Offset OUT Path Details, Offset OUT Detail Clock Path

OFFSET Constraints

OFFSET OUT Path Details

The example path below passed the timing constraint by .533 ns. The slack equation shows how the slack was calculated. Data delay increases the clock to out time and clock delay also increases the clock to out time. The clock arrival time is also taken into account. In this example the clock arrival time is 0.000 ns; therefore, it does not affect the slack.

If the clock edge occurs at a different time, this value is also added to the clock to out time. If this example had the clock falling at 5.000 ns, 5.000 ns would be added to the slack equation because the initial edge of the corresponding PERIOD constraint is HIGH.

Note: The clock falling at 5.000 ns is determined by how the PERIOD constraint isdefined, for example PERIOD 10 HIGH 5.

Example:

======================================================================

Slack:	0.533ns (requirement - (clock arrival + clock
path + data path + uncertainty))
Source:	wr_addr[2] (FF)
Destination:	efl (PAD)
Source Clock:	wclk rising at 0.000ns
Requirement:	10.000ns
Data Path Delay:	9.952ns (Levels of Logic = 4)
Clock Path Delay:	-0.485ns (Levels of Logic = 3)
Clock Uncertainty:	0.000ns

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

OFFSET OUT Detail Clock Path

In the following example, because the OFFSET OUT path starts with the clock, the clock path is shown first. The clock starts at an IOB, goes to a DCM, comes out CLK0 of the DCM through a global buffer. It ends at a clock pin of a FF.

The Tdcmino is a calculated delay. This is the equation:

Clock Path: rclk_in to rd_addr[2]

Location	Delay type	Delay(ns) Logical
Resource(s)
-------------------------------------------------
A8.I	Tiopi	0.825	rclk_in
			read_ibufg
DCM_X1Y1.CLKIN	net (fanout=1)	0.798	rclk_ibufg
DCM_X1Y1.CLK0	Tdcmino	-4.290	read_dcm
BUFGMUX7P.I0	net (fanout=1)	0.852	rclk_dcm

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8.2i specifications

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Xilinx 8.2i manual Offset OUT Path Details, Offset OUT Detail Clock Path

Models: 8.2i

OFFSET Constraints

OFFSET OUT Path Details

OFFSET OUT Detail Clock Path

8.2i specifications