R

Chapter 13: Interfacing to Other Cores

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 GTP transceiver, 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 FXT Devices

Figure 13-5illustrates 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.

DCM

BUFG

userclk2 (125MHz)

CLKIN CLK0

 

 

 

FB

BUFG

userclk (62.5MHz)

CLKDV

 

 

 

component_name_block

(Block Level from example design)

brefclkp

IBUFGDS

IPAD

 

 

 

 

IPAD

 

clkin

 

brefclkn

(125MHz)

1-Gigabit Ethernet

MAC

LogiCORE

gtx_clk

gmii_rx_clk

gmii_txd[7:0] gmii_tx_en

gmii_tx_er

gmii_rxd[7:0]

gmii_rx_dv gmii_rx_er

mdc

mdio_in

mdio_out

mdio_tri no connection

Ethernet 1000BASE-X

PCS/PMA or SGMII

LogiCORE

gmii_txd[7:0]

gmii_tx_en

userclk

gmii_tx_er userclk2

gmii_rxd[7:0]

gmii_rx_dv gmii_rx_er

mdc

mdio_in

mdio_out

mdio_tri

RocketIO I/F

Virtex-5

GTX

RocketIO

REFCLKOUT

CLKIN

TXUSRCLK0

TXUSRCLK20

RXUSRCLK0

RXUSRCLK20

Figure 13-5:1-Gigabit Ethernet MAC Extended to Include 1000BASE-X PCS and

PMA Using a Virtex-5 GTX Transceiver

184

www.xilinx.com

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

 

 

UG155 March 24, 2008

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Xilinx 1000BASE-X manual Virtex-5 FXT Devices, Clkdv