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AR# 8923

Virtex-E 2.1i PAR: pad report does not include the pads for LVDS/LVPECL N side inputs

Description

Keywords: Virtex, Virtex-E, LVDS, PAR

Urgency: Standard

Problem Description:

Pad report from par doesn't have any of the N-side input pads listed. But they are used
in the hardware. Some of the board level simulation tools may need to have the pad
report that has all the pin information, including the N-side input pads. How to create
a pad report that includes the N-side input pads?

Solution

Designing with LVDS/LVPECL requires you to lock down all the IO pins before running
the implementation process. Therefore, The pad report created will always have the
same pin locations. To create a report with the N-side inputs, users must add them in
the pad report manually. Since all the pins have the same location, the pad report from
each implemenation will always be the same, which means the users only need to add
the N-side pads in the pad report once, save it in a different area, and use it over and
over again.

Here is an example on how to add the N-side input pins in the pad report.

the differential pair has the name, data_p for the P-side, and data_n for the N-side,
the pad report only shows the P-side as:

data_p INPUT A20

To add the N-side, add the additional line in the pad report:

data_n INPUT C21

So the pad report shows:

data_p INPUT A20
data_n INPUT C21
AR# 8923
Date Created 03/29/2000
Last Updated 12/10/2001
Status Archive
Type General Article