Answers Database
1.5i/2.1i: Virtex Back Annotation - Incorrect models for OBUF_GTL and OBUFT_GTL
Record #6062
Problem Title:
1.5i/2.1i: Virtex Back Annotation - Incorrect models for OBUF_GTL and OBUFT_GTL
Problem Description:
Urgency: Standard
General Description:
Simulations using the simprims models show that GTL outputs drive '1' and '0'.
GTL is an open drain technology. Inactive devices drive '1' and active device
drive '0' resulting in an undefined state. The inactive devices should drive a 'Z'.
Solution #1651 (http://www.xilinx.com/techdocs/1651.htm) gives the
the definition of an open-drain output.
The OBUF_GTL.v model should be written as
or OR1 (TS, I, gts);
bufif0(O, 1'b0, TS);
The OBUFT_GTL.v model should be written as
or OR1(TS, I, T, gts);
bufif0(O, 1'b0, TS);
This goes along with SIMPRIM models as well.
Solution 1:
A data file patch for this issue is available at:
ftp://ftp.xilinx.com/pub/swhelp/M1.5i_updates/15i_sp2_anno_ws.tar.gz
ftp://ftp.xilinx.com/pub/swhelp/M1.5i_updates/15i_sp2_anno_pc.zip
This fix only works with non-correlated (no .ngm file used) back annotation.
CAUTION: This FTP Update is intended as a fast response for the following
customer issue only. The risk inherent in this fast response is that there
is not enough time or resources available for the full regression testing
that is done for the Service Pack Updates and there is a higher risk of
introducing new problems. It is recommended that customers always install
the latest Service Pack Update, but only install FTP Updates when needed to
resolve specific issues.
NOTE: This FTP Update is only compatible with an A1.5i/F1.5i system that
have Service Pack 2 installed. It corrects the following issue:
End of Record #6062 - Last Modified: 07/19/99 10:56 |
