Re: Rebuilding wearable...

From Wear-Hard Mailing list Archive (WH) Maintained by R. Paul McCarty

Thus spake Daniel Parrott Ashbrook:
> On 4/21/06, Andrew Plumb <> wrote:
>> Also think more along the lines of distributed computing.  By using
>> gumstix+netCF pairs wired up to a hub you can use as many or as few
>> devices as you wish, including hanging something like nano-itx board off
>> the internal network to act as USB host.  Design the networking
>> infrastructure using Power-over-Ethernet and you can also distribute
>> power/charging to all your devices.
>
> That's a possibility, but there are some problems with that. If you
> stuff them all in one box, suddenly your wearable is huge again and
> you might as well go with PC/104. If you try to distribute them about
> your body, you have wiring problems - after wearing many varieties of
> computers on a daily basis for many years, I can tell you that the
> fewer wires you have running around your body the better. Of course
> power is a concern as well - the more processors you have eating
> power, the less battery life you get. And, of course, the more
> computers you have hanging around running their own independent
> operating systems, the more likely you are to have stuff fail on you.
>
> Not that it's a bad idea, but there are definitely hurdles to overcome.

Hi Dan,

Yup, no arguments from me.  Anything bulkier than a portable CD player's
dimensions is a non-starter.

To clarify on the distributed-power aspect, I was thinking more along the
lines of small, local rechargeable batteries (or even super- or
ultra-capacitors) at the gumstix nodes to supply the instantaneous current
needs (uptime of minutes).  That way the main power supply could be chosen
in favour of sustained current characteristics.

The wires are a pain, but at least they give you the option to
redistribute the total system mass and dynamically reconfigure it.  When
you have one CF slot you need two, when you have two you find you need an
MMC slot, etc.  You have to watch individual card power consumption too. 
One WiFi card is ok, as is one 8GB CF HD, but having both on one board
could make for some interesting brown-out conditions...  Won't know until
I have one to try. ;-)

Aside:  One really intriguing possibility with choosing the gumstix route
are the various robostix boards for controlling custom mechatronic
devices.

Andrew.

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