Fake a PC connection via USB cable mod to fool the iPod Touch 3

  • Thread starter Thread starter Man-wai Chang
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Man-wai Chang

I can't charge an iPod Touch 3 via a disconnected, powered USB hub.

How could I mod the cable pins of the USB cable to make iPod Touch 3
think it's connecting to a PC?

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Why don't you just get one of these things:

I have leisure time to fiddle with the wires. That means I don't need to
spend a dime. :)

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Man-wai Chang said:
I have leisure time to fiddle with the wires. That means I don't need to
spend a dime. :)

It is possible the chip inside the hub, turns off the power to the
ports on purpose. It could be based on there being no upstream
connection to the hub. Perhaps when the upstream connector has
a signal on it, the chip turns on its outputs. And the "turning on"
would be via the external "current monitoring" chips. They have
MOSFETs inside for switching the power.

If possible, you'd open the hub, get the main chip number, and find
a datasheet for it. But there is no guarantee you'll be able to
find the datasheet. Some companies are very stingy with technical
documents.

Paul
 
If possible, you'd open the hub, get the main chip number, and find
a datasheet for it. But there is no guarantee you'll be able to
find the datasheet. Some companies are very stingy with technical
documents.

Could I just connect the 2 data pins of the USB port to a resister?
Could this fake a PC connection?

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Man-wai Chang said:
Could I just connect the 2 data pins of the USB port to a resister?
Could this fake a PC connection?

Why not just find a conventional USB connector, and wire the hub AC adapter
right to the USB connector ?

For example, the USB connector on the front of your computer case, may have
a wire harness on it that connects to the motherboard. If you wire the
USB VCC and GND pins on that cable, to a power source, you can make a
"charging station" for yourself. (In other words, disconnect the wire
harness from the motherboard, and then arrange it so the AC adapter
is connected to the appropriate pins.)

*******

The USB spec itself, is around a 500 page PDF.

Sites like this, attempt to put some of the information in a usable
form. So you may get a better idea of how difficult it will be, from
this information. I don't know what your hub would do, if
it was in Suspend mode.

http://www.beyondlogic.org/usbnutshell/usb2.shtml#PowerVbus

*******

I wouldn't even bother with the hub. I'd find a USB connector (even
a USB cable assembly you removed from a PC could be used), and make
a simple wire assembly to make a charging station from it.

I saw a number of dumb web pages, that concentrated more on building
a "box" to hold the charger project, than on the wiring itself. In
this example, they're using a battery as the source of power, and
a three terminal regulator. That's to show all that you'd need in
your case, is to connect the +5V and GND from your AC adapter DC output,
to the red and black wires on the USB connector. Red is usually +5V and
black is usually ground.

http://www.crunchgear.com/2009/11/02/build-your-own-battery-powered-usb-charger/

Before connecting any devices to your wired project, you'd check the pinout.
For example, take note of the "receptacle" diagram here, the location of the
polarizing tab, which pin has VCC and which has ground. Only pin 1 and
pin 4 on the receptacle should need to be wired, to make a charging
station. When wiring connectors like this, I like to verify my wiring,
before actually connecting any expensive devices to them. 6 pin Firewire
connectors for example, are extremely dangerous when it comes to wiring
mistakes. If you're going to wire a USB connector yourself, check
and double check the results before using it.

http://www.interfacebus.com/usb-cable-diagram.html

Paul
 
Why not just find a conventional USB connector, and wire the hub AC adapter
right to the USB connector ?

Because it seems that the iPod refused to charge itself without
detecting Windows.

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Man-wai Chang said:
Because it seems that the iPod refused to charge itself without
detecting Windows.

Hmmm. This isn't encouraging. It looks like they *do* play
tricks with D+ and D- on some of their products. But this
doesn't tell me what to do for your model.

http://pinouts.ru/Devices/ipod_pinout.shtml

http://www.instructables.com/id/Ipod-Touch-Charger-100-works/

Since you're an expert with resistors now, perhaps it's time for
a few experiments ? :-)

OK. I see a post here.

http://www.applegazette.com/iphone/you-cant-charge-the-iphone-3g-on-ipod-audio-systems/

"Yvonne says: July 26, 2010 at 8:35 pm

By the way, if you can get inside your old charging devices there is a fairly
simple way to modify them to work with the newer iPods if you are somewhat
handy with a soldering iron.

it works great with my new iPod Touch 3G.

You will need four 47K ohm resistors (1/8 watt is large enough, but any wattage
will work) and possibly a few inches or small gauge wire."

[Note - I've taken the liberty of drawing a diagram of the circuit.]

+5V --------------+-------------+--- +5V
| |
Power 47K 47K
Source | |
on +---> D+ +---> D-
this | |
side 47K 47K
| |
GND --------------+-------------+--- GND
\ /
\______________________/
|
This portion defines the four USB
pins of your charger jack.

What this circuit is doing, is placing 2.5 volts (an intermediate voltage)
on the Data plus and Data minus signals. By using 47K (47000 ohm 1/8 watt)
resistors, the intermediate voltage is exceedingly weak, so cannot harm
anything. If you were to connect a multimeter to the D+ or D- nodes,
you would likely find them at voltages other than exactly 2.5 volts,
due to loading from the iPod. What matters, is whether you see
the charging icon or not.

HTH,
Paul
 
What this circuit is doing, is placing 2.5 volts (an intermediate voltage)
on the Data plus and Data minus signals. By using 47K (47000 ohm 1/8 watt)
resistors, the intermediate voltage is exceedingly weak, so cannot harm
anything. If you were to connect a multimeter to the D+ or D- nodes,
you would likely find them at voltages other than exactly 2.5 volts,
due to loading from the iPod. What matters, is whether you see
the charging icon or not.

Interesting... let me think about it first... :)

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Because it seems that the iPod refused to charge itself without
detecting Windows.

Interesting. It also seems to me that Amazon Kindle either does this,
or has a problem with the charger (more likely), as it often seems to
not what to charge by itself.

But I have an iPod (from 5 years ago) that does not seem to have this
problem.

RL
 
But I have an iPod (from 5 years ago) that does not seem to have this

The one I got (as a gift) is iPod Touch 3 64G.

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Since you're an expert with resistors now, perhaps it's time for
a few experiments ? :-)

Not yet. Not until I blew up a few resistors and hurt myself! :)

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Not yet. Not until I blew up a few resistors and hurt myself! :)

Well... someone had done it already. That saves some of my time.

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Not yet. Not until I blew up a few resistors and hurt myself! :)
Well... someone had done it already. That saves some of my time.

Left out the link:

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Interesting. It also seems to me that Amazon Kindle either does this,
or has a problem with the charger (more likely), as it often seems to
not what to charge by itself.

But I have an iPod (from 5 years ago) that does not seem to have this
problem.
I don't know whether this is relevant. I just got a Kindle (the 3G
whispernet version) and it will not charge from USB if it's connected to
Windows, so the manual says. You have to disconnect it.
 
I don't know whether this is relevant. I just got a Kindle (the 3G
whispernet version) and it will not charge from USB if it's connected to
Windows, so the manual says. You have to disconnect it.

Now that's interesting...

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Man-wai Chang said:
Left out the link:

Yeah, I had something like that happen in one of my labs in university.

Some other students, on a table about 20 feet from where I was,
connected one of these across 230 VAC. The resistance of one of
these is pretty low, and I worked out later, the resistor was called
on to dissipate 5kW. The supply side had a high breaker rating,
because it is supplying power to large motors in the lab. So the
circuit breaker didn't trip.

http://www.faqs.org/photo-dict/photofiles/list/1829/2409rheostat.jpg

( Used with laboratory motor-generator sets like this one. This
example is modern, while ours were ancient, perhaps from 1940 or
so. )

http://2.imimg.com/data2/MP/YH/MY-1696031/8alternator-motor-500x500.jpg

The coils of wire on the ceramic former, were glowing cherry red in
color (just like a toaster). After a few seconds, the individual
coils of wire fell off the ceramic core, and dropped to the table top.
The table had a laminated plastic top, and each time a cherry red coil
would drop, a small puff of smoke would come from the plastic it would hit.

I got to see all that, as I was racing across the lab to hit the
power switch... :-)

The students standing next to the table, were frozen there in
shock, so I had to run across and kill the power. They're supposed
to do that (turn off the power) themselves.

Good times...

Some other students, managed to ruin one of those motor-generator
sets, but I wasn't there to see that one. Just my luck.

Paul
 
The students standing next to the table, were frozen there in
shock, so I had to run across and kill the power. They're supposed
to do that (turn off the power) themselves.

Were they girls? Maybe they really wanna enjoy the firework... ;)

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Man-wai Chang said:
Were they girls? Maybe they really wanna enjoy the firework... ;)

No, they were geeky guys, that had never been in an emergency
situation before. They were just standing there, like dummies :-)
Dummies, lit up by the cherry colored glow of their
5000 Watt resistor connection mistake.

For a second or two, I just stood there too, staring at *them*
and waiting for them to react - because they were right next
to the damn power switch. When that didn't appear to be happening,
I had to race over and kill the power.

Thank God nobody was electrocuted in that lab.

Geeks can be *unbelievably* stupid. I had an engineer at
work, *pick up a soldering iron by the hot end*. Yes,
he was burned. He's actually a very bright designer,
and does good work. But he's not practical. For example,
I doubt he could change a flat tire on a car. He wouldn't
be able to find the car jack.

Paul
 
and waiting for them to react - because they were right next
to the damn power switch. When that didn't appear to be happening,
I had to race over and kill the power.
Thank God nobody was electrocuted in that lab.

This only meant they were not well-trained. :)
Geeks can be *unbelievably* stupid. I had an engineer at
work, *pick up a soldering iron by the hot end*. Yes,

I did it once as well. I also wrapped my hand on a hot glass tube by
accident during a chemistry experiment. :)



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Man-wai Chang said:
This only meant they were not well-trained. :)


I did it once as well. I also wrapped my hand on a hot glass tube by
accident during a chemistry experiment. :)

Ouch!

Paul
 
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