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R
Chapter 5: Using the Client-side GMII Data Path
gmii_tx_clk
IPAD
gmii_txd[0]
IPAD
gmii_tx_en
IPAD
gmii_tx_er
IPAD
Virtex-4 Devices
The logic described previously for
1.A DCM may be used on the gmii_tx_clk clock path for the
2.Input Delay Elements may be used on the GMII data path, as illustrated in Figure
The IODELAY elements can be adjusted to
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| PCS/PMA |
IBUFG |
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| BUFG | |
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| gmii_tx_clk_bufg |
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| IDELAY |
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userclk2 (if RocketIO is used) gtx_clk (if TBI is used)
Transmitter
Elastic
Buffer
IBUF
IDELAY | D Q | gmii_txd_int[0] |
gmii_txd[0] |
IBUF
IDELAY | D Q | gmii_tx_en_int | gmii_tx_en |
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IBUF
IDELAY | D Q | gmii_tx_er_int | gmii_tx_er |
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Figure 5-16: External GMII Transmitter Logic for Virtex-4 Devices
64 | www.xilinx.com | Ethernet |
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| UG155 March 24, 2008 |