OpenMV N6 not enumerating on USB and steady red LED

OpenMV Boards
1

Hi all,

I have an OpenMV N6 that Windows reports as an “Unknown USB Device (Device Descriptor Request Failed)” as soon as it’s plugged in. The green power LED lights up normally, but a red LED also lights up steadily alongside it and holding RESET to GND turns the red LED off while releasing it turns it back on, suggesting the board keeps trying to boot and failing.

I’ve tried multiple unplug/replug cycles to catch the auto-bootloader window, different USB cables, and different USB ports/PCs. I checked with Zadig whether a DFU device was hiding under a different entry and the only device shows up as USB ID 0000:0002, meaning no real descriptor was ever received.

I also tried forcing BOOT0 to 3.3V to try to reach the STM32N6’s system/serial bootloader, and attempted to connect via STM32CubeProgrammer over USB expecting the standard ST DFU VID/PID (0483:DF11). Even in this forced ROM bootloader state, the board still fails to enumerate at all, with the exact same “Unknown Device” behavior.

Has anyone seen this exact failure mode, or is there anything else worth checking ?

2

Mmm, this is a pretty bad hardware failure, We have the red led on the board connected to the system ROM boot failure pin. It blinking means that the chip’s ROM bootloader isn’t able to start up the system initially.

I also tried forcing BOOT0 to 3.3V to try to reach the STM32N6’s system/serial bootloader, and attempted to connect via STM32CubeProgrammer over USB expecting the standard ST DFU VID/PID (0483:DF11). Even in this forced ROM bootloader state, the board still fails to enumerate at all, with the exact same “Unknown Device” behavior.

This is typically unbreakable. Do you know what happened to the board?

3

Thanks for replying.

I’ve been using this board for a nocturnal insect and bat detection setup, running it outdoors at night. I don’t have a specific incident I can point to (no drop noticed), but given the outdoor/nighttime use, humidity and condensation seems like a plausible cause. Do you think this could be the cause? And if so, what can I do to confirm it?

4

Not really sure, you probably need to get a second unit and get it to fail in the same way. Condensation would likely be the killer.

We are working on an outdoor IP rated case for the N6 and RT1062 at the moment which should make deployment for this situation easier.