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AR# 4943

Abel macro feedthroughs are being ignored in F1.5

Description

Keywords: 9500, fitter, hitop, abel, macro, feed through, trimming

Urgency: Standard

General Description:

Using Foundation schematic with an ABEL Macro.
If an output is connected directly to an input then the fitter trims the signal.

example:

module fd_thru
Title 'Macro with 1 input and 2 outputs. 1 output inverted, the other is a direct feed through'

Declarations

IN PIN;
OUT1 PIN;
OUT2 PIN;

Equations

OUT1 = IN;
OUT2 =!IN;

end fd_thru

On the schematic the pins are simply connected to buffers and pads.
The fitter trims OUT1 but OUT2 is fit correctly.
This problem exists for 9500 and 9500xl only.
FPGA implementation works correctly.

Solution

The current solution is to add logic to the ABEL file. Possibly put an inverter
inside and on the output of a macro with direct feedthroughs.

This has been fixed in software version 2.1
AR# 4943
Date Created 10/30/1998
Last Updated 06/10/2002
Status Archive
Type General Article