RTOS building blocks for system development
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RTOS Building Blocks for System
Development
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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o
o
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Consultation
Managed services
Sourcing
Training
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
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
RTOS Building Blocks for System
Development
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
RTOS Building Blocks for System
Development
Outline
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Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Introduction
• RTOS = Objects + Services
• Objects
o
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They are used to build the application.
Thread, Mutex…
• Services
o
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They allow the developer to create, manipulate, and manage
system resources and entities in order to facilitate application
development.
Thread management APIs, Mutex management APIs…
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Defining Public Resources
• Some objects are public.
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They can be accessed from any thread.
• Accessing a public object is not like owning it.
o
o
Mutex can be accessed from any thread A public object
A mutex has only 1 owner at a time A private ownership
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Data Types
• Using C compiler primitive data types is not wise.
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int, char, double…
• C code should be portable.
• RTOSes provide special data types.
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The wrap the C compiler primitive ones.
They ensure compiler and architecture portability.
In uCOS-II: INT8U, INT8, INT16U…
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Data Types cont’d
• RTOS defines its own data types.
o
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To define its own objects
In uCOS-II: OS_EVENT, OS_STK, OS_FLAG_GROUP…
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Thread
• Independent program segment
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Independent execution, independent processing
• Has its own stack
• Threads in the same process share the same address space.
• Every process has at least 1 thread.
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Most RTOSes consist of a single process and multiple threads.
Process 1
Amr Ali Abdel-Naby@2010
Process 2
RTOS Building Blocks for System
Development
Process 3
Thread cont’d
• Each thread has a Task Control Block (TCB)
• Every task is assigned a TCB when created.
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Thread cont’d
• A TCB contains:
o
o
o
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Task’s priority
Task’s state
A pointer to the task’s top of stack
Other task’s related data
• TCBs reside in RAM.
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Memory Pools
• Memory Block Pool
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Fixed size based
Size > 1 byte
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o
o
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Each pool can have different
block size
Less flexible
No fragmentation
Faster access
Used in most of RTOSes
Amr Ali Abdel-Naby@2010
• Memory Byte Pool
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Smallest size is byte
Several C heaps
Allocation is for any size
Defragmentation is needed
Faster allocation speed
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Application Timer
• Enable applications to execute their functions at specific intervals
of time
• One-shot
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Expire only once
• Periodic
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Repeating intervals
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Mutex
• Controls threads access to a
critical section
• Priority inheritance
• Priority ceiling
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Counting Semaphore
• Used for
o
o
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Event notification
Thread synchronization
Mutual exclusion but no
ownership as in mutex
Counting semaphore
binary semaphore
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
Outline
•
•
•
•
•
•
•
•
•
•
•
Introduction
Defining Public Resources
Data Types
Thread
Memory Pools
Application Timer
Mutex
Counting Semaphore
Event Flag Group
Message Queue
Summary of Thread Synchronization and Communication
Amr Ali Abdel-Naby@2010
RTOS Building Blocks for System
Development
