STM32G4 hardfault when entering sleep mode in debug mode

[mak22223]

Description of defect

STM32G474RE (NUCLEO-G474RE) gets hardfault when in debug mode and sleep mode is entered. Seems to be similar to #12294 and #12717. It only happens if debug build type is used or debugger connected once until power cycle. As I understand it happens because DBGMCU register values are not reset by hardware reset.

Target(s) affected by this defect ?

STM32G474RE (Nucleo board), but most probably whole G4 series.

Toolchain(s) (name and version) displaying this defect ?

I've tested two different configs (Windows):

• PlatformIO (toolchain-gccarmnoneeabi @ 1.90201.191206)
• GNU Arm Embedded Toolchain 10.3-2021.10

What version of Mbed-os are you using (tag or sha) ?

mbed-os-6.17.0

What version(s) of tools are you using. List all that apply (E.g. mbed-cli)

• PlatformIO 6.1.10 (framework-mbed @ 6.61700.0, tool-openocd @ 3.1200.0)
• Latest mbed-cli with latest openOCD.

How is this defect reproduced ?

To reproduce the bug you have to put device into sleep mode. In my case the following snippet is enough:
main.cpp

#include "mbed.h"

int main()
{
  ThisThread::sleep_for(1000ms);
  while (true) {}
}

The device puts crash info into VCP and led starts blinking as mbed enters mbed_die function.

Solution

According to the errara sheet (2.2.8) it is enough to add ISB insruction after WFI in targets\TARGET_STM\TARGET_STM32G4\STM32Cube_FW\STM32G4xx_HAL_Driver\stm32g4xx_hal_pwr.c line 475. Don't know whether it is needed at line 566, because it works after adding ISB after 475 line.