The Quub
		The Quub is an open-source microcontroller system based on tiny "core processor" boards, a system of addressable daughter boards, and provision for simple networking.   The Quub system has the following features. Processor independent, core processor boards are being designed with AVR ATmega1284 and 328, PIC 18F2520 and Picaxe 20x2 at this point. Tiny form factor, 1.8 x 1.8 inches (46x46mm). Fits with up to three daughter boards into a 2x2x2" aluminium cube (hence the name). If not using 2x2" tube for an enclosure any number of daughter boards can be stacked (above or below the core processor). Daughter boards can be dumb IO or smart co-processors. Up to 9 (expandable to 16) daughter boards (called "Stackables") can be addressed and can therefore share the same processor IO lines. They can be dumb (just hardware) or smart (with on-board processor). The primary inter-processor communications method is SPI for speed, however I2C is also supported by the backplane. Smart stackables can often be used as stand-alone processors, the backplane groups certain signals to accomodate this. Some smart stackables boards can even be used as Arduino clones. Support for multi-processor systems with co-processor interrupts. Up to two "communications areas" on core processor boards that can connect directly to USB or serial cables + provision for tiny interface boards for line drivers (RS-485/232, LIN, CAN etc). If not used for comms these communications areas can be used for small mezzanine boards on a core processor to house mass storage, Ethernet interface, real time clock etc. Cable connection for power and network on the underside of core processor boards and some smart stackables so the enclosure can be bulkhead mounted with no visible wiring. 48-way backplane using stackable headers that has up to 32 IO signals, plus power, debug bus and 2 signals routed to the rear connector. VCC and VBAT can be sourced from the main board, from any stackable daughter board, either communications areas, or from the rear connector. Some smart stackables can control the system VBAT and therefore be used to shut down a system and wake it using an RTC or pushbutton interrupt. Provision for in-system programming of any co-processor via the backplane using the SPI signals and a PGM control signal. Provision for debugging any of the co-processors or the core processor via four debug signals on the backplane. Adapter to allow any core processor access to Arduino shields. A system of I2C-based IO Nodules that standardise the interface with common sensors. The Quub is a general-purpose embedded microprocessor system, the form factor can accommodate designs from the simplest Picaxe-based flashing-LED project to a complex multi-processor device. It has been designed to... Provide a similar concept to the Arduino but to address some of the Arduino shortcomings while acknowledging the huge Arduino user base, the Arduino's beginner-friendly programming environment, and provide access to existing Arduino hardware. Be processor independent and give access to a wide range of peripheral hardware to users of AVRs, PICs, Picaxes, etc. Provide an easy upgrade path to users of less powerful paradigms, for example a Picaxe user can avail themselves of existing Quub peripheral boards and many Arduino shields using the standard Picaxe programming interface and Basic language. As the user becomes more proficient with embedded systems they can move to say using C on a PIC-based core processor and still use the same peripheral boards. Facilitate the development of multi-processor systems by allowing all co-processors to be programmed from a single ISP header and debugged with a single connection. Be designed to actually fit into something. Quub is designed to fit into lengths of standard 2x2" aluminium extrusion so a finished product can be made to look reasonably professional without expensive machining.   Please note that despite some of the system complexities detailed here Quub processors can always be used as a typical embedded processor in the same spirit as the various Arduinos and Arduino clones.