framework-stm32cube: Custom HSE_VALUE is "overridden" by value from package's template stm32f4xx_hal_conf

[mirao]

Steps to reproduce:

• Download the project https://github.com/mirao/stm32f4discovery/tree/master/stm32cube-printfOverUSB_UART It's a demo of "printf" over UART on STM32F4 Discovery. It's using an external PL2303 converter to be able to print from MCU to PC's serial console
• Comment out the "build_flags" lines in platform.ini, this way:

  ; build_flags =
  ;     -DHSE_VALUE=8000000U

• Follow the README.md (how to connect device, build and upload)
• When app is built and uploaded to MCU, open serial console and see output

Expected result:

• text "Hello World!"

Actual result:

• displayed characters are corrupted:

The problem is that the constant HSE_VALUE originally set to 8MHz by STM32Cube (see #define in Inc/stm32f4xx_hal_conf.h in project's root) isn't taken into account. App uses the default value from .platformio/packages/framework-stm32cube/f4/Drivers/STM32F4xx_HAL_Driver/Inc/stm32f4xx_hal_conf.h instead and it is 25Mhz.

But serial input/output over UART doesn't work well with such frequency.

Workaround:

• Hardcode the constant value to platformi.ini. It takes precedence before #define in source code

  build_flags =
  -DHSE_VALUE=8000000U

  Used SW and HW:

• MCU STM32F407-DISC1
• Ubuntu 19.04
• VSCode 1.38.1
• pio 4.0.3
• ststm32 5.6.0
• framework-stm32cube 2.0.181130
• STM32CubeMX 5.3.0
• platformio.platformio-ide@1.8.3

[valeros]

Your workaround with build_flags is the best solution at the moment. We plan to improve the build script for stm32cube framework, so it'll be able to handle such cases.

[mirao]

Just FYI: I've found out, that the external HSE oscillator was enabled because I confirmed the dialog Initialize all peripherals with their default mode? in STM32CubeMX when I was creating a new project. But the demo works even with internal HSI. It can be enabled in STM32CubeMX in "Clock Configuration => PLL Source HSI". HSI has only one frequency 16MHz and thus there's no need to apply any workaround.

[raphaelmor]

Just adding my 2 cents (I spent a few days struggling with the same issue with I2S). From what I understand (being a newbie with STM32, HAL, and Platformio), stm32f4xx_hal_conf.h is supposed to be copied into the application code and customized. I have no idea how to do that (given that platformio is so good at hiding those details), so I used the workaround of using build flags too.