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).

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

I have a short UCF file with the following content: ...
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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 ...
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479 views

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 ...
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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....
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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 ...