Questions tagged [ucf]

User Constraint Files (UCF) are a proprietary file format from Xilinx for constraining a hardware design. UCF files are not supported in Xilinx Vivado. The replacement format is called Xilinx Design Constraints (XDC).

User Constraint Files (UCF) are a proprietary file format from Xilinx for constraining a hardware design. UCF files are used by Xilinx ISE tools for timing and physical constraints. UCF files are saved as:
- *.ucf (user constraints)
- *.xcf (XST synthesis constraints)
- *.ncf (netlist constraints)

UCF files are not supported in Xilinx Vivado. The replacement format is called Xilinx Design Constraints (XDC), a scripting language (TCL) based syntax.

9 questions

votes

2 answers

VHDL many .ucf files or not

I have a very basic question about VHDL. Do we need a separate .ucf file for each .vhd file or not? The reason I am having many .vhd files because each of the entity specifies a different interface. Should I combine all of them? For example, I am…

spi lvds ucf

asked Jan 09 '18 at 17:17

Lac

votes

1 answer

Using the UCF constraints to assign one of two output ports

I've got a CPLD design which has one spare (Debug) pin. I'm trying to find out if it's possible to use the UCF file to select which output port (NET) that pin becomes. The problem is however, that I've got two different nets I may want to connect…

programmable-logic ise ucf

asked Nov 08 '15 at 20:44

Matthew Millman

votes

2 answers

Constraining a 7 segment display in VHDL

Right now I'm just trying to configure a single digit 7 segment display, and I'm pretty stuck. All of the resources I can find say to use a 7 bit logic vector and just stop there. So I understand how it works, the logic vector turns on (or in my…

fpga xilinx ucf

asked Mar 13 '14 at 00:01

user9892

vote

1 answer

Constraint relative arrival time for a group of signals

Imagine a situation where the absolut delay of a group of signals doesn't matter, but it must be ensured each signal of the group has roughly the same delay until it reaches a certain point, say a FF. How does the constraint for this look like? E.g.…

fpga vhdl xilinx constraints ucf

asked Nov 04 '15 at 13:49

andrsmllr

vote

1 answer

How should I translate old TIG statement from UCF to new Vivado XDC files?

I have a short UCF file with the following content: ## Fan Control ## ============================================================================= ## Bank: 15 ## VCCO: 1.8V (VCC1V8_FPGA) ## Location: J48,…

xilinx vivado ucf xdc

asked Jul 23 '15 at 11:38

Paebbels

3,897
2
18
43

vote

1 answer

Why does Xilinx Translate for Virtex-6 not know IOSTANDARD LVDS?

I'm using several Xilinx FPGAs and boards from Spartan3E up to KC705/VC707 and I'm very familiar with UCF files, but there is one question that bothers me... Why does translate for Virtex-6 not know IOSTANDARD LVDS, but translate for Series7…

xilinx synthesis ise virtex-series-fpga ucf

asked Mar 17 '15 at 23:31

Paebbels

3,897
2
18
43

votes

1 answer

Assigning specific bits of vector to outputs in verilog ucf

When I set up my module, I have code like input signed [7:0] SIGNAL but in the UCF I want to assign each bit individually. Currently my code in the UCF looks something like NET "SIGNAL[0]" LOC = P35 | IOSTANDARD = LVCMOS33 | DRIVE = 8 | SLEW =…

fpga verilog input spartan-6 ucf

asked Aug 08 '18 at 16:30

Auden Young

votes

1 answer

Clock doesn't seem to tick

I have been working on a program for class which acts as a stopwatch, but I've been having troubles where it doesn't work. (Only one digit, the first that would be shown on the four digit display is ever used, and it is always at 0.) After putting…

verilog clock debugging ise ucf

asked May 03 '15 at 22:20

Smurfton

votes

2 answers

Usage of UCF file and Clock Divider?

I know VHDL and I understand the syntax but I never programmed an FPGA before. I am going to write soon my first VHDL code and then upload my code to Xilinx FPGA. When writing VHDL code we have entity. On the examples I saw, signals in UCF file are…

fpga vhdl xilinx ucf

asked Apr 30 '14 at 21:25

Anarkie