Introduction to uCOS II v2 6 m8
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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
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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
Message Mailboxes
•
A message mailbox is
a μC/OS-II object that
allows a task or an
ISR to send pointersized variable to
another task.
OSMboxCreate()
OSMboxPost()
Task
OSMboxPend()
OSMboxAccept()
OSMboxQuery()
Task
ISR
OSMboxPost()
OSMboxAccept()
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Message
Creating a Mailbox, OSMboxCreate
OS_EVENT *OSMboxCreate (void *msg)
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msg: A pointer to a message to deposit in the mailbox
o
o
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If null, mailbox is empty & used to signal occurrence of events
If ! null, mailbox is used to access shared 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 Mailbox, OSMboxDel
OS_EVENT *OSMboxDel (OS_EVENT *pevent, INT8U opt, INT8U
*err)
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pevent: A pointer to the mailbox to be deleted
opt: Delete options
o
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 mailbox.
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Deleting a Mailbox, OSMboxDel
cont’d
OS_EVENT *OSMboxDel (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 Mailbox,
OSMboxPend
void *OSMboxPend (OS_EVENT *pevent, INT16U timeout, INT8U
*err)
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pevent: A pointer to the mailbox to pend to
timeout:
o
o
•
err:
o
o
o
o
o
0 wait for ever
!0 wait with specific timeout
No error
Timeout
pevent is not a mailbox.
pevent is null.
Called from ISR
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Sending a Message to a Mailbox,
OSMboxPost
INT8U OSMboxPost (OS_EVENT *pevent, void *msg)
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pevent: A pointer to the mailbox to post to
msg: A pointer to the message to send
Return value:
o
o
o
o
o
No error
Mailbox is full.
pevent is not a mailbox.
pevent is null.
Posting a null pointer
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Sending a Message to a Mailbox,
OSMboxPostOpt
INT8U OSMboxPostOpt (OS_EVENT *pevent, void *msg, INT8U
opt)
•
•
OSMboxPostOpt = OSMboxPost + options
opt:
o
o
Post to a single waiting task
Post to all tasks waiting
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Getting a Message without Waiting,
OSMboxAccept
void *OSMboxAccept (OS_EVENT *pevent)
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•
pevent: A pointer to the mailbox to pend to
Return value:
o
o
!Null Message received
Null Case of error or mailbox is empty
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Obtaining the Status of a Mailbox,
OSMboxQuery
INT8U OSMboxQuery (OS_EVENT *pevent, OS_MBOX_DATA
*pdata)
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•
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pevent: A pointer to the desired mailbox
pdata: A pointer to the returned mailbox information
Return value:
o
o
o
No error
pevent is not a mailbox.
pevent is null.
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Using a Mailbox as a Binary
Semaphore
OS_EVENT *MboxSem;
void Task (void *pdata){
INT8U err;
for (;;) {
OSMboxPend(MboxSem, 0, &err); /* Obtain access to resource */
/* Task has semaphore, access resources */
OSMboxPost(MboxSem, (void*)1); /* Release access to resource */
}
}
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
Using a Mailbox Instead to Signal
Occurrence of Events
OS_EVENT *MboxTimeDly;
void Task1(void *pdata){
INT8U err;
for (;;) {
OSMboxPend(MboxTimeDly, timeout, &err); /* Wait for event */
/* Code after time delay */
}
}
void Task2(void *pdata){
INT8U err;
for (;;) {
OSMboxPost(MboxTimeDly, (void *)1); /* Signal event */
...
}
}
Amr Ali Abdel-Naby@2010
Introduction to uCOS-II V2.6
