difference between three NCD files

[sraza]

Hello every one

This is not very critical question but I am always baffled that why there are three NCD files generated duing the implemntaion phase. Is it that each phase has its own NCD file ?

Thanks

[vsrunga]

Hi,

Yes, each stage in implementation outputs its own ncd, you can distinguish them by the name xxx _map.ncd for MAP phase and xxx.ncd for PAR phase.

Please refer below links for few more details on their description

http://www.xilinx.com/support/documentation/sw_manuals/xilinx11/ise_c_implement_fpga_design.htm

http://www.xilinx.com/itp/xilinx10/isehelp/ise_c_implement_fpga_design.htm

http://www.cs.indiana.edu/hmg/le/project-home/xilinx/ise_7.1/doc/usenglish/de/dev/xflow.pdf

Hope this helps

Regards,

Vanitha

[bwade]

There are only two NCD files created during the implementation flow but there are five different views of the design captured:

NGD - Output of NGDBuild. This is a compilation of all logical netlists prior to map

NGM - An intermediate file for Map contains two differerent views of the design as it's being processed by map. I'ts kept around for back annotation and guide flow usage.

Mapped NCD -  Output of Map. This is the packed and placed design prior to routing.

Routed NCD - Output of PAR. This is the routed design.

The acronym PAR stands for "place and route" and PAR used to do both place and route until the tools was improved to do pack and place together during the Map phase.