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AR# 543

XABEL 5.1/EPLD designs: FOE pins are active *high*

Description


LONG DESCRIPTION:

PROBLEM:

Customer assigns a pin in XABEL/ABEL to a FOE (Fast Output Enable) pin, but
when the design is compiled, the pin assigned to the FOE pin is assigned to
a different pin.

Solution


CAUSE:

The user defined in ABEL/XABEL code a FOE pin, but the FOE signal was
defined as active-low in the code.

SOLUTION:

The FOE are active high by architecture. The only way to get an active low
FOE is to reroute the signal through the AND-array and a macrocell. So, the
user must either allow this rerouting of the signal, or invert the FOE signal
outside of the device.








AR# 543
Date Created 09/20/1995
Last Updated 01/15/2003
Status Archive
Type General Article