
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
•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
Virtex-5 FXT Devices
Figure 13-5 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.
DCM | BUFG | userclk2 (125MHz) |
CLKIN CLK0 |
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|
| |
FB | BUFG | userclk (62.5MHz) |
CLKDV |
| |
|
|
component_name_block
(Block Level from example design)
brefclkp | IBUFGDS | ||
IPAD |
|
| |
|
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IPAD |
| clkin | |
| |||
brefclkn | (125MHz) |
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
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 |
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| UG155 March 24, 2008 |