Pin Constraints File (.pcf)


This file is in a different usage than the Pin Constraints File in XML format (see details in Pin Constraints File (.xml))

The PCF file is the file which users should craft to assign their I/O constraints

An example of the file is shown as follows.

set_io a pad_fpga_io[0]
set_io b[0] pad_fpga_io[4]
set_io c[1] pad_fpga_io[6]
set_io <net> <pin>

Assign a net (defined as an input or output in users’ HDL design) to a specific pin of an FPGA device (typically a packaged chip).


The net should be single-bit and match the port declaration of the top-module in users’ HDL design


FPGA devices have different pin names, depending their naming rules. Please contact your vendor about details.