Thank you a lot for your help,
From: Ash Charles <ash@...>
To: kris duff <t_dufff@...>; General mailing list for gumstix users. <gumstix-users@...>
Sent: Thursday, August 9, 2012 12:14:02 PM
Subject: Re: [Gumstix-users] lan9221 vs lan9512
On Thu, Aug 9, 2012 at 8:11 AM, kris duff <t_dufff@...> wrote:
> I'm looking to do my own daughterboard for the overo com. On the the
> chestnut, the gumstix team uses the ethernet lan chip LAN9221. I have found
> that the LAN9512 (the one used by rasp. pi) is cheaper and gives 2 usb
> ports. Is it possible, easily, to use the LAN9512 with the gumstix ?
Definitely. In fact, Beagleboard uses this chip (or maybe it is the
LAN9514 version) and you could definitely hang it off one of the USB
ports from the COM on a custom expansion board.
> I don't undestand yet the difference between the chips..
The LAN9221 is somewhat unique in that the GPMC (general purpose
memory controller, i.e. it acts like a memory device) rather than an
upstream USB bus provides the connection to the processor. The
ethernet from the LAN9521x series is basically like using one of those
USB to ethernet dongles. It has the disadvantage of ethernet
connectivity breaking if there is a problem with USB but is simpler to
use and gives you the extra USB ports for less money. As with
everything, it is a tradeoff!