Usb charge

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WarlockM

Member
Nov 20, 2010
11
13
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.
 

adolfotregosa

Senior Member
Apr 22, 2005
374
61
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..
 
Last edited:

WarlockM

Member
Nov 20, 2010
11
13
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+.
 

MizGarfield

Member
Aug 16, 2007
27
2
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.
To charge your GT with any usb charger you have to make a little adapter.

How can you do that? You need an extra device adapter? Please explain.
 
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WarlockM

Member
Nov 20, 2010
11
13
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.
 

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adolfotregosa

Senior Member
Apr 22, 2005
374
61
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.


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 ??? :D no need for resistors, only 5.3V MAX and d+ and d- shorted
 

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geogetski666

Senior Member
Oct 25, 2009
96
5
Quezon City
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- :)
 

WarlockM

Member
Nov 20, 2010
11
13
@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
 

adolfotregosa

Senior Member
Apr 22, 2005
374
61
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.
 
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WarlockM

Member
Nov 20, 2010
11
13
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
 

rick75204

Member
Oct 14, 2006
10
1
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.
 
Last edited:
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wnpaul

Member
Oct 13, 2007
37
1
May I just ask some clarifying questions?

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.

Does it matter WHICH resistor you join to which of these two wires?

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.

So that you have effectively bridged the red wire with 30K-Ohms to one of either green or white running to the TAB?

6. Repeat the above process with the Black wires and 10K-Ohm Resistor.

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?
GalaxyTabChargingCable.png
 

kupuguy

Member
Nov 11, 2010
38
2
Oxford
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
 

paulshields

Senior Member
Nov 17, 2006
382
54
Liverpool
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!).
 

AlexVallat

Senior Member
Jun 16, 2008
120
17
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.
 

eiem

Member
Jan 11, 2008
31
0
45
Clarify

Sorry guys, only a clarification.

As far as i understood:
  1. the GT DOES charge with *any* charger (or connection to PC);
  2. if you use the original charger (2Amp), it charges showing the charging-icon;
  3. 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);
  4. 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!!
 

sedde

Senior Member
Dec 24, 2006
457
10
Thessaloniki
Sorry guys, only a clarification.

As far as i understood:
  1. the GT DOES charge with *any* charger (or connection to PC); Yes but slower than the original charger
  2. if you use the original charger (2Amp), it charges showing the charging-icon; Yes, exactly
  3. 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.
  4. 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!!


Thats it for now.
 
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Zeron.Wong

Member
Oct 30, 2010
33
1
Shanghai
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
 

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  • 11
    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.
    2
    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.


    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 ??? :D no need for resistors, only 5.3V MAX and d+ and d- shorted
    2
    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.
    1
    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.
    To charge your GT with any usb charger you have to make a little adapter.

    How can you do that? You need an extra device adapter? Please explain.
    1
    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.
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