ben-wpan: commercial description

[Werner Almesberger]

With the atben and atusb boards inching towards tuxbrain's shop, it's
time to write a proper product description. I thought of the following
items. (More comments at the end.)

First, there would be a part that's common for atben and atusb, with a
few placeholders for device-specific details/clarifications.

  <device> is a wireless IEEE 802.15.4 sender/receiver operating in the
  2.4 GHz band, <device-specific>

  Technical specification:

  - Transmit power up to 3 dBm (2 mW)
  - Built-in antenna
  - Standard data rate 250 kbps (non-standard and with reduced range,
    up to 2 Mbps)
  - Typical indoors distance between sender/receiver XX m
  <more>
  - Linux drivers, hardware design, firmware, and test software are all
    Open Source and available under Free licenses (GPLv2+, LGPLv2.1+,
    CC-BY-SA 3.0)
  - Note: IEEE 802.15.4 is not compatible with WiFi(tm) or BlueTooth(tm).
    You need a pair of IEEE 802.15.4 devices for communication.

The atben-specific part would be:

  <device> = atben
  <device-specific> = designed to give the Ben NanoNote short-range
    wireless connectivity.
  <more> =
    - Plugs into the Ben's 8:10 card slot
    - Requires product-specific Linux driver
    - Note: this is not an SDIO(tm) device and will only work in
      products specifically supporting it.

The atusb-specific part would be:

  <device> = atusb
  <device-specific> = that provides IEEE 802.15.4 connectivity via USB.
  <more> =
    - USB(tm) Full-Speed device 
    - Requires product-specific Linux driver
    - AVR(r) microcontroller with 32 kB flash memory (currently 24 kB
      used)
    - Note: firmware currently only supports Linux

Some remarks:

- I kept the technicality at an intermediate level. If it's considered
  too much, one could drop the following items without significant loss
  of information:

  - transmit power
  - built-in antenna
  - list of licenses

  Also not entirely vital are:

  - "Plugs into the Ben's 8:10 card slot"
  - "USB(tm) Full-Speed device"
  - AVR microcontroller

- there's a relatively long list of compatibility notes. I think we
  need those to make it clear that this isn't just some WLAN or BT
  device, or that it'll work in someone's Windows PC.

- I left the maximum distance open. The devices from the production run
  will be a far more reliable base for such measurements than my
  prototypes, so I hope tuxbrain can provide that data. For reference,
  my own results were:
  http://downloads.qi-hardware.com/people/werner/wpan/tmp/apt-wa.pdf

- I didn't mention higher-level protocol support (IPv4/dirtpan and
  IPv6/6LoWPAN), because area is still under construction.

- we also need to say something about the case, e.g., whether this
  will be a kit of board + sugru, or what else was decided.

Please comment.

Thanks,
- Werner