QuantumLeaps / Qpn
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NOTE: If your company has a policy forbidding open source in your product, all QP frameworks can be licensed commercially, in which case you don't use any open source license and you do not violate your policy.
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.
Documentation
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:
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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.
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Communicate among active object threads asynchronously via event objects. Using asynchronous events keeps the threads running truly independently, without blocking on each other.
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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).
Maturity
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 increasingly popular dual licensing model, in which both the open source software distribution mechanism and traditional closed source software distribution models are combined.
NOTE: If your company has a policy forbidding open source in your product, all QP frameworks can be licensed commercially, in which case you don't use any open source license and you do not violate your policy.
QP-nano Documentation
The QP-nano Manual is located online at: https://www.state-machine.com/qpn