[gta02-core] how many gta02-core devices ?

Werner Almesberger werner at openmoko.org
Mon Apr 26 10:22:24 CEST 2010


Radek Polak wrote:
> Btw maybe stupid idea: if we had 3 SD card slots, you could buy Wifi SD card, 
> Bluetooth SD card or GPS SD card. All of them should be possible to buy.

Heh, modular designs helped the Apple ][ and the IBM PC to
greatness, why not us ? :-)

I did a quick Google search for WLAN, BT, and GPS SD cards, and the
results are as follows:

- WLAN

  http://www.google.com/products?hl=en&q=wlan+sdio&scoring=p
  Lowest price for 802.11b: USD 26.85
  Lowest price for 802.11g: USD 50.92
  They all seem to have a common form factor.

  Scary:
  http://www.alibaba.com/product/tw100428701-100236228-0/Micro_Sdio_Wlan_Card_802_11n.html
  But requires Linux 62.6. Considering that we're barely at 2.6.34
  after something like 19 years, it would take something like 430
  more years. A admire their long-term planning, though.

- BT

  http://www.google.com/products?hl=en&q=bluetooth+sdio&scoring=p&show=dd&sa=N&lnk=next&start=50
  Lowest price: USD 114.95
  Form factor seems to be the same as for WLAN.

  http://www.google.com/products?hl=en&q=bluetooth+sd&scoring=p&show=dd&sa=N&lnk=next&start=30
  Lowest price: USD 50
  Seems to be a bit longer than the other cards.

- GPS

  http://www.google.com/products?hl=en&q=gps+sdio&scoring=p&show=dd&sa=N&lnk=next&start=40
  Lowest price: USD 84.50
  Form factor like BT/WLAN, plus large antenna at the end.

Are these results representative ?

The cost of the WLAN subsystem (B/G) should be around USD 30, so
this would compare favourably. BT and GPS cards seem to be priced
excessively, though.

Size is another issue. E.g., the socket Go Wi-Fi! [1] is 40 x 24
mm.  Two "internal" SD slots (i.e., no protruding parts) would
already consume about half the PCB space of a GTA02-sized device.
GPS seems excessively large. I'd also be concerned about antenna
placement. (WLAN and BT are sturdier than GPS.)

[1] http://www.socketmobile.com/elqNow/elqRedir.htm?ref=http://www.socketmobile.com/pdf/wireless-lan/spec_sheet.pdf

Then there's the driver issue. There should be acceptable choices
for WLAN. Not sure what the situation is with BT and GPS.

There's also the issue that we have only a single SDIO interface
in the CPU. But one could probably just bit-bang GPS ...

- Werner



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