PWM freq output on APM

Navio / Edge Flight stack
1

Hello there,

I set up a mirco servo as tilt servo for a PiCam. I set up RC10_FUNCTION=7 in order to plug servo on NAVIO output 10 and stabilize tilt.

But when I attach the servo to NAVIO port 10 it does not work as expected. It simply get hotter and hotter, a vibration sound is produced.

This is the Micro Servo.

My educated guess is that the NAVIO is outputting PWM at 490 Hz and that is not liked by analog micro servo.

I do not find a way in ArduCopter to set PWM output frequency at 50 Hz.

The RC_SPEED I suppose changes the frequency on ALL PWM output.

Any thought?

Thanks in advance
Fabio

1 Like
2

Hello,

Analog servos do not like 490Hz PWM, which should be used in ArduCopter. If you use 50Hz you will only give motor updates 50 times per second, that is not enough.

Unfortunately, RC_SPEED changes all outputs and there is no way to control channel frequencies one by one.

I would suggest using digital servos that are fine with fast PWM updates.

3

I have just tested a cheap HXT900 servo and it is fine at 200Hz PWM, main loop in APM runs at 100Hz, so this should be enough. You can simply set RC_SPEED parameter.

4

Thanks for your valuable hints.

F