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AR# 8245

2.1i : 9500 : Hprep6 : Inverted global tristates do not tristate properly


Keywords: 2.1i, hprep6, CPLD, 9500, tristate, global

Urgency: Standard

General Description:
I am using an inverted global tristate in my design, and although
the simulation is fine, it does not work in the hardware. The
tristate signal is never released, even though the control signal
states it should be.


A problem has been found in the CPLD fitter and how it handles
inverted tristate controls. The conditions that cause this to occur

- Must be using 9536/9572/95108
(XL not affected, the other 9500 devices not affected)


- Must use the positive AND negative form of the global tristate
for the entire design. If the global tristates are ALL in the
positive form OR all in the negative form, there is no problem.

The workaround is to UNCHECK under the Design Manager
Use Global Output Enable(s)

This has been fixed in 2.1i service pack 5.
AR# 8245
Date Created 12/09/1999
Last Updated 08/27/2001
Status Archive
Type General Article