[iyonix-support] Re: USB ext hd & Fat32FS
- From: Alan Adams <alan@xxxxxxxxxxxxxxxx>
- To: iyonix-support@xxxxxxxxxxxxx
- Date: Thu, 14 Apr 2011 12:24:45 +0100
In message <8ac8b9c351.c.n.l.f@xxxxxxxxxx>
Chris F <c.n.l.f@xxxxxxxxxx> wrote:
> In message <4DA630F5.5010900@xxxxxxxxxx>
> John Ballance <jwb@xxxxxxxxxx> wrote:
>>>
>> The USB rules are quite simple.
>> A USB port must provide 1/2 amp if powered.. i.e. its in a box with
>> connected power supply.
>> If not so, i.e. it is a hub on the end of a USB lead, then if no power
>> supply on this hub, total available power is 1/2 amp for the hub and any
>> sockets on the hub.
>> IF the hub has a power supply, then it can source 1/2 amp at each USB
>> socket.
>> It is not unusual for external devices to need more than 1/2 amp. The
>> usual convention then is to have a power supply with this device.
>> Occasionally you'll see a bodge that perhaps feeds off 2 (or more) USB
>> sockets.
>> Incidentally the USB stack interrogates the usb device and will only
>> enable it if it reports as needing less power htan available on that USB
>> socket.
>> Hope that helps
> I get it, I think;
> The Iyo has 4 USB sockets. Each one may, or may not, be cabable of
> providing 1/2A.
> If I take just one of those sockets and attach my external drive and
> it doesn't spin (and it doesn't) then it might if I use a double
> headed usb cable and plug the double ends into 2 of the USB sockets.
> However, IIRC, it's not usually a good idea to try drawing too much
> current from electronic sources; so a more sound strategy should be to
> take a USB extension lead from just one of the Iyo USB sockets, hang a
> powered USB hub on its other end and use the (supplied) single ended
> cable into one of the new hub's sockets.
> If that doesn't work, substitute the double-ended USB cable and it
> 'should' work; and if it does, the SafeStore needs more than 1/2 amp
> and it's now drawing its current from the 2 x 1/2amp available at the
> usb sockets on the external hub.
> Yes?
Yes.
Which model Simplesave is it? They run from 320GB to 2TB, and the top
two have external power units.
Alan
--
Alan Adams, from Northamptonshire
alan@xxxxxxxxxxxxxxxx
http://www.nckc.org.uk/
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