Rtos By Avanish Agarwal


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Real time operating system
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Rtos By Avanish Agarwal

  1. 1. Real Time Operating Systems (RTOS) Presented By Mr. Avanish Agarwal Mr. Makesh Iyer V.P.M’s Polytechnic College, Thane TECHNOPHILLIA 2009 25th & 26th Feb.
  2. 2. Moving Ahead.. <ul><li>What is a real-time OS? </li></ul><ul><li>OS Types </li></ul><ul><li>OS Basics </li></ul><ul><li>RTOS Basics </li></ul><ul><li>Real-time Example </li></ul><ul><li>Summary </li></ul><ul><li>References </li></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  3. 3. What is a Real-time OS? <ul><li>A RTOS (Real-Time Operating System) </li></ul><ul><ul><li>Is an Operating Systems with the necessary features to support a Real-Time System </li></ul></ul><ul><ul><li>What is a Real-Time System? </li></ul></ul><ul><ul><ul><li>A system where correctness depends not only on the correctness of the logical result of the computation, but also on the result delivery time </li></ul></ul></ul><ul><ul><ul><li>A system that responds in a timely, predictable way to unpredictable external stimuli arrivals </li></ul></ul></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  4. 4. Why RTOS?? TECHNOPHILLIA 2009 25th & 26th Feb.
  5. 5. Types of Real Time Systems <ul><li>Based on the consequences during system failure: </li></ul><ul><li>Hard Real time Systems </li></ul><ul><ul><li>Failure to respond to any single event is considered as complete system failure </li></ul></ul><ul><li>Soft Real Time Systems </li></ul><ul><ul><li>The consequences during system failure are not hazardous (matter of life and death). Failure to respond to any event only degrades the performance but not considered as system failure. </li></ul></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  6. 6. OS Basics <ul><li>“An OS is a system program that provides an interface between application programs and the computer system (hardware)” </li></ul><ul><ul><li>Primary Functions </li></ul></ul><ul><ul><ul><li>Provide a system that is convenient to use </li></ul></ul></ul><ul><ul><ul><li>Organize efficient and correct us of system resources </li></ul></ul></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  7. 7. <ul><li>RTOS Basics </li></ul><ul><li>Central Purpose of a RTOS </li></ul><ul><ul><li>Scheduling of the CPU </li></ul></ul><ul><ul><ul><li>Applications are structured as a set of processes </li></ul></ul></ul><ul><ul><ul><ul><li>At least 3 states are needed to allow the CPU to schedule </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ready – waiting to run (in ready list) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Running – process (thread or task) is utilizing the processor to execute instructions </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Blocked – waiting for resources (I/O, memory, critical section, etc.) </li></ul></ul></ul></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  8. 8. RTOS Basics Running Ready Blocked Dispatch Block Timer Run out Wakeup Process States & Transitions or Basic Kernel TECHNOPHILLIA 2009 25th & 26th Feb.
  9. 9. Interrupts <ul><li>Some events can’t wait for next loop iteration e.g. </li></ul><ul><ul><li>Communication channels </li></ul></ul><ul><ul><li>Transient events </li></ul></ul><ul><li>A solution: Cyclic executive plus interrupt routines </li></ul><ul><li>Interrupt: Environmental event that demands attention </li></ul><ul><ul><li>Example: “byte arrived” interrupt on serial channel </li></ul></ul><ul><li>Interrupt routine: Piece of code executed in response to an interrupt </li></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  10. 10. Handling Interrupts TECHNOPHILLIA 2009 25th & 26th Feb. 1. Normal program execution 2. Interrupt occurs 3. Processor state saved 4. Interrupt routine runs 5. Interrupt routine terminates 6. Processor state restored 7. Normal program execution resumes
  11. 11. Real-time Example <ul><li>A device which we generally use </li></ul><ul><li>is iPod </li></ul><ul><li>It has to play the songs without </li></ul><ul><li>Any input combining with memory </li></ul><ul><li>i.e. flash memory </li></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  12. 12. Flow Chart of iPod TECHNOPHILLIA 2009 25th & 26th Feb. Power ON State ROM code invoke Booting Play Song/ Video Display Photos Configure Device RTOS Kernel ( Scheduler + Interrupt handler ) USB connect ISR Store Songs, Videos And Terminate USB USER Input ISR IPod Acts as storage device (Slave Mode)
  13. 13. Interrupts in iPod <ul><li>Main Interrupts are </li></ul><ul><li>USB Interrupt </li></ul><ul><li>User Interrupt </li></ul><ul><li>USB Interrupt- </li></ul><ul><li>Occurs when USB connection found </li></ul><ul><li>User Interrupt- </li></ul><ul><li>Occurs when user gives command in foreground </li></ul><ul><li>or background </li></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  14. 14. RTOS Application Areas TECHNOPHILLIA 2009 25th & 26th Feb. <ul><li>Examples of Real-Time Systems </li></ul><ul><li>Microwave ovens. </li></ul><ul><li>Medical monitoring systems. </li></ul><ul><li>Car control systems: ABS systems and engine control. </li></ul><ul><li>Air craft systems. </li></ul><ul><li>Chemical factory control system. </li></ul><ul><li>Polled loop system </li></ul><ul><li>Nuclear power plant control systems . </li></ul>
  15. 15. Summary <ul><li>A RTOS should be predictable regardless of the system load and size of queues/lists </li></ul><ul><li>RTOS should always support pre-emptive priority scheduling </li></ul><ul><li>The memory model utilized is very important to the performance and predictability of your RT system </li></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  16. 16. References <ul><li>What Makes A Good RTOS, RTOS Evaluation Program, Real-Time Magazine , Version 2.0, 28 February 2000. </li></ul><ul><li>VxWorks Guide, WindRiver Systems. </li></ul><ul><li>Embedded Systems- Architecture, Programming & Design Second Edition by Raj Kamal ( McGraw Hill Companies) </li></ul><ul><li>Unix Concept & Programming by Murugan Sethuranman </li></ul><ul><li>OSEK/VDX-Operating System. Version 2.2.2, July 2004. </li></ul><ul><li>8051 RTOS Guide </li></ul><ul><li>RTOS Evolution Project Issue 1.1 Doc. DSE-RTOS-EVE-001b </li></ul><ul><li>Embedded Real-time Systems Programming by Sriram V. Iyer, Pankaj Gupta </li></ul>TECHNOPHILLIA 2009 25th & 26th Feb.
  17. 17. Thank You!! TECHNOPHILLIA 2009 25th & 26th Feb.