BaseType_t xTaskCreate( TaskFunction_t pvTaskCode,
const char * const pcName,
unsigned short usStackDepth,
Create a new task and add it to the list of tasks that are ready to run.
must be set to 1 in FreeRTOSConfig.h, or left undefined (in which case it will
default to 1), for this RTOS API function to be available.
Each task requires RAM that is used to hold the task state, and used by the task
as its stack. If a task is created using xTaskCreate() then the required RAM is automatically
allocated from the FreeRTOS heap. If a task is created
using xTaskCreateStatic() then the RAM is
provided by the application writer, so can be statically allocated at compile time. See the
Static Vs Dynamic allocation
page for more information.
If you are using FreeRTOS-MPU then
it is recommended to use xTaskCreateRestricted()
in place of xTaskCreate().
Pointer to the task entry function (just the name of the function that
implements the task, see the example below).
Tasks are normally
as an infinite loop, and must never attempt to return
or exit from their implementing function. Tasks can however
A descriptive name for the task. This is mainly used to facilitate
debugging, but can also be used to
obtain a task handle.
The maximum length of a task's name is set using the
configMAX_TASK_NAME_LEN parameter in FreeRTOSConfig.h.
The number of words (not bytes!) to allocate
for use as the task's
stack. For example, if the stack is 16-bits wide and usStackDepth is
100, then 200 bytes will be allocated for use as the task's stack.
As another example, if the stack is 32-bits wide and usStackDepth is
400 then 1600 bytes will be allocated for use as the task's stack.
The stack depth multiplied by the stack width must not exceed the
maximum value that can be contained in a variable of type size_t.
See the FAQ How big should the stack be?
A value that will passed into the created task as the task's parameter.
If pvParameters is set to the address of a variable then the variable
must still exist when the created task executes - so it is not valid
to pass the address of a stack variable.
The priority at which the
created task will execute.
Systems that include MPU support can optionally create a task in a
privileged (system) mode by setting bit portPRIVILEGE_BIT in uxPrriority.
For example, to create a privileged task at priority 2 set uxPriority
to ( 2 | portPRIVILEGE_BIT ).
Used to pass a handle to the created task out of the xTaskCreate()
function. pxCreatedTask is optional and can be set to NULL.
If the task was created successfully then pdPASS is returned. Otherwise
errCOULD_NOT_ALLOCATE_REQUIRED_MEMORY is returned.
/* Task to be created. */
void vTaskCode( void * pvParameters )
/* The parameter value is expected to be 1 as 1 is passed in the
pvParameters value in the call to xTaskCreate() below.
configASSERT( ( ( uint32_t ) pvParameters ) == 1 );
for( ;; )
/* Task code goes here. */
/* Function that creates a task. */
void vOtherFunction( void )
TaskHandle_t xHandle = NULL;
/* Create the task, storing the handle. */
xReturned = xTaskCreate(
vTaskCode, /* Function that implements the task. */
"NAME", /* Text name for the task. */
STACK_SIZE, /* Stack size in words, not bytes. */
( void * ) 1, /* Parameter passed into the task. */
tskIDLE_PRIORITY,/* Priority at which the task is created. */
&xHandle ); /* Used to pass out the created task's handle. */
if( xReturned == pdPASS )
/* The task was created. Use the task's handle to delete the task. */
vTaskDelete( xHandle );
Copyright (C) 2004-2010 Richard Barry. Copyright (C) 2010-2016 Real Time Engineers Ltd.
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