Navigator+Pi4 Change PWM Outputs from 400Hz to 50Hz

Blue Robotics Products Flight Controllers
1

Hi,
I’m using the Navigator+Pi4 PWM Output pins to control an ESC + brushless DC motor.
I’m using a 50Hz ESC, so it wants a 20ms period, and 1-2ms pulse widths (for low and high command).

Using an Oscilloscope I see the output frequency for the Navigator boards PWM pins is around 463 Hz, so the period is around 2.1ms. The pulse widths are in the correct range, 1.1-1.9ms, but the signal frequency is to fast.

Is there a parameter in BlueOS or QGroundControl where I can update the PWM frequency to 50Hz/20ms period?

Thank you!
-Andrew

2

Hi @north,

If it’s possible (/implemented) it will be via either the RC_SPEED and/or the SERVO_RATE parameter (I’ve linked to the ArduCopter docs, since I believe that’s what you’re using).

BlueOS does not currently support changing the firmware parameters, so you’ll need to use QGroundControl (or some other control station software) to try changing it.

3

Thanks for the quick reply Eliot. This worked! I changed the RC_SPEED parameter from 490Hz to 50Hz and now I’m getting nice control over the motor/ESC.

Also, tip for anyone trying to set up RC motor control with the PWM pins. In order to control PWM pin 1 on the Navigator, I had to change the SERVO1_FUNCTION parameter from Motor1 to RCIN1.

Thanks again Eliot!

1 Like