Introduction to uCOS-II V2.6


About SwiftACT
• A Technology services startup company
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Under establishment

• Areas of specialties:
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Mobile telecommunication services development
Embedded systems development

• Types of services:
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Consultation
Managed services
Sourcing
Training

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6

About Me
• Graduated 2004
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ECE, ASU: 5 yrs distinction

• 5+ years in embedded systems development
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SDLC, Apps, MW, DD, Porting, ...

• 3+ years in SW engineering
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PSP, CMMI, Systematic reuse, ...

• 3+ years in SW testing
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IBM certified, ISTQB certified, ...

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


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.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


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

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Outline
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Introduction to µC/OS-II
Kernel Structure

Task Management
Time Management
Semaphore Management
Mutual Exclusion Semaphores
Event Flag Management
Message Mailbox Management
Message Queue Management
Memory Management

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Outline
•
•
•
•
•
•
•
•
•
•

Introduction to µC/OS-II
Kernel Structure
Task Management
Time Management

Semaphore Management
Mutual Exclusion Semaphores
Event Flag Management
Message Mailbox Management
Message Queue Management
Memory Management

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Task Management APIs
• Available task operations are:
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Task creation
Stack checking
Task deletion
Requesting a task deletion
Changing a task’s priority
Task suspension

Task resumption
Getting task’s info
Task name manipulation

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Creating a Task, OSTaskCreate
INT8U OSTaskCreate (void (*task)(void *pd), void *pdata, OS_STK
*ptos, INT8U prio)
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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:
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No error
Priority exist

Invalid priority

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


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)
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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

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6



Task Stacks
• Each task has its own stack.
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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);

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Task Stacks cont’d
• Dynamic allocation may suffer from fragmentation.

3 KB

A (1KB)


(1KB)

B
(1KB)

B
(1KB)

C

• Your code should support(1KB)
stacks that(1KB)
grow in either direction.

OS_STK TaskStack[stack_size];
...
#ifdef OS_STK_GROWTH == 0
OSTaskCreate(task, pdata, &TaskStack[0], prior);
#else
OSTaskCreate(task, pdata, &TaskStack[stack_size-1], prior);
#endif
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6


Stack Checking
• Assume stack is cleared at the beginning.

Amr Ali Abdel-Naby@2010


Introduction to uCOS-II V2.6


Stack Checking, OSTaskStkChk
INT8U OSTaskStkChk (INT8U prio, OS_STK_DATA *pdata)
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prio: The task priority
pdata: A pointer to stack data
Return value:
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No error
Invalid priority
Task does not exist.
Task options does not support stack checking.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Deleting a Task, OSTaskDel
INT8U OSTaskDel (INT8U prio)

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prio: Priority of the task to delete
Return value:
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No error
Invalid priority.
Task does not exist.
Deleting idle task
Deleting a task from ISR

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Requesting to Delete a Task
• A deleted task should delete its resources as well.
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To avoid leaks

• The OSTaskDelReq is the keyword.
void RequestorTask(void * pdata){

...
if(TasktoBeDeleted needs to be deleted){
while(OSTaskDelReq(Task_TO_DEL_PRIO) != OS_TASK_NOT_EXIST)
OSTimeDly(1);
}
void TaskToBeDeleted(void * pdata){
...
...
}
if(OSTaskDelReq(OS_PRIO_SELF) == OS_TASK_DEL_REQ){
Release any resources & de-allocate any dynamic memory;
OS_DEL(OS_PRIO_SELF);
}
else{
/* Application code*/
}
...
}

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Requesting to Delete a Task,
OSTaskDelReq
INT8U OSTaskDelReq (INT8U prio)
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prio: Priority of the task to be deleted
Return value:
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No error
Invalid priority
Task does not exist.
Deleting idle task
Deleting a task from ISR

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Changing a Task’s Priority,
OSTaskChangePrio
INT8U OSTaskChangePrio (INT8U oldprio, INT8U newprio)
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oldprio: The old priority
newprio: The new priority
Return value:
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No error
Invalid priority
Task to change priority does not exist.
New priority already exists.
Changing IDLE priority

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Resuming a Task, OSTaskResume
INT8U OSTaskResume (INT8U prio)
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prio: The priority of the task to resume
Return value:
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No error
Invalid priority

Task is not suspended.
Task does not exist.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Suspending a Task, OSTaskSuspend
INT8U OSTaskSuspend (INT8U prio)
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prio: The priority of the task to suspend
Return value:
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No error
Invalid priority
Suspending idle task
Task does not exist

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6



Getting Info About a Task,
OSTaskQuery
INT8U OSTaskQuery (INT8U prio, OS_TCB *pdata)
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prio: The priority of the task to obtain its information
pdata: A pointer to returned task information
Return value:
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No error
Invalid priority
Task does not exist.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Getting a Task’s Name,
OSTaskNameGet
INT8U OSTaskNameGet (INT8U prio, char *pname, INT8U *err)
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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:
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No error
Task does not exist.
A null pointer is passed for the name.
Invalid priority

Return value: Length of the string

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Naming a Task, OSTaskNameSet
void OSTaskNameSet (INT8U prio, char *pname, INT8U *err)
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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:
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No error
Task does not exist.
Name too long
A null pointer is passed for the name.
Invalid priority

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6