Introduction to uCOS II v2 6 m3

Amr Ali Abdel-Naby@2010 Introduction to uCOS-II V2.6Creating a Task, OSTaskCreate INT8U OSTaskCreate void *taskvoid *pd, void *pdata, OS_STK *ptos, INT8U prio • task: A pointer to the ta

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Introduction to uCOS-II V2.6

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Amr Ali Abdel-Naby@2010 Introduction to uCOS-II V2.6

About SwiftACT

• A Technology services startup company

o Under establishment

• Areas of specialties:

o Mobile telecommunication services development

o Embedded systems development

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About Me

• Graduated 2004

o ECE, ASU: 5 yrs distinction

• 5+ years in embedded systems development

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Copyright

• Materials in this course is the property of Amr Ali Abdel-Naby

• Reproduction or transmission of the materials in any manner without the copyright owner permission is a law violation

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Course References

• MicroC/OS-II The Real-Time Kernel, 2nd Edition, by Jean J Labrosse

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• Mutual Exclusion Semaphores

• Event Flag Management

• Message Mailbox Management

• Message Queue Management

• Memory Management

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• Mutual Exclusion Semaphores

• Event Flag Management

• Message Mailbox Management

• Message Queue Management

• Memory Management

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Task Management APIs

• Available task operations are:

o Task creation

o Stack checking

o Task deletion

o Requesting a task deletion

o Changing a task’s priority

o Task suspension

o Task resumption

o Getting task’s info

o Task name manipulation

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Creating a Task, OSTaskCreate

INT8U OSTaskCreate (void (*task)(void *pd), void *pdata, OS_STK

*ptos, INT8U prio)

• task: A pointer to the task's code

• pdata: A pointer to an optional data area which can be used to pass parameters to the task when the task first executes

• ptos: A pointer to the task's top of stack

• prio: The task's priority

• Return value:

o No error

o Priority exist

o Invalid priority

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Creating a Task, OSTaskCreateExt

INT8U OSTaskCreateExt (void (*task)(void *pd), void *pdata, OS_STK *ptos, INT8U prio, INT16U id, OS_STK *pbos, INT32U stk_size, void *pext, INT16U opt)

• OSTaskCreate +

• id: Task’s ID, not used currently

• pbos: A pointer to the task's bottom of stack

• stk_size: A pointer to the task's top of stack

• pext: A pointer to a user supplied memory location which is used as a TCB extension

• opt: Additional information (or options) about the behavior of the task

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Task Stacks

• Each task has its own stack

o It must be:

 Declared as OS_STK

 Consistent & contiguous memory

• It can be allocated static

• Or dynamic OS_STK MyTaskSTack[stack_size];

OS_STK *pstk;

pstk = (OS_STK*)malloc(stack_size);

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Task Stacks cont’d

• Dynamic allocation may suffer from fragmentation

• Your code should support stacks that grow in either direction

A (1KB)

C (1KB)

B (1KB)

#else OSTaskCreate(task, pdata, &TaskStack[stack_size-1], prior);

#endif

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Stack Checking

• Assume stack is cleared at the beginning

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Stack Checking, OSTaskStkChk

INT8U OSTaskStkChk (INT8U prio, OS_STK_DATA *pdata)

• prio: The task priority

• pdata: A pointer to stack data

• Return value:

o No error

o Invalid priority

o Task does not exist.

o Task options does not support stack checking.

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Deleting a Task, OSTaskDel

INT8U OSTaskDel (INT8U prio)

• prio: Priority of the task to delete

• Return value:

o No error

o Invalid priority.

o Deleting idle task

o Deleting a task from ISR

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Requesting to Delete a Task

• A deleted task should delete its resources as well

o To avoid leaks

• The OSTaskDelReq is the keyword

void RequestorTask(void * pdata){

} else{

/* Application code*/

}

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Requesting to Delete a Task, OSTaskDelReq

INT8U OSTaskDelReq (INT8U prio)

• prio: Priority of the task to be deleted

• Return value:

o No error

o Invalid priority

o Deleting idle task

o Deleting a task from ISR

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Changing a Task’s Priority, OSTaskChangePrio

INT8U OSTaskChangePrio (INT8U oldprio, INT8U newprio)

• oldprio: The old priority

• newprio: The new priority

• Return value:

o No error

o Invalid priority

o Task to change priority does not exist.

o New priority already exists.

o Changing IDLE priority

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Resuming a Task, OSTaskResume

INT8U OSTaskResume (INT8U prio)

• prio: The priority of the task to resume

• Return value:

o No error

o Invalid priority

o Task is not suspended.

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Suspending a Task, OSTaskSuspend

INT8U OSTaskSuspend (INT8U prio)

• prio: The priority of the task to suspend

• Return value:

o No error

o Invalid priority

o Suspending idle task

o Task does not exist

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Getting Info About a Task, OSTaskQuery

INT8U OSTaskQuery (INT8U prio, OS_TCB *pdata)

• prio: The priority of the task to obtain its information

• pdata: A pointer to returned task information

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Getting a Task’s Name, OSTaskNameGet

INT8U OSTaskNameGet (INT8U prio, char *pname, INT8U *err)

• prio: The priority of the task that you want to obtain its name

• pname: A pointer to an ASCII string that will receive the name of the task

• err:

o No error

o A null pointer is passed for the name.

o Invalid priority

• Return value: Length of the string

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Naming a Task, OSTaskNameSet

void OSTaskNameSet (INT8U prio, char *pname, INT8U *err)

• prio: The priority of the task that you want to assign a name to

• pname: A pointer to an ASCII string that contains the name of the task

• err:

o No error

o Name too long

o A null pointer is passed for the name.

o Invalid priority

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