R

Chapter 6: The Ten-Bit Interface

Method 2

This logic from method 1 relies on pma_rx_clk0 and pma_rx_clk1 being exactly 180 degrees out of phase with each other because the falling edge of pma_rx_clk0 is used in place of pma_rx_clk1. See the data sheet for the attached SERDES to verify that this is the case. If not, the logic of Figure 6-7illustrates an alternate implementation where both pma_rx_clk0 and pma_rx_clk1 are used as intended. Each bit of rx_code_group[9:0] must be routed to two separate device pads. The IODELAY elements shown on Figure 6-7can be used to compensate for any bus skew that has resulted.

Ethernet 1000BASE-X PCS/PMA

or SGMII LogiCORE

IOB LOGIC

 

BUFG

 

 

 

 

 

pma_rx_clk0

 

 

 

IODELAY

pma_rx_clk0_bufg

 

 

 

(62.5 MHz)

 

 

 

IOB LOGIC

IBUFG

IBUF

pma_rx_clk0

IPAD

rx_code_group0[0]

rx_code_group0_reg[0]

Q D

IODELAY

 

 

 

 

 

rx_code_group[0]

IPAD

IOB LOGIC

 

BUFG

pma_rx_clk1

 

 

 

 

 

 

 

IODELAY

pma_rx_clk1_bufg

 

 

 

 

 

(62.5 MHz)

 

 

 

IOB LOGIC

IBUFG

IBUF

pma_rx_clk1

IPADrx_code_group[0]

rx_code_group1[0]

rx_code_group1_reg[0]

Q D

IODELAY

 

 

 

 

 

rx_code_group[0]

IPAD

Figure 6-7:Alternate Ten-Bit Interface Receiver Logic - Virtex-5 Devices

76

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

 

 

UG155 March 24, 2008

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Xilinx 1000BASE-X manual 7Alternate Ten-Bit Interface Receiver Logic Virtex-5 Devices