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AR# 3276

4.2i Foundation Schematic - NGDBuild: "ERROR: basnu - logical net "net_name_int" has both active and tristate (or "multiple") drivers"

Description

Keywords: NGDBuild, active, 3-state, 3 state, tri-state, tristate, drivers

Urgency: Standard

General Description:
My design contains multiple top-level sheets and signals that are connected from sheet-to-sheet. NGDBuild is reporting the following error:

"ERROR: basnu - logical net "net_name_int" has both active and tristate drivers."

(or "ERROR: basnu - logical net "net_name_int" has multiple drivers.")

Solution

This error occurs when the design uses I/O terminals for nets and/or I/O markers for busses to connect signals from one top-level sheet to another top-level sheet.

I/O terminals should ONLY be used to connect signals between levels of hierarchy (i.e., to connect a lower-level schematic to a macro symbol). To connect signals between schematic sheets on the same level, simply leave the net dangling, and be sure it has the same name on both sheets -- the name correspondence will ensure the logical connection.

For all signals that connect one top-level sheet to another:

1. Nets

a. You must redraw nets to use hanging wires:
- Draw the net and right-click.
- Go to the "Add net or bus name" icon in the left-hand toolbar.

b. Name the net.

2. Busses

a. Double-click on the desired bus.
b. Select "NONE" for I/O marker.
AR# 3276
Date Created 01/09/1998
Last Updated 08/12/2003
Status Archive
Type General Article