FreeRTOS篇9：计数型信号量

一.什么是计数型信号量？

计数型信号量相当于队列长度大于1 的队列，因此计数型信号量能够容纳多个资源，这在计数型信号量被创建的时候确定的。

二.计数型信号量相关 API 函数

计数型信号量的释放和获取与二值信号量完全相同！

参数：

uxMaxCount：可以达到的最大计数值 uxInitialCount：创建信号量时分配给信号量的计数值

返回值：

成功，返回对应计数型信号量的句柄；失败，返回 NULL 。

三.实操

1.实验需求

创建一个计数型信号量，按下 KEY1 则释放信号量，按下 KEY2 获取信号量。

2.cubeMX配置

将 Config parameters 标签里的 USE_COUNTING_SEMAPHORES 设置为 Enabled 。

3.代码实现

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * File Name          : freertos.c
  * Description        : Code for freertos applications
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 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 "FreeRTOS.h"
#include "task.h"
#include "main.h"
#include "cmsis_os.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
/* 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 ---------------------------------------------------------*/
/* USER CODE BEGIN Variables */

/* USER CODE END Variables */
osThreadId taskGiveHandle;
osThreadId taskTakeHandle;
osSemaphoreId myCountingSemHandle;

/* Private function prototypes -----------------------------------------------*/
/* USER CODE BEGIN FunctionPrototypes */

/* USER CODE END FunctionPrototypes */

void StartTaskGive(void const * argument);
void StartTaskTake(void const * argument);

void MX_FREERTOS_Init(void); /* (MISRA C 2004 rule 8.1) */

/* GetIdleTaskMemory prototype (linked to static allocation support) */
void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize );

/* USER CODE BEGIN GET_IDLE_TASK_MEMORY */
static StaticTask_t xIdleTaskTCBBuffer;
static StackType_t xIdleStack[configMINIMAL_STACK_SIZE];

void vApplicationGetIdleTaskMemory( StaticTask_t **ppxIdleTaskTCBBuffer, StackType_t **ppxIdleTaskStackBuffer, uint32_t *pulIdleTaskStackSize )
{
  *ppxIdleTaskTCBBuffer = &xIdleTaskTCBBuffer;
  *ppxIdleTaskStackBuffer = &xIdleStack[0];
  *pulIdleTaskStackSize = configMINIMAL_STACK_SIZE;
  /* place for user code */
}
/* USER CODE END GET_IDLE_TASK_MEMORY */

/**
  * @brief  FreeRTOS initialization
  * @param  None
  * @retval None
  */
void MX_FREERTOS_Init(void) {
  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

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

  /* Create the semaphores(s) */
  /* definition and creation of myCountingSem */
//  osSemaphoreDef(myCountingSem);
//  myCountingSemHandle = osSemaphoreCreate(osSemaphore(myCountingSem), 3);
 myCountingSemHandle =xSemaphoreCreateCounting(3,0);
  /* 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) */
  /* definition and creation of taskGive */
  osThreadDef(taskGive, StartTaskGive, osPriorityNormal, 0, 128);
  taskGiveHandle = osThreadCreate(osThread(taskGive), NULL);

  /* definition and creation of taskTake */
  osThreadDef(taskTake, StartTaskTake, osPriorityNormal, 0, 128);
  taskTakeHandle = osThreadCreate(osThread(taskTake), NULL);

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

}

/* USER CODE BEGIN Header_StartTaskGive */
/**
  * @brief  Function implementing the taskGive thread.
  * @param  argument: Not used
  * @retval None
  */
/* USER CODE END Header_StartTaskGive */
void StartTaskGive(void const * argument)
{
  /* USER CODE BEGIN StartTaskGive */
  /* Infinite loop */
  for(;;)
  {
	if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
	{
	osDelay(20);
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET)
		{
		if(xSemaphoreGive(myCountingSemHandle)==pdTRUE)
			printf("计数型信号量放入成功\r\n");
			else
				printf("计数型信号量放入失败\r\n");
		}
		while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_0)==GPIO_PIN_RESET);
	}
    osDelay(10);
  }
  /* USER CODE END StartTaskGive */
}

/* USER CODE BEGIN Header_StartTaskTake */
/**
* @brief Function implementing the taskTake thread.
* @param argument: Not used
* @retval None
*/
/* USER CODE END Header_StartTaskTake */
void StartTaskTake(void const * argument)
{
  /* USER CODE BEGIN StartTaskTake */
  /* Infinite loop */
  for(;;)
  {
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
	{
	osDelay(20);
		if(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET)
		{
		if(xSemaphoreTake(myCountingSemHandle,0)==pdTRUE)
			printf("计数型信号量放入成功\r\n");
			else
				printf("计数型信号量放入失败\r\n");
		}
		while(HAL_GPIO_ReadPin(GPIOA,GPIO_PIN_1)==GPIO_PIN_RESET);
	}
    osDelay(10);
  }
  /* USER CODE END StartTaskTake */
}

/* Private application code --------------------------------------------------*/
/* USER CODE BEGIN Application */

/* USER CODE END Application */