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

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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Reply to
Man-wai Chang
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Why don't you just get one of these things:

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...and be done with it.

Reply to
Grinder

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

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Reply to
Man-wai Chang

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

Reply to
Paul

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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Reply to
Man-wai Chang

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.)

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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.

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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.

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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.

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Paul

Reply to
Paul

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

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Reply to
Man-wai Chang

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.

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

OK. I see a post here.

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"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

Reply to
Paul

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+5V ---50k --- D- | 10k | GND ---40K --- D+

Is this safe? Would it work?

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Reply to
Man-wai Chang

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As you're not putting more than 3.3V on the data lines it looks fine to me.

There's a standard for power-only USB sockets. it's basically 5V and some resistors, I'm not sure how close to it that layout it is, I'd research and try the standard way first.

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Reply to
Jasen Betts

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At initial glance it seems good, but I haven't read the whole USB charging specification.

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Reply to
Jasen Betts

Too much information.... -_-"

Are you saying that the voltage over D+ and D- should be smaller than

2.0V and 2.5V respectively?
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   @~@   Might, Courage, Vision, SINCERITY.
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Reply to
Man-wai Chang

The only maximum voltage number I saw quoted for those pins was 3.6V I skimmed it, mostly I did searches and looked at the diagrams.

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Reply to
Jasen Betts

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