Marco Tedaldi wrote:
Pat Cheney schrieb:
Motorola: 5pin?
Blackberry: 4pin?
Nuvi: 4pin?

Which of these three is using the "correct" usb-standard pinout?

I think both of them are ok... Thats the nice things about standards.
There are so many, you can choose whichever you want ;-)

And as far as I can see only the motorola phone is behaeving correctly,
and all the other equipment is breaking the USB-Standard.

A USB port must be able to supply a current of up to 1A. But it is also
true that You can connect several devices to one singe usb port (over a
passive usb hub).

So a device has to draw at most 100mA (or 150mA) at the beginning of a
connection. It has than to request more power from the host, which is
keeping a list of connected devices and power consumption. Only if the
port would not get overloaded, the host (in most cases a PC or laptop)
will acknowledge the request. Otherwise the request is declined and the
device is not allowed to draw more than the 100mA.

So A device that just draws full current without communicating with the
host is breaking the rules.

For USB-Loaders there is an exception. The specification says that a
simple loader should short the two data lines. Than the device is
allowed to draw full current (depending on specification 1A, 1.5A or 1.8A).

So it seems the motorola device is behaeving correctly, while the other
devices do it wrong. Attaching more than one such device which draws too
much current to a USB Port might damage your Mainboard.

That's also the reason why these dual connectors which are sometimes
used with external hard drives are out of specification (and useless in
many cases anyway).

kruemi


And does that explain why you need 5 wires??

My reading skills must be impaired...