STM32F0 minimal RTOS example doesn't work

vas · ‎2025-02-18

Hi fellow engineers,

I'm trying to create a minimal example of blinky using an RTOS task in STM32CubeIDE. My MCU is a bare STM32F070CBT6. The code ends up in Default_Handler just a moment after the start

WWDG_IRQHandler stop.png

IOC file is as follows, nothing is configured, except FREERTOS, GPIO port for the LED and TIM6 as timebase source

#MicroXplorer Configuration settings - do not modify
CAD.formats=
CAD.pinconfig=
CAD.provider=
FREERTOS.IPParameters=Tasks01
FREERTOS.Tasks01=defaultTask,24,128,StartDefaultTask,Default,NULL,Dynamic,NULL,NULL
File.Version=6
GPIO.groupedBy=Group By Peripherals
KeepUserPlacement=false
Mcu.CPN=STM32F070CBT6
Mcu.Family=STM32F0
Mcu.IP0=FREERTOS
Mcu.IP1=NVIC
Mcu.IP2=RCC
Mcu.IP3=SYS
Mcu.IPNb=4
Mcu.Name=STM32F070CBTx
Mcu.Package=LQFP48
Mcu.Pin0=PC13
Mcu.Pin1=VP_FREERTOS_VS_CMSIS_V2
Mcu.Pin2=VP_SYS_VS_tim6
Mcu.PinsNb=3
Mcu.ThirdPartyNb=0
Mcu.UserConstants=
Mcu.UserName=STM32F070CBTx
MxCube.Version=6.13.0
MxDb.Version=DB.6.0.130
NVIC.ForceEnableDMAVector=true
NVIC.HardFault_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:false\:false
NVIC.NonMaskableInt_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:false\:false
NVIC.PendSV_IRQn=true\:3\:0\:false\:false\:false\:true\:false\:false\:false
NVIC.SVC_IRQn=true\:0\:0\:false\:false\:false\:false\:false\:false\:true
NVIC.SavedPendsvIrqHandlerGenerated=true
NVIC.SavedSvcallIrqHandlerGenerated=true
NVIC.SavedSystickIrqHandlerGenerated=true
NVIC.SysTick_IRQn=true\:3\:0\:false\:false\:false\:true\:false\:true\:false
NVIC.TIM6_IRQn=true\:3\:0\:false\:false\:true\:false\:false\:true\:true
NVIC.TimeBase=TIM6_IRQn
NVIC.TimeBaseIP=TIM6
PC13.GPIOParameters=GPIO_Label
PC13.GPIO_Label=LED_G
PC13.Locked=true
PC13.Signal=GPIO_Output
PinOutPanel.RotationAngle=0
ProjectManager.AskForMigrate=true
ProjectManager.BackupPrevious=false
ProjectManager.CompilerOptimize=6
ProjectManager.ComputerToolchain=false
ProjectManager.CoupleFile=false
ProjectManager.CustomerFirmwarePackage=
ProjectManager.DefaultFWLocation=true
ProjectManager.DeletePrevious=true
ProjectManager.DeviceId=STM32F070CBTx
ProjectManager.FirmwarePackage=STM32Cube FW_F0 V1.11.5
ProjectManager.FreePins=false
ProjectManager.HalAssertFull=false
ProjectManager.HeapSize=0x200
ProjectManager.KeepUserCode=true
ProjectManager.LastFirmware=true
ProjectManager.LibraryCopy=1
ProjectManager.MainLocation=Core/Src
ProjectManager.NoMain=false
ProjectManager.PreviousToolchain=
ProjectManager.ProjectBuild=false
ProjectManager.ProjectFileName=FreeRTOS_ThreadCreation.ioc
ProjectManager.ProjectName=FreeRTOS_ThreadCreation
ProjectManager.ProjectStructure=
ProjectManager.RegisterCallBack=
ProjectManager.StackSize=0x400
ProjectManager.TargetToolchain=STM32CubeIDE
ProjectManager.ToolChainLocation=
ProjectManager.UAScriptAfterPath=
ProjectManager.UAScriptBeforePath=
ProjectManager.UnderRoot=true
ProjectManager.functionlistsort=1-SystemClock_Config-RCC-false-HAL-false
RCC.FamilyName=M
RCC.IPParameters=FamilyName,PLLCLKFreq_Value,PLLMCOFreq_Value,TimSysFreq_Value,USBOutputFreqValue,VCOOutput2Freq_Value
RCC.PLLCLKFreq_Value=16000000
RCC.PLLMCOFreq_Value=16000000
RCC.TimSysFreq_Value=8000000
RCC.USBOutputFreqValue=16000000
RCC.VCOOutput2Freq_Value=8000000
VP_FREERTOS_VS_CMSIS_V2.Mode=CMSIS_V2
VP_FREERTOS_VS_CMSIS_V2.Signal=FREERTOS_VS_CMSIS_V2
VP_SYS_VS_tim6.Mode=TIM6
VP_SYS_VS_tim6.Signal=SYS_VS_tim6
board=custom
isbadioc=false

The only change in the main.c is the LED toggle

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "cmsis_os.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
/* Definitions for defaultTask */
osThreadId_t defaultTaskHandle;
const osThreadAttr_t defaultTask_attributes = {
  .name = "defaultTask",
  .stack_size = 128 * 4,
  .priority = (osPriority_t) osPriorityNormal,
};
/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
void StartDefaultTask(void *argument);

/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  /* USER CODE BEGIN 2 */

  /* USER CODE END 2 */

  /* Init scheduler */
  osKernelInitialize();

  /* USER CODE BEGIN RTOS_MUTEX */
  /* add mutexes, ... */
  /* USER CODE END RTOS_MUTEX */

  /* USER CODE BEGIN RTOS_SEMAPHORES */
  /* add semaphores, ... */
  /* USER CODE END RTOS_SEMAPHORES */

  /* USER CODE BEGIN RTOS_TIMERS */
  /* start timers, add new ones, ... */
  /* USER CODE END RTOS_TIMERS */

  /* USER CODE BEGIN RTOS_QUEUES */
  /* add queues, ... */
  /* USER CODE END RTOS_QUEUES */

  /* Create the thread(s) */
  /* creation of defaultTask */
  defaultTaskHandle = osThreadNew(StartDefaultTask, NULL, &defaultTask_attributes);

  /* USER CODE BEGIN RTOS_THREADS */
  /* add threads, ... */
  /* USER CODE END RTOS_THREADS */

  /* USER CODE BEGIN RTOS_EVENTS */
  /* add events, ... */
  /* USER CODE END RTOS_EVENTS */

  /* Start scheduler */
  osKernelStart();

  /* We should never get here as control is now taken by the scheduler */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOC_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(LED_G_GPIO_Port, LED_G_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin : LED_G_Pin */
  GPIO_InitStruct.Pin = LED_G_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(LED_G_GPIO_Port, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/* USER CODE BEGIN Header_StartDefaultTask */
/**
  * @brief  Function implementing the defaultTask thread.
  * @PAram  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartDefaultTask */
void StartDefaultTask(void *argument)
{
  /* USER CODE BEGIN 5 */
  /* Infinite loop */
  for(;;)
  {
	HAL_GPIO_TogglePin(LED_G_GPIO_Port, LED_G_Pin);
    osDelay(1);
  }
  /* USER CODE END 5 */
}

/**
  * @brief  Period elapsed callback in non blocking mode
  * @note   This function is called  when TIM6 interrupt took place, inside
  * HAL_TIM_IRQHandler(). It makes a direct call to HAL_IncTick() to increment
  * a global variable "uwTick" used as application time base.
  * @PAram  htim : TIM handle
  * @retval None
  */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
  /* USER CODE BEGIN Callback 0 */

  /* USER CODE END Callback 0 */
  if (htim->Instance == TIM6) {
    HAL_IncTick();
  }
  /* USER CODE BEGIN Callback 1 */

  /* USER CODE END Callback 1 */
}

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @PAram  file: pointer to the source file name
  * @PAram  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

My assumption was that such a minimal example should work right off the bat but apparently that's not the case :)

Could someone point me at what I'm missing here please?

vas · ‎2025-02-18

This thread helped to solve the issue.

Temporary Solution:
For those facing the same issue, add the following line to the User Code section in FreeRTOSConfig.h:
/* USER CODE BEGIN Defines */ 
/* Section where parameter definitions can be added (for instance, to override default ones in FreeRTOS.h) */
#include CMSIS_device_header
/* USER CODE END Defines */

View solution in original post

ahsrabrifat · ‎2025-02-18

I think you need to disable WWDG in NVIC.

vas · ‎2025-02-18

I believe it's disabled

I didn't touch any defaults.

vas · ‎2025-02-18

I can't find SysTick_Handler implementation anywhere though. Neither in port.c, nor in stm32f0xx_it.c

When I implement an empty handler the execution constantly ends up in it. I am a novice at embedded programming but I feel like this might be the issue. Also I found this thread that can be related.

vas · ‎2025-02-18

Should this be grayed out, and if not, how to fix that?

vas · ‎2025-02-18

This thread helped to solve the issue.

Temporary Solution:
For those facing the same issue, add the following line to the User Code section in FreeRTOSConfig.h:
/* USER CODE BEGIN Defines */ 
/* Section where parameter definitions can be added (for instance, to override default ones in FreeRTOS.h) */
#include CMSIS_device_header
/* USER CODE END Defines */