Xilinx Virtex-4 - Transmit (TX) Client - 8-Bit Wide Interface

40 www.xilinx.com Embedded Tri-Mode Ethernet MAC User Guide
UG074 (v2.2) February 22, 2010
Chapter 3: Client, Host, and MDIO Interfaces
R
Transmit (TX) Client – 8-bit Wide Interface
In this configuration, CLIENTEMAC#TXD[15:8] and CLIENTEMAC#TXDVLDMSW must
be tied to ground.
Normal Frame Transmission
The timing of a normal outbound frame transfer is shown in Figure 3-3. When the client
transmits a frame, the first column of data is placed on the CLIENTEMAC#TXD[7:0] port,
and CLIENTEMAC#TXDVLD is asserted High. After the Ethernet MAC reads the first
byte of data, it asserts the EMAC#CLIENTTXACK signal. On subsequent rising clock
edges, the client must provide the rest of the frame data. CLIENTEMAC#TXDVLD is
deasserted Low to signal an end-of-frame to the Ethernet MAC. In SGMII or 1000BASE-X
PCS/PMA mode, the PCS engine inserts code characters in the data stream from
CLIENTEMAC#TXD. Table 3-1 describes these code characters, and IEEE Std 802.3, Clause
36 has further definitions. The encapsulated data stream then appears on EMAC#PHYTXD
and goes to the MGT. Along with EMAC#PHYTXCHARISK and
EMAC#PHYTXCHARDISPMODE, the MGT encodes the incoming data to the appropriate
8B/10B stream.
Figure 3-3: Normal Frame Transmission Across Client Interface
CLIENTEMAC#TXCLIENTCLKIN
EMAC#PHYTXD[7:0]
(SGMII or 1000BASE-X
PCS/PMA only)
EMAC#PHYTXCHARISK
(SGMII or 1000BASE-X
PCS/PMA only)
EMAC#PHYTXCHARDISPMODE
(SGMII or 1000BASE-X
PCS/PMA only)
CLIENTEMAC#TXDVLD
EMAC#CLIENTTXACK
CLIENTEMAC#TXUNDERRUN
EMAC#CLIENTTXCOLLISION
EMAC#CLIENTTXRETRANSMIT
CLIENTEMAC#TXFIRSTBYTE
ug074_3_05_080705
CLIENTEMAC#TXD[7:0]
DA SA DATAL/T
/T/ /R/
PRE
/S//I1/ /I2/ /I2/ /I2/ /I2/
FCS
SFD
/I1/
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