embOS-Classic
embOS-Classic has proven its reliability in billions of deployed devices over several decades, and it lays the foundation for all embOS editions.
Overview
embOS-Classic is a preemptive real-time operating system (RTOS) designed to serve as a foundation for developing embedded applications. It is available for all popular cores, compilers, and development tools. Now in its fourth decade of continuous use and enhancement, embOS-Classic has been deployed in several billion devices across a wide range of application areas.
Key features
embOS-Classic is straightforward to use and guarantees fully deterministic real-time operation for any embedded device. It is highly portable and fully API-compatible on any platform, which makes it simple to port applications to different cores. Tasks can be created easily, and they communicate with each other safely via mechanisms such as semaphores, mailboxes, and events.
Reliability
embOS-Classic is already deployed across several billion devices, and it is available with certification in functional safety in accordance with IEC 61508 SIL 3, IEC 62304 Class C, and ISO 26262 ASIL D.
Efficiency
embOS-Classic is a high-performance real-time operating system. It has been optimized for minimum memory consumption in both RAM and ROM.
Availability
embOS-Classic supports virtually any core and compiler through more than 80 embOS-Classic ports, including over 500 board support packages for the embedded market.
Use cases
The versatile nature of embOS-Classic makes it a core ingredient in any firmware that has to handle tasks that require synchronization, timely responses, and multiple tasks or threads in parallel. This means it is applied across a wide range of different areas. An example of this versatility would be use with IP stacks and USB-Host stacks, which are nearly impossible to run without the scheduling provided by an RTOS.
Internet of Things
By handling networking stacks and background tasks efficiently, embOS-Classic provides a reliable foundation for IoT applications that require stable networking and efficient task management.
Consumer electronics
embOS-Classic: The first choice for any consumer-electronics device—whether in entertainment, communications, or white goods.
Industrial controls
embOS-Classic is an essential component in industrial control systems—particularly in applications where deterministic and reliable behavior is absolutely required.
How embOS-Classic works
embOS-Classic is a preemptive multitasking system. Each task has a fixed priority, and the scheduler determines what task to execute—ensuring that the highest-priority executable task is always running. If a lower-priority task is active, it is immediately interrupted when a higher-priority task becomes ready. This enables preemptive multitasking. Tasks are activated by traditional periodic system ticks that are generated by a hardware timer at specified intervals. These can serve as a foundation for time-based functions, such as task delays or timeouts. The scheduler can also be triggered by external interrupts, such as the press of a button that activates a specific task. This approach ensures efficient CPU utilization by guaranteeing that time-critical tasks always take precedence, while background processes run only when no higher-priority tasks are active.
For detailed information, please see the online documentation for embOS.
Memory protection
embOS-Classic is also available with embOS-MPU (memory protection unit) technology, which leverages a processor's MPU in order to isolate individual tasks both from each other and the operating system. This ensures that errors in one application do not affect an entire system and that safety-critical functions are executed reliably. As a result, embedded systems benefit from enhanced stability, as unprivileged tasks have only controlled access to memory regions, peripherals, and operating-system objects.
More information is available on the embOS-MPU page.
Supported cores and compilers
embOS-Classic is available for different core and compiler combinations, all of which are listed in SEGGER's complete overview of embOS ports. This list is regularly updated. If a core or compiler is not on the list, SEGGER will port embOS-Classic to that target. Questions? Contact us.
embOS-Classic packages
The embOS RTOS can be delivered as an object-code or source-code package. The source-code package expands on the object-code package by including embOS source code. Using embOS source code enables the use of application-specific compiler options. Compile time switches allow users to customize embOS by enabling only required functionalities. Adding embOS source code to a project provides additional insight when debugging at source level.
Both embOS packages include the same ready-to-use board support packages for various devices and evaluation boards.
| Features | Object code | Source code | |
|---|---|---|---|
| embOS object code library | |||
| embOS source code library | |||
| embOSView – Profiling PC tool | |||
| embOS manual | |||
| CPU- and compiler-specific manual | |||
| Release notes | |||
| embOS IDE plugins | |||
| SystemView instrumentation | |||
| Device support | |||
| Board support packages | |||
| Updates and technical support | |||
| Feature & maintenance updates | |||
| Technical support | |||
Supported Not supported
Licensing
embOS-Classic is available under various embedded software license models. All user-created hardware components are royalty free, and there are no additional fees or limits on production volume. Every license model includes a 6-month support-and-update agreement, and there is also an option to extend both support and updates for an additional 12 months. To purchase a license, please contact us.
*Applies only to a second license and any additional license(s) purchased for the same product under the Single Product License and Single Developer License.
Friendly License
embOS-Classic is also available under SEGGER's Friendly License, which allows free-of-charge use for non-commercial, evaluation, and educational purposes. With this license, the product is fully functional and there are no technical limitations. All ports, including several BSPs for popular evaluation boards from leading semiconductor vendors, can be downloaded for evaluation at https://www.segger.com/downloads/embos/.
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