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STM32 Cube IDE: Reset_Handler() at 0x80021e0


Hi STM team,

I am using the STM32WL55CCU6 MCU on a custom PCB project. I actually have two of these. One is working as a master, while the other operates as a slave. My slave device is working properly, but the master is not. 

Problem Statement: When debugging, a tab appears with the information: "Reset_Handler() at 0x80021e0". Attached is a screenshot. I am not sure what is causing this, but I think it is blocking my code from executing properly because when I place breakpoints at the printf() and APP_LOG() debugging statements, these do not execute, and no output is shown on the terminal.


Note: under Properties > C/C++ Build > Settings MCU GCC Assembler > Debugging I have set to maximum (-g3). Under MCU GCC Compiler > Optimization I have set to None (-O0).


When I change these configurations to default (-g) and optimize for Debug (-Og) respectively, the warning tab that appears changes to: "main() at 0x8000a94". Attached is a 2nd screenshot depicting this.


I am using STMCubeIDE Version 1.14.0 I have included a 3rd photo showing the software versions I am using. I have double checked my pin configurations, clock settings and there are no errors or warnings that show up after building. I have looked at the online forums and I can't find anything helpful. Is there anyone that can help me troubleshoot this issue? It is time sensitive, and I am a software developer for a company. We are customers of ST. If there is another way to get in contact with an ST FAE, I would appreciate that information as well. 


Please let me know if there is any other relevant information I can provide.


Thank you for any support in advance,













If code can't be found, it's possible your debugging configuration doesn't have debugging enabled. You can enable this in project settings (C/C++ Build -> Settings).

If the IDE can't make the link between source code and what's running, none of your breakpoints will work.

If you feel a post has answered your question, please click "Accept as Solution".
Pavel A.
Evangelist II

Hi, on your 1st screenshot the debugger is stopped at the breakpoint on main(). This is normal. Double click on the main() item in the stack trace pane on the left, the editor should activate main.c and position somewhere in the main() function. If this happens, all is good.

On your 2nd screenshot, the stack trace pane is not shown. This is unusual. Can you manually bring up the stack trace view? If you open disassembly, does it look sane?