Tasks
[More about tasks…]

Implementing a Task

A task should have the following structure:
    void vATaskFunction( void *pvParameters )
    {
        for( ;; )
        {
            -- Task application code here. --
        }

        /* Tasks must not attempt to return from their implementing
        function or otherwise exit.  In newer FreeRTOS port
        attempting to do so will result in an configASSERT() being
        called if it is defined.  If it is necessary for a task to
        exit then have the task call vTaskDelete( NULL ) to ensure
        its exit is clean. */
        vTaskDelete( NULL );
    }
 
The type TaskFunction_t is defined as a function that returns void and takes a void pointer as its only parameter. All functions that implement a task should be of this type. The parameter can be used to pass information of any type into the task – this is demonstrated by several of the standard demo application tasks.

Task functions should never return so are typically implemented as a continuous loop. Again, see the RTOS demo application for numerous examples.

Tasks are created by calling xTaskCreate() or xTaskCreateStatic(), and deleted by calling vTaskDelete().

[Back to top]



Task Creation Macros

Task functions can optionally be defined using the portTASK_FUNCTION and portTASK_FUNCTION_PROTO macros. These macro are provided to allow compiler specific syntax to be added to the function definition and prototype respectively. Their use is not required unless specifically stated in documentation for the port being used (currently only the PIC18 fedC port).

The prototype for the function shown above can be written as:

void vATaskFunction( void *pvParameters );
Or,
portTASK_FUNCTION_PROTO( vATaskFunction, pvParameters );
Likewise the function above could equally be written as:
    portTASK_FUNCTION( vATaskFunction, pvParameters )
    {
        for( ;; )
        {
            -- Task application code here. --
        }
    }
 



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