PWM dithering with DMA

hoang pham86

I would like to dither the PWM duty cycle by triggering DMA cycle by cycle.

EX: for a 2 bit PWM. I would like to alternate the duty cycle pattern cycle by cycle

00 01 00 01 00 01

I am trying to operate at a high pwm frequency and do not want to load down the processor with this task. DMA triggering is preferred

Can someone help me with this?

over 9 years ago

0 Bob Crosby over 9 years ago

TI__Guru 72500 points

You can generate a DMA request on the "compare equal" of the PWM. The issue may be the response time. How high a frequency?

0 hoang pham86 over 9 years ago in reply to Bob Crosby

Prodigy 80 points

We are targeting between 700-800 kHz. Is there an existing app note that can give us some guidance on this.

Thanks,

0 Bob Crosby over 9 years ago in reply to hoang pham86

TI__Guru 72500 points

Edit:

At that speed, using the DMA to write to the eCMP registers should work. Let me discuss this with some of my colleagues. Have you considered using an N2HET?

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PWM dithering with DMA