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[on:]

Is it possible to phase shift two PWM signals 90 degrees, without using delays?

[Reply #1 on:]

I had thought about this a few days ago, in some context that might sound very idiotic,

But i think, if we have 2 separate microcontrollers, or arduinos, communicating through serial or through some other interface like I2C,
we can have a phase shift between the PWM signals.

I havent actually tried doing this, and i just *think* this might work. It might also sound idiotic, but i am kinda new here.

Regards

[Reply #2 on:]

I havent actually tried doing this, and i just *think* this might work

No way can you make that work.

As the PWM is based on the timers if you take two timers and set them to run at the same frequency then it might be possible. However setting the initial offset could be tricky.

[Reply #3 on:]

I succeed. In datasheet: .
Set two PWM signals:
- First PWM channel CALG = 0 (left aligned) with freqA (running on CLKA)
- Second PWM channel CALG =1 (center aligned) with freqB (running on CLKB)

The center aligned period is twice as long as the left aligned. If we take freqB = freqA *2 we get a phase shift of 90 degrees. Note: This works a duty cycle of 50% only ( I use it to generate encoder pulses).

[Reply #4 on:]

The SAM also has a PWM engine that will (I think) produce synced waveforms out of phase. As I understand it any PWMLx and PWMHx pair will do this but it's not supported by the Arduino libraries so you'll have to cut your own driver code.

______
Rob

[Reply #5 on:]

Note: This works a duty cycle of 50% only ( I use it to generate encoder pulses).

Yes it is easy to do things when you do not do them correctly or only approximate what is being asked for.