Answers Database
SYNPLIFY: How to synthesize the OE FF in the SpartanXL, XC4000XLA/XV, and Virtex IOB?
Record #3372
Problem Title:
SYNPLIFY: How to synthesize the OE FF in the SpartanXL, XC4000XLA/XV, and Virtex IOB?
Problem Description:
Urgency: Hot
General Description: Is there Synplify support of the OE FF
in the SpartanXL, XC4000XLA/XV, and Virtex IOB?
Solution 1:
For Spartan-XL, and XC4000XLA/XV, the methodology was introduced in M1.5i
as a hardmacro within Epic. See (Xilinx Solution 5140) for details.
The (Xilinx XAPP123) explains how to utilize this flip-flop.
It is available at http://www.xilinx.com/xapp/xapp123.pdf
For Virtex, the fact that the FF is generic ("anonymous" ), should not be an
issue if MAP knows how to pull the FF into an IOB location. The current Virtex
mapper knows how to do this if the FF has the "IOB=TRUE" attribute. Please
see (Xilinx Solution 5675) for details on declaring IOB flip-flops within Virtex.
Synplify does provide the mechanism to pass attributes through the HDL,
however, there are 2 outstanding enhancements against this mechanism.
Synplify provides the xc_props and xc_ioff, but both are not yet available for
the Virtex synthesis engine.
End of Record #3372 - Last Modified: 08/26/99 19:34 |
