We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 6679

F1.5i Simulator: Driving a bus in CC Mode get overwritten


Keywords: Simulation, Simulator, CC, bidirectional, bus

Urgency: Standard

Description: When simulating a bidirectional signal it is important to use the CC mode to allow the input to be overwritten by the output. When a bus has pulldowns on it in CC mode these pulldown will overwrite the input and prevent any forced signals.


This error only occurs in simulation and will not pass over to the actual device. To properly simulate the bus it would be necessary to temporarily remove the pulldowns.

This works correctly in 4.2i release which means it was probably fixed somewhere in the 2.1 time frame.
AR# 6679
Date Created 06/03/1999
Last Updated 03/07/2002
Status Archive
Type General Article