Answers Database
Virtex: The data inputs of a MUXF6 can only come from the output of a MUXF5
Record #4915
Product Family: Software
Product Line: M1 Implementation
Product Part: Virtex Pro-Unified Libs
Problem Title:
Virtex: The data inputs of a MUXF6 can only come from the output of a MUXF5
Problem Description:
urgency: standard
general description:
The data inputs(I0 & I1) of the MUXF6 can only come from the outputs of a MUXF5.
This is a physical limitation of using the MUXF6. If the data inputs of a MUXF6
do not come from a MUXF5, a user will get a message from map(A1.5p) of the following form:
ERROR: xvkma F6MUX <instance name of muxf6> fed from illegal source through
net/signal: <netname that does not originate from muxf5>
(only legal sources are F5MUXes)
The select input for the MUXF6 doesn't have to originate from a muxf5.
Solution 1:
If you run into this problem from a synthesized HDL design, which does
not instantiate the MUXF6, then the synthesis tool has inferred the use
of a MUXF6 incorrectly. Contact your synthesis vendor for help.
Solution 2:
If you run into this problem with a synthesized(HDL) or schematic design,
and you have instantiated the MUXF6, there two several options:
(1) The easiest option is to remove the MUXF6 altogether and replace it with either a MUXF5, or RTL.
(2) Instead of directly connecting a signal to the inputs of a MUXF6, indirectly
connect it to the MUXF6 by routing the signal through a MUXF5 first.
End of Record #4915 - Last Modified: 10/28/98 09:58 |
