From: Franc Zabkar <fzabkar@in...> - 2011-10-15 07:56:08
>Date: Thu, 11 Aug 2011 13:18:23 +0100
>From: Tim Small <tim@...>
>Subject: [smartmontools-support] Icybox IB319 external enclosure -
> broken JMicron bridge chip?
>Content-Type: text/plain; charset=ISO-8859-1
>I have an Icybox IB-319 (IB-319StUS2-B) (EAN 4250078184485 ) - it has a
>JMicron JM20329 USB bridge chip in it. When connected over either USB
>or eSATA, running smartctl can make the bridge chip lock up.
>I can't really understand what's causing this in eSATA mode, because
>looking at the PCB traces, the eSATA signals do not go through the
>JM20329 - (actually the eSATA connector and the JM20329 have their data
>lines wired together, and then there are capacitors in between those
>traces and the SATA connector which goes to the drive - no other
>connections to the SATA data lines). Maybe the JM20329 eavesdrops on
>the eSATA traffic?
FYI, here is a datasheet:
... and a reference circuit:
On 15/10/11 08:54, Franc Zabkar wrote:
> FYI, here is a datasheet:
Thanks for that. I eventually came to the conclusion that the issue in
eSATA mode was due to a bad eSATA cable and/or connector which shipped
on/with the Icybox unit. Dunno what caused the USB issue (and didn't
investigate further as I planned to use eSATA only with this enclosure).
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From: Franc Zabkar <fzabkar@in...> - 2011-10-15 19:46:48
ISTM that the design is double-terminating the SATA Tx/Rx signal
pairs. This must be asking for trouble. And even if the bridge chip
had an activate termination, and if the bridge could be kept quiet
during eSATA mode, then the additional signal traces would still
constitute a reflective stub that would affect the signal integrity.
I've seen other designs where the eSATA signals pass through the
bridge IC. I would think that would be a much better approach.
At 01:22 AM 16/10/11, you wrote:
>On 15/10/11 08:54, Franc Zabkar wrote:
> > FYI, here is a datasheet:
>Thanks for that. I eventually came to the conclusion that the issue in
>eSATA mode was due to a bad eSATA cable and/or connector which shipped
>on/with the Icybox unit. Dunno what caused the USB issue (and didn't
>investigate further as I planned to use eSATA only with this enclosure).