Is a good idea, right now, the keyboard layout make hard to route the processor / signals (with 4 layers) If we move the processor, (ram+nand) + LCD's back-light circuit to the same board we can design a lot of different "keyboard pcbs" using a two layer PCB. So, we can provide some special signals in the flexible tape (20 lines in BEN). Mandatoty signals: GND, VCC, usb (2) SD(7) Audio(6) keyboard (16)

With this architecture the "main"bord is the LCD board and the daughter card will be the keyboard pcb, so if any want to design a different application just need to make one cheap card.

Carlos


2010/7/14 Andrés Calderón <andres.calderon@emqbit.com>
On Wed, Jul 14, 2010 at 5:12 AM, Werner Almesberger <werner@openmoko.org> wrote:
> Ron K. Jeffries wrote:
>> Let;s consider at the same time increasing the vertical depth
>> of the bottom half of the nanonote case, to allow greater freedom for
>> adding PCB(s).
>
> Hmm, it'a already fairly thick compared to the other dimensions.
> Another way to get more space would be to reduce the size of the
> main PCB.
>
> The total vertical space available at the moment is quite large,
> so most modern components - including many connectors - should
> fit.
>
> You can also tweak things a little to save space. For example,
> I used the following techniques for IDBG:
>


What if the LCD PCBs is replaced by a new PCB with the SoC, RAM and
FLASH (and the LCD DC/DC converter, of course). May be enough room for
this components behind the LCD .

Thus, the keyboard PCB is available for anything.

BR,

   Andrés Calderón
   Cel:     +57 (300) 275 3666

> - use of a thin PCB. At the DIY electronics corner shop, you'll
>  typically find PCBs with a thickness of 1.6 mm. For such a
>  small board, 0.8 mm are more than sufficient. They're a little
>  harder to obtain, but they exist. You can even find bare PCBs
>  as thin as 0.4 mm.
>
> - use of a mid-mounted component. The USB receptacle is not
>  mounted above the board but it rests in a hole in the board,
>  saving 1.25 mm of precious height.
>
>  See also
>  http://www.almesberger.net/misc/ben/idbg-v1-pcb.jpg
>  and
>  http://www.almesberger.net/misc/ben/idbg-v1-side.jpg
>
> - case modding. The whole assembly was still a little too thick
>  to fit. So I dug a hole for the top of the connector:
>
>  http://www.almesberger.net/misc/ben/idbg-v1-hole.jpg
>
> Most of this could also be applied to other designs.
>
> - Werner
>
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--
Carlos Iván Camargo Bareño
Profesor Asistente
Departamento de Ingeniería Eléctrica y Electrónica
Universidad Nacional de Colombia
cicamargoba@unal.edu.co