atben/atusb real life signal strength test

Ron K. Jeffries rjeffries at gmail.com
Fri Jan 21 10:31:08 EST 2011


Speaking only for myself, if you eventually switch to
the AVR microcontroller I will die and go to heaven.

But enough about me. ;)
---
Ron K. Jeffries






On Fri, Jan 21, 2011 at 06:55, Werner Almesberger <werner at openmoko.org>wrote:

> Wolfgang Spraul wrote:
> > wow excellent results, congratulations!
>
> Thanks ! :)
>
> > Now we need to take it into production... :-)
>
> Yup. The next steps:
>
> - I've re-layouted the atben board to make it a little shorter, but
>  haven't built that board yet
>
> - there's some more cleanup needed in the footprints and such
>
> - once the cleanup is done, I'll make a few atben/atusd boards for
>  testing of the last design changes (I don't expect them to affect
>  the overall performance) and references for production
>
> - the latter then go on a plane to Adam
>
> - since we still need some sort of cases, one of each boards will
>  go as mechanical sample to Joachim
>
> - while things get rolling on the production side, there will be time
>  to take care of putting things together on the software side,
>  namely make 6LoWPAN work.
>
> Open issues:
>
> - there are still some details in the PCB manufacturing process to
>  hash out. The WPAN boards have fairly narrow mechanical tolerances,
>  so it's important that there are no misunderstandings about how to
>  interpret the data.
>
> - likewise, the footprints need refining for proper production. In
>  particular, I have to make sure that the solder paste areas are a
>  bit smaller than the copper underneath. (This wasn't an issue with
>  the prototypes because my DIY process only uses the copper layers.)
>
> - the casing, mentioned above. It should be cheap and easy to make,
>  look not too horrible, protect the board against accidental
>  contact, and it should be removable. My suggestion would be a
>  sleeve of some elastic material that would be put around the board.
>  It would be open on the Ben or USB side.
>
>  If we drop the removability requirement, then one could of course
>  just dunk the boards in silicone and end up with a nice thick
>  protective layer. Here are some experiments I did a while ago with
>  the kind of silicone sold as bathroom sealant at hardware stores:
>
> http://downloads.qi-hardware.com/people/werner/wpan/tmp/silicone-coating.jpg
>
>  To decrease the viscosity of the silicone, I diluted it with paint
>  thinner or acetone. Paint thinner worked a little better, but
>  there's hardly any difference in the final result.
>
>  The silicone will come off when cut, so in a pinch, even this
>  contraption could be reworked:
>  http://downloads.qi-hardware.com/people/werner/wpan/tmp/coat-cut.jpg
>
> - finally, Joachim pointed out that Atmel have released a new series
>  of USB microcontrollers that approach the ones by Silicone Labs in
>  terms of integration and price. Because AVR is rather popular in
>  the hobbyist and Open Hardware scene, this may be a more attractive
>  choice than the C8051F326 I'm using at the moment.
>
>  My plan is to go ahead with the C8051F326 for now, but to make a
>  variant of atusb with the ATmega32U2-MU (I can't efficiently source
>  the smaller ATmega8U2 or ATmega16U2 at the moment, but that may be
>  a cost reduction option for the future) and see how well it works.
>  If it's good, we can change to the new design either before
>  production or for possible later runs.
>
> - Werner
>
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