Today I switched to 4.2.0rc1 firmware to use the PLND_XY_DIST_MAX parameter during my precision landings. On my hex, I use AUX OUT 1/SERVO9 to control a servo that tilts my camera via PWM. The servo is powered from a 5v BEC plugged into AUX OUT 6. During missions, it is controlled by Drone kit. Currently, I can move the servo freely by hand, whereas previously I couldn’t move it because of the PWM signal “locking” it in place.
On 4.1.5 I had full control of the servo in mission planner “Servo/Relays” (PWM range 825-1825), but since upgrading I cannot move the servo in mission planner. I read the note on the “common-servo” page in ardupilot.org but I still could not remedy the issue. Other posts in the 4.2 section seem to have to do with relays, not servo PWM control.
One thing that looks suspicious in the parameter file is that the MOT_PWM_TYPE has been set to “5” (DShot300) but the motors are connected to servo1 to servo6. I think this is a CubeBlack (or similar) which has an IOMCU meaning the DShot only works on the auxiliary outputs (see wiki here).
I’m still investigating why this would stop the PWM outputs on ch9 from working…
… I’ve reproduced the issue and added it to our 4.2 issues list. Thanks very much for finding this!