yashsingh1/xdaforums huggingface dataset:
[Nexus 7 Q&A, Help & Troubleshooting] pokey9000:
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:

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:

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):

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.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
pokey9000: You said N1. Are you referring to the Nexus One or was that a typo? If that was a typo, then if you can measure the current drawn when the Nexus 7 is at something like 50%, then that would be great.
[Nexus 7 Q&A, Help & Troubleshooting] krelvinaz:
The "Borrowed" Nexus 7 that I've been using since Wed has its original OEM charger still sealed in the package in the box at my office in my filing cabinet.

I've been using up till yesterday the charger from my Kindle Fire which is a 2.1A AC charger. I also picked up a Blackberry Playbook charger a while back which was cheap(er) that also outputs the same.

I had noticed some time before that when I charged my phone with a dock that I had with the chargers it came with, the Rezound would say it was charging but say it was on USB. Much slower to charge. but when I used either the KF or the PB charger with the same dock, the phone would say charging AC instead of USB...

Charged really fast.

So that is what I've been using.

Sold the KF the other day so "I" only have one of them now.

Today without the KF charger at home (the PB one is also at work) I just plugged in using the normal adapter and it said it was charging, but said it was USB and barely kept up while using the device. Was at around 49% most of the day.

I eventually I grabbed my wife's KF charger from the other room, plugged it in and within an hour or so near 100%. and of course it says Charging AC.
[Nexus 7 Q&A, Help & Troubleshooting] pokey9000:
Er yeah. Used to have a Nexus One and it slipped. I'll see what I can do after it runs down some more.

---------- Post added at 02:27 AM ---------- Previous post was at 02:14 AM ----------

You could build your own adapter. If you have a microUSB cable to sacrifice, you could try hacking it for charging, or for a more elegant solution build this adapter, but leave off the resistors since we don't need 'em.

I'm sure someone sells something like this, but all I could find prefab is for iStuff.
[Nexus 7 Q&A, Help & Troubleshooting] eyesparky:
It seems to charge fine with every micro USB charger and cable combination I have in the house.
[Nexus 7 Q&A, Help & Troubleshooting] martyg7:
Maybe there is a low hanging software fix to be had in this driver before we go hack all our chargers and cables?

It never occurred to me the tablet may still be taking a 500mA charge even though the indicator is off.

I need to test this with my aftermarket Apple chargers.

I broke out an old USB cable this morning, and checked the USB wall warts I have lying around.

(a) My (new) 4-port Monoprice 8856 and my aftermarket iPhone chargers all fail to show a charge on my N7.

(b) The N7 OEM charger and a LG charger from my Optimus V both show charging.

(c) Plugging into a USB port on my laptop shows charging

Using a DVM, I observed

(a) Have D+/- biased at around 2.0-2.5v; dmesg shows OTHER usb_cable_state = 0

(b) Have D+/- shorted and floating; dmesg shows DCP usb_cable_state = 3

(c) dmesg shows SDP usb_cable_state = 1
[Nexus 7 Q&A, Help & Troubleshooting] cybermage1:
Keep this in mind

Keep in mind that the USB standard actually defines a communications protocol that controls the amount of power produced from the adapter end of the line. A device can ask for various levels of amperage that are then provided by the power supply. Not saying that's what's happening here, but it's something to investigate. A lot of charging adapters designed for a given unit don't support it because they expect to only produce exactly what was needed for the phone or whatever it was designed for.

Also, 2A charging is beyond what the USB spec provides, so it's basically guaranteed to be non-standard. It doesn't surprise me that it may need a special cable to get the fast charge either, because most USB cables aren't designed to carry that kind of current.

So the real question: Is there a single after-market power supply that will charge your phone or BT headset at 200mA, while still providing the 2A that the Nexus 7 requires? Preferably with multiple USB ports on the charger? And another that does the same from your car?
[Nexus 7 Q&A, Help & Troubleshooting] pokey9000:
IIRC the Kindle Fire kernel had a driver for the SMB347 that at least hinted at the command to force the charging mode. I haven't looked at the N7 source but it's probably similar. It's i2c so it should be easy to control from userland.
[Nexus 7 Q&A, Help & Troubleshooting] martyg7:
One more thing I forgot in the original post:

I got the same results whether I used the supplied Nexus7 cable or commodity micro USB cables.

So I am pretty well convinced there is nothing magic about the N7 cable - It's just a regular USB cable.
[Nexus 7 Q&A, Help & Troubleshooting] pokey9000:
The USB spec has both an in-band current negotiation protocol for powering devices that are communicating over the cable, and an out of band protocol for charging-only. The DCP mode is part of the out-of-band and specifies max 1.5A charge current.

The adapter is likely rated at 2A to provide a bit of margin for occasionally exceeding the spec (the charger can pull up to 2.5A from the port) and cable losses.

A normal microUSB cable should be good to the 1.5A charging spec. The connector is good to 1.8A over the power and ground pins, and I've never seen a connector that refused to handle 12% overcurrent.
[Nexus 7 Q&A, Help & Troubleshooting] martyg7:
I can confirm the tablet does charge with this setup, even though none of the indicators are on.

From my crude calculations, it looks like the battery is being pumped at the 2.5W rate (15% / Hr)

---------- Post added at 08:16 AM ---------- Previous post was at 08:05 AM ----------

I took a quick peek at the source code yesterday -- <KERNEL>/drivers/power/smb347-charger.[ch]

I do not see any obvious parsing for options when the module is inserted.

But the source look pretty straightforward.

Before I dig further into this, I really need the detailed datasheet for this charger chip.

All I was able to find on the Summit Microelectronics website is a summary page.

If anyone has the full SMB347 datasheet, could they please post a link into this thread.

Do we know for sure SMB347 is the exact chip?

Or does Asus use a clone that happens to have the same programming model?

I couldn't tell going back through the teardown pictures.
[Nexus 7 Q&A, Help & Troubleshooting] extric:
I tried the following chargers (all continental EU versions)

Ipad 10W Charger : Charges but no indicator

Iphone EU 5W Charger (flat one): Charges slow but no indicator

Galaxy Tab 10.1 Charger: Charges and Indicator ----> This does not charge the ipad or iphone

Brodit carkit charger (for iphone): No Indicator and not sure about the charging

No name 2A ebay car charger: charges and Indicator

Kensington Iphone Night Stand: No Indicator and no charge
[Nexus 7 Q&A, Help & Troubleshooting] kmandel:
Is this still available on ebay (url)?
[Nexus 7 Q&A, Help & Troubleshooting] linkinparkfan007:
Works

LG Optimus One 5V 700MA Charger

Doesn't Charge:

Digital Solutions 5V 500MA Charger

http://ecx.images-amazon.com/images/I/51syecVMCpL._SL250_.jpgCreative Vado HD 5V 1AMP

http://vancouver.canadianlisted.com...voltage-usb-charger-20-vancouver_2591279.html 5V 1AMP
[Nexus 7 Q&A, Help & Troubleshooting] dSayonarab:
tl;dr: As long as it's rated 2A and free of "designed for iStuff", it should charge anything you own (except for iStuff) as fast as the device can pull current from it. The device should not explode.

?A Sleep and Charge USB 3.0 port on my Toshiba Satellite L750: Charges N7@~2A (reports AC), charges SXS*@1.5A

2A ASUS Nexus 7 charger: Roughly same as above

2A HP Touchpad charger: Roughly same as above.

1.2A Logitech charger bundled with M950 mouse: Charges N7@~1.2A (reports AC), charges SXS@~1.2A

1.2A Nokia charger bundled with N97: Roughly same as above

?A Sony CP-ELS Portable USB Charger: Roughly same as above

.7A LG charger: Barely charges SXS faster than discharge, can't handle N7

Original iPad 2 charger: Refuses to allow over 500mA draw for anything except mom's iPad 2 and iPhone 4

Momax charger "for iPad/iPod/iPhone": Same as above

All of the above charge my Plantronics Handsfree Bluetooth headset, my Logitech M950 mouse (contains Sanyo Eneloop 1.2V "min 1900mAh" long-life NiMH battery), Logitech K800 keyboard (contains two Eneloops), and the aforementioned Sony portable charger (2000mAh Li-Ion), as well as my brother's LG flip phone. None of the above devices have exploded, spontaneously combusted, leaked, or otherwise been damaged in any way by any of the above chargers.

Tested the above with a range of cables including two bargain bin 1 meter cables, cable for my SXS, cable for the N7, cables from my two Logitech devices, and the very short cable that came with the Sony portable charger. The N97 charger's cable is permanently attached. iPhone4 and iPad 2 were tested with original Apple charge/sync cable.

* = Sony Xperia S
[Nexus 7 Q&A, Help & Troubleshooting] krelvinaz:
I've been mixing up Kindle Fire and Blackberry Playbook tablet chargers and they all work well.

I like the Playbook charger because it has a 6ft cable. The NX7 cable is short.

I also picked up some HP Touchpad tablet chargers when they were cheap and they worked well too.

I don't have (never had) the HP or Blackberry, but I did have a KF and wanted additional chargers for it. It is a 1.8A rated device.

Once source

http://www.amazon.com/gp/product/B004OZMWUS
[Nexus 7 Q&A, Help & Troubleshooting] linknight:
I just received this charger yesterday and it works perfectly. It has 2 ports, one for Apple products, and one for non-Apple products. You can charge through both but according to the manual, putting apple in non-apple port and vice-versa may charge slow.

http://www.amazon.com/PowerGen-Travel-Charger-Devices-included/dp/B0073FCPSK
[Nexus 7 Q&A, Help & Troubleshooting] Se7enLC:
I have a pile of different chargers at my disposal, as well as a short "USB current draw jig" that I assembled (Male + Female USB-A, GND, D- and D+ connected straight, VCC test points for an ammeter).

I've modified a number of USB chargers so that they would work with the Samsung Galaxy Nexus. That phone requires D- and D+ to be shorted in order to convince the phone that it's ok to draw > 500mA. There is a "Fast Charge" kernel mod to allow the phone to just draw maximum current regardless of the charger type. I've verified that it works (draw of between 950mA and 1.0A from various USB ports and chargers that normally are recognized as USB chargers).

With the Nexus 7, I'm not having particularly good testing luck so far. When testing current draw using the stock charger, I can see a 1.3A draw. So far so good. When I attach to a charger that can supply 2A that has been modified to short D- and D+, the Nexus 7 will still only draw 400mA and does not claim to be charging. Must be something else the Nexus 7 is looking for. Any ideas? Does the D-/D+ point need to be grounded, held to 5V, or is floating ok? Or does Asus do something random like Apple and require that D- and D+ be held to specific voltages?
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
I'm pretty sure that any device that draws more than 1A requires specific voltage to be applied to D+/D-, and that's why I started this thread, to figure out what those voltages are.
[Nexus 7 Q&A, Help & Troubleshooting] martyg7:
Please refer to posts 20 and 25 earlier in this thread.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
I just charged my tablet overnight using a Galaxy Tab charging adapter between the micro USB cable and the stock Nexus 7 charger and it charged at the same rate as if I was plugged directly into the charger, so I think that the Nexus 7 uses the same signaling as the Galaxy Tab series. If someone wants to try it on their own, I mentioned the charging adapters in post #7 (you can buy or build your own). This should enable high current charging on any 2A/5V charger, and you should be able to use any Galaxy Tab charger without an adapter.

For everyone reporting that various chargers "work", to confirm that it's indeed charging at the correct rate, you should use some type of battery monitoring app. I use Battery Monitor Widget because it logs the battery state every five minutes (make sure that you add the widget to your home screen). For consistent comparisons, try to see how long it takes for your tablet to go from 55% to 100% using both the stock charger and whatever other charger/adapter you use. For comparison, it takes my tablet exactly two hours to go from 55% to 100%.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
Does anyone have a Galaxy Tab charger that they can use to test my theory that it uses the same signaling as the Nexus 7? I sold mine (along with the Tab itself) so unfortunately I can't test it. I don't have any other 2A wall chargers to test with either. I have a 2.1A iPad car charger that worked properly with my Tab after I plugged in the adapter, but I don't anticipate taking any drives long enough in the near future to meaningfully test the charge rate of the Nexus 7.
[Nexus 7 Q&A, Help & Troubleshooting] BotsOne:
AFAIK The difference between charging via a computer and charging via wall charger is that the data pins are shorted when you plug the usb cable into a wall wart. This lets the device know that it's plugged into the wall and not a computer.

There is a current limiter in the device itself, and if the pins are shorted, it will allow the device to draw power at a higher current, unshort the pins and it will limit the current being drawn so that you don't get a voltage drop on the 5 volt rail in your computer.

Feel free to correct me if I'm wrong.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
Just shorting the data pins isn't enough (this goes for any tablet). I explained this in post #9.
[Nexus 7 Q&A, Help & Troubleshooting] dunneldeen:
My Testing

Results from my testing of the chargers I had on-hand. All measurements were taken by Battery Monitor Widget, on a 95-99% charged battery, after ~10 minutes charging. Readings are estimated milliamps + or - (+ meaning it's charging, - means it is discharging; larger + numbers are best.) Not entirely scientific, but perhaps a clue. Be wary of anything that says it was designed for the iPad.

Charger Configuration +/- mA Charging Indicator

Unplugged with screen mostly off -2mA Discharging

Laptop USB 2.0 port via USB 2.0 hub +145mA USB Plugged / Charging

Laptop USB 3.0 port direct +287mA USB Plugged / Charging

Laptop USB 2.0 port direct +287mA USB Plugged / Charging

HTC (Desire HD) Stock Charger +441mA AC Plugged / Charging

Cosmos 4 port iPad compatible Charger -2mA Discharging

iPhone Stock Charger -2mA Discharging

Belkin 2 USB 3 AC Plug Travel Adapter -2mA Discharging

Nexus Stock Charger +445mA AC Plugged / Charging

Motorola MicroUSB Charger,

(Not USB, came with H17 headset) +387mA AC Plugged / Charging
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
You need to run down your battery more before trying such tests because all devices charge at a lower rate the closer they are to 100%, so at 95% all charging is pretty much a trickle charge and won't show the charging potential of the charger. The mA shown on Battery Monitor Widget also isn't a great point of reference because it would be like trying to calculate how fast you were going for an entire trip based on a single reading of your speedometer. The mA shown will change up and down during charging. The most reliable way to see how effective each charger is would be to run your battery significantly down (I'd say at least down to 75% if not lower) and then see how long it takes to charge back up to 100% (Battery Monitor Widget can tell you this in the history). For reference, it takes me exactly two hours to go from 55% to 100% on the stock charger.
[Nexus 7 Q&A, Help & Troubleshooting] sstuner:
Here is a great link on "How USB charging works, or how to avoid blowing up your smartphone"

http://www.extremetech.com/computin...ks-or-how-to-avoid-blowing-up-your-smartphone

Hope this helps.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
I've read that article in the past and it's not particularly useful. It leads readers to believe that all you need to do is buy a high current charger and your device will instantly use it to its full potential. It doesn't mention at all that different devices can charge at different rates on the same charger, nor does it discuss why.
[Nexus 7 Q&A, Help & Troubleshooting] janedoesmith:
http://xdaforums.com/showthread.php?p=29983624#post29983624
[Nexus 7 Q&A, Help & Troubleshooting] Entropy512:
The Galaxy Tab charger adapter mentioned there is more than what is necessary.

All the N7 wants to see is D+ and D- shorted (as covered before).

The reason Galaxy Tab chargers work is that the method they use (shorting D+ and D- together AND also using resistors so they float at around 1.2 volts) will get detected as a "standard" charger by devices only looking for the standard. The pullup in the device is strong enough to override the resistors in typical Tab chargers.

So:

iPad chargers won't charge Galaxy Tab devices or ones that follow the USB standard (like the N7)

USB Standard chargers won't charge iPads or Galaxy Tabs, but will charge devices that follow the standard (N7)

Galaxy Tab chargers won't charge iPads, but will charge Galaxy Tabs AND devices that expect a standard charger

In addition, the SMB347 has an Automatic Input Current Limit (AICL) feature to reduce current of charger voltage drops. Many of the reports are indicating to me that the AICL is set too strict. Unfortunately, the datasheet for the SMB347 is not public.
[Nexus 7 Q&A, Help & Troubleshooting] mihirdshah1:
I forgot to return the ASUS charger and the USB cable along with my defective replacement 7 to Google. Should I be worried?
[Nexus 7 Q&A, Help & Troubleshooting] kmandel:
Perhaps more than necessary, but will it allow any charger (Apple, cigarette lighter, generic) to charge the N7 at the chargers maximum and show as AC connected to the N7?

If so the $3.40 seems well worth it and avoids hacking up adapters or cables.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
I made that post a long time ago before testing was done on the charging behavior, so my Galaxy Tab example was just that, an example. I had assumed that the Nexus 7 required special signaling to charge at full speed like other tablets. I was wrong, but at the time, no testing had been done.
[Nexus 7 Q&A, Help & Troubleshooting] Ghisy:
I was wondering if I could use my Asus Transformer (TF101) charger to charge my Nexus 7. It seems like it ouputs 2A so it should be fine, right? Thanks.
[Nexus 7 Q&A, Help & Troubleshooting] AZImmortal:
Yes, any 1A+ charger will do with the stock cable because with the stock cable, the Nexus 7 can only draw up to 1A. It's been discovered that you need a micro USB cable with thicker charging wires than the stock cable to charge faster than 1A.
[Eee Pad Transformer General] wontstoptalking:
I just sent this message to Asus:

I love the TF101, but my screen has white blotches on it.

They appeared a few weeks ago. I'm not sure why--I've almost never brought device out of the house, and it has absolutely no damage to it. I've never dropped it or done anything to it that should cause problems.

The blotches are caused by the screen being brighter in some areas than in other areas. There's also light that spills in from the bottom of the screen. I will upload photos that should demonstrate this.

It's difficult to see in the photos, but it is very noticeable when using the device. It's especially annoying when there is a dark background or image on the screen, and it makes it hard to read black text in those areas.

I have done some google searching and discovered that a few other people have been having similar problems.

The device was bought only 6 months ago, so I hope I'm still under some type of warranty. The problem is a lot worse than it looks in the picture.

I'm wondering if you have any service options available for me?

Thanks! It is otherwise a great product, and I'm very happy to hear it is scheduled to receive Jelly Bean.

//end message

Here are two photos of the problem. I'm wondering if anyone here has had similar issues? A google result brought up a few threads, but not many on XDA.

http://imgur.com/a/ujLXs
[Eee Pad Transformer General] entropism:
I had that same issue, and they had to replace my screen under warranty.
[Eee Pad Transformer General] tomoooo:
Have it too. I thought I caused it by accidentally pressing the screen ( even I do not remember doing it).

And it looks like hw fault. GreatI have to look for the bill.
[Transformer TF300T Q&A, Help & Troubleshooting] RTwoD2:
I have been a lurker for over 4 years, but have never run into a problem I could not solve without lots of reading. I unfortunately do not have the 10 post minimum to post in the development forum in this thread: http://xdaforums.com/showthread.php?t=1720980.

I have tried EVERY root method available for PC, but have run into driver issues every time. So now I'm on to trying on my Mac. Only issue is that my tf300 came on .30. Is the method in this thread usable on .30? There is no feedback so I cannot ascertain this. I'd rather try it on my mac before trying to troubleshoot all my issues with the PC methods.

Any guidance appreciated!
[Transformer TF300T Q&A, Help & Troubleshooting] L551:
I don't know about that one, but I used http://xdaforums.com/showthread.php?t=1704209 on my mac without issue on .30.
[Galaxy S III Q&A, (US Carriers)] hahmjt:
i heard fido sim works on rogers GS3 without unlock, is this true?

has anyone tried it?
[Galaxy S III Q&A, (US Carriers)] djnoicatse:
You'll need a micro sim card and yes I've heard from multiple people that it indeed works without unlocking the device.