Motorcontroller BADVOLTAGE_FAULT

[Olaf_70]

Hi all,

I built my own motorcontroller with an Arduino Nano and a Pololu-Bridge. It connects to my Tinypilot via UART... so far so good. But the voltagemeasurement shows 20.43V and makes a BADVOLTAGE_FAULT.

I measured the pin A0 and I see 5,7 Volts, regardless of the voltage, I connect to my board. So I think the Arduino treats the pin A0 as an output. Where else should the 5,7V come from?

any ideas?

[ironman]

Hey, recognize that schema ;-) Remember to put a voltage divider on the Tx.

The voltage you measure seems to be about the max of the range, as indicated in motor.ino line 60. That would happen when R6 is not connected to ground. In that case, the input would be clipped by the protection diodes inside the arduino. It would be clipped against 5V, and with the diode voltage drop, you would measure 5.6V over it. So, I'd give that R6 a good scrutany. BTW this would also happen if you swapped R3 and R6 accidentally.

[seandepagnier]

The A0 pin is an input. It should not source current. I would check the R3 and R6 resistors.

[Olaf_70]

found it! Thanks for Your help. I swapped the resistors R3 and R6 because I was a little careless in layouting: the resistors names on the PCB are swapped.
@ironman: The voltage divider for the TX is on the Raspi side... like in your schematics ;-)