Brushed With Relay AUXOUT5 relay not working

I’m using “Cytron MDD20A 20Amp 6V-30V DC Motor Driver” which require an AUXOUT pin for direction.

I changed MOT_PWM_Type to 3. Relay_PIN to AUXOUT5 and SERVO13_Fuction = 33 (Motor 1)
ServoOutput page has Servo1 Ground Steering and Servo3 Throttle

Between GND and Signal pin, Servo 3 shows 2.9+ volts when throttle is fully up or fully down.
But I can’t get any voltage on Auxout5 for forward or reverse direction control.

Which parameter am I missing or if any of them incorrect here?


Did you configure Aux5 for GPIO?

The signal is PWM and it needs to be armed to produce output for the motors. Steering will work w/o being armed.

Thank you very much. I’ve set the Servo13_Fuction (which is AuxOut5) to be -1 (GPIO) and that fixed the issue. I’m now getting 3.27 volts as my reverse signal. Instead of -1, I had used 33, which is Motor1, but I assume that’s for a different configuration. Thanks again

ArduPilot has amazing documentation, but I couldn’t find this particular answer anywhere (using -1 input for Servo13_Functoin, when using Brushed with Relay). If you know where information about this is mentioned, I’d love to read it, maybe I’ll learn something new.

Google “ardupilot gpio”.

Thank you, that really helped. The article for GPIOs was in the Advanced Configuration section. I had one more question from this page (Brushed Motors — Rover documentation)

It says that if “regular Pixhawk or Cube autopilot MAIN OUT 1 ~ 4 are in group1 meaning that if any brushed motors are configured for MAIN OUT 1 to 4 then servos must be connected to output 5 or higher”

I’m using Brushed with Relay which has RC servo outputs for Steering via MainOut1 and duty cycle voltage (0 to 3.27v) for throttle in MainOut3. and AuxOut5 which gives 3.27 volts signal when throttle goes in reverse. So I have brushed motor and PWM configured in 1 & 3.

The Messages Tab, shows “RCOUT: Brush:1-8 PWM:10-14”. But is servo 1 brush? (9-Auxout1 is GPIO)

And one last question regarding GPIO_MASK. Does this parameter allow you to turn any pin into a GPIO pin as well? So either that or enter -1 for SERVOx_Function parameter? But it’s only good for 1 pin then?