Custom calypso board

Mathias K. kesmtp at freenet.de
Wed Jul 11 09:39:21 UTC 2012


On 11.07.2012 10:26, Harald Welte wrote:
> the core modem design is 40 x 29.8mm in size, but that of course
> excludes things like the sim card reader, or any other new components we
> may add.

So it looks like the MiniPCI Express Card on this picture 
http://en.wikipedia.org/wiki/File:MiniPCI_and_MiniPCI_Express_cards.jpg ?

> After some first checking, that size would actually even fit nicely
> within the mechanical form factor of the C1xx boards, as they have at
> least something like 36 x 70 mm mechanical form-factor.

The question is, if you want to build a modem or re-engineer a phone for cases that:

 > There are some signs that the supply of Motola C1xx phones is not
 > endless, after all.

And this include the cases as well.

> Now if thre was an _easy_ way to make one circuit board that would both
> fit into the C1xx case _and_ also have a board edge connector for use in
> a back-plane, I would consider doing that.

Make it simple.

> my first idea is to have a 'break away' backplane connector that one
> would simply break off to mount it in a phone case.   But then, if it is
> intended to be broken (e.g. by perforating with a series of holes), the
> PCB might break when it is plugged into the backplane and somebody
> pushes it sidewise.

The 'break away' connectors came from manufacturing and they are not made to use it on "harsh" 
environments.

>>>   * expose JTAG
>>
>> 1.27mm 10 pol Pin-Header on the opposite side of the board edge
>> connector, this make it possible to debug the board in a backplane
>
> yes, good point.  However, on that side there is likely the RF
> transceiver and the antenna connections :(  You probably don't want the
> transmitter near the jtag cable...

For development that's fine i think. But this is related to the planed backplane connector.

>
>>>   * board-edge connector for plugging many boards into one backplane
>>
>> I would suggest the ERNI SMC. There are also a cable assembly available.
>> http://www.erni.com/fileadmin/medien/downloadcenter/smc/ERNI-SMC-e.pdf
>
> undoubful great connectors, but I really wanted to keep it low cost,
> thus the proposalf of using PCIe connectors on the backplane.  Needs no
> connector on the board itself, just a bit of board footprint.

Yes but that's only simple on one site and the board price increase because the extra milling ways 
but maybe for a 6 plane pcb it's not that much.

I think the initial hurdle to get it run on the table is really high with this kind of connector.

How a developer or backplane board should looks like and whats the estimated price relative to the 
modem price?


Regards,

Mathias





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