RE: [ethmac] necessity of preamble during reception

[Illan Glasner <IGlasner@mrv.com>]

Yes you are tho' keep in mind the the SFD is not 1011 but rather 10101011 as
many time since in FE we work in nibble boundry it is common to define pre
as 1010 and sfd as 1011 and in such case you need at least one pre before
the sfd.

have a nice day

   Illan

-----Original Message-----
From: Karthik D [mailto:karthikd@myw.ltindia.com]
Sent: Friday, December 06, 2002 6:14 AM
To: ethmac@opencores.org
Cc: mkrishna@tataelxsi.co.in
Subject: Re: [ethmac] necessity of preamble during reception


** Proprietary **
** High Priority **

"RX_DV (Receive Data Valid) is driven by the PHY to indicate that the PHY is
presenting recovered and decoded nibbles on the RXD bundle and that the data
on RXD is synchronous to RX_CLK. RX_DV shall transition synchronously with
respect to the RX_CLK. RX_DV shall remain asserted continuously from the
first recovered nibble of the frame through the final recovered nibble and
shall be negated prior to the first RX_CLK that follows the final nibble. In
order for a received frame to be correctly interpreted
by the Reconciliation sublayer and the MAC sublayer, RX_DV must encompass
the frame, starting no later than the Start Frame Delimiter (SFD) and
excluding any End-of-Frame delimiter"

This tells that we need to look for valid SFD rather than Preamble to
receive the frame.

Hope i am correct...

Karthik D. 

>>> mkrishna@tataelxsi.co.in 12/06/02 05:45PM >>>
hi all,

I have simple doubt.During reception of a frame is it required that all
the preamble(i.e 6 octets) has to be received or is it suffucicient that
a valid SFD is received before the frame can be processed.

Thanks in advance
Mohan

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