
DIY Cellphone - eksith
http://web.media.mit.edu/~mellis/cellphone/index.html
======
GuiA
The creator of this is David Mellis, who is one of the creators of the Arduino
project. Apparently he's now in Leah Buechley's group at the Media Lab, which
does some great work: [http://hlt.media.mit.edu](http://hlt.media.mit.edu)

This is fantastic, and I'm excited to see what more David will be working on
in the future; his dissertation will be an interesting one :)

~~~
eksith
I can't wait either!

I've seen a few DIY projects here and there involving GSM, but his name is
what really caught my eye in the first place.

You may also find these interesting:

[http://www.open-electronics.org/gsm-gps-shield-for-arduino/](http://www.open-
electronics.org/gsm-gps-shield-for-arduino/)

[http://www.instructables.com/id/ArduinoPhone/](http://www.instructables.com/id/ArduinoPhone/)

I'm sure there's room to mix and match improvements.

~~~
rsync
... all of which have totally locked up, closed off baseband firmware. Which
can be controlled all the way down to _DMA_ by OTA updates by a provider.

No, none of this is very interesting at all until there is an open, free
baseband firmware.

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reedlaw
Does it require any binary blobs for the GSM module or other components? If
not, this would be a pretty good choice for someone wanting complete control
over his phone's software stack.

~~~
dchichkov
I'm pretty sure it does. Binary blobs hidden in the GSM module and
communication with the GSM module is done with AT commands via some serial
bus.

~~~
reedlaw
Binary blobs embedded in hardware are acceptable from a free software
standpoint. As long as they can't be remotely updated.

~~~
ansible
Almost all wireless modems can be remotely updated. So this phone is mostly
running proprietary software. That will be the case for any cellular
technology for the foreseeable future.

~~~
pampa
There is an open source implementation of GSM baseband software
[http://bb.osmocom.org/trac/](http://bb.osmocom.org/trac/). Very limited
hardware support though.

~~~
ansible
Huh, that's interesting, I hadn't heard about that before.

I don't think most people will find this helpful though. One of the main
problems is that the chip vendors don't tend to release the hardware
specifications and development tools.

Several of the USA carriers are itching to phase out all their 2G networks, so
that they can re-use that spectrum for LTE. So a 2G baseband has limited
usefulness moving forward.

Adding to that, implementing any kind of 3G (WCDMA, HSPA) is an order of
magnitude more complex. Just the handoffs between a 2G and 3G cell tower are
complex.

Sadly, LTE is sort of simpler than the 3G technologies, because its all just
data (no special transfer mode just for voice). However, instead just going
all IP protocols for voice and other services, they decided to implement a
host of new and complex protocols for Voice-over-LTE (VoLTE). And some of the
current chipsets now have to handle handoffs between LTE, 3G and 2G.

So this open-source stack will not get carrier approval. And even if it were
to get popular, the FCC would likely throw up a stink, and the carriers would
start banning users that are using a non-approved 2G stack. They would be
somewhat justified in that because the existing baseband implementations go
through extensive (and expensive) compatibility testing to make sure they
place nice with the network under all possible conditions.

If you want to do open-source radio, your first fight is to get some spectrum
that can be used unlicensed. There's big competition for the best frequencies
(that can carry enough data and have decent range), so the spectrum auctions
cost billions of dollars, and the winners are the existing major players.

~~~
reedlaw
So it sounds like there's little chance of a truly open source cellphone. What
a shame. I wonder what the privacy implications are of having a remotely-
updatable module inside every phone. Can carriers break encryption this way?
Or otherwise snoop on users?

~~~
ansible
_I wonder what the privacy implications are of having a remotely-updatable
module inside every phone. Can carriers break encryption this way? Or
otherwise snoop on users?_

Yes they can snoop on the users, but they can do that now, without any changes
to the radio firmware on the phone. The modem can't really do anything without
the carrier's network.

If you mean spying on users by surreptitiously turning on the microphone,
that's something where you want to control the phone's application processor
rather than the modem firmware. Mostly because modern phone architectures have
the microphones connected to the app processor instead of directly to the
modem as in the feature-phone days (like a few years ago). Modern phones have
sophisticated echo and noise reduction and use multiple microphones for that.
And the audio is now used for other applications (like Skype or video
recording) so it makes sense to hook up the microphones to the app processor
instead.

------
zooka2
I made my own cellphone once by purchasing the battery separately.

~~~
fac13
My thought exactly, the first time I saw this.

But this is a _much_ more advanced project - you need to supply your own box
to put it in too ..

------
pcunite
Cool ... this gives me hope for the future I want.

The day will come when we will all hold cell phone _shaped_ PCs. You'll be
able to interact with them as you do now. However, when placed within 10 feet
of a keyboard or mouse, they'll automatically (configurable) and wirelessly
use those peripherals ... keyboard and monitors on the fly baby!

Imagine optional super thin _foldable_ displays to pack in the bag ...
keyboards too ... or, go big and use production color accurate displays like
my NEC 2490WUXi2. Thus making our own like this seems appropriate.

~~~
eksith
I'm not sure if the idea of "peripherals" matching such a device appeals to
me.

Let's think about this... A keyboard is basically a device for entering text
via mechanical (or touch) _switches_ which appear on your console/screen. A
mouse is a virtual index finger.

Even though most of us can't imagine our daily lives without them at the
moment, they both seem archaic in a way. Don't get me wrong; I think that's
part of their appeal (I have an IBM model M somewhere in storage), but their
high-tech-ness(?) is a bit of a non-sequitur when the day comes when our
phone/device/gadget/pc-thing can talk effortlessly to a keyboard and mouse.

It's almost as if a mirror with built in camera interfacing to your straight
razor. Some things are best left old-fashioned.

~~~
krapp
Pens and pencils are archaic interfaces as well, but they're still perfectly
suited for their task.

~~~
eksith
Yes, and we don't link them to our phones either. ;)

~~~
Kerrick
But we certainly do link them to our computers.
[http://www.wacom.com/](http://www.wacom.com/)

------
cinquemb
Previous discussion:
[http://news.ycombinator.com/item?id=5441650](http://news.ycombinator.com/item?id=5441650)

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derekp7
Only one question -- can you take this on a plane?

A while ago I had a cell phone where the battery charging circuitry went out.
The battery was 3.6v, so I hooked up (via Velcro) a AAA battery holder and
used rechargable NiMH batteries. However I was told (when I called the airline
I was traveling) that it most likely wouldn't make it past TSA.

~~~
droopybuns
Permission Procurement difficulty: High. Likelihood of success: Low.

Forgiveness Procurement difficulty: Low. Likelihood of successs: High.

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agumonkey
I'm happy to scan through the bill of material, I was curious about what price
point could be a headless cellular widget for bike tagging.

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mknappen
Spooky- Just this morning I decided that building a cell phone would be my
next evening project.

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Vistz
I can't wait to get the SDK and start developing apps for this.

