Using Apple high power charging?

[mjmfilms]

Hey all,

I've been getting the "your phone is using more power than the charger can provide, please switch to a wall outlet" message a few times, which got me thinking. My old iPhone (and iPads) can negotiate with my mac for a full 1100 mA of power, over the 500 mA that a USB port normally gives. The increased juice is what makes wall charging so much better.

Is there any way to hack this ability into an Android phone, specifically the Thunderbolt?

Some reference I've found:
Apple and other USB charger secrets
Powering Apple and third party peripherals through USB

Thanks all! Really love reading the posts on here.

 

[nkk]

This is all IIRC, so forgive me if some of this is off. I have not read the USB spec sheet in a while

USB cords have 4 pins, 2 data (D- and D+) and 2 for current (I- and I+). Normally I+ carries 3.7 V and I- -1.7V for a total of 5V on the I line.

The way it works after you plug in the usb cord is:
I+ to 3.3V @100mA by the host controlled by a current limiting chip

The device (your phone in this case) then can draw up V on one of the lines (forget which) to request 1000mA or do something else (leave it or draw down, again I forget) for 500mA. It can also request 100mA. Note that many computer ports will not provide 1000mA (this could be your problem right here)

The host says ok, and limits the current to that amount. The power lines are then set at their voltage (3.3 and -1.7), current is limited, and everyone is happy.

Device sends its info to the host (is it a usb stick, external signal processor of some sort (think a digital to analog convertor like in any mp3 player of your phone), phone, etc)

I do not know what of this is hackable easily, so a dev would have to answer.

I do see that that first article sort of tries to explain it. I think it is mostly wrong, but then again I could be wrong. Heck, I could be thinking of a totally different spec entirely. letme check on this for you and get back.

-Nkk

 

[dm33]

This is all IIRC, so forgive me if some of this is off. I have not read the USB spec sheet in a while

I haven't read the details lately, but my understanding is that its all non standard usage of USB.

Apple has a mechanism to request higher power. 1000ma from a port for iPhone. iPad can request 2000ma. Most current Macs can send 1000ma. Only the recently updated Macbook Pros can supply 2000ma.

HTC has their own but different mechanism for requesting higher power. It can also request 1000ma. The HTC wall charger supplies 1000ma (1A). The HTC approach is incompatible with the Apple approach.

 

[dmunz]

Along these lines, if you have an iPad can you use the larger Apple adaptor to charge the TB? Or will the TB wall adaptor work on the iPad? Both without damaging the device of course.

It would be nice as a trael option to only carry one wall adaptor.

FWIW
DLM

 

[drewcam888]

standard usb ports on windows computers only output 500mA this is a limitation of the usb port controller.

 

[LoyalServant]

Standard USB period doesn't allow it.
Apple toyed around with USB... technically it's not standard USB.
There were some battles about this some years back.

It's not worth trying to mess with it IMHO.. and it can get dangerous for device, computer and user.

 

[mjmfilms]

If there was a way to activate the high power, though, what would be dangerous about it? Both devices can handle the 1000ma, which is provided with the same mechanism as the normal 500ma but just at a higher amperage, right?

Would be great to find a way to activate it..

 

[drewcam888]

The computer can't handle it without possibly firing the usb controller. It isn't possible on a Windows PC.

 

[LoyalServant]

If there was a way to activate the high power, though, what would be dangerous about it? Both devices can handle the 1000ma, which is provided with the same mechanism as the normal 500ma but just at a higher amperage, right?

Would be great to find a way to activate it..

It's not in the specification.
Universal Serial Bus - Wikipedia, the free encyclopedia

A unit load is defined as 100 mA in USB 2.0, and was raised to 150 mA in USB 3.0. A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0

Apple changed their hardware so that it communicates with other Apple devices.
The USB hub in a non-apple computer is simply not capable of supplying the power to the external device, because it's going to follow the USB specification that Apple does not follow.. they make their own rules.

This is also a hardware + software change.
It's not worth messing with the hardware to support it and it's likely not something that us hacker types can implement in software either.

My disclaimer about damaging something still stands.. improperly charging any battery can cause it to explode or burn you.
You can also damage the host device or the device to be charged.

USB 3 has a charge mode that can deliver the current.. it will be in computers and phones before long

 

[dm33]

I'm not sure about the Apple approach. I wouldn't be surprised if its pretty sophisticated and involves checking device ids. Basically real protocol and communication going on.

The HTC approach is electrical. No smarts to it. Something about tying the middle two USB lines together.