u/LORDWDX

Hi, I’m currently setting up a PicoMMU using an EBB42 v1.2 connected over USB to a BTT Pi 1.2 (not CAN for the moment).

I successfully flashed the EBB42 with updated Klipper firmware and the board was initially detected correctly as stm32g0b1xx. Klipper communication was working.

Then I configured the MMU gear motor using the EBB42 extruder driver. As soon as I tested the motor with MANUAL_STEPPER, Klipper reported:

TMC 'manual_stepper mmu_gear' reports error: DRV_STATUS: 000e0090 s2vsa=1(ShortToSupply_A!) olb=1(OpenLoad_B!)

I suspected the motor wire order might be incorrect, so I powered everything off and changed the motor wiring.

After that, the EBB42 became unstable on USB:

• sometimes detected as OpenMoko, Inc. stm32g0b1xx
• sometimes completely absent from lsusb
• no consistent USB enumeration anymore
• LEDs on the board still power on and react to reset
• reflashing through DFU completed successfully once (File downloaded successfully), but the USB instability remained afterward

At the moment:

• the board powers on
• LEDs work
• USB communication is intermittent or absent
• tested with different USB cables and ports
• issue persists even with nothing connected except USB

I would like to know:

1. Could an incorrect stepper motor phase order alone cause this behavior?
2. Is it more likely that a short occurred on the motor/TMC side?
3. Does this sound like damaged USB hardware, damaged TMC2209, or possibly recoverable over CAN/STLink?
4. Are there known EBB42 v1.2 failures matching these symptoms?

Thanks.