Generate a new channel based on data from other channels

Please refer to the post below for a more comprehensive description.


I’m recording the PWM signal sent to a stepper motor controller.

In this implementation, PWM duty cycle remains stable at ~50% but frequency changes from 127 to 500 Hz. Channel 0 captures steps and Channel 1 the direction.

I would like to display the frequency in an additional channel, for example as an analog measure just below. How to perform that?

Below is a mock-up with Frequency (Hz) corresponding to Channel 0.

I’ve recorded the trace: Session 0 - PWM.sal (28.4 KB)

Similar question if frequency remains constant but duty cycle changes.

Thank you!

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I would absolutely love to see this type of capability too. An analog-ish ‘psudo-waveform’ showing RC-servo angles over time, for example. Or PWM duty cycle corresponding to motor power, etc. etc. Super super useful.

I’ve created the idea Turn PWM metrics into additional channel.

Please click the upvote button!

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There are other ideas on there. One of which I made. The general idea is that it’d be nice if one could take data from one or more existing channels and turn that into data for a generated channel. Most of us wanted to go the other way from what you want. As in, maybe take an analog signal and turn it into a digital signal with hysteresis. But, I think the general idea is still the same - take data from one place, transform it, place it in a new channel. So, my recommendation would be for Saleae to make a generic interface for data transforming that allows people to generate new channel data.

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@Collin Yes, you are right. I like the idea of a broader implementation.

So I’ve changed the title of the thread from Turn PWM metrics into additional channel to Generate a new channel based on data from other channels.

I hope the new title reflects the general idea better.

the opening post just provided an example based on a real case. I went through the list of ideas but didn’t find a suitable entry so I added mine.

@joe_garrison @markgarrison @rani This means the Logic software would have now three kinds of channels:

  • logic, the historic foundation of Saleae,
  • analog, introduced with the + series of analysers,
  • virtual or calculated —whatever catchy name for marketing!—, based on data from other existing channels, to prepare the future.
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