Can't connect to target STM32f105RC.

[OBorr.1]

Hello Community!

I was using a system controlled with the STM32f105RC, I was able to program it with the ST-Link. In that system I got a problem so I had to change to another board with the same characteristics but, when I did so, I wasn't able to program any other system with that microcontroller.

I used the ST-Link to program another system with a STM32f103 microcontroller an it worked, but with the board that I need to use It's simply not working.

It's not only that board, I have another board with the same characteristics that I was able to program, but now I'm not able to program it any more.

Any help will save me.

Thanks!

[Tesla DeLorean]

If the NRST pin is wired in your design you can perhaps use "Connect Under Reset"

Try pulling the BOOT0 high to stop code on the processor running and blocking the SWD/JTAG connectivity.

Determine if the devices have protection measures enabled.

Check that the ST-LINK is getting the target voltage on pin 1 or 2 of the 20-pin header.

Try both STM32 Cube Programmer, and older ST-LINK Utilities.