Slashdot Mirror
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?
Most phones also also have an rs-232 serial connection and some of the other pins are used for the initial programming (data lines to the eeprom?). If the phone just needed power and usb, I would agree that the proprietary connector should be avoided.
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
From http://www.usb.org/developers/usbfaq/#pow1
1. How much power does a system in S3 need to supply to USB?
----
A: 500mA per USB port. See section 7.2.3 for the details of device behavior during suspend and resume.
----
Presumably this has something to do with it. HTH. HAND.
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.
Cell phone companies sell the phones to cellular carriers, who resell them at a loss (at best breakeven on a cheap phone). Perhaps at the beginning of life on an exclusive hot phone the carrier might make some money, but most phones are sold at less than the company paid for it. Accessories (and contract replacement phones are sold at a huge markup (>50% or more) to offset some of the initial loss on the phone. If the end user can buy cheap accessories for their new phone from a third party, the cellular company is out even more, hense the non standard connectors.
If you don't believe me, go find one of Nextel's SEC filings such as this one, go to page 54 and do the math yourself. Nextel paid $2.0 billion for handsets and accessories in 2004, and sold them for $1.4 billion. (The second line relates to an accounting gimmick Nextel previously used to minimize this cost). The three following explanatory paragraphs explain that the handsets are subsidized, but accessories are sold with gross margin (not subsidized).
Nextel's subsidies might be larger than other phone companies (due to only a single supplier), but all of them sell phones at a loss.
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
One specific example would be Verizon's crippling of the Motorola V710 .
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.
I've seen about four posts saying this in this thread - and I'm browsing at +5.
Don't you guys have IrDA?
I'm in the UK, and pretty much every GSM phone I've come across in recent years has an IrDA port to connect to your laptop.
You can then go to the manufacturer's website and get a 'handset manager' program (aimed, I gather, at companies who want to give thier employees identical phonebooks and suchlike). You can then use the IR link to download and upload images, ringtones, operator logos (back when they existed), text messages, and phone books.
Does the US not have this?
Michael
"Goodness me, how unlike the FBI to abuse the trust of the American public." -- The Onion
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.
Not as common on larger devices, but it is found increasingly in small devices like digital cameras.
A few phones, but they're mostly (if not all) GSM phones, which constitute (my guess) a little less than half of the US market. They tend to be higher-end models and smartphones (although my cheap T300 had IR.) Bluetooth is more common.
You can then use the IR link to download and upload images, ringtones, operator logos (back when they existed), text messages, and phone books.
At least on my Sony Ericsson, you didn't need any special software to transfer files or individual phone book entries. With the right software, you could back up the phone book and SMS boxes completely.
I wanted to be able to transfer data off of my cell phone. I also wanted to be able to add my own ring tones.
I found a phone that let me do this. I got the MPX220 smart phone. This phone connects through USB both for charging and data tranfer. I just plug in and drag an mp3 or midi to the phone and I have a new ring tone. My phone also plays music. I have minor complaints about some of the software but overall I'm very happy with this phone.
Stop whinning about your phone. Get a better one. Phone you want is out there. If you look around you can even get phones like this free with a two year contract.
The RazrV3 is for people who want style more than functionality.
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.
I have a really cool 5 port 10/100 Switch with Uplink that come out-of-the-back with both a 5V DC plug & and cool little USB to DC plug.
So you can power it off the mains or if out in the field from the USB port on a laptop, I even powered it off my iRiver IH340. Which was pretty cool.
I just wish this could be done on all devices.
I work with Shitty Palm Zire 21,Zire 71, Zire 72,Treo 600, T3 & T5..., all with different power supplys and USB leads its a fucking joke....