R

Chapter 6: The Ten-Bit Interface

Spartan-3, Spartan-3E and Spartan-3A Devices

The logic described previously for Virtex-II and Virtex-II Pro devices does not meet the input setup and hold requirements for TBI with Spartan-3, Spartan-3E and Spartan-3A devices. A DCM must be used on both the pma_rx_clk0 and pma_rx_clk1 clock paths (see Figure 6-3). This is performed by the example design delivered with the core (all signal names and logic match Figure 6-3).

Phase shifting may then be applied to the DCM to fine-tune the setup and hold times at the TBI IOB input flip-flops. Fixed phase shift is applied to the DCM using constraints in the example UCF for the example design. See “Constraints When Implementing an External GMII” in Chapter 12 for more information.

component_name_block (Block Level from example design)

IOB LOGIC

Ethernet 1000BASE-X PCS/PMA

 

 

 

 

 

or SGMII LogiCORE

 

 

 

 

 

 

BUFG

DCM

 

IBUFG

 

 

 

pma_rx_clk0

 

 

 

 

 

pma_rx_clk0

 

CLK0

CLKIN

IPAD

 

 

 

 

FB

 

 

pma_rx_clk0_bufg

 

 

IOB LOGIC

 

(62.5 MHz)

 

 

 

 

BUFG

DCM

 

IBUFG

 

 

 

 

 

pma_rx_clk1

pma_rx_clk1

 

CLK0

CLKIN

IPAD

 

 

 

 

FB

 

 

pma_rx_clk1_bufg

 

IOB LOGIC

 

(62.5 MHz)

 

 

 

 

 

 

 

IBUF

 

rx_code_group0_reg[0]

 

 

rx_code_group[0]

rx_code_group0[0]

Q

D

IPAD

 

 

rx_code_group1[0]

rx_code_group1_reg[0]

Q

D

 

 

 

rx_code_group_ibuf[0]

 

 

 

 

 

 

 

 

Figure 6-3:TBI Receiver Logic for Spartan-3, Spartan-3E, and Spartan-3A Devices

72

www.xilinx.com

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

UG155 March 24, 2008

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Image 72
Xilinx 1000BASE-X manual Componentnameblock Block Level from example design