Introduction to RTOS m2

Introduction to RTOS About SwiftACT • A Technology services startup company o 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 RTOS About Me • Graduated 2004 o ECE, ASU: yrs distinction • 5+ years in embedded systems development o SDLC, Apps, MW, DD, Porting, • 3+ years in SW engineering o PSP, CMMI, Systematic reuse, • 3+ years in SW testing o IBM certified, ISTQB certified, Amr Ali Abdel-Naby@2010 Introduction to RTOS 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 RTOS Outline • • • • • • Introduction Tasks Semaphores Message Queues Other Kernel Objects Other Kernel Services Amr Ali Abdel-Naby@2010 Introduction to RTOS Outline • • • • • • Introduction Tasks Semaphores Message Queues Other Kernel Objects Other Kernel Services Amr Ali Abdel-Naby@2010 Introduction to RTOS The RTOS Multitasking Model • Multiple tasks o Each a sequential “thread” of execution • Explicit task manipulation o Task Task Task Separate context for each task P1 P2 P3 • Pre-emption is dynamic: The highest priority ready task is the Kernel task that must be running Amr Ali Abdel-Naby@ 2009 Real-Time Operating Systems Definition of a Task • A task is an independent thread of execution capable of executing in parallel with other threads of execution • Each task has its own stack o Maybe more than stack  Supervisor mode stack, user mode stack • A task may synchronize and/or communicate with other tasks o o Primary mechanism is messages Also shared memory (with semaphores) • You must write programs for your application tasks o Tasks may make service calls to the RTOS, to invoke RTOS services Amr Ali Abdel-Naby@2010 Introduction to RTOS The Task Control Block - TCB • Managed by RTOS for each task o o o o o o o o o o Current state of task Unique ID of task Priority of task Type of task Stack location and size Current stack pointer File and line info (for debug) Waiting messages Desired messages Task TCB Task TCB Task • Useful for debugging, error handling TCB Amr Ali Abdel-Naby@ 2009 Real-Time Operating Systems Task States & Transitions Ready Needed resource is available + HPT is ready Blocked Amr Ali Abdel-Naby@ 2009 HPT became ready No HPT is ready Needed resource is available + No HPT is ready Running Needed resource is unavailable Real-Time Operating Systems System vs Application Tasks • Systems tasks o o o Created by the kernel Have reserved priorities Initialization task, Idle task, logging task … • The kernel jumps to a predefined entry point • From the entry point, the developer can o o Initialize and create other application tasks , As well as other kernel objects, which the application design might require Amr Ali Abdel-Naby@2010 Introduction to RTOS Typical Task Operations • Task creation and deletion o o Create Delete • Task scheduling o o o o o Suspend and Resume Get Priority and Set Priority Preemption Lock and Preemption unlock Delay Restart • Obtaining task information o o Get ID Get TCB Amr Ali Abdel-Naby@2010 Introduction to RTOS Typical Task Structure Run to Completion RunToCompletionTask(){ Initialize application Create kernel objects Create endless loop tasks Delete or Suspend task } Amr Ali Abdel-Naby@2010 Endless Loop EndLessLoopTask(){ Initialization code Loop forever { Loop body } } Introduction to RTOS [...]... information o o Get ID Get TCB Amr Ali Abdel-Naby@2010 Introduction to RTOS Typical Task Structure Run to Completion RunToCompletionTask(){ Initialize application Create kernel objects Create endless loop tasks Delete or Suspend task } Amr Ali Abdel-Naby@2010 Endless Loop EndLessLoopTask(){ Initialization code Loop forever { Loop body } } Introduction to RTOS ... reserved priorities Initialization task, Idle task, logging task … • The kernel jumps to a predefined entry point • From the entry point, the developer can o o Initialize and create other application tasks , As well as other kernel objects, which the application design might require Amr Ali Abdel-Naby@2010 Introduction to RTOS Typical Task Operations • Task creation and deletion o o Create Delete • Task