Pixhawk not controlling servos

Posted by Samuel Rosenstein on April 6, 2016 at 4:47pm

Ok, this is an odd problem. Here goes:

I have the pixhawk armed without GPS (solid blue light, APM Planner says "armed").

Pixhawk is plugged into my computer over USB

BEC powering servos (well, one servo at the moment) by it's plugged into the AUX rail. 

PPM input through RC IN. 

Radio is calibrated and reading fine (when I move the sticks, I see the correct movement in APM Planner). 

The Pixhawk says it's giving servo output (I went to the failsafe tab and watched the servo output) and it's moving.

HOWEVER the servo doesn't move. I've tried Ail, Thr, Elev, Rud and none work. 

I've reflashed the Pixhawk and that didn't fix the problem. (I'm a bit of a diy dev). 

Any ideas on what I can test? 

Is is possible that everything works except for the servo output (something blown)?

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Replies

  • Angel Espinal March 24, 2018 at 5:44pm

    Hey, i guess i have the same problem, i am using rover, i have the rc calibration done well, the pwm is ok coming from the RC, but it comes wrong from the output channels, for example, my limits in the rc calibration are from 1060 to 1800 pwm, but servo output is around 200 pwm, how can i do a full system reflash? just reinstalling the FW?

    Samuel Rosenstein said:

    Hey - so found out it was an error on boot:

    "Unable to open /dev/pwm output 0"

    That ArduPilot was spitting out. Not sure why this error was occurring, but a full system reflash (to the newest version in the github) fixed it! :P

    Does anyone happen to know what that error is, or why it occurs?

    Pixhawk not controlling servos
    Ok, this is an odd problem. Here goes: I have the pixhawk armed without GPS (solid blue light, APM Planner says armed ). Pixhawk is plugged into my…
  • Paul Harris April 8, 2016 at 6:36am

    In plane mode the servos for Aileron , rudder ext don't go on the AUX Pins they go on the normal pins and so does the BEC to power them.

    I found on my board that the AUX pins are for channels 9 and above so you need at least a 9 channel radio to use them, although there might be a way to map them to lower channels, but I have not yet found it.

    On mine I have

    Aileron on Main Out 1

    Elevator on Main Out 2

    ESC on Main Out 3

    Rudder on Main Out 4

    In my case I am using an ESC with BEC so don't need a separate one for the servos.

    Aux 1 is connected to the flaps via channel 9

    Aux 2 is connected to the gear via channel 10

    Give it a go

    Paul

    • Samuel Rosenstein > Paul Harris April 15, 2016 at 8:01pm

      Problem solved: This was the problem solved by the newest version of Arduplane: 3.5.2. We were having the memory issue on boot and therefore couldn't use any aux pins. 

  • Samuel Rosenstein April 6, 2016 at 8:20pm

    Hey - so found out it was an error on boot:

    "Unable to open /dev/pwm output 0"

    That ArduPilot was spitting out. Not sure why this error was occurring, but a full system reflash (to the newest version in the github) fixed it! :P

    Does anyone happen to know what that error is, or why it occurs?

  • Christopher Rice April 6, 2016 at 6:48pm

    Try and connect over telemetry if you have the radios hooked up, the power from the Battery Monitor (if you are using) will power the Pixhawk, and the ESC/BEC will power the rail. Also it could be your servo is bad??

  • Bruce Baxter April 6, 2016 at 5:35pm
    Is the servo reading the signal?

    With power off, move the servo and power on. Does it move?

    I think the pixhawk has varying output modes, 400hz vs 50hz etc
This reply was deleted.