vTaskDelay
[Task Control]

task. h
void vTaskDelay( const TickType_t xTicksToDelay );

INCLUDE_vTaskDelay must be defined as 1 for this function to be available. See the RTOS Configuration documentation for more information.

Delay a task for a given number of ticks. The actual time that the task remains blocked depends on the tick rate. The constant portTICK_PERIOD_MS can be used to calculate real time from the tick rate – with the resolution of one tick period.

vTaskDelay() specifies a time at which the task wishes to unblock relative to the time at which vTaskDelay() is called. For example, specifying a block period of 100 ticks will cause the task to unblock 100 ticks after vTaskDelay() is called. vTaskDelay() does not therefore provide a good method of controlling the frequency of a periodic task as the path taken through the code, as well as other task and interrupt activity, will effect the frequency at which vTaskDelay() gets called and therefore the time at which the task next executes. See vTaskDelayUntil() for an alternative API function designed to facilitate fixed frequency execution. It does this by specifying an absolute time (rather than a relative time) at which the calling task should unblock.

Parameters:
xTicksToDelay The amount of time, in tick periods, that the calling task should block.
Example usage:

 void vTaskFunction( void * pvParameters )
 {
 /* Block for 500ms. */
 const TickType_t xDelay = 500 / portTICK_PERIOD_MS;

     for( ;; )
     {
         /* Simply toggle the LED every 500ms, blocking between each toggle. */
         vToggleLED();
         vTaskDelay( xDelay );
     }
}





Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

FreeRTOS v10.2.1 is available for immediate download. MIT licensed, includes 64-bit RISC-V, NXP Cortex-M33 demo & Nuvoton Cortex-M23 demo & STM32H745 dual core (AMP) demo.

New Updates to MIT licensed IoT MQTT and POSIX libraries are now available. New library IoT HTTPS is available.  Includes demo projects.

View a recording of the “OTA Update Security and Reliability” webinar, presented by TI and AWS.

Careers

FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners
ARM Connected RTOS partner for all ARM microcontroller cores
Espressif ESP32
IAR Partner
Microchip Premier RTOS Partner
Renesas
STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0
Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers
OpenRTOS and SafeRTOS
Xilinx Microblaze and Zynq partner