| Developer | Express Logic (original) Microsoft (former) Eclipse (current) |
|---|---|
| Written in | C |
| Working state | Current |
| Source model | Open source |
| Initial release | 1997 |
| Latest release | 6.4.1 [1] / February 28, 2024 |
| Repository | github |
| Marketing target | Embedded systems, IoT |
| Update method | Re-install |
| Package manager | None |
| Platforms | ARC, ARM, Blackfin, CEVA, C6x, MIPS, NXP, PIC, PowerPC, RISC-V, RX, SH, SHARC, TI, V850, Xtensa, x86, Coldfire, others |
| Kernel type | Embedded, deterministic, real-time microkernel, picokernel |
| Default user interface | Embedded UI support (GUIX) |
| License | MIT License (as of 2023) |
| Official website | threadx.io |
ThreadX is a deterministic embedded real-time operating system (RTOS) programmed mostly in the language C. It was originally released in 1997 as ThreadX when Express Logic first developed it, later it was renamed to Azure RTOS (2019) after Express Logic was purchased by Microsoft, [2] then most recently it was renamed again to Eclipse ThreadX (2023), or "ThreadX" in its short form, after it transitioned to free open source model under the stewardship of the Eclipse Foundation. [3]
In 1997, ThreadX was first released and marketed by Express Logic of San Diego, California, United States. It was developed by William Lamie, [4] who was also the original author of Nucleus and PX5 RTOS, and was President and CEO of Express Logic. ThreadX version 4 was introduced in 2001, version 5 was introduced in 2005, then version 6 was introduced in 2020 (latest major version). FileX – the embedded file system for ThreadX was introduced in 1999. NetX – the embedded TCP/IP networking stack for ThreadX was introduced in 2002. USBX – the embedded USB support for ThreadX was introduced in 2004. ThreadX SMP for SMP multi-core environments was introduced in 2009. ThreadX Modules was introduced in 2011. ThreadX achieved safety certifications for: TÜV IEC 61508 in 2013, and UL 60730 in 2014. GUIX – the embedded UI for ThreadX was introduced in 2014.
On April 18, 2019, Microsoft purchased Express Logic for an undisclosed sum and it was renamed to Azure RTOS. [2]
On November 21, 2023, Microsoft announced Azure RTOS would be transitioning to an open source model under the stewardship of the Eclipse Foundation, and making the project available under the permissive MIT License. [3] With Eclipse Foundation as the new home, Azure RTOS was renamed to Eclipse ThreadX, or "ThreadX" in its short form.
The name ThreadX was derived from the threads that are used as the executable elements, and the letter X represents context switching, i.e., it switches threads.
ThreadX provides priority-based, preemptive scheduling, fast interrupt response, memory management, interthread communication, mutual exclusion, event notification, and thread synchronization features. Major distinguishing technology characteristics of ThreadX include preemption-threshold, priority inheritance, efficient timer management, fast software timers, picokernel design, event-chaining, and small size: minimal size on an ARM architecture processor is about 2 KB.
ThreadX supports multi-core processor environments via either asymmetric multiprocessing (AMP) or symmetric multiprocessing (SMP). Application thread isolation with memory management unit (MMU) or memory protection unit (MPU) memory protection is available with ThreadX Modules.
ThreadX has extensive safety certifications from Technischer Überwachungsverein (TÜV, English: Technical Inspection Association) and UL (formerly Underwriters Laboratories) and is Motor Industry Software Reliability Association MISRA C compliant.
ThreadX is the foundation of Express Logic's X-Ware Internet of things (IoT) platform, which also includes embedded file system support (FileX), embedded UI support (GUIX), embedded Internet protocol suite (TCP/IP) and cloud connectivity (NetX/NetX Duo), and Universal Serial Bus (USB) support (USBX). ThreadX has won high appraisal from developers and is a very popular RTOS. [5]
As of 2017 [update] , according to marketing research firm VDC Research, the ThreadX RTOS has become one of the most popular RTOSes in the world, having been deployed in over 6.2 billion devices, including consumer electronics, medical devices, data networking applications, and SoCs. [6]
ThreadX implements a priority-based, preemptive scheduling algorithm with a proprietary feature called preemption-threshold. The latter has been shown to provide greater granularity within critical sections, reduce context switches, and has been the subject of academic research on guaranteeing scheduling. [7]
ThreadX provides a unique construct called event chaining, [8] where the application can register a callback function on all application programming interfaces (APIs) that can signal an external event. This helps applications chain together various public objects in ThreadX such that one thread can effectively block on multiple objects.
ThreadX also provides counting semaphores, mutexes with optional priority inheritance, event flags, message queues, software timers, fixed sized block memory, and variable sized block memory. All APIs in ThreadX that block on resources also have an optional timeout.
ThreadX offers multi-core processor support via either AMP or SMP. Application code isolation is available through ThreadX Modules component.
ThreadX (and FileX and NetX Duo) have been precertified by SGS-TÜV Saar to the following safety standards: IEC 61508 SIL 4, IEC 62304 Class C, ISO 26262 ASIL D, and EN 50128 SW-SIL 4.
ThreadX (and FileX and NetX Duo) have been precertified by UL to the following safety standards: UL/IEC 60730, UL/IEC 60335, UL 1998
ThreadX has also been certified to DO-178 standards by various military and aerospace companies. It is supported by popular Transport Layer Security (SSL/TLS) libraries such as wolfSSL. [9]
As of 2017, ThreadX is packaged as part of X-Ware IoT Platform in full source code and with no runtime royalty payment.
The major ThreadX components are:
ThreadX is the real-time operating system (RTOS).
FileX is an optional file system for ThreadX. It supports FAT12, FAT16, FAT32, and exFAT file systems. The latter extends FAT file sizes beyond 4 GB, which is useful for large video files.
It also offers fault tolerance and supports direct NOR and NAND flash memory media through optional flash wear leveling product called LevelX.
GUIX is an optional graphical user interface (GUI) for ThreadX. It provides a 2D computer graphics system that supports multiple display devices with a variety of screen resolutions and color depths. Many predefined graphical widgets are available. A Windows WYSIWYG host tool called GUIX Studio automatically generates C code for GUIX to execute at runtime.
NetX Duo is an optional TCP/IP network system for ThreadX. It supports both IPv4 and IPv6 networking with IPsec network security. TCP and UDP socket layers are provided by TLS / DTLS. Optional protocols include ARP, Auto IP, DHCP, DNS, DNS-SD, FTP, HTTP, ICMP, IGMP, mDNS, POP3, PPP, PPPoE, RARP, TFTP, SNTP, SMTP, SNMP, and Telnet. IoT Cloud protocol support includes CoAP, MQTT, and LWM2M. NetX Duo also supports Thread and 6LoWPAN. In 2017, ThreadX and NetX Duo became a Thread Certified Product. [10]
USBX is an optional Universal Serial Bus (USB) system for ThreadX. It supports both host / device / on-the-go (OTG). Host controller support includes EHCI, OHCI, and proprietary USB host controllers.
It supports these USB Device Classes: Audio, Asix, CDC/ACM, CDC/ECM, DFU, GSER, HID, PIMA, Printer, Prolific, RNDIS, and Storage.
TraceX is optional host software that provides a graphical view of ThreadX RTOS events. It requires Windows XP or later.
Some examples of products that use ThreadX:
OS-9 is a family of real-time, process-based, multitasking, multi-user operating systems, developed in the 1980s, originally by Microware Systems Corporation for the Motorola 6809 microprocessor. It was purchased by Radisys Corp in 2001, and was purchased again in 2013 by its current owner Microware LP.
QNX is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market.
VxWorks is a real-time operating system developed as proprietary software by Wind River Systems, a subsidiary of Aptiv. First released in 1987, VxWorks is designed for use in embedded systems requiring real-time, deterministic performance and in many cases, safety and security certification for industries such as aerospace, defense, medical devices, industrial equipment, robotics, energy, transportation, network infrastructure, automotive, and consumer electronics.
JTAG is an industry standard for verifying designs of and testing printed circuit boards after manufacture.
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.
Blackfin is a family of 16-/32-bit microprocessors developed, manufactured and marketed by Analog Devices. The processors have built-in, fixed-point digital signal processor (DSP) functionality performed by 16-bit multiply–accumulates (MACs), accompanied on-chip by a microcontroller. It was designed for a unified low-power processor architecture that can run operating systems while simultaneously handling complex numeric tasks such as real-time H.264 video encoding.
The Quick Emulator (QEMU) is a free and open-source emulator that uses dynamic binary translation to emulate a computer's processor; that is, it translates the emulated binary codes to an equivalent binary format which is executed by the machine. It provides a variety of hardware and device models for the virtual machine, enabling it to run different guest operating systems. QEMU can be used with a Kernel-based Virtual Machine (KVM) to emulate hardware at near-native speeds. Additionally, it supports user-level processes, allowing applications compiled for one processor architecture to run on another.
FreeRTOS is a real-time operating system kernel for embedded devices that has been ported to 40 microcontroller platforms. It is distributed under the MIT License.
A Bluetooth stack is software that is an implementation of the Bluetooth protocol stack.
TI-RTOS is an embedded tools ecosystem created and offered by Texas Instruments (TI) for use across a range of their embedded system processors. It includes a real-time operating system (RTOS) component-named TI-RTOS Kernel, networking connectivity stacks, power management, file systems, instrumentation, and inter-processor communications like DSP/BIOS Link. It is free and open-source software, released under a BSD license.
ChibiOS/RT is a compact and fast real-time operating system supporting multiple architectures and released under a mix of the GNU General Public License version 3 (GPL3) and the Apache License 2.0. It is developed by Giovanni Di Sirio.
MQX is a real-time operating system (RTOS) developed by Precise Software Technologies, Inc., and currently sold by Synopsys, Embedded Access, Inc., and NXP Semiconductors.
T-Kernel is an open source real-time operating system (RTOS) designed for 32-bit microcontrollers. It is standardized by T-Engine Forum, which distributed it under T-License agreement. There is also a corresponding Micro T-Kernel (μT-Kernel) implementation designed for embedded systems with 16-bit or 8-bit microcontrollers.
STM32 is a family of 32-bit microcontroller integrated circuits by STMicroelectronics. The STM32 chips are grouped into related series that are based around the same 32-bit ARM processor core: Cortex-M0, Cortex-M0+, Cortex-M3, Cortex-M4, Cortex-M7, Cortex-M33. Internally, each microcontroller consists of ARM processor core(s), flash memory, static RAM, debugging interface, and various peripherals.
Mbed is a development platform and operating system for internet-connected devices based on 32-bit ARM Cortex-M microcontrollers. The project was a collaboratively developed by Arm and its technology partners. As of July 2024 Mbed is no longer actively developed by Arm.
XMC is a family of microcontroller ICs by Infineon. The XMC microcontrollers use the 32-bit RISC ARM processor cores from ARM Holdings, such as Cortex-M4F and Cortex-M0. XMC stands for "cross-market microcontrollers", meaning that this family can cover due to compatibility and configuration options, a wide range in industrial applications. The family supports three essential trends in the industry: It increases the energy efficiency of the systems, supports a variety of communication standards and reduces software complexity in the development of the application's software environment with the parallel released eclipse-based software tool DAVE.
Zephyr is a small real-time operating system (RTOS) for connected, resource-constrained and embedded devices supporting multiple architectures and released under the Apache License 2.0. Zephyr includes a kernel, and all components and libraries, device drivers, protocol stacks, file systems, and firmware updates, needed to develop full application software.
PX5 RTOS is a real-time operating system (RTOS) designed for embedded systems. It is implemented using the ANSI C programming language.
William (Bill) Lamie is an American software engineer. He is known as the author of the Nucleus, ThreadX and PX5 real-time operating systems (RTOS).
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