Lesson 27 Choosing a Real-Time Operating System.ppt
- 1. Unit 9 Embedded application Lesson 27 Choosing a Real-Time Operating System
- 2. 2023/8/26 2 Lesson 27 Choosing a Real-Time Operating System • Backgrounds • Text tour • Language in use – Vocabulary
- 3. 2023/8/26 3 • Terminology – Debugger A debugger or debugging tool is a computer program that is used to test and debug other programs (the "target" program). Backgrounds
- 4. Stack • In computer science, a stack is an abstract data type that serves as a collection of elements, with two principal operations: push, which adds an element to the collection pop, which removes the most recently added element that was not yet removed. 2023/8/26 4
- 5. 2023/8/26 5 – Source code In computing, source code is any collection of computer instructions, possibly with comments, written using a human- readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source code. – The source code is often transformed by an assembler or compiler into binary machine code understood by the computer. Backgrounds
- 6. Integrated development tool • An integrated development environment (IDE) is a software application that provides comprehensive facilities to computer programmers for software development. An IDE normally consists of a source code editor, build automation tools and a debugger. 2023/8/26 6
- 7. 2023/8/26 7 - Interrupt latency In computing, interrupt latency is the time that passes from when an interrupt is generated to when the source of the interrupt is serviced. For many operating systems, devices are serviced/operated as soon as the device's interrupt handler/ISR is executed. Backgrounds
- 8. 2023/8/26 8 Text tour • Outline – Introduction (para.1, 2) – Characteristics of an RTOS (para.3-8) – Selection process (para.9-12)
- 9. 2023/8/26 9 Introduction • The term "real time" means the computer problem for which a late answer is as bad as a wrong one. • A real-time system has been described as one which "controls an environment by receiving data, processing them and returning the results sufficiently quickly to affect the environment at that time". • The term "real-time" is also used in simulation to mean that the simulation's clock runs at the same speed as a real clock and in process control and enterprise systems to mean "without significant delay". • Designers of real-time embedded systems spends large portion of time • Worst-case performance A. Command & Interrupt signal B. Interrupt latency C. Triggering the Breaking Mechanism
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- 11. 2023/8/26 11 Characteristics of an RTOS • To earn the distinctive title " RTOS ", an operating system should… – be deterministic (calculable i.e. vendors must publish datasheets) – have guaranteed worst-case interrupt latency – have guaranteed context-switch times (i.e. the amount of time required to perform a context switch.) **context switch is the process of storing and restoring the state of a process or thread so that execution can be resumed from the same point at a later time.
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- 13. 2023/8/26 13 Selection process • A wide variety of OSs are available to suit most projects and pocketbooks. – at the lower end • a basic preemptive(automatic) scheduler • a few other key system calls – at the higher end • the basic scheduler • a lot of functionality
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- 15. 2023/8/26 15 Selection process • It can be difficult to decide – Try putting your processor, real-time performance and budgetary requirements first. – Then contact the vendors for more detailed technical information. • Decision based on compatibility with choice of cross-compiler, debugger and other development tools. • Decide what additional features are most important for your project.
- 16. 2023/8/26 16 • Vocabulary – Suffice execution source Language in use
- 18. 2023/8/26 18 Suffice in dictionary • To meet present needs or requirements; be sufficient: – These rations will suffice until next week. • To be equal to a specified task; be capable: – No words will suffice to convey my grief.
- 19. 2023/8/26 19 Suffice in text • Average or expected-case analysis simply will not suffice.
- 20. 2023/8/26 20 Suffice in use • suffice for • suffice it to say that...
- 21. 2023/8/26 21 Execution in dictionary • The act of executing something. • The state of being executed. • The manner, style or result of performance: – The plan was sound; its execution, faulty. • The act or an instance of putting to death or being put to death as a lawful penalty.
- 22. 2023/8/26 22 Execution in text • An operating system is said to be deterministic if the worst-case execution time of each of its system calls is calculable.
- 23. 2023/8/26 23 Execution in use • program execution • step execution • execution of contract
- 24. 2023/8/26 24 Source in dictionary • The point at which something springs into being or from which it derives or is obtained. • The point of origin, such as a spring, of a stream or river. • One that causes, creates, or initiates; a maker.
- 25. 2023/8/26 25 Source in text • Those at the lower end of the spectrum offer just a basic preemptive scheduler and a few other key system calls. These operating systems are usually inexpensive, come with source code that you can modify, and do not require payment of any royalties.
- 26. 2023/8/26 26 Source in use • capital source • constant flow source • constant voltage source • noise source