The Industrial Grade

The RTOS of choice for serious developers

The PX5 RTOS is ultrasmall (< 1KB for minimal use), enabling its use in some of the most memory-constrained devices. It is one of the smallest RTOSes available, requiring less than 1KB of FLASH and 1KB of RAM on typical 32-bit microcontrollers.

Its ultrahigh performance (sub-microsecond context switching and API calls on most microprocessors) and rich determinism make it ideal for the most demanding real-time needs.

PX5 RTOS also boasts best-in-class safety and security. The entire PX5 RTOS code base is rigorously tested - 100% C statement and branch decision coverage testing for every release. In addition, The PX5 RTOS also offers patent-pending Pointer/Data Verification (PDV) technology, a unique way to provide unprecedented run-time function pointer, system object, buffer, and stack verification. In addition, the PX5 RTOS has been certified to the highest levels of the IEC 61508 functional safety standard, including IEC-61508 SIL 4, IEC 62304 Class C, ISO 26262 ASIL D, and EN 50128 SW-SIL 4.

Most importantly, the PX5 RTOS is simple. The API consists of a native implementation of the well-known POSIX pthreads standard, which makes PX5 RTOS applications easily portable to any POSIX pthread implementation, such as in Linux or even other RTOSes.

PX5 RTOS also offers optional POSIX pthreads extensions that are designed specifically for deeply embedded, real-time applications.

The Industrial Grade PX5 RTOS is an advanced, 5th generation RTOS designed for the most demanding embedded applications.

PX5 RTOS Diagram

Mouse over for component details
PX5 RTOS C Implementation (px5.c) PX5 RTOS Binding Layer (px5_binding.s)
  • Small & Fast
  • Advanced, 5th Generation
  • Deterministic
  • Easy to Use
  • Safe and Secure
  • Pre-certified to highest IEC 61508 levels
  • Native pthread API
  • Pointer/Data Verification
  • Asymmetric Multiprocessing (AMP)
  • Symmetric Multiprocessing (SMP)
  • Cortex-M/R/A & RISC-V
  • Arm 64-bit Support
  • IAR, GCC, Arm tools
  • Full Source & No Royalties
  • Professional Support

Fast & Deterministic

The PX5 RTOS is extremely fast and efficient. On typical 32-bit microcontrollers running at 80MHz, most API calls and context switches complete in less than one microsecond. The PX5 RTOS is also deterministic. The processing for each API and context switch is completely predictable and not a function of how many threads are active. For example, the processing required to obtain a semaphore is the same whether two or 100 threads are active.


The PX5 RTOS is one of the smallest RTOSes available, requiring less than 1KB of FLASH and 1KB of RAM on typical 32-bit microcontrollers. Equally important, since the PX5 RTOS is implemented with loosely coupled C functions, size automatically scales based on the application's use. If the API and associated functions are not used, they are simply not brought into the image by the linker.

Functional Safety Certification

The PX5 RTOS is certified by SGS-TUV Saar for safety-critical systems, meeting IEC-61508 SIL 4, IEC 62304 Class C, ISO 26262 ASIL D, and EN 50128 standards. This confirms its suitability for developing safety-related software to the highest integrity levels. SGS-TUV Saar, a joint venture of Germany’s SGS-Group and TUV Saarland, is a leading independent company for testing and certifying embedded software worldwide. IEC 61508, along with related standards like IEC-62304, ISO 26262, and EN 50128, ensures functional safety across various sectors, including medical devices, industrial machinery, automobiles, and railway control systems.


The PX5 RTOS is composed of two main source files, namely px5.c and px5_binding.s. These files can be easily dropped into any C main project example and PX5 is ready to run. No complicated projects and/or linker control file changes are necessary. Using PX5 in your application is just as easy. Simply include pthread.h and add a call to px5_pthread_start to your C main function, as follows:

#include <pthread.h>

int    main()

  /* Start PX5.  */ 
  px5_pthread_start(1, NULL, 0);

  /* Once px5_pthread_start returns, the C main function
     has been elevated to a thread - the first thread in
     your system!  */

     /* PX5 RTOS API calls are all available at 
        this point. For this example, simply sleep for 
        1 second.  */

This small example shows that the PX5 RTOS is easy to install and use, taking only minutes of your time. The processor/tool binding layer examples can also serve as a starting point. The native POSIX pthreads API support also simplifies development. This well-known API reduces the learning curve for new developers. It also enables code sharing between any devices based on embedded Linux.


The PX5 RTOS is a 5G RTOS implementation. It has unique data encapsulation technology which helps compilers generate the most efficient code and at the same time reduces namespace collision with the application. The PX5 RTOS also offers Memory Guardian technology, a unique technology for unprecedented run-time function pointer, linked-list, and stack verification. Finally, central error handling - with optional user enhancement - helps facilitate building more robust applications.

Full Source Code

The PX5 RTOS is delivered with complete source code, including the PX5 RTOS binding layer source. The source code is designed to be easily understood. It is also rigorously tested - 100% C statement and branch decision coverage testing for every release. The PX5 RTOS offers the highest quality source on the market.

Processor Support

Most (99%) of the PX5 RTOS is written in ANSI C, which makes it highly portable to any processor architecture that has C compiler support. Because of this, the PX5 RTOS supports most of the popular embedded MCU and MPU architectures, including ARM's Cortex-M, Cortex-R, Cortex-A, and RISC-V architecture families.

Tool Support

As with its processor support, the PX5 RTOS supports most popular embedded development tools, including those from IAR, ARM, and GCC.


PX5 offers royalty-free licensing for the PX5 RTOS. Like the product itself, the PX5 RTOS licensing is simple and easy to work with.


Professional Support

Always ready to help, the embedded software experts on the PX5 support team promise quick action on every request. Unlike as with many open source and even some commercial options, you’re not on your own when using PX5 RTOS.



To take advantage of the advanced PX5 RTOS in your next embedded design, please contact us about licensing options today!

Please also reach out to us if you have any questions about the PX5 RTOS and how it might benefit your development.



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Video Tutorials

Take a look at our collection of video tutorials that will help you learn more about PX5 RTOS and the embedded industry in general. Our video tutorials cover various topics, from installation and configuration to advanced features. The video tutorials are produced by PX5 RTOS experts and are designed to be bite-sized and informative.

Please let us know if you have any questions, comments, or suggestions – Enjoy!

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PX5 RTOS Video on display

From PX5 Blog

Free PX5 RTOS Download Evaluations

Please check out our free PX5 RTOS evaluation packages for some of the most popular evaluation boards and development tools to see first hand how PX5 RTOS can help improve your development!

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