I had a problem with STMF334R8, I loaded the same program on several boards with some STLINK V-2, via CubeIDE and then I was unable to get them to connect again to the computer to load another program with any kind of st link. What could cause that?

[XZuri.1]

I had a problem with STMF334R8, I loaded the same program on several boards with some STLINK V-2, via CubeIDE and then when I tried to conect the MCU's again to the computer i had an error: failed to initialize GDB server, and in the console it appeared not device found. I cannot even connect those MCU's to my computer not even with a STLINK V3, but I could connect other boards that weren't programmed the days before with the ST link V3 but not the ST link V2.

The boards and the code loades was working fine it was just they could not be reprogrammed or reloaded with other code. We tried to erase the flash while forcing a hardwere reset using St Link Utility but was not satisfactory either. It could not get connected even for to erase the flash memory.

I had to extract the chips from those boards with failures, put another one in and the they were able to be programmed again with the st link V3. Can anybody help me find what went wrong, please, in order to not commit the same mistake again? It is some protection against copy that was activated on the MCU? it is just something wrong on STlink V2 that corrupted the chips?

Thank you

[TDK]

If you run STM32CubeProgrammer in standalone mode, are you able to connect to them? I would also try with the older but still working "STM32 ST-Link Utility" to see if they respond.

You have NRST hooked up to the ST-Link interface, right? Otherwise, reinitializing the SWD pins will prevent ST-Link from working.

[XZuri.1]

I had to change the MCU in that board, the others boards where finally programmed by changing to a ST link V3 with no problems. Maybe I used a STLink that spoiled the MCU. The connexión was right in every moment and all the boards aret he same. Maybe it was a statics problem or it was ST link v2 fault... I don’t know what happenned, I cannot program anything else again with the stlink v2 that i used and I don’t want to try it in case it brakes again a MCU...

Thanks for your answer