I have extracted VHDL source of my design from Xilinx ISE.
It uses UNISIM library to model Look-Up Tables and Flip-Flops and other components.
When I simulate my VHDL design (a combinational circuit) using ModelSIM, there are no delays displayed in simulated WaveForms.
I want to know how can I add delay to elements of UNISIM library and then see its effect on MODELSIM simulation?
VHDL: Simulating Delay for ISE UNISIM components
isemodelsimsimulationvhdlxilinx
Related Solutions
Your design will not function correctly if it runs at 100 MHz but is only spec'd (by the tools) to run at 50 MHz. If it does, then it's a one-off miracle that wouldn't work when you make a change and rerun the tools. Don't do it. Don't even do it if your clock is 100 MHz and the tools tell you the design can run at 99.5 MHz.
To solve your problem you can either write a simple 'divide by power of 2' clock divider to reduce the clock frequency (something like this in Verilog):
reg [n:0] count;
always @(posedge CLK_100) begin
count <= count + 1;
end
BUFG bg_0 (.I(count[m]), .O(CLK_DIV));
(where 'm' <= 'n' and 'bufg' is a global clock buffer, and must be used for synchronous designs) or use a Digital Clock Manager (DCM).
Hopefully that solves your pipelining issues as well unless you absolutely have to run the entire design at 100 MHz. Other than pipelining you can consider using FIFOs if you have part of the design running at 50 MHz and the other at 100 MHz, but you'll have to say a bit more about what you're doing to get more meaningful help here.
- compile UNISIM libraries by runnin
compxliband following wizard. - then in your modelsim, library pane add new library.
- after that add library from existing library and point to folder which contains compiled
version of unisim, e.g. it is
C:\Xilinx\10.1\ISE\vhdl\mti_se\unisimfor me
After that you can have fun with UNISIM :)
Best Answer
Each synthesis step generates it's own simulation model. So start start place&route and select 'generate post par simulation model' afterwards. Now you can launch your selected simulator iSim or vSim from ISE.