AR# 543: XABEL 5.1/EPLD designs: FOE pins are active *high*
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.