[Community] [Gta04-owner] Phone based on raspberry pi?

wonderphone at posteo.de wonderphone at posteo.de
Thu Jul 31 21:55:29 CEST 2014

Hi David,

At first I thought no one answered to your post about design but see 
what you have got! If you want flexibility that cannot be made real in 
small quantities, why not assemble a custom phone out of standard 
components. It will be cool but probably not small - let's see what 
Radek will achieve.

Cheers all,


Am 31.07.2014 16:45 schrieb Dr. H. Nikolaus Schaller:
> Am 31.07.2014 um 15:52 schrieb Radek Polak:
>> On Thursday, July 31, 2014 15:25:46 Dr. H. Nikolaus Schaller wrote:
>>> I just realized this:
>>> Unsoldering the USB, Ethernet and the power jack from the 
>>> BeagleBoneBlack
>>> and adding a Display+GSM+Battery cape? Could give a 20-25mm thick 
>>> sandwich
>>> in the size of a GTA04... And the BBB is ~40 EUR. So if someone 
>>> wants do
>>> develop such things, goldelico can give a help to bring it to mass
>>> production.
>> Hi Nikolaus,
>> do you have ideas about the modem which could be used and how to 
>> attach it?
> Well, any GSM/UMTS module should fit, though I don't know if USB is
> available on the header pins.
> For GPRS/EDGE an UART is fast enough.
>> Nice. Btw few other random things:
>> - one of the GTA04 problems is price. Using cheap already built 
>> motherboard could be solution?
> Not really. 30-50% of the total price is independent of the
> electronics. I.e. warranty, logistics, packaging,
> quality tests, certification, VAT etc. and not to forget engineering 
> cost.
> Some components are needed and cost independently of the CPU being a
> mass produced SBC or
> built onto the main board:
> e.g. modem, display, battery, speakers, microphone, connectors etc.
> And the PCB itself.
> The PCB could probably be designed using 4 layers which is cheaper 
> than 8.
> So without doing a real analysis, I would assume that only 10-20% of
> the 100% total cost are
> affected by the way the CPU is built. So if you leave out the CPU the
> price of the total system would
> go down by 20% :)
> The key problem is that everything is too expensive... Because we
> have so small quantities.
> If we could build e.g. 5000 GTA04 boards, they could be much cheaper.
> This is why I suggest that someone interested in such a concept
> really makes a drawing
> (block diagram) of such a device so that it lists all (nothing
> missing! Even some simple capacitors
> might cost 30ct each at 200 units) components, looks up the cost of
> components (e.g. octopart.com [1])
> that are needed and tries to find out what the components cost for
> 200 units. The sales price required
> so that nobody has to subsidize is 2-3 times as high as the pure 
> component cost.
> This would IMHO be quite an instructive exercise.
> - there can be community around the motherboard which could help with 
> kernel/SW.
> Another problem is case. 3D printed case for GTA02/GTA04 is hardly
> usable. It has thin walls that are easily breakable. It also has to be
> very precise because of earpiece and other components.
> Not necessarily. We have a 3D design that nicely fits around the
> GTA02/04, has required wall thichness and bays for earpiece and
> speakers etc and works:
> http://www.openphoenux.org/ohs
>> rom%20GTA04.pdf
>> Some designer should of course touch the edges... Could cost around 
>> 50 EUR per unit if printed commercially.
>>> But if we design the PCB and other components so that they require 
>>> less precision then 3D printing/milling would be much easier.
> ap; margin-top: 0px; margin-bottom: 0px; margin-left: 0px;
> margin-right: 0px; text-indent: 0px; ">Btw you dont need HW buttons at
> all - you can double tap display for waking the phone. Without HW
> buttons the case can be much more simple and the phone could be water
> proof.
> Well, you need some charging contact pads anyways and maybe a
> power-on/off button.
> BR,
> Nikolaus
> Links:
> ------
> [1] http://octopart.com
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