介紹兩個定時器任務如何通過定時器 handle 共用一個回撥函式。

1、標頭檔案宣告和函式定義

#include "FreeRTOS.h"
#include "task.h"
#include "timers.h"
#include "supporting_functions.h"

#define mainONE_SHOT_TIMER_PERIOD		( pdMS_TO_TICKS( 3333UL ) )
#define mainAUTO_RELOAD_TIMER_PERIOD	( pdMS_TO_TICKS( 500UL ) )

// 定時器共用回撥函式
static void prvTimerCallback( TimerHandle_t xTimer );

// 定時器 handle 定義
static TimerHandle_t xAutoReloadTimer, xOneShotTimer;
 

2、啟動定時任務

int main( void )
{
	BaseType_t xTimer1Started, xTimer2Started;

	// 定義 one-shot 定時任務
	xOneShotTimer = xTimerCreate( "OneShot",				
								  mainONE_SHOT_TIMER_PERIOD,	
								  pdFALSE,					
								  0,							
								  prvTimerCallback );		

	// 定義自動過載定時任務
	xAutoReloadTimer = xTimerCreate( "AutoReload",		
									 mainAUTO_RELOAD_TIMER_PERIOD,	
									 pdTRUE,					
									 0,								
									 prvTimerCallback );	

	if( ( xOneShotTimer != NULL ) && ( xAutoReloadTimer != NULL ) )
	{
		// 啟動定時任務
		xTimer1Started = xTimerStart( xOneShotTimer, 0 );
		xTimer2Started = xTimerStart( xAutoReloadTimer, 0 );

		if( ( xTimer1Started == pdPASS ) && ( xTimer2Started == pdPASS ) )
		{
			/* Start the scheduler. */
			vTaskStartScheduler();
		}
	}

	for( ;; );
	return 0;
}
 

3、軟體定時器回撥函式

static void prvTimerCallback( TimerHandle_t xTimer )
{
	TickType_t xTimeNow;
	uint32_t ulExecutionCount;
	
	ulExecutionCount = ( uint32_t ) pvTimerGetTimerID( xTimer );
	ulExecutionCount++;
	vTimerSetTimerID( xTimer, ( void * ) ulExecutionCount );

	xTimeNow = xTaskGetTickCount();

	if( xTimer == xOneShotTimer )
	{
		vPrintStringAndNumber( "One-shot timer callback executing", xTimeNow );
	}
	else
	{
		vPrintStringAndNumber( "Auto-reload timer callback executing", xTimeNow );

		if( ulExecutionCount == 5 )
		{
			xTimerStop( xTimer, 0 );
		}
	}
}