10-25-2012 08:48 AM
I am a beginner to use Xilinx FPGA. I try to use UCf file to do pin assignments. I just want to make whether I should use these commands:
NET "Pin1" IOSTANDARD = LVCMOS25;
NET "Pin1" LOC = A9;
What is the mean of the first command?
And whether these commands work for both Verilog and VHDL design? If somebody can give a link to show demos in UCF constrain, that will be great.
Thanks very much.
10-25-2012 02:28 PM
Have you read the sticky README thread in the New Users Forum? There should be links to tutorials for beginners, which may be helpful to you.
I use a text editor for editing .UCF file. The PLANAHEAD program is a glossy windows app for editing the signal and location constraints ad assignments in the .UCF file. You will most likely prefer.Planahead. There is a user manual for Planahead, I believe.
The first line specifies a signaling standard for the IO signal named "Pin1". The signaling standard is 2.5V Low Voltage CMOS. If you look in the IO User Guide for the device family you are using, you should see descriptions of the available signaling standards.
The.UCF file uses a Xilinx-developed syntax which is neither Verilog nor VHDL.
-- Bob Elkind
10-25-2012 07:33 PM
10-26-2012 05:18 AM - edited 10-26-2012 05:19 AM
ucf is for implementation, e.g. ngdbuild/translate.
xcf is an optional constraint for file XST synthesis.
You may find this useful:
http://www.xilinx.com/support/documentation/sw_manuals/xilinx14_2/cgd.pdf (Xilinx Constraints Guide)