Required Constraints

R

GMII_TX_CLK

Data Sheet report:

-----------------

All values displayed in nanoseconds (ns)

Setup/Hold to

clock gmii_tx_clk

 

 

 

------------

+

------------+

------------+------------------

+

--------

+

 

Setup to

Hold to

Clock

Source

clk (edge) clk (edge) Internal Clock(s)

Phase

------------

+

------------+

------------+------------------

+

--------

+

gmii_tx_en

-6.501(R)

7.875(R)gmii_tx_clk_bufg

0.000

gmii_tx_er

-6.504(R)

7.878(R)gmii_tx_clk_bufg

0.000

gmii_txd<0>

-6.506(R)

7.880(R)gmii_tx_clk_bufg

0.000

gmii_txd<1>

-6.521(R)

7.893(R)gmii_tx_clk_bufg

0.000

gmii_txd<2>

-6.518(R)

7.890(R)gmii_tx_clk_bufg

0.000

gmii_txd<3>

-6.515(R)

7.889(R)gmii_tx_clk_bufg

0.000

gmii_txd<4>

-6.521(R)

7.894(R)gmii_tx_clk_bufg

0.000

gmii_txd<5>

-6.520(R)

7.895(R)gmii_tx_clk_bufg

0.000

gmii_txd<6>

-6.514(R)

7.889(R)gmii_tx_clk_bufg

0.000

gmii_txd<7>

-6.513(R)

7.889(R)gmii_tx_clk_bufg

0.000

------------

+

------------+

------------+------------------

+

--------

+

The implementation requires -6.501 ns of setup. Figure 12-4illustrates that this represents a figure of 1.499 ns relative to the following rising edge of the clock (because the IDELAY has acted to delay the clock by an entire period when measured from the input flip-flop). This is less than the 2 ns required, and so there is slack.

The implementation requires 7.893 ns of hold. Figure 12-4illustrates that this represents a figure of -0.107 ns relative to the following rising edge of the clock (because the IDELAY has acted to delay the clock by an entire period when measured from the input flip-flop). This is less than the 0 ns required, and so there is slack.

GMII_TXD[7:0], GMII_TX_EN, GMII_TX_ER

8 ns

-6.501 ns

 

 

 

 

 

tHOLD = 7.893 - 8

 

 

 

 

 

 

 

 

 

 

 

= -0.107 ns

7.893 ns

 

 

 

 

 

 

 

tSETUP = 8 - 6.501 = 1.499 ns

8 ns

Figure 12-4:Timing Report Setup/Hold Illustration

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

www.xilinx.com

177

UG155 March 24, 2008

Page 177
Image 177
Xilinx 1000BASE-X manual 4Timing Report Setup/Hold Illustration