2025-12-16 10:25 PM
Hello STM32 Community,
I am a newbie and facing an issue with my NUCLEO-STM32H755ZI board.
I am unable to connect to the STM32H755 target using STM32CubeProgrammer, even though the ST-LINK appears to be working correctly,
Board: NUCLEO-STM32H755ZI
Debugger: On-board ST-LINK
USB connection: CN1 (USB-A to Micro-B).
ST-LINK is detected correctly by Windows
ST-LINK Virtual COM Port is visible in Device Manager
Target voltage ~3.27 V is shown in Cube programmer.
Green power LED (LD3) is
2025-12-16 10:35 PM
Hi,
Did it work before? Did you flash anything?
Try connecting with setting: hardware reset.
Did you change/set the power supply setting?
Maybe then need start the bootloader by setting the boot0 high and then power up with dfu mode to recover to a working state.
2025-12-17 2:45 AM
@AScha.3 wrote:Did you change/set the power supply setting?
@Renee - see: How to unbrick an STM32H7 after setting the wrong power mode.
Also, for general debugger connection issues:
How to solve connection errors when connecting and programming the STM32 target board.
How to solve debugger connection issues.
2025-12-18 5:39 AM
Hello @Renee,
Try to connect to the bootloader and make a full erase of the flash.
1. Power off the board.
2. put a wire between pin 7 and pin 5 of CN11 => BOOT0 pin linked to VDD.
3. Power on the board.
If you haven't changed the default boot addresses defined in the option bytes, the STM32H7 will run the bootloader. You shall be able to connect with STM32CubeProgrammer.
2. Make a full chip erase.
3. Remove the wire => BOOT0 = 0 (Pull down resistor on the board => c.f. the board schematics)
4. Power off/on the board.
Now you should be able to connect and see the memory content as 0xFF => flash erased.
2025-12-18 5:47 AM
Make sure you are using a USB cable with data lines. Your results are consistent with a power-only USB cable.
2025-12-18 6:51 AM
@TDK wrote:Your results are consistent with a power-only USB cable.
I don't think so:
@Renee wrote:
ST-LINK is detected correctly by Windows
ST-LINK Virtual COM Port is visible in Device Manager
Target voltage ~3.27 V is shown in Cube programmer.
all of which indicates a data connection is present ?
2025-12-18 7:06 AM
Hmm, that's valid, but looking again, that doesn't really like up with:
> Red ST-LINK LED is blinking
which indicates enumeration failed. I'm probably misinterpreting.
If you programmed something on the board, it could be a power setting issue. You'll have to boot into the bootloader to recover.
How can I recover my STM32H7/STM32H7RS board after... - STMicroelectronics Community