Course 101: Lecture 4: A Tour in RTOS Land
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This document provides an overview of various real-time operating systems (RTOS) suitable for embedded systems, including proprietary options like Windows CE and Nucleus, as well as open-source alternatives like Linux and eCos. Each OS is described with respect to its features, licensing costs, and application examples, highlighting the diversity in embedded system requirements. The content culminates in the advantages of open-source operating systems, emphasizing community support and configurability.
Course 101: Lecture 4: A Tour in RTOS Land
- 1. Linux For Embedded Systems ForArabs Ahmed ElArabawy Course 101: Introduction to Embedded Linux
- 2. Lecture 4: A Tour in RTOS Land
- 4. Windows CE • Developed by Microsoft • Has recently been replaced by Windows Embedded Compact • Has the mix of the windows desktop and embedded devices requirements • Suitable for embedded devices that require also a good user interface • Medium to Large HW requirements: • Footprint of OS around 200-350KB • May run in under a 1MB of memory • True RTOS, has a deterministic behavior • Cost is around $3 per device license + Initial Cost for tools
- 6. Nucleus • Developed by Mentor Graphics • Portable to different devices (Microcontrollers and Micro - Processors) • Foot print as small as 2KB • Support unique power management features • Power/clock gating • Deep sleep modes • Cost is about • $13K for the OS license per implementation • $3K per seat for the tools • Royalty free
- 7. Application Examples • Very widely used
- 8. Threadx • Developed by Express Logic, Inc. by the same the author of Nucleus • Small footprint ( can go as low as 2KB on Microcontrollers) • True RTOS, Fast and deterministic behavior • Fast boot time (This is very important for devices that can't afford a long boot time) • Flexible licensing models + Royalty free
- 9. Application Example Hewlett-Packard use ThreadX in all of their printers, • Inkjets • LaserJets • All-in-One
- 10. Application Example Broadcom use ThreadX in a lot of its Chips for cell phones in their communication processors
- 11. VxWorks • Developed by Wind River Systems, 1987 • Legacy RTOS. Used to be the top OS for Embedded Platforms • Not used recently for small system, but still considered by heavy Institutions (such as Aerospace and Defense) • Expensive licensing cost + Royalty cost • Other OS’s with their latest development are catching up
- 15. Is Free Really Free ?? • Free for freedom and not for free drink • Free means freedom to run, study, copy, modify, distribute both the original code and the modified versions • Free/Open source OS’s include: • The OS itself (the kernel) • Development tools: Compilers, Debuggers, toolchains, … • Support libraries: C library, XML parsers, Security, command line utilities • Keep in mind the licensing risks (GPL, LGPL, … ) • Licensing terms • Might mean you can not have a proprietary system • Might mean you need to give up your source code
- 16. Advantages of Open Source OS • Cost perspective • Kernel, development tools, associated libraries and support tools, applications, … • Big community help and support • Ability to understand and control details of operation • Availability of online resources and documents • Fast release cycles • Ability to influence the future of the OS
- 17. Linux (www.kernel.org ) • Most popular Open Source OS • Big Community Support • Distributions • Build your own distribution • Redhat • Suse • Ubuntu • And many others • GPL v2.0 License • Require 32bit processors with MMU • Highly configurable, RAM and Storage requirements according to configurations • Not a real RTOS • Sometimes used with patches to support hard real time embedded applications (such as RTLinux)
- 18. uClinux (www.uclinux.org ) • Started as a port of Linux for systems with, • Micro-controllers • Processors without MMU • Used for simple Embedded devices • Now highly integrated with the Linux mainstream as a patch • Used in several devices such as, • DVD players • Security cameras • VoIP phones • Scanners
- 19. eCos (http://ecos.sourceware.org ) • Suitable for smaller embedded systems • Small footprint, with low requirement on resources • Modified GPL License to give developer more rights to use it without need to GPL his code • One of the most popular open source RTOS in the world today • Highly configurable (eCos stands for the "Embedded Configurable Operating System") • Support multi-tasking with priority-based real-time scheduler • standards based APIs • True RTOS, Highly deterministic behavior • Highly portable to most of 32 bits processors
- 20. Application Example Sony, Playstation 3 Gaming Console for WiFi support
- 21. Application Example Samsung, latest LCD HDTVs (32-70 inch) to support multi-media playback via USB2 from cameras, mp3 players and flash drives
- 22. Application Example Eye-Fi Wireless SD Cards that use WiFi to transfer images between camera and computer
- 23. Nuttx • First released by Gregory Nutt in 2007 with BSD license • True RTOS (deterministic) • Small footprint • Supports from simple 8 bit processors (such as Zilog Z80) to 32 bit processors (such as ARM-9, x86) • Supports C & C++ development • TCP/IP Stack and USB support • Support multitasking with FIFO and round-robin scheduling • Support pre-emption • Highly configurable • Supports Standard APIs such as ANSI and POSIX • Used in MP-3 players, Auto-pilot, …