FreeRTOS timer group

Introduce

FreeRTOS The time base of software timer group is realized based on the beat of system clock . When creating a software timer , Specify the callback function of the software timer , Implement the corresponding functions in the callback function .FreeRTOS The software timer provided supports single mode and periodic mode ： The single mode is after the user creates the timer and starts the timer , When the scheduled time expires, it will not be executed again ; The cycle mode is that this timer will execute repeatedly according to the set time cycle .

Be careful ： The timer callback function is executed in the timer task , In practical application, it is forbidden to call any function that suspends timer task in timer callback function , such as vTaskDelay(),vTaskDelayUntil() And non-zero delay message queue and semaphore related function . Suspend timer task , This will cause the relevant functions of the timer task to be performed incorrectly .

FreeRTOSConfig.h To configure

#define configUSE_TIMERS 1

#include "timers.h"

Correlation function

function xTimerCreate

function xTimerStart

function pvTimerGetTimerID

void *pvTimerGetTimerID( TimerHandle_t xTimer ); /*  Timer handle */

function pvTimerGetTimerID Used to return the use function xTimerCreate Software timer created ID.

Use

Definition Timer

static TimerHandle_t xTimers = NULL;					 
			xTimers = xTimerCreate("Timer",          /*  The name of the timer  */
							       3000,    /*  Timer cycle , Unit clock beat  */
							       pdTRUE,          /*  periodic  */
							       (void * )0x01,      /*  Timer ID */
							       vTimerCallback); /*  Timer callback function  */

			if(xTimers == NULL)
			{
    
				/*  Not created successfully , The user can add the handling mechanism of creation failure here  */
			}
			else
			{
    
				 /*  Start timer , The system will not start working until it is started  */
				 if(xTimerStart(xTimers, 100) != pdPASS)
				 {
    
					 /*  The timer has not yet entered the active state  */
				 }
			}		

Callback function

static void vTimerCallback(xTimerHandle pxTimer)
{
    
	uint32_t ulTimerID;

	configASSERT(pxTimer);

	/*  Get the timer time to  */
	ulTimerID = (uint32_t)pvTimerGetTimerID(pxTimer);
	
// /*  Processing timer 0 Mission  */
// if(ulTimerID == 0)
// {
    
// bsp_LedToggle(1);
// }
	
	/*  Processing timer 1 Mission  */
	if(ulTimerID == 1)
	{
    
			uint8_t data[]="This is a Timer";
			taskENTER_CRITICAL();   /*  Enter the critical area  */
			HAL_UART_Transmit(&huart1,data,sizeof(data),0xff);
			taskEXIT_CRITICAL();  	/*  Exit critical region  */	
	}
}

Reference documents

course