USB port : short-circuit safety?

hi all

i introduced a class into arduino and told them only to work with an external power supply and right jumper setting. so a short-circuit has an effect only at the power supply - which is normally able to handle them.
when a short-circuit appears at the usb port, two mac dealers insured me that the port isn’t safe, so it would damage the logic board. today i’ve talked with an embedded linux developer and he told me that several short-circuits on the usb at his non apple laptop never hat an effect (because the os internal looks if the current is more then the 100mA enabled, and turns off if it is more)

are there an infos or results from users, what happens on a short-circuit at usb?

thanks

Hi,

when messing around with USB hardware I alway put an active hub between the computer and the object I hack on. I guess it’s better to blow up a cheap hub rather than the USB ports on a G5.

that’s a good idea.

btw if you work with an external power supply the chance of USB short circuit is near 0
(unless the board is sitting on a table full of bits of wires creating short circuits underneath)

My experience so far shows me that when you short circuit the arduino board, the USB port shows up as having been disconnected on the mac, even though no physical disconnection has occured. Whether or not that’s an indication of a protective measure by my powerbook… I have no idea.
-steve