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How to output a PPM signal channel from RX to a PWM Output?

Posted by Peter on September 14, 2013 at 3:12pm

Hey there,

I have just spent hours to find out how to use one of the APM 2.5 PWM outputs as a relay for one PPM input channel.

Task is to control a FPV camera which has a PWM input for mode selection. My RX has 4 PWM channels but is used as 8 channel PPM source. All TX channels are available and calibrated in Mission Planner and APM is controlling a quad.

What I wish to achieve is that TX channel 8 from within the PPM signal is forwarded to let's say OUT8 as PWM.

How is this possible?

For now I found the parameter RCx_FUNCTION with the value 1, meaning RCPassThru. This sounds pretty much like what I'm looking for and so I set RC8_FUNCTION = 1 and connected my cameras contol input to OUT8. But changing TX channel 8 does nothing on the camera. Is there something I have missed here?

Thanks & best regards,

Peter

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Tags: ppm, pwm, rcpassthru
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Replies

  • Duncan J April 7, 2014 at 11:14pm

    any idea how I can change the tail servo for a tricopter from #7 output on APM to #8 somehow?

  • Antoine Lagarde October 14, 2013 at 7:51am

    Any update on this? I'm trying to do the same thing except I have all the 8 motor outputs used as I'm on an octo

  • Rich October 13, 2013 at 5:05pm

    I know you can read RC signals (PPM and PWM) using the PulseIn function. I'm still figuring this out myself, but PulseIn might be a good place to start looking. Once you have the signal you could pass it through manually or apply whatever logic you wish, I presume.

  • João Victor Fortes Carvalho October 4, 2013 at 6:36am

    I am also having problem with this, I trigger a camera connected in channel 7 manualy for testing purpose, lately I wish it controlled by apm to trigger it thought missions, as now I cant control channels thought output, is there anything we should do?

  • Peter September 15, 2013 at 5:13am

    Just found this Issue on GitHub.

    Actually I try to use the Boscam Cobra HD which is controlled the same way as the HD19 which was mentioned in Issue #286.

    Does it mean that RCPassThru is not yet working at all in ArduCopter? Or is it supposed to work on other channels but not yet on channel 6?

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