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From: johnp at probo.com<johnp@p...>
Date: Tue Dec 27 21:50:26 CET 2005
Subject: [usb] USB 2.0 core K chirp generation issue?
According to the UTMI spec (page 31), the state of the TxReady pin
is undefined in the TxWait state (see figure 12). Given that, I
believe the following code will block the K Chirp generation if the
UTMI interface has the TxReady signal asserted to a 1 by default.

always @(posedge phy_clk)
if(TxReady || tx_first) DataOut <= tx_data;
else
if(drive_k) DataOut <= 8'h00;

I suspect it should actually be
always @(posedge phy_clk)
if(drive_k) DataOut <= 8'h00;
else
if(TxReady || tx_first) DataOut <= tx_data;

Any thoughts on this?

John Providenza

Follow up	Author
[usb] USB 2.0 core K chirp generation issue?	Rudolf Usselmann