STM32CUBEIDE FreeRTOS操作教程（六）：recursive mutexes互斥信号量
STM32CUBE开发环境集成了STM32 HAL库进行FreeRTOS配置和开发的组件，不需要用户自己进行FreeRTOS的移植。这里介绍最简化的用户操作类应用教程。以STM32F401RCT6开发板为例，只用到USB，USART1极少的接口，体现FreeRTOS的各种操作过程。
操作教程（六）配置FreeRTOS及相关环境，实现LED闪灯功能及基于recursive mutex递归互斥信号量的USB虚拟串口双任务打印输出。两个任务轮流获取和释放互斥信号量，在得到信号量时向外打印输出，其中任务会在获取两次信号量后向外打印输出，然后释放两次信号量。
递归互斥信号量是可以对单个信号量进行多次获取和释放的信号量，对于一个任务而言当然获取了多少次后就应该释放多少次，然后其它任务才能去获取改信号量。因为中断服务程序中不能应用阻塞时间，所以递归信号量不能用在中断服务程序中，也就是主要用在任务过程中。
FreeRTOS的教程较多，推荐参考正点原子所出的《STM32F407 FreeRTOS开发手册》了解相关知识。
STM32CUBEIDE工程配置
选择TIM1(也可以是其它TIM)作为FreeRTOS操作系统占用的时钟源：
配置时钟树包括USB的48MHz时钟：
配置PC13为低电平点灯的管脚：
配置USB串口:
配置UART1串口（但本例中不用到UART1):
FreeRTOS配置
任务实现
基于前述的配置，main.c代码里会加载Free-RTOS的配置，并启动几个任务的调度，当然，此时的任务都是什么也不干。实现LED闪灯，就在LED闪灯任务里加入代码即可：
void StartTask_TASK_LED_FLASH(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_LED_FLASH */
/* Infinite loop */
for(;;)
{
osDelay(1000);
HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
}
/* USER CODE END StartTask_TASK_LED_FLASH */
}
也就实现了LED闪灯功能，其中osDelay(1000);实现1秒时间的操作系统调度延时，也就是1秒执行一次LED灯的亮灭。osDelay(1）；是最小的调度延时，为1毫秒。要实现更小的延时，则可以用微秒延时函数实现，参考《STM32 HAL us delay（微秒延时）的指令延时实现方式及优化》
main.c文件里两个任务分别通过获取递归互斥信号量权柄，再发送信息：
void StartTask_TASK_USB_VCOM_H(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_USB_VCOM_H */
BaseType_t err_stu = pdFALSE;
/* Infinite loop */
for(;;)
{
osDelay(8);
err_stu = xSemaphoreTake(USB_VCOM_RcsMutex01Handle, USB_VCOM_xBlockTime);
if(err_stu==pdTRUE)
{
if(USB_CONN_STATUS())
{
usbprintstring("High Priority Task Outputting\r\n");
}
xSemaphoreGive(USB_VCOM_RcsMutex01Handle);
}
}
/* USER CODE END StartTask_TASK_USB_VCOM_H */
}
void StartTask_TASK_USB_VCOM_L(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_USB_VCOM_L */
BaseType_t err_stu = pdFALSE;
/* Infinite loop */
for(;;)
{
osDelay(5);
err_stu = xSemaphoreTake(USB_VCOM_RcsMutex01Handle, USB_VCOM_xBlockTime); //First get
if(err_stu==pdTRUE)
{
xSemaphoreTakeRecursive(USB_VCOM_RcsMutex01Handle, USB_VCOM_xBlockTime);//Second get
if(USB_CONN_STATUS())
{
usbprintstring("Low Priority Task Outputting\r\n");
}
xSemaphoreGive(USB_VCOM_RcsMutex01Handle); //First release
xSemaphoreGiveRecursive(USB_VCOM_RcsMutex01Handle); //Second release
osDelay(10);
}
}
/* USER CODE END StartTask_TASK_USB_VCOM_L */
}
完整的main.c代码：
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2023 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.
*
******************************************************************************
*/
//Example 6: LED flash + Recursive Mutex.
//Written by Pegasus Yu
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "cmsis_os.h"
#include "usb_device.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "semphr.h"
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
__IO float usDelayBase = 7.63238716; //For STM32F401RCT6 working in 84MHz main clock
void PY_Delay_us_t(uint32_t Delay)
{
__IO uint32_t delayReg;
__IO uint32_t usNum = (uint32_t)(Delay*usDelayBase);
delayReg = 0;
while(delayReg!=usNum) delayReg++;
}
/* 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 ---------------------------------------------------------*/
UART_HandleTypeDef huart1;
DMA_HandleTypeDef hdma_usart1_rx;
/* Definitions for defaultTask */
osThreadId_t defaultTaskHandle;
const osThreadAttr_t defaultTask_attributes = {
.name = "defaultTask",
.stack_size = 128 * 4,
.priority = (osPriority_t) osPriorityNormal,
};
/* Definitions for TASK_LED_FLASH */
osThreadId_t TASK_LED_FLASHHandle;
const osThreadAttr_t TASK_LED_FLASH_attributes = {
.name = "TASK_LED_FLASH",
.stack_size = 128 * 4,
.priority = (osPriority_t) osPriorityLow,
};
/* Definitions for TASK_UART1 */
osThreadId_t TASK_UART1Handle;
const osThreadAttr_t TASK_UART1_attributes = {
.name = "TASK_UART1",
.stack_size = 128 * 4,
.priority = (osPriority_t) osPriorityLow,
};
/* Definitions for TASK_USB_VCOM_H */
osThreadId_t TASK_USB_VCOM_HHandle;
const osThreadAttr_t TASK_USB_VCOM_H_attributes = {
.name = "TASK_USB_VCOM_H",
.stack_size = 128 * 4,
.priority = (osPriority_t) osPriorityHigh,
};
/* Definitions for TASK_USB_VCOM_L */
osThreadId_t TASK_USB_VCOM_LHandle;
const osThreadAttr_t TASK_USB_VCOM_L_attributes = {
.name = "TASK_USB_VCOM_L",
.stack_size = 128 * 4,
.priority = (osPriority_t) osPriorityLow,
};
/* Definitions for USB_VCOM_RcsMutex01 */
osMutexId_t USB_VCOM_RcsMutex01Handle;
const osMutexAttr_t USB_VCOM_RcsMutex01_attributes = {
.name = "USB_VCOM_RcsMutex01",
.attr_bits = osMutexRecursive,
};
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_USART1_UART_Init(void);
void StartDefaultTask(void *argument);
void StartTask_TASK_LED_FLASH(void *argument);
void StartTask_TASK_UART1(void *argument);
void StartTask_TASK_USB_VCOM_H(void *argument);
void StartTask_TASK_USB_VCOM_L(void *argument);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
uint8_t USB_CONN_STATUS(void);
uint8_t CDC_Transmit_FS(uint8_t* Buf, uint16_t Len);
void usbprintstring(char * data)
{
if(CDC_Transmit_FS((uint8_t *)data, strlen(data))==USBD_BUSY)
{
PY_Delay_us_t(1000000);
CDC_Transmit_FS((uint8_t *)data, strlen(data));
}
}
void usbprintarray(uint8_t * data, uint16_t len)
{
if(CDC_Transmit_FS(data, len)==USBD_BUSY)
{
PY_Delay_us_t(1000000);
CDC_Transmit_FS(data, len);
}
}
BaseType_t USB_VCOM_pxHigherPriorityTaskWaken;
TickType_t USB_VCOM_xBlockTime = 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();
MX_DMA_Init();
MX_USART1_UART_Init();
/* USER CODE BEGIN 2 */
PY_Delay_us_t(1000000);
/* USER CODE END 2 */
/* Init scheduler */
osKernelInitialize();
/* Create the recursive mutex(es) */
/* creation of USB_VCOM_RcsMutex01 */
USB_VCOM_RcsMutex01Handle = osMutexNew(&USB_VCOM_RcsMutex01_attributes);
/* USER CODE BEGIN RTOS_MUTEX */
/* add mutexes, ... */
USB_VCOM_RcsMutex01Handle = xSemaphoreCreateRecursiveMutex(); //"USB_VCOM_RcsMutex01Handle = osMutexNew(&USB_VCOM_RcsMutex01_attributes);" is bad code. Redefine here.
/* 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);
/* creation of TASK_LED_FLASH */
TASK_LED_FLASHHandle = osThreadNew(StartTask_TASK_LED_FLASH, NULL, &TASK_LED_FLASH_attributes);
/* creation of TASK_UART1 */
TASK_UART1Handle = osThreadNew(StartTask_TASK_UART1, NULL, &TASK_UART1_attributes);
/* creation of TASK_USB_VCOM_H */
TASK_USB_VCOM_HHandle = osThreadNew(StartTask_TASK_USB_VCOM_H, NULL, &TASK_USB_VCOM_H_attributes);
/* creation of TASK_USB_VCOM_L */
TASK_USB_VCOM_LHandle = osThreadNew(StartTask_TASK_USB_VCOM_L, NULL, &TASK_USB_VCOM_L_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};
/** Configure the main internal regulator output voltage
*/
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
RCC_OscInitStruct.PLL.PLLQ = 7;
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();
}
}
/**
* @brief USART1 Initialization Function
* @param None
* @retval None
*/
static void MX_USART1_UART_Init(void)
{
/* USER CODE BEGIN USART1_Init 0 */
/* USER CODE END USART1_Init 0 */
/* USER CODE BEGIN USART1_Init 1 */
/* USER CODE END USART1_Init 1 */
huart1.Instance = USART1;
huart1.Init.BaudRate = 115200;
huart1.Init.WordLength = UART_WORDLENGTH_8B;
huart1.Init.StopBits = UART_STOPBITS_1;
huart1.Init.Parity = UART_PARITY_NONE;
huart1.Init.Mode = UART_MODE_TX_RX;
huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart1.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART1_Init 2 */
/* USER CODE END USART1_Init 2 */
}
/**
* Enable DMA controller clock
*/
static void MX_DMA_Init(void)
{
/* DMA controller clock enable */
__HAL_RCC_DMA2_CLK_ENABLE();
/* DMA interrupt init */
/* DMA2_Stream2_IRQn interrupt configuration */
HAL_NVIC_SetPriority(DMA2_Stream2_IRQn, 5, 0);
HAL_NVIC_EnableIRQ(DMA2_Stream2_IRQn);
}
/**
* @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();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(LED_GPIO_Port, LED_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : LED_Pin */
GPIO_InitStruct.Pin = LED_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LED_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)
{
/* init code for USB_DEVICE */
MX_USB_DEVICE_Init();
/* USER CODE BEGIN 5 */
/* Infinite loop */
for(;;)
{
osDelay(1);
}
/* USER CODE END 5 */
}
/* USER CODE BEGIN Header_StartTask_TASK_LED_FLASH */
/**
* @brief Function implementing the TASK_LED_FLASH thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask_TASK_LED_FLASH */
void StartTask_TASK_LED_FLASH(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_LED_FLASH */
/* Infinite loop */
for(;;)
{
osDelay(1000);
HAL_GPIO_TogglePin(GPIOC, GPIO_PIN_13);
}
/* USER CODE END StartTask_TASK_LED_FLASH */
}
/* USER CODE BEGIN Header_StartTask_TASK_UART1 */
/**
* @brief Function implementing the TASK_UART1 thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask_TASK_UART1 */
void StartTask_TASK_UART1(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_UART1 */
/* Infinite loop */
for(;;)
{
osDelay(1);
}
/* USER CODE END StartTask_TASK_UART1 */
}
/* USER CODE BEGIN Header_StartTask_TASK_USB_VCOM_H */
/**
* @brief Function implementing the TASK_USB_VCOM_H thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask_TASK_USB_VCOM_H */
void StartTask_TASK_USB_VCOM_H(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_USB_VCOM_H */
BaseType_t err_stu = pdFALSE;
/* Infinite loop */
for(;;)
{
osDelay(8);
err_stu = xSemaphoreTake(USB_VCOM_RcsMutex01Handle, USB_VCOM_xBlockTime);
if(err_stu==pdTRUE)
{
if(USB_CONN_STATUS())
{
usbprintstring("Task 1 Outputting\r\n");
}
xSemaphoreGive(USB_VCOM_RcsMutex01Handle);
}
}
/* USER CODE END StartTask_TASK_USB_VCOM_H */
}
/* USER CODE BEGIN Header_StartTask_TASK_USB_VCOM_L */
/**
* @brief Function implementing the TASK_USB_VCOM_L thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTask_TASK_USB_VCOM_L */
void StartTask_TASK_USB_VCOM_L(void *argument)
{
/* USER CODE BEGIN StartTask_TASK_USB_VCOM_L */
BaseType_t err_stu = pdFALSE;
/* Infinite loop */
for(;;)
{
osDelay(5);
err_stu = xSemaphoreTake(USB_VCOM_RcsMutex01Handle, USB_VCOM_xBlockTime); //First get
if(err_stu==pdTRUE)
{
xSemaphoreTakeRecursive(USB_VCOM_RcsMutex01Handle, USB_VCOM_xBlockTime);//Second get
if(USB_CONN_STATUS())
{
usbprintstring("Task 2 Outputting\r\n");
}
xSemaphoreGive(USB_VCOM_RcsMutex01Handle); //First release
xSemaphoreGiveRecursive(USB_VCOM_RcsMutex01Handle); //Second release
osDelay(10);
}
}
/* USER CODE END StartTask_TASK_USB_VCOM_L */
}
/**
* @brief Period elapsed callback in non blocking mode
* @note This function is called when TIM1 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 == TIM1) {
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 */
例程下载
STM32 STM32CUBEIDE FreeRTOS操作教程（六）：recursive mutexes递归互斥信号量 例程
例程测试
例程测试效果如下：
–End–