Real Time Operating system (RTOS) - Embedded systems

Real Time Operating system (RTOS) - Embedded systems

• 1.
  PRESENTED BY: HARIHARAN.G 17MX105 KALAIYARASAN.D17MX106 KEERTHANA.R.A 17MX107 KIRUBHANANDHAN.R 17MX108
• 2.
   When wehear the word “Operating System” the first ones that come to our mind are Windows, Linux, Ubuntu, MacOS for computers & Android, iOS for mobiles and many more .  A real time operating system is a special type of OS specifically designed for Embedded systems.
• 3.
   The basicdifference of using a GPOS or an RTOS lies in the nature of the system – i.e whether the system is “time critical” or not.  Normal operations that we do in a computer are not time critical & nothing is going to happen if it takes a few more seconds to open a file.  But in applications like Missiles, ABS in cars, timing is very critical.
• 4.
   “The abilityof the operating system to provide a required level of service in a bounded response time.”  Example: Airbag has to be opened within a fixed time immediately after the crashing in order to protect from any injuries.
• 5.
   It respondsto inputs immediately (Real- Time).  Here the task is completed within a specified time delay.  In real life situations like controlling traffic signal or a nuclear reactor or an aircraft,The operating system has to respond quickly.
• 6.
   There aretwo basic types: (1) Hard RTOS (2) Soft RTOS
• 7.
   A hardreal-time system has time-critical deadlines that must be met; otherwise a catastrophic system failure can occur.  Examples: – air traffic control – vehicle subsystems control – Nuclear power plant control
• 8.
   In asoft real-time system, deadlines can be occasionally missed.  Missing deadlines will not cause any catastrophic failure.  Also known as “best effort” systems.  Examples: – multimedia player controls – telecom (cellular) networks switching – web sites and services – computer games.
• 9.
   Task management Scheduling  Resource Allocation  Interrupt Handling
• 10.
   In RealTime Applications, any Process which takes a specified execution time and occupies predefined amount of memory is called as a Task.  Task management is the process of managing tasks through its life cycle.
• 12.
   Each task/Processcan belong to one and only one state.  The Scheduler only operates on the processes in the Ready state.  Transitions to and from the Ready queue are based on the availability of the resources or the time resource available.
• 13.
   Creating anddeleting tasks,  Controlling task scheduling, and  Obtaining task information.
• 14.
   Task managementprovides the following information about tasks: – No of tasks – Resource Requirements – Release Time – Execution time – Deadlines  RTOS Scheduler uses scheduling algorithms to organize them.
• 15.
   Clock DrivenScheduling  Round Robin Scheduling  Priority Scheduling
• 16.
   Release time/execution time/deadline will be known well in advance.  Schedule can be computed at some regular time instances.  Minimal runtime overhead.  But it might not suitable for all applications.
• 17.
   Jobs arescheduled in FIFO manner.  Time quantum given to tasks is not based on priority.  Not suitable for precedence constrained jobs (looping statements).  Job A can run only after Job B.  No point in giving time quantum to Job B before Job A.
• 18.
   Processor isnever left idle when there are ready tasks.  Processor will be allocated to processes according to priorities.  Priorities can be decided either : • Static - at design time • Dynamic - at runtime
• 19.
   We knowthat embedded systems have limited amount of resources in terms of memory & CPU power.  So, it is essential to allocate the available resources efficiently.  The same algorithms used for scheduling are again used for resource allocation.
• 20.
   Interrupt isany external control signal which disturbs the normal execution of a system.  Interrupts cause the processor to suspend all other operations whatever it is doing & instead execute the code that will respond to the event which caused the interrupt.
• 21.
   VxWorks  LynxOS RTLinux  Windows CE  These are some of the popular RTOS used in the industry.  VxWorks is the most widely used RTOS.
• 22.
   Real timeoperating systems are used in Military, Engineering Application and Data communication systems.  Automated Missiles and space satellites are also powered by RTOS these days.  In general, any embedded system application which requires immediate real-time action uses RTOS.
• 23.
   RTOS canrun on applications in any diverse and challenging environment conditions also.  It runs efficiently even on very limited Hardware resources.  It consumes less power and memory.  Kernel size is very small and can fit limited ROM storage of embedded systems.
• 24.
   http://www.circuitstoday.com/gpos-versus-rtos-for- an-embedded-system  https://www.enotes.com/homework-help/what-some- examples-real-time-operating-systems-why-276796 http://www.circuitstoday.com/what-is-real-time- operating-system-rtos  https://www.thegeekstuff.com/2012/02/rtos-basics/