Overview of QP-nano™

QP-nano™ is the smallest member of the QP™ product family. QP-nano™ is an ultra-lightweight alternative to a traditional real-time kernel or RTOS specifically designed for low-end 8- and 16-bit embedded microcontrollers (MCUs), such as AVR, MSP430, 8051, PICmicro, 68HC(S)08, M16C, and many others. QP-nano™ enables parallel execution of multiple hierarchical state machines, which communicate by sending and receiving lightweight events. Typically, QP-nano™ requires around than 1-2KB of ROM and just a few bytes of RAM per state machine.

Most of QP™ is written in portable ANSI-C, with microprocessor-specific and compiler-specific code kept to a minimum for ease of portability.

QP™ includes a simple non-preemptive scheduler as well as fully-preemptive real-time kernel (QK-nano) to provide preemptive multitasking capabilities (requires more stack space). QP™ is very compact, typically taking about 1-2KB of code space (depending on the code density of the target processor) and only several bytes of RAM (not including the stack). QP™ can be used in microcontrollers with 100 bytes of RAM and a few KB of ROM. If you can program your application in C at all, you most likely can afford QP™.

The core components of QP™ are available under the dual-licensing model, that is, under the open source license (GPL) and also under flexible, royalty-free commercial licenses designed for customers who want to retain the proprietary status of their code and implementations.

Top of page

Features

• Full support for hierarchical state nesting.

• Guaranteed entry/exit action execution on arbitrary state transition topology with up to 4 levels of state nesting.

• Full support of nested initial transitions.

• Highly maintainable boilerplate state machine representation in C code that is very easy to modify and extend at any stage of the development cycle.

• Extremely small RAM/ROM footprint. A state machine instance in QEP-nano requires only one function pointer and an event in RAM (altogether typically 4 bytes). The hierarchical state ma-chine code takes about 700-900 bytes of code space while the simpler “flat” finite state ma-chine takes only about 60 bytes of code space (ROM). QF-nano requires typically around 500 bytes of ROM and just a few bytes of RAM. Of course, you must also budget some RAM for the C stack.

• No RAM required for representing states and transitions—number of states limited only by the code space (ROM).

• Provisions in the code for placing constants in code space (ROM).

• Support for events with one scalar parameter, configurable to 0 (no parameter), 8, 16, or 32-bits.

• Support for up to 8 concurrently executing state machines (active objects)

• Built-in cooperative, priority-based scheduler for Run-To-Completion (RTC) execution of active objects.

• Configurable for fully preemptive multitasking kernel (QK-nano) (requires more stack than the non-preemptive option)

• Idle-time callback for implementing power-saving modes.

• One single-shot time event (timer) per active object with configurable tick-counter dynamic range: 0 (no timer), 8, 16, or 32-bits

• Comprehensive documentation.

• Development kits for various MCUs and compilers available online.

• Royalty-free licensing model and commercial support contracts

Top of page

Version: March 24, 2007