Integrating with the 1-Gigabit Ethernet MAC Core

R

Features of this configuration include:

Direct internal connections are made between the GMII interfaces between the two cores.

If both cores have been generated with the optional management interface, the MDIO port can be connected up to that of the 1-Gigabit Ethernet MAC core, allowing the MAC to access the embedded configuration and status registers of the Ethernet 1000BASE-X PCS/PMA or SGMII core.

Due to the embedded Receiver Elastic Buffer in the MGT, the entire GMII is synchronous to a single clock domain. Therefore userclk2 is used as the 125 MHz reference clock for both cores, and the transmitter and receiver logic of the 1-Gigabit Ethernet MAC core now operate in the same clock domain.

Virtex-5 LXT and SXT Devices

Figure 13-4illustrates the connections and clock management logic required to interface the Ethernet 1000BASE-X PCS/PMA or SGMII core (when used in 1000BASE-X mode) to the 1-Gigabit Ethernet MAC core.

 

 

 

 

 

brefclkp

IBUFGDS

 

 

 

 

 

IPAD

 

 

 

 

 

 

IPAD

clkin

 

 

 

 

BUFG

brefclkn

(125MHz)

 

 

 

 

 

 

 

userclk2

component_name_block

 

 

 

 

 

(Block Level from example design)

 

 

 

 

(125 MHz)

 

 

 

 

 

 

 

 

 

1-Gigabit Ethernet

 

Ethernet 1000BASE-X

 

Virtex-5

 

MAC

 

PCS/PMA or SGMII

 

 

 

 

GTP

 

LogiCORE

 

LogiCORE

 

 

 

 

RocketIO

 

 

 

 

 

 

 

gtx_clk

 

 

 

 

REFCLKOUT

 

gmii_rx_clk

 

 

 

 

CLKIN

 

 

 

 

 

 

 

 

 

 

TXUSRCLK0

 

gmii_txd[7:0]

 

gmii_txd[7:0]

 

 

TXUSRCLK20

 

gmii_tx_en

 

gmii_tx_en

userclk

 

RXUSRCLK0

 

 

 

 

 

 

 

gmii_tx_er

 

gmii_tx_er

userclk2

 

RXUSRCLK20

 

gmii_rxd[7:0]

 

gmii_rxd[7:0]

 

 

 

 

gmii_rx_dv

 

gmii_rx_dv

 

 

 

 

gmii_rx_er

 

gmii_rx_er

 

 

 

 

 

 

 

 

RocketIO I/F

 

 

mdc

 

mdc

 

 

 

 

mdio_in

 

mdio_in

 

 

 

 

mdio_out

 

mdio_out

 

 

 

 

mdio_tri

no

mdio_tri

 

 

 

 

 

connection

 

 

 

 

 

Figure 13-4:1-Gigabit Ethernet MAC Extended to Include 1000BASE-X PCS and

PMA Using a Virtex-5 GTP Transceiver

Ethernet 1000BASE-X PCS/PMA or SGMII v9.1

www.xilinx.com

183

UG155 March 24, 2008

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Xilinx 1000BASE-X manual Virtex-5 LXT and SXT Devices, Gtp