Introduction to uCOS II v2 6 m9

Introduction to uCOS-II V2.6


About SwiftACT
• A Technology services startup company
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Under establishment

• Areas of specialties:
o
o

Mobile telecommunication services development
Embedded systems development

• Types of services:
o
o
o
o

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


Message Queues
•

A message queue is
a μC/OS-II object
that allows a task or
an ISR to send
pointer-sized
variables to another
task.

OSQPost()
OSQPostFront()
OSQFlush()
OSQPostOpt()

OSQCreate()

OSQPend()
OSQAccept()
OSQQuery()

Task

Task

ISR

Amr Ali Abdel-Naby@2010

OSQPost()
OSQPostFront()
OSQFlush()
OSQAccept()
OSQPostOpt()

Introduction to uCOS-II V2.6

Message


Creating a Message Queue,
OSQCreate
OS_EVENT *OSQCreate (void **start, INT16U size)
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start: A pointer to the base address of the message queue storage area
size: # of elements in queue
Return value:
o
o

Non-null for successful creation
Null for failure

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Deleting a Message Queue, OSQDel
OS_EVENT *OSQDel (OS_EVENT *pevent, INT8U opt, INT8U *err)
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pevent: A pointer to the message queue 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 message queue.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Deleting a Message Queue, OSQDel
cont’d
OS_EVENT *OSQDel (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 for a Message at a Queue
(Blocking), OSQPend
void *OSQPend (OS_EVENT *pevent, INT16U timeout, INT8U *err)
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pevent: A pointer to the message queue to pend to
timeout:
o
o

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0  wait for ever
!0  wait with specific timeout

err:
o
o
o
o
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No error
Timeout
pevent is not a message queue.
pevent is null.
Called from ISR

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Sending a Message to a Queue
(FIFO), OSQPost
INT8U OSQPost (OS_EVENT *pevent, void *msg)
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pevent: A pointer to the message queue to post to
msg: A pointer to the message to send
Return value:
o
o
o
o

No error
Message queue is full.
pevent is not a message queue.
pevent is null.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6

Sending a Message to a Queue
(LIFO), OSQPostFront
• OSQPostFront = OSQPost with LIFO instead of FIFO

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Sending a Message to a Queue
(FIFO or LIFO), OSQPostOpt
INT8U OSQPostOpt (OS_EVENT *pevent, void *msg, INT8U opt)
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OSQPostOpt = OSQPost + options
opt:
o
o
o
o

Post with FIFO
Post with LIFO
Post with FIFO + Broadcast
Post with LIFO + Broadcast

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6

Getting a Message without Waiting,
OSQAccept
void *OSQAccept (OS_EVENT *pevent, INT8U *err)
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pevent: A pointer to the message queue to pend to
err:
o
o
o
o

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No error
pevent is not a message queue.
pevent is null.
Queue is empty.

Return value:
o
o

!0  Message received
0  Case of error or message queue is empty

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Flushing a Queue, OSQFlush
INT8U OSQFlush (OS_EVENT *pevent)
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pevent: A pointer to the message queue to be flushed
Return value:
o
o
o

No error
pevent is not a message queue.
pevent is null.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Obtaining the Status of a Queue,
OSQQuery
INT8U OSQQuery (OS_EVENT *pevent, OS_Q_DATA *pdata)
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pevent: A pointer to the desired message queue
pdata: A pointer to the returned message queue information
Return value:
o
o
o

No error
pevent is not a message queue.
pevent is null.

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6


Using a Message Queue when
Reading Analog Inputs

M
U
X

Amr Ali Abdel-Naby@2010

ADC

ADC
Task

Introduction to uCOS-II V2.6


Using a Queue as a Counting
Semaphore
OS_EVENT *QSem;
void *QMsgTbl[N_RESOURCES];
void main(void){
...
QSem = OSQCreate(&QMsgTbl[0], N_RESOURCES);
for (i=0; iOSQPost(QSem, (void*)1);
}
...
}
void Task(void *pdata){
INT8U err;
for (;;) {
OSQPend(&QSem, 0, &err); /* Obtain access to resources */
/* Task has semaphore, access resources */
OSQPost(QSem, (void*)1); /* Release access to resources */
}
}

Amr Ali Abdel-Naby@2010

Introduction to uCOS-II V2.6