Database Users

Usb charge

Hi. I've solved the problem of using other chargers with GT.
Like Apple, Samsung used a little trick with their chargers.
To charge your GT with any usb charger you have to make a little adapter.
Usb pinout:
gnd d- d+ 5v
To work you must short d+ and d-.
From 5v use a 33k resistor to d+/d-.
From gnd use a 10k resistor to d+/d-.
If you have multimeter you should obtain ~4v between 5v and d+/d-; and ~1v between gnd and d+/d-.
I tested it and it's working.

Hi, it's not a trick but a standard. You only need to short d+ with d-, the resistors are not needed. Just be sure that the charger outputs closest to 5v possible, around 5.2~3 usually work for everything. About 5.6v and it start not to work on some devices, like apple..

Maybe, I have to test that
I know it's not a trick, I should wrote "trick".
For example GT adapter outputs 5.31v.
Apple adapter worked with 1 22k resistor between d- d+.

WarlockM said:
Hi. I've solved the problem of using other chargers with GT.
Like Apple, Samsung used a little trick with their chargers.
To charge your GT with any usb charger you have to make a little adapter.
Usb pinout:
gnd d- d+ 5v
To work you must short d+ and d-.
From 5v use a 33k resistor to d+/d-.
From gnd use a 10k resistor to d+/d-.
If you have multimeter you should obtain ~4v between 5v and d+/d-; and ~1v between gnd and d+/d-.
I tested it and it's working.
Click to expand...
Click to collapse
WarlockM said:
To charge your GT with any usb charger you have to make a little adapter.
Click to expand...
Click to collapse
How can you do that? You need an extra device adapter? Please explain.

I've tested with d-/d+ shorted and it's not working.
@MizGarfield if u have 1 usb extension cable u can cut it on half.
Tie together white and green wires.
Tie black wires and conected to that 1 end of 10kohm resistor, the other end tie it to green/white wire.
Same to red wires but use 33kohm resistor.
See att. Sry for drawing.

bookmarking this for later use

WarlockM said:
I've tested with d-/d+ shorted and it's not working.
@MizGarfield if u have 1 usb extension cable u can cut it on half.
Tie together white and green wires.
Tie black wires and conected to that 1 end of 10kohm resistor, the other end tie it to green/white wire.
Same to red wires but use 33kohm resistor.
See att. Sry for drawing.
Click to expand...
Click to collapse
You don't need that for modern devices has i told you. It did not work because you did it wrong. I have all my usb chargers working the new way, you even have wikipedia talking about it. You have to cut the data + and - on the power supply from the female usb port and short only the female d+ and d-. Trust me it works and it is alot simpler.
Edit : from wikipedia "The Dedicated Charging Port shorts the D+ and D- pins with a resistance of at most 200 Ω. The short disables data transfer, but allows devices to detect the Dedicated Charging Port and allows very simple, high current chargers to be manufactured. The increased current (faster, 9 W charging) will occur once both the host/hub and devices support the new charging specification."
""As of June 14, 2007, all new mobile phones applying for a license in China are required to use the USB port as a power port.[35][36] This was the first standard to use the convention of shorting D+ and D-.[37]""
http://apple.slashdot.org/story/10/08/03/1743240/Hardware-Hackers-Reveal-Apples-Charger-Secrets
""We all love to call out Apple when they design deliberate incompatibility into their devices, but there is a perfectly valid technical reason for what Apple is doing here, and, in fact, they are following a USB specification (which LadyAda unfortunaterly didn't even test).
Without data communications or when suspended, devices may legally draw no more than 2.5mA from a host, which is useless for charging. In fact, even if you're generous and pretend they're connected, devices are not allowed to draw more than 100mA without negotiating for a higher current, which requires actually talking to the host, and 100mA is still too little to charge properly. 500mA is the maximum allowed by the USB spec, but devices must negotiate it (there may be too many devices on the bus for negotiation to succeed).
Before there was a spec for "dumb" USB chargers, Apple used the resistors as a sentinel to avoid drawing too much current from undersized chargers in order to avoid damaging the host. This is a hack, but it works, and honestly, we're smart enough to figure out a couple resistors on the data lines. It's not like they're using crypto auth on the charger. They have a perfectly valid reason to do this. Devices which charge from "dumb" chargers aren't following the spec, though this is a common industry practice.
As it turns out, the USB-IF came up with a USB Battery Charging spec [usb.org]. The spec is long and boring, but it boils down to: short together the data lines (no resistors required) and you indicate that you're a dumb charger that can supply anywhere from 0.5A to 1.5A.
Guess what happens when you short the data lines of an iPhone 3G and supply 5V [marcansoft.com]. Did Apple just follow a standard? Incredible!
(Yes, I'm not following the USB spec there by in turn using a USB cable to supply the 5V and not negotiating over its data lines. I didn't feel like grabbing a dedicated 5V PSU for the shot, so sue me.)"""
http://marcansoft.com/transf/iphonechg.jpg
ok ??? no need for resistors, only 5.3V MAX and d+ and d- shorted

Thnx for the tip gonna try this later on my sanyo eneloop power booster tried it yesterday without this mod and it doesn't charge so gonna look for a AF to AF converter and modify it to gound the D+ and D-

@adolfotregosa
I tried again shorting d-d+, with iphone it works but with GT it's not working.
I use BatteryWatch and it is saying Not Charging. It's detecting the connection like usb port but is not. I use some device build by myself with 1 amp capabilities. D- and D+ r free of any connection and i can do with them what i want.
I dont say you r wrong but it's not working with GT.
Sent from my GT-P1000 using XDA App

but smt is wrong on your custom setup, voltage ??
EDIT: i just measure the original charger and it has no resistance between the data and power pins.
I think i know what could be wrong, when you plug in the Tab and it says not charging, how many volts have you got at that time ?
The original charger is very good because when it not charging the tab it has 5.3x volts but when you plug it in it lowers to 4.8x V Max and that is very good ! most chargers tend to lower much more (bad quality or just not powerful enough) and that is what causes the not charging messages on the tab or other devices.
Well i rest my case on this.

My device with no load it have 5.21v and with load 5.03v so it's not from him and i have another supply 5v/12 amp and it's doing the same (not charging, only with data shorted).
When u r trying to measure the original ps u can read ~7k between gnd and data but from 5v to data u cant because it have some capacitors.
Maybe samsund did something else, i have to try, maybe data pins drawing some current (mA) and that's why it's not working with only shorting them.
For the moment it's the only (working) solution i've found and i'm happy with it .
P.S. If i'm not finding anything else the last resort will be to open the original ps
Sent from my GT-P1000 using XDA App

USB Charger
This is what worked for me.
Items Needed:
USB Extension Cable
33k-Ohm Resistor (Shack Part No. 271-1129)
10k-Ohm Resistor (Shack Part No. 271-006)
Steps:
1. Cut USB Extension Cable in half, lets name the 2 halves, the half you will plug into the power suppy will be called "Cable A" and the half that you plug into the Galaxy Tab Data Cable will be called "Cable B"
2. On 'Cable A" strip outer plastic to expose all wires within, eliminate Green and White on this cable only as it will not be needed, leaving you with only the Red and the Black Cables
3. On "Cable B" strip outer plastic to expose all wires within, this should leave you exposing all 4 wires
4. On "Cable B" strip both the Green and White wires and join thes 2 wires with the 2 resistor ends (you should be using the resistor ends that have the red band with these wires), these can be joined by either soldering or just twisting together.
5. Strip Red wire from both cables and join together with the 33k-Ohm Resister (this will be the larger of the 2 resistors and should also be the end with the Gold Band) and as well join these together with solder or just twisting together.
6. Repeat the above process with the Black wires and 10K-Ohm Resistor.
7. No finally use Electrical Tape or Shrink Tubing to cover all your work.
This worked using it on a Champtek 5v 2.1a USB Car Charger and Home Charger. Also worked with iPhone charger. Also works with Original Galaxy Tab.
Hope this helps out.

May I just ask some clarifying questions?
rick75204 said:
This is what worked for me.
...
4. On "Cable B" strip both the Green and White wires and join thes 2 wires with the 2 resistor ends (you should be using the resistor ends that have the red band with these wires), these can be joined by either soldering or just twisting together.
Click to expand...
Click to collapse
Does it matter WHICH resistor you join to which of these two wires?
rick75204 said:
5. Strip Red wire from both cables and join together with the 33k-Ohm Resister (this will be the larger of the 2 resistors and should also be the end with the Gold Band) and as well join these together with solder or just twisting together.
Click to expand...
Click to collapse
So that you have effectively bridged the red wire with 30K-Ohms to one of either green or white running to the TAB?
rick75204 said:
6. Repeat the above process with the Black wires and 10K-Ohm Resistor.
Click to expand...
Click to collapse
And bridged the black wire with 10K-Ohms to the other of either green or white running to the TAB?
Would this be an accurate picture, with the 33K Ohm Resistor on the left, and the 10K Ohm Resistor on the right?

I think the intention was that you short the green and white wires together: so you are connecting both wires to both resistors.
That way the two data lines are both held at a fixed voltage of about 1.2V

Thanks, that clarified it.

I noticed today that if I connect my Tab to my keyboard (standard Apple USB KB with keypad, connected to a circa 2006 iMac), the device started charging according to battery stats. When it was plugged in it was at 48% and it ended up at around 60% after a few hours. Am I being deceived or something? I was under the impression that it would only charge if connected to the mains charger. Well I guess I'll see how long it runs now it's off the leash and see if it lasts till the morning (left my charging cable at work - D'oh!).

No, it definitely does charge even when it says it isn't - just slowly. I've got a 2A non-official USB charger that charges it up pretty quick, but still says it isn't charging. If the screen is off, it will even charge off one of those tiny Kindle chargers that must be delivering less than 500mA, but *really* slowly.

Clarify
Sorry guys, only a clarification.
As far as i understood:
the GT DOES charge with *any* charger (or connection to PC);
if you use the original charger (2Amp), it charges showing the charging-icon;
if you use a non-original charger, it charges in any case but NOT showing the charging-icon and depending on the charger power (even 1Amp charges, or 500mAmp, *VERY-REALLY* slowly);
if you use a non-original charger with the two resistors (33k + 10k) it charges showing the icon (even with a 1Amp).
Can anybody confirm if i understood well?
Thanks!!

eiem said:
Sorry guys, only a clarification.
As far as i understood:
the GT DOES charge with *any* charger (or connection to PC); Yes but slower than the original charger
if you use the original charger (2Amp), it charges showing the charging-icon; Yes, exactly
if you use a non-original charger, it charges in any case but NOT showing the charging-icon and depending on the charger power (even 1Amp charges, or 500mAmp, *VERY-REALLY* slowly); Yes.
if you use a non-original charger with the two resistors (33k + 10k) it charges showing the icon (even with a 1Amp). Depends, i get various results even though i am using the mod since day 1.
Can anybody confirm if i understood well?
Thanks!!
Click to expand...
Click to collapse
Thats it for now.

It seems that the Tab could recognize the status of the usb connection by measuring the usb data rx/tx wire level. If it is not shorted, the "pluged in but not in charging" status will appear, as the mismatch voltage of the usb connection is made.
Sent from my XT701 using XDA App

Proprietary charger?

I've read that the Nexus 7 charges via regular micro USB (no proprietary port or cable) and that the charger is a 2A charger. Has anyone figured out the proprietary aspects of the charger that signal to the Nexus 7 that it's connected to the charger and that it's ok to draw 2A?

Bump.

I think it just dumps 2A into all the devices. 99% of USB devices have resistors in them to limit the current
Sent from my Nexus 7 using xda app-developers app

It needs a 2amp charger... 1amp will keep it on indefinitely but wont charge... with less than 1amp (say keyboard USB port) the battery will lowly drain on while the power indicator shows charging and eventually the screen will go nuts and the device will crash/shutoff
Sent from my Nexus 7 using xda premium

pixelchemist said:
It needs a 2amp charger... 1amp will keep it on indefinitely but wont charge... with less than 1amp (say keyboard USB port) the battery will lowly drain on while the power indicator shows charging and eventually the screen will go nuts and the device will crash/shutoff
Sent from my Nexus 7 using xda premium
Click to expand...
Click to collapse
Don't think you are accurate. If computer usb can charge the device (0.5A from usb port on computer), any charger can charge n7, albeit charger with lower current will take longer to fully charge the device. Tried 1A charger on N7, no problem.
Sent from my Galaxy Nexus using xda premium

There is the standard CYA in the manual to only use the cable and charger supplied with the unit. If it is fully powered down, pretty much any microUSB will charge it... eventually. That's not necessarily the best thing for the battery. If the power is under 2A as suggested, depending upon what you're doing with the tablet, it may just be enough to keep it running, or, could actually drop to zero even in use. (This happened with my Nook Color, for example). YMMV, but on the stock charger, the recharge is pretty quick. My only quibble is that there is no notification light to alert you to charge completion, or other notifications you might get (gMail, texts through Google voice, etc.).

tylerwatt12 said:
I think it just dumps 2A into all the devices. 99% of USB devices have resistors in them to limit the current
Sent from my Nexus 7 using xda app-developers app
Click to expand...
Click to collapse
This is incorrect. It's not up to the charger to push 2A, but rather up to the device to pull 2A through signaling of specific voltages on the data lines. For example, if you were to normally plug any tablet besides an iPad into an iPad charger (2.1A), the most you can expect to pull is 1A because the tablet doesn't know that it's connected to a 2.1A charger. The internals of the iPad charger will only tell an iPad that it's connected to a 2.1A charger. In order to charge at 2A with another tablet on the iPad charger, you need to do something like this example with the Galaxy Tab:
http://forum.xda-developers.com/showthread.php?t=845844
Or buy a pre-made adapter:
http://www.dealextreme.com/p/usb-ma...ung-galaxy-tab-p7500-more-black-127843?item=6
So the Nexus 7 charger must have something going on to tell the Nexus 7 that it's connected to the right charger because it can't try to pull 2A from every USB port that it's plugged into (some computers will actually shut down if something tries to draw too much power through the USB ports).
bitbearmi said:
My only quibble is that there is no notification light to alert you to charge completion, or other notifications you might get (gMail, texts through Google voice, etc.).
Click to expand...
Click to collapse
NoLED can alert you about notifications by flashing icons corresponding to the notification on the screen. It turns the screen on, which will obviously drain your battery, but there's a setting to disable turning on the screen when the proximity sensor is "close", so what you can do is put it screen-side down when it's off the charger to keep it from turning on the screen. It's not as elegant as a notification LED or backlight notifications (which is what I'm used to), but it's better than nothing.

Something I'd like to add not sure if its true but it was an explanation relating to this I saw when shopping around for an in car charger and makes some sense.
Android will reduce the power it pulls from a USB port if it detects it as a data port as opposed to an AC connection in order to conform to the official USB specs.
Apparently some chargers are wired incorrectly (data pins should be cross connected in chargers for it to be recognised as a charger if I remember the description) and will be picked up as a data port. Some devices will just use as much power as possible on data ports but ones that conform to the specs will take only the amperage outlined in USB specs.
Like I said its just something I remember don;t shout at me if I'm talking mince.
Sent from my Transformer while the N7 is lost in the Play Store Black Hole.
16gb N7 UK ordered 3rd July.

It's mildly related to proper charging. Basically, for any tablet, there are three charging states. The first is USB mode, where the data pins aren't shorted (as if the device was connected to a computer's USB port), which draws a maximum of 0.5A. The second is AC mode, where the data pins are shorted, which draws a maximum of 1A. The third mode is what I'll call high speed AC, and this is the mode we're after. Not only are the data pins shorted, but voltage is being applied to the data pins in a specific way to each device family. When the device detects this mode, it'll think that it's connected to its own charger and try to draw up to 2A.
Every device family has its own required voltages on the data lines, and by families, I mean products that have interchangeable chargers (like iPads, Galaxy Tabs, Transformers, etc) so if we can figure out what the Nexus 7 needs, then we can use any 2A charger with it (like using an iPad car charger). I just realized that others have said that they were able to charge at high speed with their Transformer charger, so I suspect that we can refer to Transformer charging adapters to get it working.

I haven't taken apart my Nexus 7 charger to see what's inside mainly because I've only got the one...
but I did verify that the D+ and D- pins on the USB are shorted, but there is no discernable voltage being applied to either.

So I set up my meter (and sacrificed my really short asus OEM charging cable) to measure the current draw while charging... this is what I found:
OEM charging cable appears to be just a regular old USB cable, unless there is something happening in the micro usb end, which I really doubt.. but I don't have any adapter to check if this is the case.
When D- and D+ are floating and not shorted together, the Nexus 7 draws ~1A but the charging indicator does not come on.
When D- and D+ are shorted together the Nexus 7 draws ~1A and the charging indicator does come on.
I could not get the Nexus 7 to draw 2A. Maybe I broke something
-J

Thanks for making the sacrifice. I guess more testing is needed.

I think the theory that it doesn't draw more than 1.0a may be correct. But it is still finicky about the charger. I have a palm OEM charger with palm cable and it doesn't charge the N7. I have a Nokia 1.2a charger and Blackberry 1.8a charger and they both seem to charge near the same rate, as fast as the Asus OEM charger.

Just as another data point, I tried connecting my n7 to the ipad ac charger, which is a 2A charger. It doesn't charge at all against the ipad charger.

kmandel said:
Just as another data point, I tried connecting my n7 to the ipad ac charger, which is a 2A charger. It doesn't charge at all against the ipad charger.
Click to expand...
Click to collapse
Anybody with the N7 that charges on the iPad charger? If so, I want to return it.
Domi

Limited charging options
dmalovic said:
Anybody with the N7 that charges on the iPad charger? If so, I want to return it.
Domi
Click to expand...
Click to collapse
It won't charge off an OEM iPad charger, just checked. It also won't charge off a Monoprice 3x outlet with 2x 2.1a usb directly connected to the usb ports or a 2.1a backup battery. Damn device is really picky about the source.
It will charge off my Touchpad and Vizio tablet charger.
I'm really bummed out it won't charge off the monoprice 3x outlets 2x usb since I bought a bunch of them when they were on sale and put them through out my house.

kkeo said:
It won't charge off an OEM iPad charger, just checked. It also won't charge off a Monoprice 3x outlet with 2x 2.1a usb directly connected to the usb ports or a 2.1a backup battery. Damn device is really picky about the source.
It will charge off my Touchpad and Vizio tablet charger.
I'm really bummed out it won't charge off the monoprice 3x outlets 2x usb since I bought a bunch of them when they were on sale and put them through out my house.
Click to expand...
Click to collapse
Same here.. just tried an ipad charger and it didn't work.. this is the oem ipad 3 charger. Also tried ipad 1 charger (should be same thing) didn't work.. going to try a charger for a Dell Streak 7.. see if it works.

Mine is also very picky. I used the stock Asus charger with a longer micro usb cable and it didn't charge while I was using the tablet over a period of around an hour. It maintained the % charge of the battery but didn't increase it. When I went back to the stock cable, it charged during use. Wouldn't be a real big deal if they hadn't scrimped on the cable to where it's only 3 feet long. What a pain.

A little OT, but my ASUS 1366 motherboard has an update you can install that allows the USB ports to charge an iPad at 1 amp instead of the normal .5 amp. I haven't tried it with the N7, but I suspect it won't work. Maybe another update will be released considering they make both devices, although my mb is kind of old...2009. I wonder if the USB2 specs allow for 2A charging and also if the newer USB3 spec allows more amps to be provided. If it doesn't, it should considering some of the latest power hungry devices.
Sent from my Nexus 7 using xda app-developers app

I looked at this too, and tried a few different configurations.
Measurements taken with my N7 at 95% charge. I expect higher power draw at lower charge.
.445mA - PC USB port
.440mA - APC USB battery pack directly connected
.443mA - iPhone 3G USB charger
.820mA - stock charger
.815mA - APC USB battery pack with D+/- disconnected at the host and shorted at the device end (actually 10 ohm resistor)
.818mA - APC USB battery pack with D+/- removed on host, shorted on device, and resistor divider for 1.2V on both pins (Samsung type)
I chose the APC battery pack as it provides a solid 5V at 1A. It also has D+/- wired iPhone-style.
Wondering what the charger driver thinks of this, I looked at dmesg just after every attempt. I see:
connected to PC USB:
Code:
smb347_charger: [cable_type_detect] Reg3F : 0xc0
smb347_charger: [cable_type_detect] Reg3E : 0x0c
Cable: SDP
========================================================
battery_callback usb_cable_state = 0
========================================================
connected to iPhone or APC charger:
Code:
smb347_charger: [cable_type_detect] Reg3F : 0xc0
smb347_charger: [cable_type_detect] Reg3E : 0x0b
Cable: OTHER
========================================================
battery_callback usb_cable_state = 0
========================================================
connected to stock, or APC with either of my adapters (cut & shorted or Samsung):
Code:
smb347_charger: [cable_type_detect] Reg3F : 0x83
smb347_charger: [cable_type_detect] Reg3E : 0x0a
Cable: DCP
========================================================
battery_callback usb_cable_state = 3
========================================================
So the charger limits to ~500mA when using an iPhone-pinned charger (OTHER) or a live USB host (SDP), and allows high current charging when D+/- is shorted regardless of being pulled to a given voltage. SDP is USB 2.0. charging spec terminology for Stanard Device Port, meaning a 500mA limited USB port, while DCP means Dedicated Charging Port which means that D+/- are shorted and can supply up to 1.5A.
This uses the SMB347 USB charge controller, same as the Kindle Fire, which works the exact same way.
TL;DR: Cut D+/- between the charger and device and short D+/- at the device for full current charging.

What pins should i short for a wall charger for my defy?

I just bought a universal wall charger for my defy that likes to freeze my touchscreen when plugged in. after some research i found that, if i understood it correctly, typical smart phone wall chargers have the 2 data pins (pins 2 and 3) shorted with a 200k ohm resistor at the phone. I opened my wall charger (at the male usb port, cause thats how its wired) and it has pins 3 and 5 (data + and ground) shorted with a 200k ohm resistor. i believe this is whats causing my frozen touch screen issue.
can someone tell me if the data ports are what needs to be shorted, or is the data/ground short is fine?:cyclops::good:

USB to DC charging pinout

Hello
I'm hoping some USB expert can help me out here, I'm trying to make a USB to DC (2.5mm plug) cable that can supply 2A, I have the popular HP Touchpad wallcharger that's rated 5v 2A , so I took a spare quality usb cable (copper cables) it has red, black, green, white (and a big bare metal cable and aluminum wrapping, shielding probably), the DC plug end has two wires red + black, so I hook up red to red black to black (red is 5V black is ground, tested using a multimeter) but I don't seem to be getting as good of results that the stock cable I have gets, the stock cable charges the device at around 1.8 Amps , the cable I made only outputs 800ma to 1.3 amps and if I turn the brightness up it stops charging like it can't supply enough power amps (again stock cable works fine with full brightness).
I'm wondering if on the charger end I need to do something with the green, white wires they both output around 2 volts should these be shorted to the black or possibly red wires to add additional amperage?
I found a youtube video where someone made a similar PSP charger and they spliced both the green, white and blacks wires together, I just want to make sure this is correct way to do things.
youtube.com/watch?v=8WhMeZkrK8U
Btw I also purchased a pre-made cable from dealsextreme but it exhibits the same behavior where full-brightness the charging light dims and goes out on my device, I assumed the low quality of the cable was to blame or again something needs to be connected with the green, white wires.
I know similar questions have been asked before but most have dealt with USB to USB fast charging , with USB to DC I'm confused on what to do with the D- and D+ wires at the charger end should they be shorted together? or to the black cable

ok I think I answered my own question, I tried to do a Ohm test on the stock cable and it seems there was no connection to the green and white or to any of the other wires, since the Ohm reading always returned 0, red and black got a 1+ reading meaning they were connected and a circuit was completed.
Looking at my stock cable it has a big black magnet on it, researching google i found this might be a ferrite core cable, so maybe this somehow boosts the signal and lets the cable pull more amperage or something.

The cylindrical lump on some cables is a ferrite core.
Its purpose is to reduce the amount of logic-generated RF noise from finding its way onto the main span of cable and using it as an antenna.
It will not affect any aspect of charging/powering a device.
Yes, the white/green data pair are used sometimes to indicate a dedicated charger.
A dedicated charger can have more current drawn from it than a normal USB connection.
This subject is handled exhaustively here: http://forum.xda-developers.com/showthread.php?t=1384253

otyg said:
ok I think I answered my own question, I tried to do a Ohm test on the stock cable and it seems there was no connection to the green and white or to any of the other wires, since the Ohm reading always returned 0, red and black got a 1+ reading meaning they were connected and a circuit was completed.
Looking at my stock cable it has a big black magnet on it, researching google i found this might be a ferrite core cable, so maybe this somehow boosts the signal and lets the cable pull more amperage or something.
Click to expand...
Click to collapse
What are you trying to do, make another Touchpad charger? I assume you made sure it can supply up to 2A at 5V.
Many chargers including the HP Touchpad one IIRC short the green and white data wires and this tells the device it can draw more current. If your ohmmeter was reading 0 then that would mean they are shorted. I don't think they are tied to ground (black) just to each other.
The ferrite choke is there to suppress noise from the switching transformer so the device gets clean DC power when charging.

Thanks,
I was trying to make a cable for a Chinese tablet that cannot be charged through it's USB port and only has a 2.5mm dc power port, it seems to be pretty picky about the cable being used, so far the Stock cable to USB-DC to wall USB charger works fine (hp touchpad charger), and a true DC brick rated 2000ma , 5v to DC port works good, I wanted an extra cable to use to charge it with my HP usb charger so I ordered this from dx.com
http://dx.com/p/usb-to-2-5mm-dc-charging-cable-2538
as always I check the polarity and voltage of the cable and it showed 5.13 volts, and center pin positive, strangely when I hooked it to the tablet I saw the battery charging , at 100% I turned brightness up and ran a 3d game, suddenly I saw the red light switch on the tablet to indicate it's charging, strange since it was hooked up to power and was already fully charged, and another test battery was around 40% and I charged to around 80% I rebooted the tablet and the battery was at 40% again!, so thinking my battery died I re-hooked up the stock cable and charged to 80% rebooted again and battery was 80% , narrowed it down to the cheap dx.com cable not supplying enough amps or some short in the cable, this is when I decided to make my own cable.
In my post above, The USB cable I was using I ended up taking apart the usb male connector and found out although the cable was decent quality copper wires.. where it was making the connection at the USB male end the connector only had little push pins puncturing through the wire (two little metal prongs), they weren't soldiered or anything so I guess it was another cheap cable .
So I searched for another cable, finally I found an older usb cable that none of my devices use anymore, this cable actually had a copper metal shield I just connected red and black, left green and white alone not connected to anything, so far it is operating like the stock cable when fully charged I can run full brightness , cpu at fullspeed, and 3d game without the charger light on the tablet going on (I assume this means the tablet is getting enough power from the dc port and doesn't need to switch to battery), I haven't had time to charge the device with the cable yet, but I'm assuming it will work like intended.
I guess they don't make cables like they used to.

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HTC ONE Charging methods

At home I have an iPhone 5 charger and a Blackberry Bold 9900 Charger along with a Cooler Master Battery Bank. The out put on the battery bank claimed 5 Volts 2.1 Amps but when hooked up to my HTC One it showed USB Charging. I hooked it up via my iPhone 5 charger which has an output of 5 Volts and 1A and also got USB Charging but when I hooked it up via Blackberry Charger with an output of 5V / 750 mA I got Charging (AC) on my HTC One. Looks like it won't accept any higher power input than what it needs for faster charging.
Picture posted is via Blackberry Charger.

Here is a picture via Cooler Master Battery Bank showing charging (USB)

The maximum current is drawn when the battery is empty. The first phase of charging is constant current, where it will draw up to 1A from AC and 500ma from USB, then moves to constant voltage, where the current will drop off. Your battery is probably too charged to be drawing max current.
HTC phones switch to AC charging when the data pins on the USB are shorted, otherwise it's USB charging.

BenPope said:
The maximum current is drawn when the battery is empty. The first phase of charging is constant current, where it will draw up to 1A from AC and 500ma from USB, then moves to constant voltage, where the current will drop off. Your battery is probably too charged to be drawing max current.
HTC phones switch to AC charging when the data pins on the USB are shorted, otherwise it's USB charging.
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I need to double check which USB cable I had used. At work now but just saw that the USB cable I had at work was the Blackberry USB Cable and when I hooked that one up with my new HTC ONE I got AC Charging on my HTC ONE. A sales person had told me that the USB cable can make a difference at times. Will try messin around with a few wires along with my Cooler Master Battery Bank to see if the results change.

desiregeek said:
I need to double check which USB cable I had used. At work now but just saw that the USB cable I had at work was the Blackberry USB Cable and when I hooked that one up with my new HTC ONE I got AC Charging on my HTC ONE. A sales person had told me that the USB cable can make a difference at times. Will try messin around with a few wires along with my Cooler Master Battery Bank to see if the results change.
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Click to collapse
I find that the charger it came with charges it fastest. The other chargers I have used are my neuxs 4 and gs4.

The phone is looking for a 'short' across the two data wires, I believe. The HTC chargers have this so that the phone knows it's not a USB port that isn't able to deliver the current. I'm surprised the blackberry charger fooled the phone to think it's AC.