How to HSI stm32f103C8 and big memory usage

maxgerhardt · January 10, 2020, 2:31pm

So the first thing to find out is which of the two STM32 you’re using (mapple or stm32 provided one). The board’s JSON file says

github.com

platformio/platform-ststm32/blob/master/boards/genericSTM32F103C8.json#L3


      
          {
            "build": {
              "core": "stm32",
              "cpu": "cortex-m3",
              "extra_flags": "-DSTM32F103xB -DSTM32F1",
              "f_cpu": "72000000L",
              "hwids": [
                [
                  "0x1EAF",
                  "0x0003"
                ],
                [
                  "0x1EAF",

So the board speed setup is in

github.com

rogerclarkmelbourne/Arduino_STM32/blob/8f28e3b358aae831b001f872846e95cdc3eea470/STM32F1/variants/generic_stm32f103c/wirish/boards_setup.cpp#L69-L77


      
                  static stm32f1_rcc_pll_data pll_data = {BOARD_RCC_PLLMUL};

          #if !USE_HSI_CLOCK

                  __weak rcc_pll_cfg w_board_pll_cfg = {RCC_PLLSRC_HSE, &pll_data};

          #else

                  __weak rcc_pll_cfg w_board_pll_cfg = {RCC_PLLSRC_HSI_DIV_2, &pll_data};

          #endif

                  __weak adc_prescaler w_adc_pre = ADC_PRE_PCLK2_DIV_6;

                  __weak adc_smp_rate w_adc_smp = ADC_SMPR_55_5;

So you just have to define USE_HSI_CLOCK. Do that by adding

build_flags = -D USE_HSI_CLOCK

to the platformio.ini. That should be it and the board should be choosing the HSI & 72MHz configuration.

Note that this makes it impossibles to use the USB interface is it needs the HSE to generate a stable 48MHz for the USB system.

You may also try to use board = bluepill_f103c8.json to use the STM32 core (platform-ststm32/boards/bluepill_f103c8.json at master · platformio/platform-ststm32 · GitHub).

Well that’s just the thing with frameworks. Lots of boiler-plate code is compiled, even though your code just uses the GPIO and PWM (aka timers) on the board. You can generate .map files (Generate a .map file - #8 by krishna_chaitanya) and look at them using Amap | Sergey Sikorskiy to know which exact file / function / object is taking up which memory.