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Quub is an open-source, Arduino-compatible, microcontroller system
based on a core processor and addressable daughter boards.

The Quub system has the following features.

  • Processor independent, core processor boards are being designed with an 8-bit AVR ATmega2560, and 32-bit SAM3X8E at this point.
  • Small form factor, nominally 2.2 x 2.2 inches (56x56mm).
  • Daughter boards can be stacked above or below the core processor.
  • 34-way backplane using stackable headers or a physical backplane just like the "old days".
  • The backplane has provision for I2C, SPI, UART, vectored interrupts and addressing daughter boards..
  • Special consideration paid to make multi-processor systems easier to develop.
  • Up to 15 daughter boards can be addressed and can therefore share the same system IO lines.
  • Each daughter board can in turn have up to 4 addressed functions.
  • Daughter boards can be dumb IO or smart co-processors.
  • Four vectored interrupts supported from each daughter board making a total of 60 interrupt sources on a system.
  • 5V and 3V3 modules can co-exist.
  • Unique module IDs can be read by the core processor so it knows exactly what IO is connected.
  • Arduino shields directly supported at the same time as Quub modules.

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 robot controller.

If you need a system with over 200 analog inputs, or maybe 40+ serial ports, or more than 500 digital IO connections, no problems, Quub can do that and more. And if that's not enough hook up multiple Quub stacks together.

Rationale

Simple systems like Arduino and Picaxe have been around for some time now while at the other end of the complexity/power spectrum it seems that a new Linux-based 1GHz ARM board is being release every second day.

The Quub aims to sit between these extremes by providing an approach that is not only modular but that allows the use of the processor of your choice, be that a Picaxe, an ARM7, or anything in between.

All current systems either pay lip service to add-on functions or are hamstrung by a backplane design that does not allow multiple "shields" to be used without many clashing issues. The Quub aims to rectify that.

Co-processing — The Quub system is designed to make the use of co-processors easy. For example the current design for a 16-servo controller uses an LPC1227 just for this function. At $2 why not? This totally offloads this time-consuming job from the core processor. With the prices of fast CPUs falling all the time the use of such distributed processing is a valid option and it allows a collection of small simple PCBs to become a very powerful device.

Backplane — With the vast array of I2C and SPI peripheral IO chips now available it makes sense to have a backplane with just a few signals that communicates with slave devices using one of these popular serial interfaces.

The Quub then is designed to rely heavily on these serial communication methods with the majority of the IO performed by smart peripheral ICs or dedicated CPUs working as co-processors.

But most systems have these serial interfaces, what's different about the Quub backplane?

  • The main difference is that on a Quub system you can address the plugged-in modules, this means that you can for example have up to 15 identical modules and there are no pin-clashing issues. Or you can use modules from different sources and not have to worry about them using the same pins.
  • Multi-voltage support. On a Quub system 5V and 3V3 modules can happily co-exist. The design allows for this from the very beginning, it's not an afterthought.
  • Interrupts. The Quub backplane allows up to 60 vectored interrupts to be provided by modules, that's four per module. So when an event happens you can deal with it very quickly.
  • Multi-processing. Special signals allow the programming of up to 16 CPUs while they are in situ, all with a single USB connection.

 

You want Linux? — While the design of a Linux-based ARM7 board with HDMI, USB OTG and all the modern goodies is outside the scope of the current Quub brief, such a board could be designed to plug into a Quub backplane. That said there a multiple options for a high-end ARM boards these days and the Quub will not try to compete with them.

The Quub can however be used as an IO sub-system to these more powerful systems, many of which are somewhat IO challenged. Special interfaces are being designed for common development systems like the Raspberry Pi.


 


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