Re: Do they make a Motorola RAZR 5-pin USB 2.0 to mini-USB cable?

That's correct. But it's the wrong question. The USB-A side is only four pins so a cable with a five pin Mini-USB plug will have only four wires, there's just no place for the fifth wire to connect. Unless it's a cable specifically designed to solve the Motorola problem.

On the Motorola chargers, it's a five wire cable into the charger where the resistor is located.

Try this cable: .

Have you contacted Motorola to find out /exactly/ what cable is needed?

I believe the resistor is needed to "clue" the power supply that something that "wants" to be charged is connected.

Cables are cheap. I'd buy one and see what happens.

By the way, the USB-cabled charger for my Samsung cell phone will also charge my Garmin GPS. Very handy.

I'm confused because I just tested a "normal" cable and this was my observation:

Motorola RAZR V3 connected to wall-wart USB charger --> fail Motorola RAZR V3 connected to automotive USB charger --> fail Motorola RAZR V3 connected directly to Linux PC --> charged!

The weird thing is that I used the same cable for all 3 tests!

I'm sorry - but I'm still confused, especially after reading one of the reviews at that web site which said "This cable works to charge my Motorola Razr v3 from a USB port without needing the Motorola charging software."

To my knowledge, I don't have any "motorola charging software" on my Linux laptop - but I just plugged in a standard mini-USB cable (USB 2.0 on one end, mini-USB on the other) and it charged the Motorola RAZR V3.

Then I took the exact same setup, and plugged it into a wall-wart USB charger, and it failed. Likewise with the cigarette lighter USB charger in my car.

Clearly this cable does NOT have the resistor (it's a generic USB cable), and I don't know that motorola phone tools was ever installed. Looking on my system (using updatedb) I see there are "some" files with the word "motorola" in them, e.g., /usr/src/kernels/2.6.32-279.1.1.el6.x86_64/include/config/usb/serial/ motorola.h

But, no specific motorola software seems to be installed - yet - the

I suspect that Linux includes the Motorola USB drivers that enable charging from a USB port. Windows doesn't.

That looks like the Motorola USB driver.

You could sacrifice an old Motorola car charger or home charger to get half of the proper 5 pin Mini USB cable and solder it to a USB A cable and put in the resistor. Or buy the appropriate cable.

BTW, on my Google Nexus tablet, it won't charge from a standard USB cable connected to a USB charger. I have to short the USB data pins to get it to charge.

The reason Motorola and Asus and other manufacturers do this sort of thing is not just to be annoying and to sell more of their own chargers. The device needs to know how much current the charger can provide. A USB port needs to provide 500mA but the reality is that many USB chargers can provide much more the minimum, and even many computer USB ports can provide much more than the minimum. The device can charge at a higher rate if it knows the charger can provide higher current.

"According to the spec sheet for the Enhanced Mini USB interface circuit, shorting pin 2 to pin 3 (the data lines) and putting a resistor of 200kOhm on the ID pin x to pin GND will put the phone into Dumb Mid-Rate Charger (500mA) mode with 1.225 volts on pin x. Putting a

I have a later Motorola phone (W766) which usually requires a "charge only" USB cable, which has the data lines shorted on the phone end. Perhaps that would work with the RAZR.

Hi, There are proper ones aplenty on eBay.

USB has power control from the host. The Linux system is going to interrogate the phone and set up the internal hub/controller to whatever power level the phone wants.

A brainless charger can't do that negotiation. So there has to be a setup where the phone will sense the resistor and see that it's hooked up to a brainless charger and just go ahead and charge.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

On a Windows box, the Motorola phone driver isn't built in. It looks like Linux includes it so you don't need to install Motorola Phone Tools in order to charge.

But I think you've got it backwards. The USB power controller on the computer does not allow setting different current levels as requested by the phone.

What really is happening is that the USB driver is telling the phone that it's plugged into a USB port and that the phone can charge at

On my Asus/Google Nexus tablet, if you short the USB data pins then it thinks it's plugged into a 2.1A charger no matter what it's plugged into. You need to do this to use a dumb 2.1A to 12V to USB adapter, and it's part of the USB spec. But it will charge from a Motorola Micro USB car charger too, just slower.

USB ports were not designed to be used as chargers, but the USB 3.0 spec has addressed the charging issue pretty well.

I'm a little confused ...

I have both USB 3.0 and USB 2.0 ports on my Linux laptop.

Should I expect them to work differently with a standard USB-to-mini cable with the Motorola RAZR V3?

Yes, no, maybe so.

There's no short answer. A USB 3.0 port _could_ provide a higher maximum current if the computer manufacturer decides to provide the higher current, but it's not required.

A USB 2.0 port should supply a mininum of 500mA and is technically required to shut down if the current exceeds 1.25A. A USB 3.0 port should supply a minimum of 900mA and is supposed to shut down at 1.5A. But there are also higher power options if communications is not occurring simultaneously.

The reality is that both the USB 2.0 and 3.0 ports probably are able to provide 900mA, but this depends on the laptop. For example, I have a Dell netbook that shuts the USB ports down at about 700mA, but on other machines I have they'll go well over 1000mA.

I doubt if the USB driver and the phone are smart enough to negotiate to provide 900mA if the cable is plugged into the higher power port. Remember, it's the phone that decides how much current to try to draw from the USB port. The phone manufacturer has to err on the side of caution and draw only 500mA from the USB 2.0 port even though most USB

That explains why when I plugged in the Motorola RAZR V3 into both types of ports on my Linux laptop, it simply said "Charging" but didn't give any other indication.

Overloads at startup will produce error messages, followed by prompts to reset the ports.

Ports /not/ wired directly to the mainboard can fail to supply even the nominal spec'd maximum current. I have a USB 3.0 external drive that won't work with the ports on the front of the machine, but does work with those on the rear.