Add your board:

1. Create a copy of the STM32/variants/xxx folder with a name of your choice.

Use one that is the most similar to your board

2. Edit the ldscript.ld file

  1. Change the _estack to point to the end of RAM
  2. FLASH LENGTH to be the size of RAM of the microcontroller
  3. RAM LENGTH to be the size of RAM of the microcontroller


3. Edit the variant.h file

  1. Change LED_BUILTIN, MOSI, MISO... macros to point to the primary LED, primary SPI, primary I2C pins.
  2. Add board specific macros if the board has extra leds, buttons, SPI CS select lines etc...
  3. If the board has pin name - pin number assigments (for example arduino headers), Copy the VARIANT_PIN_LIST_DEFAULT from system/STM32XX/stm32_chip/stm32_STM32XXXXXX.h file, rename to VARIANT_PIN_LIST, and rearrange accordingly.

4. Edit the variant.c file

  1. Run STM32CubeMX, select the chip for your board
  2. If the board has external crystal, set RCC HSE to crystal. In clock configuration, set PLL Source to HSE, set HSE to the frequency of the board crystal.
  3. Set some peripherals (SPI, I2C, SDIO, USB, ...), so that the clock configuration will generate extra code needed for those peripherals, and bounds check the frequencies.
  4. Go to clock configuration, set everything to maximum :), let CubeMX figure out the rest.
  5. Click generate. Set toolchain/IDE to SW4STM32. Clik OK
  6. From the generated src/main.c, copy void SystemClock_Config(void) { into your variant/.../variant.c

5. Edit the boards.txt file

Copy one that is the most similar to your board

  1. Rename the board
  2. Change build.mcu= to your cortex-mX version
  3. Change build.series= to STM32XX, where XX is the chip series
  4. Change build.extra_flags=-DSTM32XXXXXX to be the exact chip version
  5. Change upload.maximum_size= and upload.maximum_data_size= to the RAM/FLASH size of the chip
  6. If the external crystal is not the board default in system/STM32XX/HAL_SRC/system_stm32XXxx.c, add -DHSE_VALUE=8000000 to
  7. TODO explain upload / usb / serial menu options

6. Restart

Restart Arduino IDE

Run examples / basic / blink