Pixhawk 6X — AUX Outputs Not Working in Mission Planner (SERVO9+ Disabled)

Achraf_RAHIB · April 9, 2025, 7:52pm

I’m working on a VTOL project using a Pixhawk 6X with ArduPlane firmware. Everything works fine on the MAIN outputs (SERVO1–SERVO8), but all AUX outputs (SERVO9 and above) are disabled in Mission Planner — I don’t even get the green PWM sliders.

What I’ve Tried:

Set SERVO_GPIO_MASK = 0
Set BRD_IO_ENABLE = 1
Set Q_ENABLE = 1
Verified OVERRIDE_CHAN = 0
BRD_SAFETYENABLE = 0 (safety button bypassed)
Disabled all GPIO usage
Assigned valid functions (motors, servos) to SERVO9_FUNCTION through SERVO14_FUNCTION
Uploaded a clean .param file with full VTOL mapping (includes tilt motors and V-tail control surfaces)

Firmware Context:

Pixhawk 6X
ArduPlane v4.4.x
On firmware 4.2 and later, BRD_PWM_COUNT no longer exists, so I couldn’t use it to enable PWM on AUX outputs.
- I’m aware that now we use SERVOx_FUNCTION = -1 to make a pin a GPIO, and we can use SERVO_GPIO_MASK if needed (which is already set to 0 in my case).

My Issue:

No matter what functions I assign to SERVO9–SERVO14, the AUX outputs remain completely disabled.
No signal, no PWM activity, nothing in Mission Planner (no green bars).
Could this be specific to the Pixhawk 6X hardware? Or maybe something firmware-related?

Any help or suggestions would be greatly appreciated!

Thanks