Tricopter, Bicopter with 400Hz PWM frequency on servo outputs

ArduCopter Copter 4.0
1

Hi,

I loaded APMCopter 4.03 onto my pixhawk, set frame class to 10 and connected the servos of my bicopter frame to the outputs set to tiltMotorleft/right. I connected power and the servos started to whine. I immediatly disconnected power again. After finding my PPM/PWM monitor I connected it to the servo outputs and it showed a frequency of 400Hz, which will destroy my servos (or any servo I know about). I looked throught the full parameter list, but could not find anything to change the PWM frequency. How I am supposed to use the bicopter frame class?

2

https://ardupilot.org/copter/docs/parameters.html#servo-rate-servo-default-output-rate

3

I searched the full parameter list for “rate”, “servo”, “pwm”, but never found this parameter. Strange.

4

I can only guess something went wrong during firmware flash, because I reflashed arducopter 4.03 and now the outputs are at 50Hz and the servo_rate parameter is there. Thank you for your help!