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AR# 12770

5.1i XST - 3-state control logic is not replicated for each IOB


Keywords: XST, 3, three, tri, state, tristate, VHDL, IOB

Urgency: Standard

General Description:
When I synthesize a design with 3-state control, XST does not replicate the logic for each IOB; one 3-state control logic is created for a bus of bidirectional ports.


To avoid this problem, change the synthesis pack option as follows:

1. Right-click on Synthesize -> Properties.
2. Choose "Xilinx-Specific Options".
3. Select "Pack Registers into IOBs".
4. Change the selection from "Auto" to "Yes".
AR# 12770
Date 10/20/2005
Status Archive
Type General Article