2 Questions About Beagle Bone Blue servo outputs

ArduRover
1

Hi all,

I have 2 questions but I figured I would knock them both out in one post:

Right now I am working on configuring my beagle bone blue to control a skid steer rover with 6 wheels using ardurover and mission planner.

Question 1: I want to test the servo outputs of my beagle bone to confirm that I have the board configured correctly before mounting it in my robot. I attached an oscilloscope to my PWM pin on the servo connection and noticed that the 7 and 8 pins on the board are always outputting 100% duty cycle signals, even when the board is disarmed. I decided to reflash my board to remove ArduRover incase something went wrong in my download. This caused for pin 7 to stop firing, but pin 8 continued. After putting ArduRover back onto the board, pin 7 was back to always outputting. My question is if this is expected with this board and ArduRover or if my hardware is at fault.

Question 2: I have not been able to find an explanation of which pins of the beagle bone correspond to the different servo settings on mission planner. As it stands right now, when I connect to my board using mission planner I am presented 16 servo outputs that I can configure. I thought that the BBB had the 8 servo pins and 4 built in motor drivers. Is it that the first 8 servos in the mission planner settings correspond to the 8 servo pin outputs and the later outputs correspond to the motor drivers?

I appreciate any guidance anyone may have! Thanks.

2

Hi @Scrubner

In true, there is only one way to solve your issue with pins - spoiler alert - this will happen to gpio too.
You need to do a custom dtb file to change the pins mode/direction.
To use ardupilot with bbblue, you need an ESC connected to servos outputs 1 to 8 - there are 2 main reaons to that, first the ardupilot on blue is using pru to generate the pwm pulses on thie servos outputs, and the second is ardupulot doesn’t support the motor driver present in the blue board .

3

Hi @juvinski,

That makes sense, I will take a crack at it, thank you for the input.