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> Usb Power Budget, Is powering usb peripherals unsafe?
post Nov 18 2006, 08:09 AM
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Joined: 19-October 05
From: Cardston, AB, Canada
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I'm running OZ on my C1000, but I think this is a fairly general question.

In kernel 2.16 and newer, if a USB device requires too much power, it is not enabled. 'dmesg' output might look like:

usb 1-2: no configuration chosen from 1 choice

To find out how much power a USB device wants, one can invoke:

lsusb -v | grep MaxPower

My card reader wants up to 250 mA, and my USB to serial converter says it might use up to 500 mA!

Post #3 on this ubuntu forum thread describes a work-around.

So my question is, is it safe to do this? [Also, I assume that people who are using kernels before 2.16 could well ask the same question, even if the device isn't automatically disabled.] Are the manufacturers of these USB products giving a high margin of error? Can a high-current device damage a Zaurus, or will it simply shorten battery life or just plain not work?

Thank you,

[Edit]. PS. Does it make any difference if the Z is plugged in or not?
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