USB Hub Annoyance

[Black Aeronaut]

You would think that a self-power USB 2.0 Hub would be capable of charging an iPod while not connected to a computer.  Honestly, I don't see any difference between a hub and the little USB-AC Outlet adapters that you see all the time now.  Anyone got any hints?  Know of a USB hub that will do the job?  I've googled around a bit and I see hints about power control chips, but I can't see how not being connected to a computer would affect that when the hub is self-powered!

[Sweno]

I'm not certain, but I would break out the volt-meter and check that you are getting the proper 2.5 volts across the data pins when it's not connected to a computer (or the computer is turned off)

AFAIK The power control chip stuff is for:

a) tricking the ipod into thinking that it's plugged into a computer

b) getting the ipod to safely accept higher voltages for faster charging.

but neither of these things should affect you.
-Terry
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"so listen up boy, or pornography starring your mother will be the second worst thing to happen to you today"
TF2: Spy

[bmull]

Here's a site with more information:  http://www.ladyada.net/make/mintyboost/icharge.html
As sweno said, if there is not voltage, and the correct amount, across the data pins the ipod won't charge.

[Sofaspud]

Add in the fact that quite a few if not most powered USB hubs expect a live PC to be connected and shut themselves off to save power (assumption on my part, there) when the PC shuts off.  It's not a bug, it's a feature!
Really.

--sofaspud
--"Listening to your kid is the audio equivalent of a Salvador Dali painting, Spud." --OpMegs

[Black Aeronaut]

Hrmph. Maybe I should talk to my Dad about puting together a hub... one that has a switch that gives you the option of full-time power or auto-power, and has all the appropriate innards to charge any ipod/iphone. Pretty sure he wouldn't mind having a little something like that to slap a patent on, as I have never seen a USB 2.0 Hub with a power switch.

[LynnInDenver]

Add in the fact that quite a few if not most powered USB hubs expect a live PC to be connected and shut themselves off to save power (assumption on my part, there) when the PC shuts off.  It's not a bug, it's a feature!
Really.

Most of the problem is that there is the Energy Star rating... which if you want to put that 'green friendly' label on your device and ensure the sandal wearing set will buy it, you have to design it so that those of us who want to recharge our USB devices are forced to rely on the computer being on... with the increased amount of websurfing going on.
I've been half tempted to go out and track down one of the wall warts you get with a phone that plugs into the phone's quite standard USB jack.
--

"You know how parents tell you everything's going to fine, but you know they're lying to make you feel better? Everything's going to be fine." - The Doctor

[Black Aeronaut]

JFerio wrote:

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Sofaspud wrote:

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Add in the fact that quite a few if not most powered USB hubs expect a live PC to be connected and shut themselves off to save power (assumption on my part, there) when the PC shuts off.  It's not a bug, it's a feature!
Really.

Most of the problem is that there is the Energy Star rating... which if you want to put that 'green friendly' label on your device and ensure the sandal wearing set will buy it, you have to design it so that those of us who want to recharge our USB devices are forced to rely on the computer being on... with the increased amount of websurfing going on.
I've been half tempted to go out and track down one of the wall warts you get with a phone that plugs into the phone's quite standard USB jack.

Huh.  Ironic, ain't it?
Well...  iPods and iPhones are unique in that they gotta talk to a chip inside a USB to make sure they get a proper charge, yes?  Think there might be a way to take advantage of that and tie that into the auto-off feature?  The idea is this: you have a USB Hub with several devices plugged in: an iPhone on port 1, a flash-drive on port 2, a USB Hard Disk Drive on port 3, a camera on port 4, and a iPod Classic on port 5.  Computer powers off, but the Hub would recognize that it still has an iPhone and an iPod on ports 1 and 5, and thus keep those ports (and those alone) powered via its own power supply.
Bonus points if we can get standard-firmware PSP and PSP-Go to charge in such a manner as well.
  

[Sweno]

Well... iPods and iPhones are unique in that they gotta talk to a chip inside a USB to make sure they get a proper charge, yes?

Nope. An iPod/iPhone/iPad will charge if it gets the standard 5v (it should tolerate 4.75 to 5.25) on the power pins and 2.5v across the data lines.

If you want to charge that iDevice faster (safely step the voltage up to 12v across the power pins)? Or transfer data? Or act as an external control interface?

Then we can talk about control chips.

But you can build a charger for an iDevice into a altoids tin with standard batteries, wires and resistors. No Chips needed.

edit: and it looks like i was wrong, you don't even need the 2.5v across the data lines:

http://www.instructables....arger-in-an-Altoids-tin/

So my guess would be an echo of what spud has said. A power saving 'feature'.
-Terry
-----
"so listen up boy, or pornography starring your mother will be the second worst thing to happen to you today"
TF2: Spy

[Wiregeek]

Edit again, Sweno, 'cause you're wrong again. You do need the 2.5v across the d-lines, that instructable will a) not charge an ipod, and b) not charge any given device for shit.

As a comparison, you are gonna get 600mah out of that circuit (in Physics Experiment Land). The battery on my cell is 2300mah, my PDA is 3300..

Hmm.. my truck is 700000mah. neat.
"No can brain today. Want cheezeburger."
From NGE: Nobody Dies, by Gregg Landsman
http://www.fanfiction.net/s/5579457/1/NGE_Nobody_Dies

[Black Aeronaut]

Well, that would explain why an iDevice needs a control chip to charge - on the scale that USB works at, that's a serious amount of juice (small wonder stuff like this jacks up your electric bills over time).

Okay, so the USB Hub would have to be 'hardy' enough to handle the kind of demand that multiple high-drain devices would place on it. This would be why most hubs have their own power supplies to begin with.

One other question: what do we know about these control chips in question? Specifically, how many ports can one control and what is its physical dimensions? If it is limited to just one or two ports and the chip is the size of a... dime I guess, then I might wnat to offset the size by including more than the usual four ports. How many ports would you think are too many?

[Rod.H]

Hmm, well I know my iPad won't charge off the USB ports my PC has, it syncs fine just forget about doing any serious charging. It's the main reason for me to always have my iPad charger (~10W USB power brick) in my bag when ever I travel with it. I think I can also charge some other USB devices with it, iPod/iPhones for a start.

As for USB charging a PSP, well a USB to the PSP's 5v DC port adaptor as seen on many a third-party accessory makers' PSP datalink cable is the easiest starting point. Even if the PSP does now support USB charging via its USB data port, it's something I don't trust.

I swear I've seen someone offering a USB hub with power switches controlling individual ports, at the time I'd considered it a folly like those xbox huge USB hubs with 100+ ports.

--Rod.H
"Ah, the PSP! The one 'true way' of enjoying a JRPG! In public, too!"

[Black Aeronaut]

Rod, seen some of those 100+ monsters over here in Japan. Part of why I was thinking of it.

I can only imagine the sort of rats nest of cabling that generates.

[Rod.H]

Ah knew I'd seen a switched USB hub recently I saw it here. According to that page BA should be able to find 'em in a local tech shop as it's a local product. As for the 100+ USB hub the only thing close I've found in my search is a 80 USB port test rig.

Still there's always this mob who are trying to sell power-points with USB charger ports built in.