How to downgrade/restore STlinkv2 ?

[ijona]

Hi,

I update my STlinkv2 from V2J29M18 to V2J34M25 firmware version and i lost the UART communication.

I have two STlinkV2 and one is always in V2J29M18 version so i'm sure that the problem come from the update.

So my question is how i can restore the V2J29M18 firmware ? (the easy way i think)

Or how to re-active the UART communication with the V2J34M25 version ?

Best regards.

[ijona]

I have tested with an old nucleo STM32L432KC to upgrade the ST-Link firmware and it's work fine.

So i also try to add a physical pull-up on Tx (and Rx) but no effect. I check with my oscilloscope the Tx Rx line with the old and the new probe it's same signal.

I think on nucleo board it's have a bride connected what isn't on my probe i need to double check this.

[ijona]

I try to connect my device through the ST-Link of my nucleo board and it's work so my problem become to my custom probe.

to be continued...

[ijona]

Ok i found what is the trouble.

On my design i leave pin28 (PB15 PWR_ENn) of the IC STM32F103CBT6 of the ST-Link in floating state (not connected at anything).

So apparently in new firmware version there is a challenge on this pin.

With a pull-up all is ok and all work fine.

Thank at all for your help.

[S C]

This looks very strange to me: PWR_ENn is an output for the ST-Link, most often driven to 0, so adding a pull-up should only increase the board consumption without any other impact (if not connected to the target). Are you sure this signal is not in shortcut with another one on your board ? Or was really used as input on your target side without being connected to the ST-Link side ? The different behaviors between ST-Link firmware versions make me firstly choose the first hypothesis.

[ijona]

In my case PWR_ENn is not connected

And now i don't understand nothing, all work without pull-up and same configuration as before just a little more hot in my room...