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4 port USB hub, 900ma per port

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EniGmA1987
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Default 4 port USB hub, 900ma per port

I came across this hub:
http://www.monoprice.com/products/pr...t=1#largeimage

Looks pretty nice, all USB 3.0 ports, capable of supplying a 900ma of power to each port. Good for all sorts of things, not just a tablet being connected to the computer.



What I was wondering about this is would it be possible to open it up and short the data pins so that it is only capable of being a charging device? If so, it probably wouldnt even need a connection to a PC, just need to be plugged into the power adapter. I am wondering on this because if possible, that would mean when only using 1 port it (theoretically) would be capable of sending 3.8A out to the one device if the device tried to pull that much. Since the tablet would see the shorted connection it should at least try to pull 2A. Anyway, I just thought it would be a fun project to try and modify in this way. I will probably get it soon and attempt this myself, and might even look into beefing up the internal power circuit area to make sure it can safely send 3+ amps out one port if asked to. It would be nice to use this in conjunction with a pogo connector and finally be able to charge faster than the tablet drains while gaming.
 
3DSammy
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Quote:
Originally Posted by EniGmA1987 View Post
... Looks pretty nice, all USB 3.0 ports, ...
Nexus 10 USB specs "microUSB v2.0"
http://www.gsmarena.com/samsung_goog...p8110-5084.php

Would you get value from USB 3.0 ports with a USB v2.0 interface?
 
skally
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To get the full USB 3.0 power of 900mA, the device has to be configured as a USB3.0 device. The hardware developer USB 3.0 command verifier tool is separate from the USB 2.0 one

I thought we had also verified the USB connector and the POGO connector are mutually exclusive in power terms, even if the charging circuit inside the Nexus 10 could be modified to accept more than 2.5A.
 
EniGmA1987
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(Last edited by EniGmA1987; 20th February 2013 at 05:43 AM.)
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Originally Posted by skally View Post
To get the full USB 3.0 power of 900mA, the device has to be configured as a USB3.0 device. The hardware developer USB 3.0 command verifier tool is separate from the USB 2.0 one

I thought we had also verified the USB connector and the POGO connector are mutually exclusive in power terms, even if the charging circuit inside the Nexus 10 could be modified to accept more than 2.5A.
Sorry, I dont scour the threads in accessories every day so thats news to me. Besides, I dont even know what "mutually exclusive" is supposed to mean in relation to this. If the pogo connector has a USB end and draws 2A from the power adapter, why wouldnt it be able to draw 2A from any source capable of putting out that much power? Your trying to tell me that the pogo connector somehow signals it is a USB2.0 device? If thats the case it wouldnt be able to draw more than the 500mA. The regular power adapter has a USB output connector after all and it can send 2A just fine. This hub has its own power adapter and doesnt try to draw the full 3.8A through a computer connection. What is the difference between the power adapter that comes with the tablet and a hub that has its own PSU to output that much and more power?



and yes I know it wouldnt transfer at 3.0 data speeds since the tablet has a 2.0 port, but I wouldn't be using the USB port on the tablet. But why would the USB somehow signal that it will only send 500mA through the pogo connector?
 
skally
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Originally Posted by EniGmA1987 View Post
Sorry, I dont scour the threads in accessories every day so thats news to me. Besides, I dont even know what "mutually exclusive" is supposed to mean in relation to this.
Mutually exclusive: charge from POGO or USB, but not both at the same time

Quote:
Originally Posted by EniGmA1987 View Post
If the pogo connector has a USB end and draws 2A from the power adapter, why wouldnt it be able to draw 2A from any source capable of putting out that much power? Your trying to tell me that the pogo connector somehow signals it is a USB2.0 device? If thats the case it wouldnt be able to draw more than the 500mA. The regular power adapter has a USB output connector after all and it can send 2A just fine. This hub has its own power adapter and doesnt try to draw the full 3.8A through a computer connection. What is the difference between the power adapter that comes with the tablet and a hub that has its own PSU to output that much and more power?



and yes I know it wouldnt transfer at 3.0 data speeds since the tablet has a 2.0 port, but I wouldn't be using the USB port on the tablet. But why would the USB somehow signal that it will only send 500mA through the pogo connector?

The POGO connector, although it connects to a USB port, is not bound by the USB specification for how much it can draw. USB chargers are available that can deliver up to 3A, but it's up to the device to request this much power.

The specifications for USB 2.0 of 500mA (and 900mA for USB 3.0) are for a power and data connection, but their is an added specification for power only of 1.8A (and 5A for USB 3.0). a hub will generally adhere to the power and data specification, while the USB PSU has no data functionality (this is determined by their being a short circuit on the D+/D- USB pair).

The reason a USB 2.0 device will not draw 900mA from a USB 3.0 port, is because it's the device that negotiates the connection, and as a USB 2.0 device, it will only request the 500mA maximum from the USB 2.0 specification.

Try to think of it this way: an incandescent light bulb will not be any brighter if you increase the power source current.
 
EniGmA1987
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Ok, but you just said everything I was talking about. So when I modify the hub to get rid of the data connection, and not even connect it to a computer and just have its power supply connected, how would that be different than simply a normal charger? The tablet would be charging through its pogo connector, and it simply plugs into the hub with a 3.8A power supply. So it wouldnt have anything to do with any USB limits then right? Cause the hub is USB3.0 ports capable so it is not like a USB 2.0 hub that wouldnt have the proper internal circuitry to push the 3.8A I will be trying to draw.
 
skally
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Originally Posted by EniGmA1987 View Post
Ok, but you just said everything I was talking about. So when I modify the hub to get rid of the data connection, and not even connect it to a computer and just have its power supply connected, how would that be different than simply a normal charger? The tablet would be charging through its pogo connector, and it simply plugs into the hub with a 3.8A power supply. So it wouldnt have anything to do with any USB limits then right? Cause the hub is USB3.0 ports capable so it is not like a USB 2.0 hub that wouldnt have the proper internal circuitry to push the 3.8A I will be trying to draw.
If you short the D+/D- pins, you can then use the hub as a standard charger PSU, capable of delivering 3.8A.

The issue is that current gets pulled, not pushed. It doesn't matter how many Amps you provide, the Nexus 10 charging circuit is only capable of pulling a maximum of 2.5A. (datasheet for the charge circuit can be found here).

From earlier posts (in one of the POGO threads, I think), there were found to be kernel limits restricting the SMB347 charging to 2A.

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