My design passes schematic design rule checks, but NGDBuild errors similar to the following are reported during the translate process:
"Checking expanded design ...
ERROR:NgdBuild:466 - output pad net 'd0' has illegal connection
ERROR:NgdBuild:466 - output pad net 'd1' has illegal connection
ERROR:NgdBuild:466 - output pad net 'd2' has illegal connection
ERROR:NgdBuild:466 - output pad net 'd3' has illegal connection"
These errors occur if the ECS schematic design uses bidirectional ports and I/O buffer symbols are present on the output, but not on the input.
If a bidirectional port is connected to the output of an OBUFT and to the D input of an FD register symbol, the errors above are reported.
To correct the problem, add an appropriate input I/O buffer symbol. The example above will be fixed if an IBUF symbol is placed between the port and the D input of the FD (or by using an IFD symbol in place of the FD symbol).