[time-nuts] Net4501's cheap...

Paul tic-toc at bodosom.net
Thu May 23 19:03:38 EDT 2013

On Thu, May 23, 2013 at 3:25 PM
> From: "David J Taylor" <david-taylor at blueyonder.co.uk>
> I have three Raspberry Pis and have not seen that behaviour.

Perhaps you have the older boards.

google "Raspberry Pi Reboots on inserting a USB device"

"by mahjongg » Mon Nov 19, 2012 12:09 am
Don't hot plug USB devices directly into the PI, if you must hot plug
plug into a hub instead!

Its called "the rush in current problem", and it makes that the
current PI itself is non "hot pluggable", note that the revision 1 PI
was hot pluggable, as the two polyfuses prevented any rush in current
because the fuses had a non zero resistance. But in the current board
there is literally zero resistance between the PI's 5V supply, and any
USB device you plug in, that means that if you plug in any USB device
with empty power decouplers, (which act as a complete short for a very
small time) then you are actually simply shorting the 5V when you plug
de USB device in.

The polyfuses in the revision 1 board however caused much greater
problems than this problem, and for that reason have been removed."

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