
Projects: hijack (Hijacking the iPhone earphone jack) - dholowiski
http://eecs.umich.edu/~prabal/projects/hijack/
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nihilocrat
Pheh, they forgot the best application ever: iPhone-controlled vibrator:

<http://www.ohmibod.com/bodyheat/>

I was at a presentation by the app's creator, apparently the hardware was
already available through some company, so you could theoretically do it with
any device that outputs to a headphone jack. The iPhone's touch interface
simply provided a ... unique and apparently (don't ask me!) expressive method
of control.

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unoti
That's truly amazing what they're doing here. I'm sorry if this is an ignorant
question, but wouldn't it make sense for there to be some kind of USB port or
something that's actually designed for I/O on the iPhone? I mean, surely
there'd be less power loss if the port was actually designed to power other
low power devices. Especially if it could mean that you don't need as powerful
of an external microcontroller for doing the hacking and encoding that's
necessary for doing all the work-arounds from not having a real IO port.

~~~
acgourley
Apple wants you to use their 30 pin interface, but that requires going through
their MFi program and that lets them control the hardware ecosystem like they
do the software ecosystem.

To be fair, there are certain advantages to hardware manufacturers willing to
jump those hurdles. You're able to ensure no one can make software for your
hardware, for one. Secondly users who plug in your hardware can automatically
be taken to the app store to download your software.

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joe_bleau
Is there anyplace online people in the MFi program hang out (forums, usenet,
mail lists, etc.)? I've got some very basic questions about the whole process,
but it seems like such a black hole (from the outside looking in).

It would be great to use the ipods or ipads for industrial data collection,
but we'll need IR and a way to get data on/off without network connectivity.

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acgourley
Not that I've seen, and the NDA you have to accept is pretty strict.

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joe_bleau
That's what I was afraid of. In the quantities we're looking at, maybe we'd be
better off jailbreaking and selling the whole thing as a package.

Or maybe I'll just drag my feet a bit and hope there's a decent Android tablet
with USB host and an SD slot coming soon...

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yesbabyyes
You should take a look at Adam from Notion Ink. It's USB host. To me that's
the killer feature, for this reason!

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jodrellblank
So far, it's vapourware. That's something I just can't get over when I
consider ordering one.

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seabee
If it's vapourware then what were they showing at CES 2011?

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haribilalic
It's vapourware until you can buy one. A lot of things that are shown at CES
do end up being cancelled before they're ever released.

~~~
yesbabyyes
The pre-orders are shipping. Mine will arrive in about two weeks.

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Timothee
I think it's a very interesting project. I've been very interested in things
that combine hardware with smart phones, since the Apple keynote that showed
the first authorized hardware "extensions". (though since then, I've been
disappointed in not seeing much of anything)

However, can anyone chime in about the differences there are between using the
iPhone jack and using the dock connector? I know you're supposed to fill out
some docs with Apple to officially hack on the dock connector, but I believe
you can find hardware to do that without Apple's consent. It looks like one
would have to go the jailbreak route with that project as well.

I imagine the main thing is that a hobbyist can much more easily/cheaply get a
jack connector than a dock connector...

~~~
acgourley
You could create un-authorized hardware and apps using the 30 pin connector,
but they would only run on jailbroken devices. There are places to buy knock-
off (non-apple made) dock connectors so some people must do this.

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frankus
Also check out the Southern Stars SkyWire. Apparently it's a true RS-232 I/O
cable that plugs into the dock connector. They use it to drive telescopes, but
apparently it's not limited to that.

<http://www.southernstars.com/products/skywire/index.html>

I've gotten as far as opening an input and output stream with it, but I
haven't had time to dig up an RS-232 device to try talking back and forth.

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acgourley
Unless you have a jailbroken device, arbitrary apps you write won't be able to
access that stream.

~~~
frankus
You can use the EAAccessory framework to talk to it. Just use the protocol
string "com.southernstars.sw9a".

What I'm not sure of is what sorts of apps they'll let into the app store that
repurpose the cable.

EDIT: Here's my test code thus far:

<https://github.com/frankus/SkyWireTest>

~~~
acgourley
Apps using that won't pass certification, but you're right you can use your
own provisioned apps.

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jrockway
Now if only you were permitted to write software to take advantage of the cool
hardware you build.

~~~
simonk
Square has their app on the marketplace. <https://squareup.com/>

~~~
acgourley
Worth noting they may have had to go through additional testing. When you
submit an app that needs MFi hardware, they make you submit the hardware as
well and test both together. They may have demanded something similar for
Square.

Also worth noting that square is not drawing power, doing so might make them
reject your app. Especially because this harvest method is fairly inefficient
(power is being converted twice before its useful). Draw on the iphone battery
may be 4x the power used.

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nickolai
Cool project!

Currently, I am a bit doubtful concerning whether drawing extra power from an
already very battery lifetime-constrained smartphone is a good idea.

On the other hand, the batteries shold improve in the future, so with a bit of
luck the idea may just as well come to maturity at the right time!

~~~
ramidarigaz
It doesn't drain the battery any more than listening to music does :) Really
cool project!

~~~
moopark
Listening to music doesn't drive a constant 22 kHz tone.

[Edit] I really don't understand -- why was I downvoted here? Can someone
explain why they think I'm wrong? Isn't a constant, high-frequency tone going
to draw more power than variable output with significant larger gaps (and a
likely lower peak voltage difference?)

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noonespecial
Wow, that's a hell of a hack just because your smartphone maker wants to rent-
seek your serial port.

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joe_bleau
Clever idea, using the audio output as a power supply.

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acgourley
7.4mW is more power than I would have thought possible. That is really cool.
Plus with some additional hackery you may be able harvest up to double by
toggling the second audio channel on and off when you don't need to receive
data from the phone.

I'm going to put together a board based on their specs. If anyone in the bay
area is interested in collaborating on a project with it shoot me an email.

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theschwa
Does anyone have information on doing something like this wirelessly? Provided
your sensor has its own power source, couldn't you use the fm receiver built
into a lot of phones to receive data from an external sensor?

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joezydeco
The O'Reilly "iPhone Hacks" book has schematics and sample code to push RS-232
in and out of the headphone jack. You'll need a self-powered device to decode
FSK on the other end, of course.

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chanux
HiJack in full case reminded of square. <https://squareup.com>

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TimothyBurgess
Maaaaan I had this idea over 2 years ago... except my ideas revolved more
around robotics. I wish I was a bit older so I had the resources (money) and
time to work on these kinds of ideas that I have. Previously, all my time was
consumed by school/internship/band (I was a signed, professional touring
musician). And now all my time is consumed by getting my startup going... in
the hopes that it will eventually be somewhat self-sustaining enough to cover
my living costs while giving me time to pursue these other more interesting
ideas. Sigh... sorry for the rant that I'm sure no one cares to read.

