Unable to Flash STM32WLE5 Custom Board Using STM32WL55JC1 Debugger – Flash/Erase Errors

[ruvaispari123gmailcom]

Hi everyone,

I'm currently trying to flash firmware to a custom board with STM32WLE5CCU6 MCU using the onboard debugger of a NUCLEO-WL55JC1 development board. I'm running into multiple issues and would appreciate any help.

Setup:

• Target MCU: STM32WLE5CCU6 (custom board)
• Debugger: Integrated ST-LINK on STM32WL55JC1 (used as programmer)
• Tools: STM32CubeIDE(Ver 1.15.1) and STM32CubeProgrammer

Issue Summary:

1. CubeProgrammer only connects at very low frequency (200 kHz SWD clock). Higher frequencies fail to detect the target.
2.  Even when connected, flashing consistently fails with different errors on both IDE and Cube programmer depending on the attempt.(in all modes)
3. . Errors observed in STM32CubeIDE:

Spoiler

Failed to execute MI command:
load ...\LoRaWAN_End_Node.elf
Error message from debugger back end:
Error finishing flash operation

4. Errors observed in STM32CubeProgrammer:

Spoiler

Error: failed to erase memory
Warning: failed to run application!
Warning: The core is kept under Reset!
Error: Start operation failed

Additional Notes:

• I verified the SWD connections (SWDIO, SWCLK, NRST, GND).
• The custom board powers up correctly.
• I am using a basic firmware from STM32CubeWL .
• Sometimes it connects, but erase or program operation fails.

I have attached the custom board schematic below.

Thanks in advance for any guidance!

Let me know if you want me to add or rephrase anything specific (e.g. schematic details, pinouts).