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Cesium RTOS represents an evolutionary leap from its predecessor, Micrium µC/OS RTOS, propelling real-time operating systems into the next generation. Cesium RTOS introduces cutting-edge advancements and enhanced capabilities, empowering embedded systems with increased performance, improved efficiency, and seamless integration.


Real-Time Kernels

Cs OS2Cs OS3

At the core of the Cesium RTOS are the Cs/OS2 and Cs/OS3 real-time kernels; highly portable, scalable, preemptive, real-time, deterministic, multitasking kernels for microprocessors, microcontrollers, and DSPs.

Offering unprecedented ease of use, the Cs/OS kernels are delivered with complete 100% ANSI C source code and in-depth documentation. They run on a huge number of processor architectures, with ports available for download.

The Cs/OS kernels allow you to adjust your system's memory footprint based on your design requirements, saving valuable memory space.

Learn more about the Cs/OS real-time kernels >


Communication Software


A compact, reliable, high-performance TCP/IP protocol stack. Features dual IPv4 and IPv6 support, an SSL/TLS socket option, and support for Ethernet, Wi-Fi, and PHY controllers.

Learn more about the Cs/NET ›


Efficient USB device stack designed for embedded systems. Includes support for Audio, CDC-ACM, CDC-EEM, HID, MSC, and Vendor classes.

Learn more about Cs/USBD ›


Efficient USB host stack for embedded systems equipped with a USB host or OTG controller. Includes many class drivers such as MSC, HID, CDC-ACM, and USB2Ser.

Learn more about Cs/USBH ›

Cs Modbus

An industrial serial communications protocol for connecting industrial devices. Scalable, works with any CPU, and supports any number of communication channels.

Learn more about Cs/Modbus › 


Storage Software


A compact, reliable, high-performance, and thread-safe embedded file system for microprocessors, microcontrollers, and DSPs. An optional journaling component provides fail-safe operation while maintaining FAT compatibility.

Learn more about Cs/FS ›


Ported to Over 50 Architectures

 Cs/OS is Available for Your Platform

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Commercial License

All Cesium RTOS software components are available under a commercial license.

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Technical Support

Cesium Support Plan

If you are currently without technical support for the Cs/OS software don’t go at it alone. Technical support services for any of the Cs/ software is readily available to all customers currently using or interested in the Cs/ family of RTOS components.

Learn how our Cs/OS product experts, with years of embedded software experience, can save you valuable engineering time and money.

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Consulting Services

Specialized Engineering Services

Do you need specialized assistance with your Cesium-based embedded project? Do you need real-time embedded software expertise for your mission critical application? For these or any other embedded software projects, help is available via our Consulting Services that are tailored to your unique needs. Please contact us with your requirements to learn how we can quickly deliver our expertise to your team.

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Cesium software includes comprehensive documentation, full source code, powerful debugging features, and support for a huge range of CPU architectures.


Cesium software offers unprecedented ease-of-use, a small memory footprint, remarkable energy efficiency, and all with a full suite of protocol stacks.


Engineers across the world building industrial controls, medical devices, and aerospace systems know they can rely on Cesium software for the foundation of exceptional products.