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Why Don't PDAs and Cellphones Use USB?
evolutionaryLawyer asks: "I have a RazrV3 phone and the charging interface is USB. This means if my cell phone is dying I get to pull a USB cable out of my bag, plug it into my laptop and charge it wherever I am, and at the same time data transfer is possible. This got me to thinking, why do all these cellphones, PDAs, and other devices use funky data and power interfaces when USB 2.0 is capable of providing both data and power in a universal format? I cannot think it is to sell cables, because I am sure they lose a lot of that to 3rd parties, not to mention that it has to be more expensive to design and manufacture these proprietary formats. Look at the PSP, it has both a power port, and a USB 2.0 port. Why shouldn't they cut out one?" While such a question is better asked of the cell phone manufacturers, it is unlikely that the average consumer would be able to get a straight answer. Can you think of plausible reasons as to why companies might be bypassing usable standards for their own proprietary cables, especially given the fact that there are third-party cables out there for just about every make and model of PDA or cellphone?
By not putting standard interfaces on, people are forced to pay for ringtones, where if they had USB, they could just drag a MIDI right to the phone.
Nothing for you to see here, Please move along.
Basic and simple answer, USB adds complexity. If the phone had only a USB plug, it would have to be a USB host to be able to allow things like corded headsets and such to attach. Then the headsets would have to be more complex, going from somethign that just passes analog data over the right pins on the connector to a full digital headset.
Power wise, USB really can't do more then 500mA of power at 5V. This is fine for cell phones like my T610 that get 450mA from the official charger at 4.7V. But for devices like the PSP, it would mean 4 times as long to charge, as the PSP power adaptor pushes out 2A or power at 5V.
It's 500mW max iirc, which is enough to keep most portable devices running, but would make charging really slow.
If they were to go to a standard connection Firewire might be nice at 12-60Wats.
But in the mean time, they'll generally use custom connectors for charging.
"The worst tyrannies were the ones where a governance required its own logic on every embedded node." - Vernor Vinge
On the contrary, you could use 1 outlet -> USB converter for all of your devices, instead of having a bulky power adapter for each of them.
And who says that you need to have both adapters?
From http://www.usb.org/developers/usbfaq/#pow1
1. How much power does a system in S3 need to supply to USB?
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A: 500mA per USB port. See section 7.2.3 for the details of device behavior during suspend and resume.
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Presumably this has something to do with it. HTH. HAND.
Camera phone? Take all the photos you like, but it's X cents per photo to get them of your phone. Address book backup? Sure, it's only X dollars a month for automatic backups! Want games on your Java enabled phone? Sure, we have a selection here for $4.99 per game per month (sorry, you can only select from this menu). Want some GREW games? We have those too (sorry, you can't code your own, BREW is proprietary).
Handset manufacturers would love to put these features in for users, but they don't because then the cell phone companies won't sell the phones and wont support them if purchesed through other channels.
jX [ Make everything as simple as possible, but no simpler. - Einstein ]
I also have a V3, and its USB power can only be used to "top off" an already existing charge. if you ever get the phone to a dead state, a USB port is useless. The usb charging doesnt begin until the software in the phone requests power from the port.
another problem, is that to charge a dead phone you need a motorola(TM) razr(TM) usb charger, which arent very redily available yet.
another problem is that a USB port cant provide enough juice to both charge the phone, and make a call. if you talk on USB power, your phone will eventually go into a totally dead state (see above for how fun that is).
yet another problem, is that file transfer over USB isnt possible (it might be with additional software). I can exchange ringtones and pictures only via bluetooth, and can sync a phone book only with USB. totally wierd.
usb provides the power specification, the cell phone would conform to the USB spec instead of the other way around.
That being said, the RazrV3 has the OPTION of charging off of USB. If the phone is dead it WILL NOT. This is because USB needs a signal negotiation before it will deliver the higher power available on USB 2.0. If the phone is dead, such negotiation is impossible. This is part of the reason that it's not done on more models.
Strangely, my Razr didn't come with a USB cable. It came with a regular wall plug. I don't need the USB (all my computers have bluetooth), but I was kind of surprised by this.
There are problems with USB 2 when it comes to power. What do you get, 5v, 500ma? Not enough to do much with. True, there are devices as large as flatbed scanners that can run entirely off this power, but it's not much.
If you try to come up with USB 3, however, and specify that it should supply more power, the problem will be that maybe the computer can't supply that much due to its power supply and requirements, etc. Which brings me to the next point: USB 3 should have some sort of specification that says a computer can decide how much power to supply through USB, based on factors like its own power usage. Then, when you plug in a device, it would automatically figure out if it has enough power or not, and perhaps a message could pop up on the computer, telling you that you're trying to overload the USB power supply.
Of course, then you'd have to take into consideration the gauge and insulation of the USB wire itself, and you'll end up with the need to put a tiny chip into compatible wires which would tell the computer what the max current carrying capacity of that cable is rated at. This all sounds quite complicated, but there's no reason why a computer can't push more power out of a USB port if all these things are taken into consideration, and all the proper power handshaking takes place from the USB port down the chain (if there are hubs, etc. in the way) all the way to individual devices. Also, you're probably not using all devices in max-power-usage mode at the same time, so the devices might talk to each other and enter power-save mode when necessary to allow other devices to be used.
This seems, again, like a very complicated solution looking for a problem, but it shouldn't be too difficult to do for next-generation USB devices, and the advantages are pretty big: Right here on my desk, I have a 6-outlet strip that isn't enough. Currently plugged in are my laptop, Mac Mini, 17" display, ethernet hub, and printer; These are just the computer peripherals. I also have, in the same area, a phone charger, small television, desk lamp, and DVD player. I need a USB hub for the Mac Mini because there simply aren't enough ports on it for all the crap I'd like to have plugged in at one time; therefore, I have so far refrained from buying a USB hub. There are not enough outlets on this wall to handle all of this. If I add another strip, I'll probably blow a fuse if all of this is on at the same time. A new USB protocol which takes into consideration a whole range of power options, negotiated in real-time by the devices themselves as they are plugged in, used, and removed, and taking into consideration the power-supplying capability of the computer, the capacity of the wires themselves, and the usage of the devices, really offers an opportunity to remove many plugs from many devices that would otherwise need them, and to greatly reduce the number of wires running across and under many desks; This would require more careful engineering by already-overworked electronics engineers who are concerned about power consumption, but I believe that with added innovation, increased customer demand for this kind of service, and the advances made each day in semiconductors, this will provide so much value for the consumer that it's worth it.
The restrictions on phones over in the US is ridiculous. I got an NEC e616 flipphone in February with all the goodies (dual video cameras, mp3, video calls, 3G network @ 384Kbps) for just under $200 Aust with 3 Mobile. It includes a USB cable and there are no file restrictions on this phone other than content bought through the 3 services (music videos, etc) cannot be copied or moved. And the calendar automatically synchronises over the 3G internet connection with my PC. American mobile carriers are an absolute joke, simple as that.