ESC feedback

  • Dev Team

    Question from customer - the modalai esc is working fine when commanded, but the RPM and voltage feedback is not available. I have attached a screenshot of the modalai_esc status which shows the feedback isn't coming in. I checked the connections, they seem fine.


  • Dev Team

    Hello, thanks for reporting. Good news is we already have a fix in for via this commit:

    It's slated to release in our next platform release (platform release 0.9), I can't mention the release date, as the release gods will then delay it... but we are getting close!!!!!

    There are pre-release channels available for developers, captured here:

  • Hey, thanks for that. I was able to pull the voxl-dev branch and got it working on the VOXL2, I can see the feedback of the RPM on the mavlink topic SERVO_OUTPUT_RAW. But the frequency is at 10Hz.
    When I try to use the following command

    mavlink stream -u "port_number" -s SERVO_OUTPUT_RAW -r 100

    I get an error stream SERVO_OUTPUT_RAW not found

    From the uart_esc code in px4-firmware I see that the uorb topic thats being used for RPM information is ESC_STATUS. And doing the following commands yields no result. The frequency is still 10Hz

    mavlink stream -u "port_number" -s ESC_STATUS -r 100

    mavlink stream -u "port_number" -s ESC_INFO -r 100

    Is there anything I can do to increase the frequency of the message ?

  • Dev Team

    Sorry for the lag, what if you use px4-listener esc_status ?

    If it's showing up there, likely we need to modify something to get this offboard....

  • So when i try px4-listener it says command not found.

    The command that works is
    listener esc_status
    This produces the following resutls
    never published

    But after some investigation, the uorb topic with the rpm information is

    I can read the output

    This topic is being published at 500Hz

    I tried to increase the rate of the following mavlink topics

    mavlink stream -u 15446 -s actuator_output -r 100
    mavlink stream -u 15446 -s ACTUATOR_OUTPUT -r 100
    mavlink stream -u 15446 -s actuator_outputs -r 100
    mavlink stream -u 15446 -s ACTUATOR_OUTPUTS -r 100

    Which results in the following error message
    ERROR [mavlink] stream ACTUATOR_OUTPUTS not found (same for all other)

  • Fixed the problem, the mavlink stream name is SERVO_OUTPUT_RAW_0.

    changing that to 200Hz gives us the RPM feedback at 200Hz on mavros

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