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AR# 10381

4.1i XC4000XL MAP - Trimming of logic driven by INFF leads to bad IOB configuration.

Description

Keywords: FATAL_ERROR:Ncd:basncsignal.c:249:1.15.22.1.2.1, basncsignal.c, basncsignal, 249, INFF

Urgency: Standard

General Description:
MAP trims the logic driven by an INFF component, but leaves an invalid IOB configuration that results in the following fatal MAP error:

"FATAL_ERROR:Ncd:basncsignal.c:249:1.15.22.1.2.1 - Could not find a bel for a signal on pin IK of comp PAD_MemData<15>. Its current programmed state is:
OKMUX:OK TRI:T IKMUX:IK ISR:RESET PULL:PULLUP OSR:RESET OINVMUX:O OCEMUX:O
OUTMUX:OQ IMUX:I SLEW:SLOW Process will terminate. To resolve this error, please consult the Answers Database and other online resources at http://support.xilinx.com"

The logic being driven by an INFF is being trimmed, leading to the removal of the input flop; however, the IK pin is still being configured, possibly because the same clock signal is on the OK pin.

NOTE: This Answer Record is only a good match for your issue if the design is 4K-based and the pin mentioned is the IK pin of an IOB.

Solution

The error occurs because the input flip-flop was removed as unused, but the IK pin was still configured for use. This inconsistency in configuration is flagged by the fatal error.

To work around this problem, block the trimming at the INFF output signal:

NET "pe_memdata_inreg<15>" S ;

This leaves a loadless net, but allows MAP to run to completion so that the source of the trimming can be investigated using the
MAP trim report.
AR# 10381
Date Created 10/25/2000
Last Updated 08/20/2003
Status Archive
Type General Article