STLink firmware bug regression: Target does not boot when powered by E5V

[SKled.1]

From finds on the web, there was, years ago, the phenomenon with STM32 Nucleo boards that, when J5 is set to E5V, and the board is powered from the E5V pin instead of USB, the target MCU will be held in reset.

I just updated the ST-link firmware on a nucleo F103RB board with the firmware that is offered by CubeIDE 1.6.1.

The firmware version was something with "3.J7..."

I then observed this effect.

My installed ST-Link Util software offered a lower version, 3.J4 something.

I downgraded to that - now it works again, i.e. the target MCU runs when externally powered and nothing is connected to the debugger USB jack.

[Markus GIRDLAND]

Hello!

Did you try with multiple MCUs or is it a specific one? Have you tried with STM32CubeIDE 1.7.0 and do you get different version numbers using that? I can try to run some tests to reproduce it later today.

[SKled.1]

It was a freshly unpacked Nucleo STM32F103RB, ordered within the past 2 years.

I only upgraded to CubeIDE 1.7.0 now and don't have the board available (it's being used in a makeshift device, where the external powering is used).

[Markus GIRDLAND]

OK, I haven't been able to reproduce yet but I have a few additional ways I want to try first.

If you find a way to reliably reproduce on STM32CubeIDE 1.7.0 then let me know!

[SKled.1]

I found another apparently unused board of the same type.

I upgraded to the STLink version that CubeIDE 1.7 offers (I believe V3J8...), and can also not reproduce it anymore, on the board of "MB1136 rev C". The other one, I only remember seeing the "rev C" and it's likely they were ordered together.

So I guess if there was nothing else wrong with my other board, the V3J7 version had a hiccup which is gone now with 3J8 .

[Markus GIRDLAND]

Thank you for testing. Hopefully it will continue to not appear with 3J8 but it's good to keep track of this as a known issue if other people run into the same issue.

If the problem starts appearing again with the newer version then let me know!