Andrew asked me to investigate the possibility of using a QSeven-based
board for the next generation flight computer.  The following
collection of words relates what I've found so far (definitely not


In short, the current Atom-based PC/104 single-board computer is too
big and sinks far too much power.

QSeven is a relatively new standard for modular computer boards that
appears promising.  The processor, RAM, and other critical bits are
all located on the module board, which plugs into a carrier board
containing physical interface support for whichever supported
peripherals the application requires.

The Qseven spec dictates small module boards (70mm x 70mm x 12mm max)
that consume no more than 12 W.  It also defines the connector that
interfaces the module to its carrier board, making the modules (more
ore less) interchangeable.  We would likely buy an off-the-shelf COM,
and design our own carrier board.

More words from the QSeven web site:

    The Qseven concept is an off-the-shelf, multi vendor,
    Computer-On-Module that integrates all the core components of a common
    PC and is mounted onto an application specific carrier board. Qseven
    modules have a standardized form factor of 70mm x 70mm and have
    specified pinouts based on the high speed MXM system connector that
    has a standardized pinout regardless of the vendor. The Qseven module
    provides the functional requirements for an embedded application.
    These functions include, but are not limited to, graphics, sound, mass
    storage, network and multiple USB ports. A single ruggedized MXM
    connector provides the carrier board interface to carry all the I/O
    signals to and from the Qseven module. This MXM connector is a well
    known and proven high speed signal interface connector that is
    commonly used for high speed PCI Express graphics cards in notebooks.
    Carrier board designers can utilize as little or as many of the I/O
    interfaces as deemed necessary. The carrier board can therefore
    provide all the interface connectors required to attach the system to
    the application specific peripherals. This versatility allows the
    designer to create a dense and optimized package, which results in a
    more reliable product while simplifying system integration. Most
    importantly, Qseven applications are scalable, which means once a
    product has been created there is the ability to diversify the product
    range through the use of different performance class Qseven modules.
    Simply unplug one module and replace it with another, no redesign is
    Qseven offers the newest I/O technologies on this minimum size form
    factor. This includes serial high speed buses such as:
    - PCIexpress
    - USB 2.0
    - ExpressCard
    - High Definition Digital Audio
    - Serial ATA
    - LPC interface
    - Secure Digital I/O interface
    - Gigabit Ethernet
    - DisplayPort, TDMS or SDVO Interface
    - LVDS Display Interface
    - CAN Bus
    Plus additional control and power management signals.

FC Requirements

* X86-based architecture (latest and greatest Atom CPU preferred)
* RAM soldered on board
* flash-based primary storage
* gigabit Ethernet
* USB 

These appear easy to satisfy.  Boards are available with Intel, AMD,
or ARM processors.  Most I've looked at include fixed RAM (multiple
GB, typically), gigabit Ethernet, and USB.  Some include on-board
eMMC.  (The standard supports SDIO through the module connector, so
the carrier could include an SD slot, if necessary.)

It's not clear if any of them include a UART on the module, but the
standard does include support for the LPC bus, so a Super I/O chip
could be included on the carrier for up to four (?) serial ports.

Heat Dissipation

Waste heat on these boards is low enough that only passive cooling is
necessary (heat sink without fan).  congatec, a module manufacturer,

    Although the heatspreader is the thermal interface where most of the
    heat generated by the module is dissipated, it is not to be considered
    as a heatsink. It has been designed as a thermal interface between the
    module and the application specific thermal solution. The application
    specific thermal solution may use heatsinks with fans, and/or heat
    pipes, which can be attached to the heatspreader.

The heat spreader is that shiny gold stripe at the top of the board in
this photo:

Presumably, we could come up with our own design if pressed for space.
Heat pipes to the airframe?


congatec conga-QA3 series
  1.46 GHz dual-core Atom E3826 model has 2 GB RAM, 4 GB eMMC, 7 W max.
  TDP.  ~$225 at Mouser.

AdLink Q7-BT
  "Qseven Module with 4th Generation Intel® Atom™ Processor E3800
  Series System-on-Chip"

  Another E3800-based module.  Same model name as AdLink's.  Hmm...

There are more boards out there, but I'm already late with this
e-mail.  We should probably talk amongst ourselves before doing any
serious shopping.

Paul Mullen

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