STM32G4 won't boot if not build_type = debug

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1

Hi guys,

I’m working with a STM32G4 and my platformio.ini look like this

; PlatformIO Project Configuration File
;
;   Build options: build flags, source filter
;   Upload options: custom upload port, speed and extra flags
;   Library options: dependencies, extra library storages
;   Advanced options: extra scripting
;
; Please visit documentation for the other options and examples
; https://docs.platformio.org/page/projectconf.html

[env:genericSTM32G431CB]
framework=stm32cube
platform = ststm32
board = genericSTM32G431CB
debug_tool = stlink
upload_protocol = stlink
board_build.stm32cube.custom_dsp_library = yes
build_flags =
    -Llib/cmsisdsp
    -lcmsisdsp

;https://community.platformio.org/t/error-object-uses-vfp-register-arguments-firmware-elf-does-not/25263/2
extra_scripts = pre:add_hardfloat.py

; TODO il faut creuser ici, le build debug desactive les optimisations
build_type = debug

I noticed that when I remove the build_type or set it to release, the upload works fine but the mcu crash.

I check the diffs between the flags according to the build_type and the differences look like that

Capture d’écran 2025-11-15 à 18.03.06
Capture d’écran 2025-11-15 à 18.03.062486×1582 452 KB

So I tried to add -Og -g2 -ggdb2 flags to my platformio.ini build_flags but hat doesn’t change anything, the mcu crash.

The mcu works properly when build_type set to debug though

Thank you

2

So, in what function does it crash? What’s the stack trace?

It might be code that is not safely written that crashes when compiler optimizations are applied.

3

It’s look like that the calls to CMSIS functions cause the crash.

I added a more recent version than the platformio default: GitHub - Sercurio/CMSIS_6_DSP-builder: A repo for building latest CMSIS DSPs for using in embedded mcu

void HAL_ADC_ConvHalfCpltCallback(ADC_HandleTypeDef* hadc) { process(0); }
void HAL_ADC_ConvCpltCallback(ADC_HandleTypeDef* hadc) { process(N); }

Inside process I’ve got calls like
arm_fir_q15(&S_am_fir_i, tmp_i, tmp_i, N / 2);

When commented out, the mcu run fine.

It’s an interrupt drived by an ADC

4

Do you have a minimal firmware that reproduces the crash? (MRE)

5

You need to at least build_unflags = -Os to properly do that, otherwise it will have both -Og and -Os.

6

Here a minimal project that call a CMSIS function and crash just after

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