R

Chapter 12: Constraining the Core

Legend:

Green - Vertical

Long Line

Orange - VFULLHEX

Red - HFULLHEX

Yellow - BRAM/

Multiplier/Slices/

MGT

Figure 12-1:Local Clock Place and Route for Top MGT

Virtex-4 RocketIO MGTs for 1000BASE-X Constraints

The constraints defined in this section are implemented in the UCF for the example designs delivered with the core. Sections from the UCF are copied into the following descriptions to serve as examples and should be studied in conjunction with the HDL source code for the example design. See also “Virtex-4 FX Devices” in Chapter 7.

Clock Period Constraints

The clock txoutclk is provided by the MGT for use in the FPGA fabric. It is connected to global clock routing to produce the usrclk2 signal. This is the main 125 MHz clock used by all core logic and must be constrained.

DCLK is a clock with a frequency between 25 and 50 MHz, which must be provided to the Dynamic Reconfiguration Port and to the calibration block of the MGT. In the example design, this is constrained to 50 MHz.

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

 

 

UG155 March 24, 2008

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Xilinx manual Virtex-4 RocketIO MGTs for 1000BASE-X Constraints, 1Local Clock Place and Route for Top MGT