SD format Zigbee card ...

Wolfgang Spraul wolfgang at
Fri Dec 4 21:33:25 EST 2009


> I am just thinking aloud but it may be better to wait for a nanonote with
> USB Host (Ya?) to easily use ZigBee USB dongels than put in effort into
> supporting microSD ZigBee for Ben only.

I know everybody thinks about "USB Host" as the very first thing.
However, the longer we don't have it the more I like that Ben NanoNote has
no USB Host :-)

You may know that we have a few (9 to be precise) prototype boards that
actually have USB Host _TODAY_ (if anybody wants to buy them please contact
Mirko at mirko at
However, I do think this is only good for development use. Someone could
attach a u-blox GPS USB dongle and start working on a great openstreetmap
application today.
2 of these boards are currently on the way to Carlos, let's see what he
does with them :-)

USB Host has two major problems in mobile use:

Anything you really connect to a USB Host plug will be BIG! If it's a
dongle, it may be so big that the connector inside the device can easily
break off.
If you first connect a cable, reducing the risk of mechanical damage to
the NanoNote, you are talking about a really geeky setup. Our cute and
tiny NanoNote in your hand, then a cable, then a dongle.

Next problem: power consumption. USB Host specifies 5V. 5V is a lot,
both inside the device and for most things you connect outside the voltage
will be less. So on our USB Host enabled boards, we had to add a voltage
converter from 3.3V to 5V just for USB Host. And then inside the dongle
it needs to be converted down again. The conversions are lossy (energy
is lost), and the chips that convert up and down are expensive.
Compare that to SDIO voltage which is 3.3V.

Bottom line - if you had a NanoNote with both SDIO and USB Host today, and
both the microSD Wi-FI card and USB Host Wi-Fi dongle would be available, I
guarantee you you would choose the microSD card. It's so small you can
actually leave it in your device. If you had multiple (like Wi-Fi + ZigBee),
you could tape them to the back of the device, or store under the battery cover
maybe :-) That's how small they are...
Power consumption will be much better with the microSD SDIO solution than
anything you connect to USB Host. 

So let's see. I am excited to see some microSD RF solutions on the horizon
(Wi-Fi and maybe ZigBee).
But before we get too excited - there is still _LOTS_ of work to make it
REALLY USEFUL for someone. Not just theoretically.
Let's try to get all that hard work done first, then we see in which cases
we can recommend, and sell, these solutions. If we say it really works, it
better actually work and not have some stupid surprise once you start
using it.
Same for USB Host. We have some prototype boards today. They were very
expensive to make but we did it. We can now jumpstart development of some
apps or hardware hacks, then we need to think how we can integrate this
into Ya to make an actual end user package out of it.
Ya will probably have a micro-AB USB Host connector, and future devices
will have USB On-The-Go as well, but how useful that will be for normal
users (as opposed to developers) remains to be seen...

Just my thinking, feedback very welcome,

On Fri, Dec 04, 2009 at 11:55:57PM +0530, rakshat hooja wrote:
> >
> > What should we do? If you are interested in some ZigBee hacking, I can put
> > a package together for you. You would probably need at least one NanoNote,
> > and 2 ZigBee cards?
> > I guess I would have to buy the 1000 USD devkit.
> > What do you think? Is anybody else interested in ZigBee? Can you or someone
> > else share some of the costs?
> > Is there another microSD ZigBee card with already proven Linux support?
> >
> > Hope this helps, let me know what you want to do,
> >
> >
> I am just thinking aloud but it may be better to wait for a nanonote with
> USB Host (Ya?) to easily use ZigBee USB dongels than put in effort into
> supporting microSD ZigBee for Ben only.
> I have copied Ranjan on this mail - He was planning to use ZigBee with the
> Freerunner for an home automation system (see
>  ) and may have more info about
> linux drivers for ZigBee USB dongles
> Rakshat

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