Learning Notes-RTOS Task creation
Task creation
1 tasks require RAM to save task-related status information (task control block)
2 A certain RAM is required as the task stack
XTaskCreate () will be allocated from the FreeRTOS heap and must provide a memory management file
Heap_4.c is used by default
3 Macro configSUPPORT_DYNAMIC_ALLOCATION must be 1
4. If the function xTaskCreateStatic () is created, these RAM will need to be provided by the user.
ConfigSUPPORT_STATIC_ALLOCATION is set to 1
5 tasks can be created before or after Task Scheduler starts.
The most commonly used one
BaseType_t xTaskCreate (TaskFunction_t pxTaskCode
Const char * const pcName
Const uint16_t usStackDepth
Void * const pvParameters
UBaseType_t uxPriority
TaskHandle_t * const pxCreatedTask)
PxCreatedTask task handle, which is the task stack of the task, which may be used by other API
The return value reflects the success or error code of the task creation.
PdPASS: the task was created successfully.
6 not commonly used
TaskHandle_t xTaskCreateStatic (TaskFunction_t pxTaskCode
Const char * const pcName
Const uint32_t ulStackDepth
Void * const pvParameters
UBaseType_t uxPriority
StackType_t * const puxStackBuffer
StaticTask_t * const pxTaskBuffer)
PxTaskBuffer: task control block.
Return value: NULL: task creation failed
Other values: the task is created successfully, and the task handle of the task is returned.
7 vTaskDelete (TaskHandle_t xTaskToDelete)
XTaskToDelete: the task handle of the task to delete.
You can use NULL as a parameter to delete the task itself
8 key experiments (learning dynamic creation):
Task creation:
# define START_TASK_PRIO 1 / / Task priority
# define START_STK_SIZE 128 / / Task stack size
TaskHandle_t StartTask_Handler; / / Task handle
Void start_task (void * pvParameters); / / Task function
XTaskCreate ((TaskFunction_t) start_task, / / Task function
(const char*) "start_task", / / Task name
(uint16_t) START_STK_SIZE, / / Task stack size
(void*) NULL, / / parameters passed to the task function
(UBaseType_t) START_TASK_PRIO, / / Task priority
(TaskHandle_t*) & StartTask_Handler); / / Task handle
VTaskStartScheduler (); / / enable task scheduling
Start the task:
TaskENTER_CRITICAL (); / / enter the critical area
/ / create a TASK1 task
.
/ / create a TASK2 task
VTaskDelete (StartTask_Handler); / / Delete the start task
TaskEXIT_CRITICAL (); / / exit the critical area
Task stack, task handle, task function declaration, etc., so that it is easy to modify. These things
Xi can put it in a .h header file.
Start tasks: create other application tasks and kernel objects such as semaphores and queues
