Custom STM32F1 board - how to add variant

[etr8]

Hello all,

it is my first time here, excuse me in advance for any stupid or wrong question i make!

I have small experience with STM32 and developed two boards based on STM32F030. In that case, to avoid configuration issues i copied a demo board pinout, clock, etc. so i was able to program it without any issue.

This time, project is a little bit more advanced and i am planning to use a STM32F103CBT6. I want to run at 72 Mhz so using CubeMX Tool i configured clock with 8 Mhz HSE and 32Khz LSE for RTC.

I can generate code and, following wiki tutorial i am trying to make a new variant to be used on arduino ide.

First attempt was to create a new folder (copying the content of F103C8T_F103CB(T-U) ) and replacing ldscript.ld and generic_clock.c
I was getting lot of errors (mainly related to system clock config).

After reading some times more the tutorial and trying to figure how to do make the variant, i see i can place an entry in boards.txt which points to a variant*.cpp file. (i copied this from the F0 family).

This is what i did:

boards.txt:

# Generic F103CBTx 8 Mhz
GenF1.menu.pnum.GENERIC_F103CBTX_8M=Generic F103CBTx (HSE 8 Mhz)
GenF1.menu.pnum.GENERIC_F103CBTX_8M.upload.maximum_size=131072
GenF1.menu.pnum.GENERIC_F103CBTX_8M.upload.maximum_data_size=20480
GenF1.menu.pnum.GENERIC_F103CBTX_8M.build.board=GENERIC_F103CBTX_8M
GenF1.menu.pnum.GENERIC_F103CBTX_8M.build.product_line=STM32F103xB
GenF1.menu.pnum.GENERIC_F103CBTX_8M.build.variant=STM32F1xx/F103C8T_F103CB(T-U)
GenF1.menu.pnum.GENERIC_F103CBTX_8M.build.variant_h=variant_GENERIC_F103CBTX_8M.h
GenF1.menu.pnum.GENERIC_F103CBTX_8M.debug.svd_file={runtime.tools.STM32_SVD.path}/svd/STM32F1xx/STM32F103.svd

variat_GENERIC_F103CBTX_8M.cpp

#ifdef __cplusplus
extern "C" {
#endif

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE|RCC_OSCILLATORTYPE_LSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.LSEState = RCC_LSE_ON;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC|RCC_PERIPHCLK_ADC;
  PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
  PeriphClkInit.AdcClockSelection = RCC_ADCPCLK2_DIV6;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}

#ifdef __cplusplus
}
#endif

The function was generated from CubeMX

variat_GENERIC_F103CBTX_8M.h is empty

If i try to compile an empty program on Arduino IDE, i get:

In file included from C:\Users\ettor\AppData\Local\Arduino15\packages\STMicroelectronics\hardware\stm32\2.10.1\cores\arduino/WSerial.h:5,
                 from C:\Users\ettor\AppData\Local\Arduino15\packages\STMicroelectronics\hardware\stm32\2.10.1\cores\arduino/wiring.h:48,
                 from C:\Users\ettor\AppData\Local\Arduino15\packages\STMicroelectronics\hardware\stm32\2.10.1\cores\arduino/Arduino.h:36,
                 from C:\Users\ettor\AppData\Local\arduino\sketches\0A502EA1DC6952206E29C98BBCAC1F55\sketch\sketch_jun9a.ino.cpp:1:
C:\Users\ettor\AppData\Local\Arduino15\packages\STMicroelectronics\hardware\stm32\2.10.1\cores\arduino/HardwareSerial.h:108:64: error: 'NUM_DIGITAL_PINS' was not declared in this scope
  108 |     HardwareSerial(uint32_t _rx, uint32_t _tx, uint32_t _rts = NUM_DIGITAL_PINS, uint32_t _cts = NUM_DIGITAL_PINS);
      |                                                                ^~~~~~~~~~~~~~~~
C:\Users\ettor\AppData\Local\Arduino15\packages\STMicroelectronics\hardware\stm32\2.10.1\cores\arduino/HardwareSerial.h:108:98: error: 'NUM_DIGITAL_PINS' was not declared in this scope
  108 |     HardwareSerial(uint32_t _rx, uint32_t _tx, uint32_t _rts = NUM_DIGITAL_PINS, uint32_t _cts = NUM_DIGITAL_PINS);
      |                                                                                                  ^~~~~~~~~~~~~~~~
exit status 1

Compilation error: exit status 1

I am a little bit lost......do you have any hint or tutorial i can follow to better understand al these concepts ?

Thanks
Ettore

[fpistm]

If your variat_GENERIC_F103CBTX_8M.h is empty this is normal you got such issue.
Error message is clear you did not defined the NUM_DIGITAL_PINS.
Take example from other variants or simply use the default generic and define your void SystemClock_Config(void) in the sketch prefixed by extern "C"

extern "C" void SystemClock_Config(void) {
....
}