USB Hubs


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Hey! An oportunity to plug my expandora system!
 
Here is a simple explanation of a complex process to get what you want. I suggest visiting your local hacker space to see if there is someone who can help you. http://hackerspaces.org/wiki/List_of_Hacker_Spaces


1. Find a USB hub you can disassemble and gut the components from.


2. Reverse Engineer the circuit board.


3. Design your own replacement board


4. Solder everything together


I am working toward doing this myself, should I make progress I will certainly let you know.
 
I was thinking of jury-rigging a 2 port hub together that would plug into the back of the pandora and allow me to attach two micro-sized usb devices(the above wifi adapter and flash drive would be awesome together).
I doubt that a single USB port can provide sufficient power for both a WiFi adapter and a flash drive without some external power source.
Copying a psx game to my Patriot 8GB stick while writing this post with a Netgear WNA1000M (both through a hub). Surfing seems to work just fine. I checked the current draw of each and they both never really get above 250 mA while in use. I don't know what the consequences of bumping up against the 500 mA limit are, however.


I am not sure where the current draws for the other wifi adapters on the wiki come from, my adapter sits at 100 mA idle (just plugged in) and uses around 200 mA while transmitting. Checked using cat current_now under the battery in the terminal.
 
I don't know what the consequences of bumping up against the 500 mA limit are, however.
It causes the Pandora to report low battery and then shut down, even when plugged in.
I couldn't replicate this.


Nothing plugged in: -290 mA


Added USB 4-port hub: -440 mA


Added wifi adapter: -586 mA


Added flash drive: -710 mA


Added USB 3.0 HD: -1,264 mA


Added Sony Walkman: -1,300 mA


Unplugged hub: -368 mA


Waited: -298 mA


So I actually see the battery reporting 1 A usage from 4 USB devices plugged in (no external power sources) all while listening to Audacious, with no ill effects.
 
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There doesn't seem to be a current limiter on the USB port.  Overloading it drains the battery really fast, and prevents it from recharging.
 
That's weird, the step-up circuit for 5 V is only designed for 500 mA cont, 750 mA peak. Anything over that should cause bad things to happen. I also kinda remember somebody talking about a 1 A fuse?
 
Interesting.


So is what I just attempted with my expensive and cherished device normally classified as 'stupid'? ^_^
 
I don't know what the consequences of bumping up against the 500 mA limit are, however.
It causes the Pandora to report low battery and then shut down, even when plugged in.
I couldn't replicate this.


Nothing plugged in: -290 mA


Added USB 4-port hub: -440 mA


Added wifi adapter: -586 mA


Added flash drive: -710 mA


Added USB 3.0 HD: -1,264 mA


Added Sony Walkman: -1,300 mA


Unplugged hub: -368 mA


Waited: -298 mA


So I actually see the battery reporting 1 A usage from 4 USB devices plugged in (no external power sources) all while listening to Audacious, with no ill effects.

That's weird, the step-up circuit for 5 V is only designed for 500 mA cont, 750 mA peak. Anything over that should cause bad things to happen. I also kinda remember somebody talking about a 1 A fuse?

That's not 1A off the USB though, that's 1A off the battery, depending on the voltage of the battery and the efficiency of the 5V power supply in the Pandora, more like 500 - 700 mA.


Lets say the battery is at 3.8v, so you are getting 3.8 x 1 = 3.8 watts. 3.8 watts / 5 volts is 760 mA, 760 * 0.9 (10% inefficient boost converter to get 5 volts, just a guess) gives us 684 mA off the USB port. A little over our limit, but should still be within the chips capabilities maybe with some voltage sag (4.9v instead of 5v). USB 5 volt voltage is allowed to be within 4.75 and 5.25 volts.
 
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Thanks for the clarification.


I would also note for the record that the hard drive was blinking the whole time, when normally the light on it stays solid shortly after plugging it in... I didn't try to copy anything to or from it, but I am guessing it wasn't getting enough juice to be usable.


// Back to the original topic ==>
 
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Stick your ear to it, you will either hear a hum, or clicking and it struggling to spin up. My drive will do that on my laptop, but not my desktop.
 
TheGrandPubaa
AIUI this should fit your needs, but might block the right trigger button.

That looks interesting, but it would definitely block the shoulder button. Also, it uses the OTG port, which would free up the main USB port, but would it provide enough voltage to run a flash drive?
 
Any usb-hubs and usb lan adapters from ebay that's worth to mention? [with links please :) ]
 
^ I would imagine that most of the ones on eBay are actually just being drop-shipped from DealExtreme. At least, that's been my experience of looking for such things. :p
 
These work with Pandora:


http://www.dealextre...sb-2-0-hub-7980


http://www.dealextre...hub-black-31667


http://www.dealextre...mallest-hub-468


http://www.ebay.com/...e-/330526418797


They all support a (not included) external power supply. The all have the same product and vendor ID.


The last one from Targus incldes a USB splitter cable that can use power from another USB port. I use it with an USB wall charger.


I also have the Griffin Smartshare USB and these hubs are generally better as some devices I have (USB Ethernet adapter) don't work with the Smartshare. Using a very short USB cable (or adapter) these little hubs use less space than the Smartshare. And in my case it also flips the USB ports to the correct side up.


You also can get away with a higher USB load if the charger is plugged into the Pandora.
 
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