Introduction to uCOS II v2 6 m6

Introduction to uCOS-II V2.6


About SwiftACT
• A Technology services startup company
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Under establishment

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

• Types of services:
o
o
o
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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


Mutexes
• They are used to gain exclusive access to resources.
• They reduce priority inversion problem (priority ceiling protocol is
supported).

OSMutexCreate()
OSMutexDel()
OSMutexPost()

Task

Amr Ali Abdel-Naby@2010

OSMutexPend()
OSMutexAccept()
OSMutexQuery()

Task

Introduction to uCOS-II V2.6


Creating a Mutex, OSMutexCreate
OS_EVENT *OSMutexCreate (INT8U prio, INT8U *err)
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prio: Ceiling priroity
err:
o
o
o
o
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No error
Called from ISR
Priority exists
Invalid priority
No available resources

Return value:
o
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Non-null for successful creation

Null for failure

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Deleting a Mutex, OSMutexDel
OS_EVENT *OSMutexDel (OS_EVENT *pevent, INT8U opt, INT8U
*err)
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pevent: A pointer to the mutex to be deleted
opt: Delete options
o
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Delete always
Delete if no pending tasks

err:
o
o
o
o
o
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No error
Called from ISR
Invalid option
There are tasks pending.
pevent is null.
pevent is not a semaphore.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Deleting a Mutex, OSMutexDel cont’d
OS_EVENT *OSMutexDel (OS_EVENT *pevent, INT8U opt, INT8U
*err)
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Return value: Null if successful

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Waiting on a Mutex (Blocking),
OSMutexPend
void OSMutexPend (OS_EVENT *pevent, INT16U timeout, INT8U
*err)
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pevent: A pointer to the mutex to acquire
timeout:
o
o

•

err:
o
o
o
o
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0  wait for ever
!0  wait with specific timeout
No error
Timeout
pevent is not a mutex.
pevent is null.
Called from ISR

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Signaling a Mutex, OSMutexPost

INT8U OSMutexPost (OS_EVENT *pevent)
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pevent: A pointer to the mutex to release
Return value:
o
o
o
o
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No error
Not mutex owner
Called from ISR
pevent is not a mutex.
pevent is null.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Getting a Mutex without Waiting,
OSMutexAccept
INT8U OSMutexAccept (OS_EVENT *pevent, INT8U *err)
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pevent: A pointer to the mutex to acquire

err:
o
o
o
o

•

No error
Called from ISR
pevent is not a mutex.
pevent is null.

Return value:
o
o

1  resource available
0  case of error or mutex is no available

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Obtaining the Status of a Mutex,
OSMutexQuery
INT8U OSMutexQuery (OS_EVENT *pevent, OS_MUTEX_DATA
*pdata)
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pevent: A pointer to the desired mutex
pdata: A pointer to the returned mutex information
Return value:
o
o
o
o

No error
Called from ISR
pevent is not a mutex.
pevent is null.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6