jsigmo
Well-known member
- Jan 22, 2012
- 176
- 2
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OK. My phone does seem to work great with an external keyboard. It even works if I use an old 7 port powered (wall wart) hub. So I figure I could have a keyboard and an external HDD that draws power from the USB port connected. I need to try that this weekend.
Now here's the kicker:
I'd love to have the phone's battery be charged from the powered hub while I've got various external devices plugged in. That would provide something like having a "dock" arrangement except that the display would obviously still just be the phone.
To do this, I'd need to get into the hub and rewire it so that the USB port that the host device (in this case, the phone) plugs into receives power from the hub's 5V supply. As it is, of course the hub only provides power out all of the slave ports which makes perfect sense.
My question would be: How does the phone determine whether it is going to supply or use power from a device plugged into its USB port? Obviously, the phone charges fine whenever I plug it into my PC or any of the various chargers. And those devices presumably do nothing more complicated than supply 5V on the 5V line in the USB interface.
The chargers are not "smart" in any way. It's the phone that's doing all of the decision making, and the battery probably contains a battery management IC that controls charging.
So I'd like to rewire my old hub and then see if it'll charge the phone while in use. But I'd rather not let the magic smoke out of the phone. And even if it doesn't do any damage, one wonders if the phone would go into "slave" mode if it sees power coming from the USB port, but puts itself into "master" mode when it doesn't. Hopefully it's more complex and subtle and would let me do what I want.
I'd just like to be able to leave the phone connected to a keyboard, mouse, and hard drive for long periods and not have its battery die in the middle of things.
Who knows? Maybe there's already a USB hub thing that's designed to do just this.
Now here's the kicker:
I'd love to have the phone's battery be charged from the powered hub while I've got various external devices plugged in. That would provide something like having a "dock" arrangement except that the display would obviously still just be the phone.
To do this, I'd need to get into the hub and rewire it so that the USB port that the host device (in this case, the phone) plugs into receives power from the hub's 5V supply. As it is, of course the hub only provides power out all of the slave ports which makes perfect sense.
My question would be: How does the phone determine whether it is going to supply or use power from a device plugged into its USB port? Obviously, the phone charges fine whenever I plug it into my PC or any of the various chargers. And those devices presumably do nothing more complicated than supply 5V on the 5V line in the USB interface.
The chargers are not "smart" in any way. It's the phone that's doing all of the decision making, and the battery probably contains a battery management IC that controls charging.
So I'd like to rewire my old hub and then see if it'll charge the phone while in use. But I'd rather not let the magic smoke out of the phone. And even if it doesn't do any damage, one wonders if the phone would go into "slave" mode if it sees power coming from the USB port, but puts itself into "master" mode when it doesn't. Hopefully it's more complex and subtle and would let me do what I want.
I'd just like to be able to leave the phone connected to a keyboard, mouse, and hard drive for long periods and not have its battery die in the middle of things.
Who knows? Maybe there's already a USB hub thing that's designed to do just this.
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