the JM128. All I had to do was re-order my code.

Brad