Nucleus RTOS
DeveloperMentor Graphics Corp., a Siemens Business
Written inC
Working stateCurrent
Source modelClosed source
Initial release1993; 31 years ago (1993)
Latest release3.x, 2017.02 / May 15, 2017; 7 years ago (2017-05-15)
Marketing targetEmbedded systems, IoT
Available inEnglish
PlatformsARM, NXP, MIPS, TI, PowerPC, Altera Nios II, Xilinx MicroBlaze, Renesas SuperH, Infineon, Atmel AT91SAM, RISC-V, others[1]
Kernel typeReal-time monolithic with hybrid support
Official websiteNucleus website

Nucleus RTOS is a real-time operating system (RTOS) produced by the Embedded Software Division of Mentor Graphics, a Siemens Business, supporting 32- and 64-bit embedded system platforms. The operating system (OS) is designed for real-time embedded systems for medical, industrial, consumer, aerospace, and Internet of things (IoT) uses. Nucleus was released first in 1993. The latest version is 3.x, and includes features such as power management, process model, 64-bit support, safety certification, and support for heterogeneous computing multi-core system on a chip (SOCs) processors.

Nucleus process model adds space domain partitioning for task and module isolation on SOCs with either a memory management unit (MMU) or memory protection unit (MPU), such as those based on ARMv7/8 Cortex-A/R/M cores.

Supported platforms

Nucleus supports many embedded processors including leading ARMv7 Cortex A, R, and M devices. Recent releases support ARMv8 64-bit devices. The official website has a full list of supported devices.[2] It includes 32-bit MCUs and MPUs, configurable devices, and 32-bit and 64-bit multi-core processors.


Nucleus 1.x was released first in 1993 by Accelerated Technology (ATI) as Nucleus PLUS. It soon became one of the most commonly used RTOSs in the embedded market. Following its early success there, ATI added support for networking, graphics, and file systems, which accelerated adoption.

Mentor Graphics acquired ATI in March 2002, which was soon followed by the second generation of Nucleus RTOS. Version 2.x was released in 2003, improving its portability across different architectures and tool sets. New components like IPv6, Flash memory file system and Universal Serial Bus (USB) 2.0 were added. Mentor replaced the legacy Codelab debugger with EDGE development tools which included compiler tools, debugger, simulator, and profiler.

Mentor Graphics introduced the 3rd generation Nucleus in 2010. Version 3.x was intended for both high-end microprocessor units (MPUs), microcontroller units (MCUs), digital signal processors (DSPs), and field-programmable gate arrays (FPGAs). For devices with limited memory resources, Nucleus was designed to scale down to a memory size of <10 kilobytes (KBs) for both code and data.

Nucleus 3.x introduced support for symmetric multiprocessing (SMP) and asymmetric multiprocessing (AMP) both unsupervised uAMP and supervised sAMP (using Mentor Embedded Hypervisor). Other additions in Nucleus 3.x:

In addition to the new features in version 3.x, Nucleus moved business model from a la carte, to one unified package.

Mentor acquired CodeSourcery in Dec 2010 to replace the EDGE development tools with the Sourcery CodeBench. Sourcery CodeBench comprises a compiler tool-chain, debugger, and trace analysis tools. The compiler tool-chain is based on GNU tool-chain. The debugger and integrated development environment (IDE) are based on Eclipse. Sourcery CodeBench supports ARM, IA-32, MIPS, and PPC architectures with built-in workflows and OS awareness for Nucleus RTOS and Mentor Embedded Linux.

Nucleus 3.x introduced a unified build and configuration system with which the Kernel is configured through a single file and builds as a single library. Like menuconfig in Linux, a user interface (UI) based configuration tool integrated with CodeBench provides the user with graphically selectable components to customize the kernel at build time. The Nucleus configuration system allows for user customization to integrate new tool-chains, architecture support and build properties.

Major components

Nucleus RTOS components include:

  1. Kernel
  2. Services
  3. Connectivity
  4. File system
  5. Networking
  6. IoT Framework
  7. Wireless
  8. Security
  9. UI & graphics




Nucleus supports the ability to connect to other devices through various interfaces including:

File system

Unlike Windows and Unix-like operating systems, Nucleus does not need a file system to work. However, for complex uses needing local storage, Nucleus supports several file systems including FAT, SAFE (fault tolerant), and LWEXT.

Multiple simultaneous file systems

Multiple media support

Nucleus provides support for different file systems and storage media through a virtual file system application programming interface (API) that allows access to the supported file systems and storage devices using the same functions calls regardless of the underlying storage format.


The Nucleus networking stack is a dual IPv4 and IPv6 stack that supports over 60 networking protocols. Nucleus networking stack supports POSIX and provides an easy to use socket based application interface. A brief list of the supported protocols include:


Nucleus supports a wide variety of encryption options for secure communications to protect data at rest or in transit. Nucleus ships with OpenSSL and an OpenSSL-like package wolfSSL (formerly CyaSSL) that is far smaller than OpenSSL for designs needing encryption but limited in memory capacity.[3] Security protocols to protect data in transit include IPsec/IKE, SSH/SSL/TLS/DTLS. Encryption includes DES, 3DES, AES, SHA-256. Public-key cryptography algorithms include RSA. Support includes X.509, RADIUS, and 802.1X.


Several Wi-Fi modules from different chip-makers like QCA, Broadcom, TI, and CSR are supported:

UI graphics

Nucleus 3.x supports OpenGL and leading 3rd party UI libraries. Nucleus supports the Qt UI framework which has been optimized for code size and integrated into CodeBench for debugging and tracing. Other UIs supported include Embedded Wizard and Socionext CGI Studio.


Recent releases of Nucleus include support for HTTPS, Constrained Application Protocol (CoAP), MQTT and 6LoWPAN.

Nucleus has also announced support for Microsoft Azure cloud computing framework.


Nucleus has been integrated with 3rd party industrial stacks from industry leaders. Industrial stack support includes OPC Unified Architecture (OPC UA) host and client and EtherNet/IP from Softing Archived 2017-08-22 at the Wayback Machine and EtherCAT from KoenigPa.


Nucleus supports asymmetric multiprocessing (AMP) mode and symmetric multiprocessing (SMP) mode for leading 32 and 64-bit heterogeneous multi-core SoCs. Nucleus is also capable of running as a GOS with Mentor Embedded Hypervisor.

When operating in AMP mode, Nucleus RTOS can coexist with other instances of Nucleus, Linux, and/or bare machine (metal) programs distributed on the other processors. In this mode, each processor is running independently and behaves as a separate system within the SoC. Mentor Embedded Multicore Framework provides interprocess communication between operating systems on the various cores, and processor life cycle management. SMP operation entails having a instantiation of Nucleus RTOS manage multiple cores simultaneously. Nucleus can distribute its operations across all cores on a multi-core device, or any subset of cores. For this purpose Nucleus offers runtime API support for bound computation domain, and control tasks and interrupt affinities for core assignment.

Product packages

Nucleus RTOS is packaged as follows:

Safety certification

Nucleus SafetyCert has been certified for the highest levels of safety for DO-178C, IEC 61508, IEC 62304, and ISO 26262.

Products using Nucleus RTOS

Example devices using Nucleus products include:

See also


  1. ^ "Nucleus OS Supported Processors".
  2. ^ "Nucleus RTOS Supported Processors". Retrieved 2017-08-22.
  3. ^ "wolfSSL User Manual – Chapter 5: Portability – Documentation". Retrieved 2019-02-14.
  4. ^ Voica, Alexandru. "MIPS in space: Inside NASA's New Horizons mission to Pluto". Imagination. Archived from the original on 2015-10-17. Retrieved 2015-10-16.
  5. ^ "IVL Technologies".
  6. ^ "ASC". Archived from the original on 2006-06-15. Retrieved 2006-06-17.
  7. ^ "TI-Nspire Technical Details -".
  8. ^ "Telephonics - Surveillance, Communications, Analysis and Integrated Solutions leader".
  9. ^ "Control Systems for Home Automation, Campus & Building Control by Crestron Electronics".
  10. ^ "Soundweb London - BSS Networked Audio Systems". BSS Networked Audio Systems.
  11. ^ "Все о глазах и зрении - офтальмологический форум" (PDF). Archived from the original (PDF) on 2007-02-05. Retrieved 2012-05-12.
  12. ^ "The evolution of the Apple iPhone and its many CPU's – Even within a model - The CPU Shack Museum". 13 August 2010.
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  14. ^ Samsung Electronics' strategy to compete in the 'bada' is..., Bloter, 2009.11.18,