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Handset Vendors Plug Micro-USB Charge Ports
ketan324 points to a Register story touting an agreement among several phone makers to settle on Micro USB for their phones' charging ports, writing "It's about time for these cellphone manufacturers to wise up and design a universal phone charger. Although many manufacturers have already 'standardized' to a mini-USB interface, there are many more out there who use proprietary adapters. I wonder how Apple will feel about this? Will they finally realize that their oh-so-special adapter is nothing more than a fudged USB interface?" No legislation required.
Often the standard USB current isn't enough to charge a device, so you must install a driver which does nothing more than increase the USB power output.
-- Ed Avis ed@membled.com
No, USB Vcc is +5 volts.
Per the USB spec, the device isn't supposed to draw more than 100mA from the port without authorization from the computer.
If I have nothing to hide, don't search me
iPhones don't need RGB or S-Video
They do if you have movies on them, and want to output those movies onto a TV screen. People probably don't do that very often, but you can do that.
Audio input and output do not (or at least should not) use the same plug as power/data (otherwise you can't charge your phone and use the headset at the same time).
iPods and iPhones have 2 different audio outs-- one being the headphone jack, which on the iPhone can also be used for headsets. So you can use that headphone jack while charging. The other audio out is in the dock connector, and it makes it so you can drop the iPhone into the dock and have the dock connect to a stereo. If not for that audio out, you'd have to drop it into the dock and then plug an additional cable from your stereo into the headphone jack.
Not only would that be slightly annoying and inconvenient, but it's my understanding that the audio from the dock is also handled differently than the headphone jack. I'm not a real audiophile, so I don't remember what the deal is, but it's something like the dock connector not running the audio through the iPhone's built-in amp. The idea is you're going to feed it into a stereo and have volume control through that stereo anyway, so it shouldn't need to deal with that. Instead you (supposedly) get cleaner audio out to your stereo.
It's a line level signal as opposed to headphone level signal. There's a difference. If you're running the signal through an external amplifier, you want line level.
In Linux, it seems like the power negotiation is part of the USB driver, not the specific device driver, since every device should do that the same way.
(So, even if there is NO Linux driver, or with the driver not loaded, the power negotiations can occur)
Which is a good idea, really.
If I have nothing to hide, don't search me
It's not about not charging, it's about charging slowly.
Stupidity is the root of all evil.
Clearly Motorola is either (a) being careful to comply fully with the USB spec, or (b) being dicks.
I would say there's about a 50/50 chance of each.
Though I've got no actual hard evidence to back it up, I seriously believe there's some sort of ultra-cheap DRM built into the chargers and phones to prevent you from buying reasonably priced travel/home replacement chargers.
It APPEARS that the difference is that some USB chargers put out 5.2 volts instead of 5. The phone likes 5.2V. It doesn't appear to like the 5V, but I think it is charging ok anyway. I've never run it down far enough to know for sure, so I can't swear that it does.
Everything else I charge on both warts charges ok, so I just swap the two if the green light on the phone doesn't come on.
The "Cheap DRM" is almost correct, the issue is that the "OEM Motorola" chargers have a resistor between pins 2 and 3 (center pins) of the mini USB plug, no USB communication (from a computer), or resistor and the phone wont charge.
Aaron Z
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote
You certainly can pull 500 mA from a port without the device asking politely, but it won't be compliant with the spec. From the USB 2.0 spec, 7.2.1, "Devices must also ensure that the maximum operating current drawn by a device is one unit load (100 mA), until configured."
The 5.0 V rail, VBUS, does not monitor the sourced current, making sure that no devices are drawing more than what they've politely asked for. The current limiting is done to protect against a direct short, often limiting a single port to 1 A (or more for ganged ports higher)