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AR# 15874

5.1i, ECS - The use of PULLDOWN/PULLUP resistors symbols causes "ERROR:HDLParsers:1402 ...Object <port_name> of mode IN cannot be updated"

Description

Keywords: PULLUP, PULLDOWN, ECS, HDLParsers, XST

Urgency: Standard

General Description:
I have applied a PULLUP (or PULLDOWN) resistor symbol to an input port in the ECS schematic entry tool. When I synthesize the design, an error message similar to the following is reported:

"ERROR:HDLParsers:1402 - C:/proj_pull/my_sch.vhf Line 50. Object in_a of mode IN cannot be updated."

Solution

This problem occurs because the Synthesis tool is tying the PULLUP/PULLDOWN resistor to an internal net that is labeled as "INPUT" or "OUTPUT".

You may avoid the error by applying the PULLUP/PULLDOWN constraint using any of the following methods:

1. Use the CONSTRAINTS EDITOR GUI to place all PULLUP/PULLDOWN resistors on the appropriate signals.

2. Place the PULLUP/PULLDOWN constraints on the appropriate net into the UCF file by using a text editor. The constraints would be entered as follows:

NET "<net_name>" PULLUP;
NET "<net_name>" PULLDOWN;

where <net_name> is the name of the input/output signal.

3. Place the PULLUP/PULLDOWN constraint onto the actual PAD in the ECS schematic entry tool, following these steps:

a) Select and highlight the appropriate net to which you wish to assign the PULLUP/PULLDOWN resistor. When you select it, right-click on the mouse and select "Object Properties".

b) From the options along the side of the GUI, select "New".

c) Under the ATTRIBUTE NAME, enter the type of resistor you wish to assign:

PULLUP or PULLDOWN

d) Under the ATTRIBUTE VALUE, enter TRUE/FALSE:

TRUE = apply resistor type to net
FALSE = do not apply resistor type to net

e) Once you have finished setting and entering the values for the signal, select "OK", then "Apply". This will apply the PULLUP/PULLDOWN resistor to the designated signal name.
AR# 15874
Date Created 10/15/2002
Last Updated 01/08/2006
Status Archive
Type General Article