
DIY cellphone - ryanmolden
http://hlt.media.mit.edu/?p=2182
======
abbot2
"Cellular connectivity is provided by the SM5100B GSM Module...". Meh. No way
a DYI. It's like you assemble your desktop PC from pieces like motherboard and
power supply and say that you built a DYI PC.

~~~
rtpg
Sure, but it would be a cool project to build up a nice phone environment
using this module.

If anything, this would be more akin to saying "I'm using hardware features on
my microprocs to do this neat thing". Not amazing engineering.

On a related note, does anyone know if we can get these modules to do data? Or
if there's a cheaper version of these modules?

~~~
abbot2
I did a quick peek at their electronics schematics. Well, believe it or not,
but it looks like designing a laser-cut custom wooden case for this phone took
much more effort than the electronics part. So, returning to my analogy: you
are building a DYI PC because you laser-cut a custom case for the off-the-
shelf parts you purchased. If this is the level of DYI to be amazed of on this
site, I'm completely confused.

~~~
ryanmolden
I posted this not so much because I was amazed by the thing itself or thought
it represented some pinnacle of "true" DIY, but more so because I like the
idea of making things that were once far out of reach of anyone but serious
hackers into something that a broader collection of people could feasibly
tackle. It isn't quite there yet, but it is due to people like this that it
will be, one day. You could nitpick all day about how most anything isn't
truly DIY unless you mine/refine all your own materials and create your
electronics from first principles, but that starts to get a bit silly.

More generally, I am a believer in the idea I first read from Clay Shirky that
as more people get involved in an area average quality goes down but
innovation goes up a lot as you get lots of people trying lots of new things,
which in the end is only goodness. Except, perhaps, for those that prefered it
remain elite so they could feel special (not saying this is you, but I see
this attitude in a lot of pioneers in areas that later become more
mainstream).

------
mellis
BTW, the latest files are here:

Hardware: <https://github.com/damellis/cellphone2hw> Software:
<https://github.com/damellis/cellphone2>

~~~
gee_totes
How's the reception and microphone quality? (i.e. how well does the sound of
your voice on the phone compare to say an iPhone or Nokia-era candybar phone?)

Also, great work! I looked into building a cell phone before, and it's an
awesome amount of work.

~~~
mellis
It apparently sounds pretty good, according to the people I've called. The
reception seems pretty standard, although I don't actually display signal
strength in the interface yet so I'm not totally sure.

------
cstuder
I'm surprised that nobody mentioned OpenMoko so far: The attempt to create a
truly open sourced mobile phone: <http://en.wikipedia.org/wiki/Openmoko>

Sadly, it failed and was abandoned in 2009.

~~~
benjamincburns
Or Silicon Valley Homebrew Mobile Phone Club in 2006. Or TuxPhone or OpenCell
(my contribution).

[Edit: Or SparkFun's original claim to fame, the Port-O-Rotary:
<https://www.sparkfun.com/categories/96>]

Personally I like the look of cardboard: <http://bit.ly/10K7Qi0> (my first DIY
cell phone)

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ck2
Didn't a marketing company recently put live messages into a magazine page
using a single chip gsm solution?

Yeah here it was: [http://creativity-online.com/work/cw-live-twitter-feed-in-
pr...](http://creativity-online.com/work/cw-live-twitter-feed-in-print--
4/29266)

I vaguely remember people changing out the gsm sim or making calls on it.

Ah nevermind, it was a fullblown android phone, not a single chip solution:
<http://mashable.com/2012/10/02/ew-has-smartphone-inside/>

------
fnordfnordfnord
My grandmother has pretty bad arthritis. No major carrier sells a handset that
is easy for my grandmother to manage. It may be time to put one together for
her.

~~~
kamjam
In the UK they sell a range of mobile phones with big buttons, particularly
for the elderly. Basic features on it only of course, but that's probably all
they will use anyway.

[http://easiphone.co.uk/index.php?main_page=index&cPath=1](http://easiphone.co.uk/index.php?main_page=index&cPath=1)

~~~
pcl
_Basic features on it only of course, but that's probably all they will use
anyway._

That's a rather self-fulfilling attitude, and I hope that we as an industry
try harder really soon.

My parents are in their late 60s, and are quite good with computers. I'm
working on a side project with a woman in her eighties who started programming
during the Eisenhower administration. And I know a number of tech folks in
their 40s or 50s who have one form or another of muscular or nervous problem.
None of them should have to compromise on features just because they want a
more accessible device.

~~~
kamjam
I didn't mean it in that sense, my parent are both pretty old but have no idea
about tech. For them this phone was perfect, since all they wanted to do was
make calls, a green button to make the call and a red button to finish the
call.

With a phone like this, there has to be a compromise somewhere. By basic
features I meant by today's smartphone standard, you are never going to get
that to that level with an LCD screen and button taking up all the phone real
estate. It is really only going to be possible for calls and SMS messages.

Of course, if they need a smartphone with big "buttons" and a big screen then
you could always buy them the Samsung Galaxy Fucking Note

[http://techcrunch.com/2012/10/26/behold-the-best-samsung-
gal...](http://techcrunch.com/2012/10/26/behold-the-best-samsung-galaxy-note-
sales-pitch-youve-ever-seen/)

------
frazerb
How to shrink a basestation into a Raspberry Pi.
<http://www.youtube.com/watch?v=GCcKgrzbix4> It's not the handset, but rather
the basestation. But the concept is similar. I saw this working. It works. And
there are open-source versions of the handset software too, although not as
mature as OpenBTS.

~~~
iuguy
Actually what these guys don't mention is that the Raspberry Pi is plugged
into a relatively huge USRP, because that kind of blows their whole "Look how
tiny it is" PR out of the water.

~~~
Swannie
+5. You can run the whole stack on a router. It's basically doing call control
for a couple of channels. The heavy lifting is done in USRP.

~~~
noselasd
The host part of OpenBTS is not just call control(Freeswitch or Asterisk
provides most of the call control part).

OpenBTS is a software defined radio and really does most of the processing in
software. The USRP provides the radio interface, up/down conversion between
baseband and carrier frequencies and the analog/digital conversion.

The USRP just sends/receives those samples without caring or knowing about
GSM. Samples are processed in software on the host, where the GSM stack is
implemented.

There's other hacks(<http://www.youtube.com/watch?v=xFjVcxMpA6c>) where you
can just use a couple of phones as the transceiver instead of the USRP.

~~~
Swannie
Right, call control with asterisk, and GSM stack in software.

As far as I was aware, the GSM processing isn't much more intensive than
equivalent: Ethernet packet assembly + TCP/IP + HTTPS?

I thought all the DSP happened in USRP. So out of that, you get a bit stream,
that is sliced into frames, and then processed like any network stack?

~~~
noselasd
No, OpeBTS does the GSM related DSP. You get a stream of I/Q samples from the
USRP, which is more or less just the digitalization of the baseband. OpenBTS
carves the time slots and "frames" out of this, does the GMSK de-modulation
and similar stuff.

Note that the lower layers of GSM is very different from e.g. ethernet. Once
you get past all the very gory stuff up to layer 2, the concepts are pretty
much the same though.

------
trotsky
Can anyone share any details about one of those laser wood cutters?
Costs/Materials/Brands/Issues etc. for a hobbyist?

~~~
noonespecial
I bought a 40 watt laser cutter/engraver from China via ebay. It cost a little
less than $1800. It cuts wood and some thin plastics (acrylic) like this quite
well.

Unfortunately, its quality was so terrible, it was little more than a box of
parts. I had to build a new stepper driver and run it from MACH3 to get any
results out of it. I also had to replace some "greased rail" style bearings
with linear ball bearings to get decent accuracy.

The one they've got at MIT probably says "Epilog" on the side and costs
somewhere between your car and your house.

Edit: I generally cut "luan" plywood 1/8" or thinner. It seems like about the
thickest I can handle. 1/16" veneer gives me the best results.

~~~
trotsky
thanks a lot to everyone who replied! Sounds like the 3d printer that i have
no use for may come before the laser cutter i have no use for :/

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DanBC
With all these open cell phone stacks: what do people do about IMEI? Isn't
modifying IMEIs illegal in many countries? Or is the IMEI already programmed
as part of some module from the factory and thus there's no need to change it?

EDIT: Whoops. I did mean IMEI and not ESN. I've edited this post.

~~~
benjamincburns
On GSM phones, ESNs don't apply. IMEIs are the equivalent, however. In that
case one of the value-adds of an integrated module is that it comes with an
IMEI. If you're going into large scale production you can pay CTIA for your
own block of IMEIs and reprogram your modules, but typically that's not worth
it. However if memory serves (it's been about 5 years) they force you into
doing this if you get above a certain production volume, otherwise it becomes
difficult tor track which chunk of the traffic is yours, and whether or not
you're shipping a ton of devices which haven't passed carrier certification,
etc.

I'd imagine it works similarly with ESNs, but I have no experience there.

------
keithpeter
<http://hlt.media.mit.edu/?p=27>

This has more possibilities to me. More exhibition with interaction from
viewers.

------
LAMike
Finally, a karma free phone. I wonder if people will start designing cases
made using a 3D printer for the next generations of these DIY cell phones.

------
mhb
I, Pencil: My Family Tree as told to Leonard E. Read:

<http://www.econlib.org/library/Essays/rdPncl1.html>

------
beerglass
It's like Raspberry Pi for cell phones...

~~~
imrehg
Combine this with the Raspberry Pi base station, and there's HackerNet :)
[http://www.newelectronics.co.uk/electronics-
news/basestation...](http://www.newelectronics.co.uk/electronics-
news/basestation-created-on-raspberry-pi/46960/)

