QP-nano real-time embedded framework/RTOS for embedded systems based on active objects (actors) and hierarchical state machines
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QP-nano framework

What's New?

NOTE: QP-nano has been discontinued from active development and support and is not recommended for new designs. This QP-nano repository is preserved for the existing user base.

LICENSING: If you are interested in commercial licensing QP-nano, please refer to section QP-nano Licensing.

QM Tool Compatibility: The last QM version that supports code generation for QP-nano is QM 5.2.3 released on 2022-11-18. Newer QM versions no longer support QP-nano.


The offline HTML documentation for this particular version of QP-nano is located in the folder html/. To view the offline documentation, open the file html/index.html in your web browser.

The online HTML documention for the latest version of QP-nano is located at: https://www.state-machine.com/qpn/

About QP-nano

QP-nano (Quantum Platform Nano) is an ultra-lightweight, open source Real-Time Embedded Framework (RTEF) for building modern embedded software as systems of asynchronous, event-driven active objects (actors). The QP-nano framework is a member of a larger QP family consisting of QP/C, QP/C++, and QP-nano frameworks, which are all strictly quality controlled, thoroughly documented, and commercially licensable.

Safer Model of Concurrency

The QP framework family is based on the Active Object (actor) design pattern, which inherently supports and automatically enforces the following best practices of concurrent programming:

  • Keep data isolated and bound to active objects' threads. Threads should hide (encapsulate) their private data and other resources, and not share them with the rest of the system.

  • Communicate among active object threads asynchronously via event objects. Using asynchronous events keeps the threads running truly independently, without blocking on each other.

  • Active object threads should spend their lifetime responding to incoming events, so their mainline should consist of an event-loop that handles events one at a time (to completion), thus avoiding any concurrency hazards within an active object thread itself.

This architecture is generally safer, more responsive and easier to understand and maintain than the shared-state concurrency of a conventional RTOS. It also provides higher level of abstraction and the correct abstractions to effectively apply modeling and code generation to deeply embedded real-time systems.

Hierarchical State Machines

The behavior of active objects is specified in QP-nano by means of Hierarchical State Machines (UML statecharts). The framework supports manual coding of UML state machines in C as well as automatic code generation by means of the free QM modeling tool.

Built-in Real-Time Kernels

The QP-nano framework can run on bare-metal single-chip microcontrollers, completely replacing a traditional "superloop" or an RTOS. The framework contains a selection of built-in real-time kernels, such as the cooperative QV-nano kernel and the preemptive non-blocking QK-nano kernel. Native QP-nano ports and ready-to-use examples are provided for such CPUs MSP430, AVRmega, and ARM Cortex-M (M0/M0+/M3/M4).


With 60,000 downloads a year, the QP family is the most popular such solution on the embedded software market. It provides a modern, reusable architecture for embedded applications, which combines the active-object model of concurrency with hierarchical state machines.

Getting Started with QP-nano

The QP-nano Reference Manual provides instructions on how to download, install, and get started with QP-nano quickly.

The AppNote: "Getting Started with QP-nano" contains also a tutorial, in which you build a simple "Blinky" application.

QP-nano Licensing

QP-nano is licensed under the dual licensing model, in which both the open source software distribution mechanism and traditional closed source software distribution models are combined.

NOTE: Even though QP-nano has been discontinued, Quantum Leaps will continue to provide commercial licenses for QP-nano to customers still interested in deploying QP-nano in closed-source products. These commercial licenses will NOT provide technical support and will be discounted accordingly.

QP-nano Documentation

The QP-nano Manual is located online at: https://www.state-machine.com/qpn

3rd-Party QP-nano Ports/Adaptations

QPN-PIC16 is an adaptation of the QP-nano framework to the Microchip PIC16 architecture as compiled by the MPALB-X IDE using the XC8 compiler (C90/C99). It allows QP-nano models developed using the QM modeling tool to be integrated with the QV-nano kernel to build Active Object applications. The very limited resources of the PIC16 family of MCUs, primarily the hardware stack, required a special version of QP-nano and a QM-Modeler editing post-processor, QM2HSM.exe, to effect.

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