Traxxas rover moves, but steering doesn't work

ArduRover Rover 4.1
21

The steering output should work without arming anyway. The motor output is disabled.

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22

if you swap the servo and motor connectors does the steering move the motor?

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23

No, but steering controls the main motor.

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24

ok then the output from the cube is fine, that leaves an issue with the servo or power.to it, do you have a 5v BEC you can connect to the servo rail thats separate from the esc?

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25

I just soldered some connectors to another servo, a Traxxas 2075. Also without success.

What is BEC? I do have a adjustable power source which I can connect to power the servo.

26

any 5V power supply will do. just so we can rule out the ESC servo power as a problem, BEC stands for Battery Eliminator Circut, basically what servo voltage regulators were called years ago when having a pack of 4AA batteries for the servos was common. some ESCs have them built in some dont.

In mission planner under status, what does the pixhawk report the servo voltage as?

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27

Do you have another servo to test with?
Just to tie up all endsā€¦

28

Sorry for the late reply, but the forum has a message threshold for new members which I apparently hit yesterday.

With 5V from an external power source, the servo also wonā€™t move.

In MissionPlanner, hwvoltage is around 4,9, servovoltage is 5916-5940.

And yes, I also have a second servo that shows the same behaviour.

I also measured the original control unit voltage on the servo channel. In center position it is 0.5V in contrast to the 0.25V from the Cube. I guess, the PWM signal is to short!? Or is this a misinterpretation?

29

At this point, I think we are all out of ideas.

Again, measuring analog voltage on a digital pin is fairly meaningless. The difference you are seeing is most likely due to 5V vs 3v3 logic levels, which I think we have ruled out as causal.

Send a clear picture of the wiring, and maybe we can visually diagnose.

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30

You could post the Parameter file but if the Steering Servo Output in Mission Planner is changing with control input itā€™s unlikely to reveal the problem.

31

I think the problem is the servo for some reason expects a 5v servo signal. the fact your motor moves ok with the steering channel rules out the cube, so i would just put it down to the 3.3v logic signal being too low for that specific servo, replace it with something non traxxas or get a logic level converter.

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32

The wiring is quite simple. The same connectors that go into the Traxxas controller are now connected to the cube. One channel for the main motor and one for the steering servo. I would rule out the wiring as the cause.

33

I think Iā€™ll give a logic level converter a try.

Thank you all for the support!

34

There are many successful examples of a Traxxas steering servo being connected to the output of Pixhawks 4ā€™ s and 2.4.8ā€™s running Ardurover. I havenā€™t seen any running Cubes. Is the Cube 3.3 V output on PWM, and the others 5? If that is the case, I would agree the 3.3 V may not be sufficient to trigger the logic to decode the PWM in the servo.