The RTEMS Project

What is RTEMS? RTEMS is an open source Real Time Operating System (RTOS) that supports open standard application programming interfaces (API) such as POSIX. RTEMS stands for Real-Time Executive for Multiprocessor Systems. It is used in space flight, medical, networking and many more embedded devices. RTEMS currently supports 18 processor architectures and approximately 200 Board support packages.

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Supported by the community

Need help? Our strong community of users and developers are always around to answer questions

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Flexible deployment options

Choose how you deploy RTEMS within your company or organisation

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Open Development

We host our own GitLab, Mailing lists and you can find us on Discord

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You are in control

The entire RTEMS development cycle is public with all source. Long term maintenance is made easy and reliable.

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30 years

RTEMS has been an open source project for 30 years. Long term support. Long term availability.

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Build where you need

RTEMS actively maintains a working toolchain for Windows, Linux, OS X and FreeBSD

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Features

RTEMS comes with a complete set of features to help you with your application.

Kernel

  • Multitasking capabilities
  • Homogeneous and heterogeneous multiprocessor systems
  • Event-driven, priority-based pre-emptive scheduling
  • Optional rate-monotonic scheduling
  • Intertask communication and synchronization
  • Priority inheritance
  • Responsive interrupt management
  • Dynamic memory allocation
  • High level of user configurability
  • Portable to many target environments

API

  • POSIX 1003.1b API including threads
  • RTEID/ORKID based Classic API (similar to pSOS+) from the VMEbus Industry Trade Association.
  • TCP/IP including BSD Sockets
  • uITRON 3.0 API
  • GNU Toolset Supports Multiple Language Standards
  • ISO/ANSI C
  • ISO/ANSI C++ including Standard Template Library
  • Ada with GNAT/RTEMS

Networking

  • High performance port of FreeBSD TCP/IP stack
  • UDP
  • ICMP
  • TCP
  • DHCP
  • RARP
  • BOOTP
  • PPP

Device Driver

  • Block Device Cache
  • Device Only File System
  • ATA Block Driver

File System

  • In-memory Filesystem (IMFS)
  • Mini-IMFS (reduced services and footprint)
  • Device File System (lowest memory Filesystem, devices only)
  • MS-DOS FAT32
  • MS-DOS FAT16
  • MS-DOS FAT12
  • RTEMS File System (RFS)
  • TFTP client Filesystem
  • NFS client

Block Devices

  • ATA Disk Drives
  • RAM Disk
  • Volatile Disk
  • Flash Disk
  • SPI SD Card

Debugging

  • GNU debugger (gdb)
  • DDD GUI interface to gdb
  • Thread aware
  • Debug over Ethernet
  • Debug over serial port

Clients

  • Domain Name Service (DNS) client
  • Trivial FTP (TFTP) client
  • Network Filesystem System (NFS) client

Servers

  • FTP server (FTPD)
  • Web Server (HTTPD)
  • Telnet Server (Telnetd)
  • Sun Remote Procedure Call (RPC)
  • Sun eXternal Data Representation (XDR)
  • CORBA
  • PPPD

Latest News

RTEMS 6.1 Released

  • January 22, 2025

    • The RTEMS Project is proud to announce the availability of the 6.1 release of RTEMS. It is available from https://ftp.rtems.org/pub/rtems/releases/6/6.1/ which includes formatted documentation, all source code, and generated Doxygen. The core developers are quite proud of this release with many features added or improved. The build system has been changed from GNU autoconf/automake to the Python based Waf which has resulted in much faster build times. The main RTEMS source repository no longer contains a network stack with the user having a choice of LibBSD, lwIP, or the legacy stack. Another important change is that a significant portion of the code has been relicensed to the 2-Clause BSD License. If you have submitted source code in the past to the RTEMS Project and not given permission via issue 3053, we would appreciate you doing so. See the release notes for more details.

    We hope the user community enjoys this release as we think they will.

    More news...