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    SEGGER embOS (Real Time Operating System) is a priority-controlled real time operating system, designed to be used as foundation for the development of embedded real-time applications. It is a zero interrupt latency, high-performance RTOS that has been optimized for minimum memory consumption in both RAM and ROM, as well as high speed and versatility. Throughout the development process of embOS, the limited resources of microcontrollers have always been kept in mind. The internal structure of embOS has been optimized in a variety of applications with different customers, to fit the needs of different industries. embOS is fully source-compatible on different platforms (8/16/32 bits), making it easy to port applications to different CPUs. Its' highly modular structure ensures that only those functions that are needed are linked, keeping the ROM size very small. Tasks can easily be created and safely communicate with each other using a complete palette of communication mechanisms such as semaphores, mailboxes, and events. Interrupt Service Routines (ISRs) can also take advantage of these communication mechanisms. The software is very easy to use and works out of the box. BSPs and projects for popular eval boards and tool chains are available.


    • Optimized for resource usage
    • Optimized for high performance
    • Platform-independent
    • Reliable due to proven code
    • Easy to implement and maintain due to global coding standards for all Segger products
    • Royalty free


    Libraries and source code

    embOS is available as library or source code; the source code version includes libraries and the source code of the libraries. Both versions come with ready to go start projects, BSPs and embOSView. Different builds of libraries are also included: Release/stack check build, typically used in the release build of the application program; Debug/profiling build typically used in the development phase. The libraries offer the full functionality of embOS including all supported memory models of the compiler, the debug libraries and the source code for idle task and hardware initialization. However, the libraries do not allow source-level debugging of the library routines and the kernel. The full source version provides the ultimate options: embOS can be recompiled for different data sizes; different compile options give full control of the generated code, making it possible to optimize the system for versatility or minimum memory requirements. The entire system can be debugged and modified.


    embOS Simulation

    embOS simulation visualizes and simulates your target hardware and allows you to write and test your application program without need of a functioning hardware. It compiles the same "C" source on a Windows PC using a native compiler. Therefore the entire application development of the simulation is identical to the one on your target system; all functions will behave in the same way.


    embOSView Profiling

    embOSView is a very helpful tool for analysis of the running target application in real time. It displays the state of a running application using embOS. All communication is done from within the communication interrupt routines. This means that the communication is none intrusive if embOSView is not connected and minimum intrusive while embOSView is connected. In the profiling build, embOS collects precise timing information for every task, which enables embOSView to show the CPU load.



    Typical Applications: Industrial Equipment, Test and Measurement Equipment, Telecommunication, Medical Equipment, Consumer Electronics

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    Key Features


    • Preemptive scheduling: Guarantees that of all tasks in READY state, the one with the highest priority executes, except for situations where priority inversion applies.
    • Round-robin scheduling for tasks with identical priorities.
    • Preemptions can be disabled for entire tasks or for sections of a program.
    • Thread local storage support.
    • Thread safe system library support.
    • No configuration needed
    • Up to 255 priorities: Every task can have an individual priority => the response of tasks can be precisely defined according to the requirements of the application.
    • Unlimited number of tasks (limited only by available memory).
    • Unlimited number of semaphores (limited only by available memory).
    • Unlimited number of mailboxes (limited only by available memory).
    • Size and number of messages can be freely defined.
    • Unlimited number of software timers (limited only by available memory).
    • Time resolution tick can be freely selected (default is 1ms).
    • High resolution time measurement (more accurate than tick).
    • Power management: Unused CPU time can automatically be spent in halt mode, minimizing power consumption.
    • Full interrupt support: Most API functions can be used from within the Interrupt Service Routines (ISRs).
    • Zero interrupt latency time.
    • Nested interrupts are permitted.
    • Start application and projects (BSPs) for an easy start.
    • Debug build performs runtime checks, simplifying development.
    • High precision per task profiling.
    • Real time kernel viewer (embOSView) included.
    • Very fast and efficient, yet small code.
    • Minimum RAM usage.
    • Core written in assembly language.
    • All API functions can be called from C /C++/assembly.
    • Initialization of microcontroller hardware as sources.
    • BSP for any unsupported hardware with the same CPU can easily be written by user.


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    Technical Specifications


    • kernel size (ROM) 1100 - 1600 byte*
    • kernel RAM usage 18 - 25 byte *
    • kernel CPU usage at 1 ms Interrupts with 10MHz M16C : less than .3%
    • RAM usage mailbox 9 - 15 byte *
    • RAM usage binary and counting semaphore 3 byte
    • RAM usage resource semaphore 4 - 5 byte *
    • RAM usage timer 9 - 11 byte *
    • RAM usage event 0
    • Basic time unit (One Tick) Default 1 ms, can be configured, Min. 100 µs (M16C@10MHz) *
    • task activation time independent of no. of tasks(e.g. typ. 12 us M16C@10MHz)
    • zero interrupt latency
    • No. of tasks : Unlimited (by available RAM only)
    • No. of mailboxes : Unlimited (by available RAM only)
    • No. of semaphores : Unlimited (by available RAM only)
    • No. of s/w timers : Unlimited (by available RAM only)
    • Max. no. of priorities : 255
    • Max. no. of tasks with identical priorities (Round robin scheduling) Unlimited


    * Depends on CPU, compiler and library model used

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    Supported Devices


    embOS has been ported to a variety of CPUs and development environments. Segger constantly add new devices to the list. Below is the list of processors supported by embOS:

    ManufacturerCore Architecture
    AlteraNIOS 2
    Analog DevicesARM7, Cortex-M3
    AtmelAVR, AVR32 UC/AP, ARM7, ARM9, Cortex-M3,Cortex-M4
    FreescaleS08, HCS12, HCS12X, Coldfire V1/V2/V3/V4, Kinetis ARM Cortex-M
    FujitsuF2MC-16LX, F2MC-16FX, FR30, FR50, FR70
    MicrochipPIC18, PIC24F/PIC24H,  dsPIC30F/dsPIC33F,PIC32
    NECK0, K4, V850, V850E, V850ES
    NXPARM7, ARM9, Cortex-M0, Cortex-M3, Cortex-M4
    RenesasH8, H8S, H8SX, M16C/R8C, M16C6X,  M32C, M16C80, R32C, RL78, RX, SH2, SH2A, SH4
    STMicroelectronicsST7, STM8, STM32 ARM Cortex‑M
    Texas InstrumentsMSP430, Cortex-A, Cortex-M
    OthersZILOG Z180, NEC 78K, Toshiba TLCS900...

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    Technical Documents

    Learning Center
    User GuideSegger: User Guide for embOS Real Time Operating System


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    Ordering Information

    Licensing Option

    Single Developer Object Code License (SOL) - The machine-readable, linkable and complied version limited to a specific CPU and complier. An SSL entitles one and only one person working on a project in a company to work with the software on one and only one personal computer at a time.


    Single Developer Source Code License (SSL) - The human-readable vesion that can be complied into object code limited to a specific CPU and complier. An SOL entitles one and only one person working on a project in a company to work with the software on one and only one personal computer at a time.


    Additional Developer License (ADL) - Developer Object Code or Developer  Source Code can be used in multiple users.


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