
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
•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
Virtex-5 LXT and SXT Devices
Figure 13-4 illustrates 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.
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| brefclkp | IBUFGDS |
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| IPAD |
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| IPAD | clkin |
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| BUFG | brefclkn | (125MHz) |
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| userclk2 | component_name_block |
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| (125 MHz) |
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| Ethernet |
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MAC |
| PCS/PMA or SGMII |
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| GTP |
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LogiCORE |
| LogiCORE |
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| RocketIO |
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gtx_clk |
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| REFCLKOUT |
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gmii_rx_clk |
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| CLKIN | |
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| TXUSRCLK0 |
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gmii_txd[7:0] |
| gmii_txd[7:0] |
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| TXUSRCLK20 |
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gmii_tx_en |
| gmii_tx_en | userclk |
| RXUSRCLK0 |
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gmii_tx_er |
| gmii_tx_er | userclk2 |
| RXUSRCLK20 |
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gmii_rxd[7:0] |
| gmii_rxd[7:0] |
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gmii_rx_dv |
| gmii_rx_dv |
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gmii_rx_er |
| gmii_rx_er |
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| RocketIO I/F |
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mdc |
| mdc |
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mdio_in |
| mdio_in |
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mdio_out |
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mdio_tri | no | mdio_tri |
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Figure 13-4: 1-Gigabit Ethernet MAC Extended to Include 1000BASE-X PCS and
PMA Using a Virtex-5 GTP Transceiver
Ethernet | www.xilinx.com | 183 |