【FreeRTOS】小白进阶之如何使用FreeRTOS多值信号量（二）

介绍多值信号量的使用。

1、头文件声明

  

   

    

     

    
    

     

      #include "FreeRTOS.h"
     
    
   

    

     

    
    

     

      #include "task.h"
     
    
   

    

     

    
    

     

      #include "semphr.h"
     
    
   

    

     

    
    

     

      #include "supporting_functions.h"
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      #define mainINTERRUPT_NUMBER 3
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      static void vHandlerTask( void *pvParameters );
     
    
   

    

     

    
    

     

      static void vPeriodicTask( void *pvParameters );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      static uint32_t ulExampleInterruptHandler( void );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      // 定义多值信号量
     
    
   

    

     

    
    

     

      SemaphoreHandle_t xCountingSemaphore;
     
    
  
 

2、启动任务

任务 vPeriodicRask 用于启动模拟中断：

  

   

    

     

    
    

     

      int main( void )
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    // 创建多值信号量，最小值 0，最大值 10
     
    
   

    

     

    
    

     

      	xCountingSemaphore = xSemaphoreCreateCounting( 10, 0 );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	if( xCountingSemaphore != NULL )
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		xTaskCreate( vHandlerTask, "Handler", 1000, NULL, 3, NULL );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
		xTaskCreate( vPeriodicTask, "Periodic", 1000, NULL, 1, NULL );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
		vPortSetInterruptHandler( mainINTERRUPT_NUMBER, ulExampleInterruptHandler );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
		vTaskStartScheduler();
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	for( ;; );
     
    
   

    

     

    
    

     
	return 0;
     
    
   

    

     

    
    

     

      }
     
    
  
 

3、定义任务

  

   

    

     

    
    

     

      static void vHandlerTask( void *pvParameters )
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	for( ;; )
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		xSemaphoreTake( xCountingSemaphore, portMAX_DELAY );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
		vPrintString( "Handler task - Processing event.\r\n" );
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      static void vPeriodicTask( void *pvParameters )
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	const TickType_t xDelay500ms = pdMS_TO_TICKS( 500UL );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	for( ;; )
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		vTaskDelay( xDelay500ms );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
		vPrintString( "Periodic task - About to generate an interrupt.\r\n" );
     
    
   

    

     

    
    

     
		vPortGenerateSimulatedInterrupt( mainINTERRUPT_NUMBER );
     
    
   

    

     

    
    

     
		vPrintString( "Periodic task - Interrupt generated.\r\n\r\n\r\n" );
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      static uint32_t ulExampleInterruptHandler( void )
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	BaseType_t xHigherPriorityTaskWoken;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      	xHigherPriorityTaskWoken = pdFALSE;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	xSemaphoreGiveFromISR( xCountingSemaphore, &xHigherPriorityTaskWoken );
     
    
   

    

     

    
    

     
	xSemaphoreGiveFromISR( xCountingSemaphore, &xHigherPriorityTaskWoken );
     
    
   

    

     

    
    

     
	xSemaphoreGiveFromISR( xCountingSemaphore, &xHigherPriorityTaskWoken );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
     
    
   

    

     

    
    

     

      }
     
    
  
 

文章来源: blog.csdn.net，作者：简一商业，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/liwei16611/article/details/82590836