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

Walter1950 Walter1950 at t-online.de
Fri Aug 1 16:24:38 CEST 2014



Dr. H. Nikolaus Schaller wrote:
> 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)
> 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/ohsw2013/3%20Misc%20new%20from%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.
>>  
>> 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.

Not exactly, see Attachment... :-)

Ciao
Walter

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