Pwmpal
paulc22
Posts: 7
Hi folks.· I'm using the PWMPAL to generate pulses.· The PWMPAL pulses 4 channels.· I need these pulses to be syncronized with each other, but what I'm seeing on the scope is a positional offset between them.· I would like to hear from someone who has used the PWMPAL who might confirm my observation, and a workaround if possible.·
Basically, I need each channel to pulse once on different portions of the same period.· It appears that each channel simply goes·about its business pulsing according to the assigned frequency and duty cycle,·but they are not time related to each other at all, except by some undocumented fixed offset which I cannot control.
This is a major disappointment to me. because controling the output pins directly w/the Stamp is way too slow.· I need to operate at the microsecond level, which the PWMPAL can do.
Paul C
Basically, I need each channel to pulse once on different portions of the same period.· It appears that each channel simply goes·about its business pulsing according to the assigned frequency and duty cycle,·but they are not time related to each other at all, except by some undocumented fixed offset which I cannot control.
This is a major disappointment to me. because controling the output pins directly w/the Stamp is way too slow.· I need to operate at the microsecond level, which the PWMPAL can do.
Paul C
Comments
You will find that many multi-channel pulse-width output controllers stagger their pulse trains between channels. There are reasons for this, but nonetheless the PWMPAL wasn’t designed to trigger each output synchronously…That’s not possible in most situations where each channel can have a different frequency. To do what you’re trying to do you’d need an SX Chip or Propeller programmed specifically for this purpose.
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Chris Savage
Parallax Tech Support