RTOS building blocks for system development

Data Types• Using C compiler primitive data types is not wise.. • RTOSes provide special data types.. Data Types cont’d• RTOS defines its own data types.. o Most RTOSes consist of a sing

RTOS Building Blocks for System

Development

About SwiftACT

• A Technology services startup company

o Under establishment

• Areas of specialties:

o Mobile telecommunication services development

o Embedded systems development

About Me

• Graduated 2004

o ECE, ASU: 5 yrs distinction

• 5+ years in embedded systems development

• 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

o Thread management APIs, Mutex management APIs…

Defining Public Resources

• Some objects are public

o They can be accessed from any thread.

• Accessing a public object is not like owning it

o Mutex can be accessed from any thread A public object 

o A mutex has only 1 owner at a time A private ownership 

Data Types

• Using C compiler primitive data types is not wise

o int, char, double…

• C code should be portable

• RTOSes provide special data types

o The wrap the C compiler primitive ones.

o They ensure compiler and architecture portability.

o In uCOS-II: INT8U, INT8, INT16U…

Data Types cont’d

• RTOS defines its own data types

o To define its own objects

o In uCOS-II: OS_EVENT, OS_STK, OS_FLAG_GROUP…

• Independent program segment

o 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

o Most RTOSes consist of a single process and multiple threads.

Thread cont’d

• Each thread has a Task Control Block (TCB)

• Every task is assigned a TCB when created

Thread cont’d

• A TCB contains:

o Task’s priority

o Task’s state

o A pointer to the task’s top of stack

o Other task’s related data

• TCBs reside in RAM

Memory Pools

• Memory Block Pool

o Fixed size based

o Used in most of RTOSes

• Memory Byte Pool

o Smallest size is byte

Event Flag Group

• Event flag 1 bit

• Used for threads synchronization

• Event flag group group of flags

• Threads can operate on any

or all of the event flags

Message Queue

• Used for thread intercommunication

• Queue that can hold 1 message = Mail box

Thread

Thread Thread

Thread Thread

Summary of Thread Synchronization and Communication

Summary of Thread Synchronization and Communication cont’d

Thread Synchronization

Event Notification

Mutual Exclusion

Inter-thread Communication