I’m trying to assemble a Balance Bot with this old MicroPix FC (Rover fmuv3, 2MB, no IOMCU), with a dual DC motor driver board requiring DIR1/2 level signals for motor directions, and PWM1/2 PWM motor signals (variable duty cycle at several kilohertz, not RC 1-2ms pulse signals (MOT_PWM_TYPE 3)), but it seems impossible to configure four GPIO’s as inputs:
12/12/2023 19:32:29 : RCOut: Brush:1-8
12/12/2023 19:32:29 : AHRS: DCM active
12/12/2023 19:32:29 : ArduPilot Ready
12/12/2023 19:32:28 : Initialising ArduPilot
12/12/2023 19:32:27 : RCOut: Initialising
12/12/2023 19:32:27 : fmuv3 003C002D 50485011 20323450
12/12/2023 19:32:27 : ChibiOS: 17a50e3a
12/12/2023 19:32:27 : ArduRover V4.4.0-beta11
The configuration parameters may be:
MOT_PWM_TYPE 3
RELAY_PIN 101 (first relay pin AUXOUT1) → DIR1
RELAY2_PIN 102 (second relay pin AUXOUT2) → DIR2
SERVO1_FUNCTION -1
SERVO2_FUNCTION -1
SERVO3_FUNCTION 73 → PWM1
SERVO4_FUNCTION 74 → PWM2
SERVO5_FUNCTION -1
SERVO6_FUNCTION -1
SERVO7_FUNCTION -1
SERVO8_FUNCTION -1
WENC_PINA 54 (AUX4)
WENC_PINB 55 (AUX5)
WENC2_PINA 57 (AUX7)
WENC2_PINB 56 (AUX6)
(Pin numbering seems strange, but MP permits it, and MP Motor Test can move motors in both directions (assigning WENC pins 105-108 has no effect for having GPIO inputs)). Anyhow, interpreting fmv3 hwdef.dat for all this is not clear.
In the past I had tried to configure this same board for Tradheli, with one signal as input to read rpm, without success, even if it should be possible, as the aux pins are the fmu pins: which are main on a flight controller without an iomcu.
So I used a Pixracer, which was cheap then, before the Chipageddon. A PixRacer cannot be used here, since it has six pins and eight are needed.
But looking at what happens with an oscilloscope, supplying the encoders with 5V, and moving the motors, the encoder signals are seen good when not connected (0 to 5V levels), but fall to 1V amplitude after connection, as if the FC signal were an output at 0V, causing a short to low level:
This happens for any SERVOx_FUNCTION value on the WENC signals above, even for SERVOx_FUNCTION=0 (disabled).
Any idea for getting GPIO inputs on MicroPix FC?