Questions tagged [modelsim]

ModelSim is hardware simulation and debug environmment targeted at ASIC and FPGA designs with native support for Verilog, SystemVerilog for design, VHDL, and SystemC.

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How can I make Verilog HDL ModelSim test bench for a simple ripple adder circuit output an addition table instead of a long list of every calculation?

I've completed my assignment and I'd like to make the output look something like this, with one table for sum output and one table for carry output: ...
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22 views

Does Quartus support UVM in files with .sv extension?

I want to learn UVM later (i am starting with verilog first, systemverilog is next) but i have this doubt in my head, i have seem examples in the web but they use Modelsim, so my doubt is, if i make ...
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2answers
75 views

Errors in VHDL code

The VHDL code was written by me for a 4-bit PIPO DFF register. I have been encountering some errors when i did so. Kindly check the code and errors below. ...
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26 views

How to log Fixed-size Array with Mentor Modelsim/Questa in a tcl with add wave *

I have Fixed-size Array in port Out but my wildcard doesn't include them and I didn't find anything in the manual. ...
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38 views

Error loading design Instantiation of 'addtwobit' failed. The design unit was not found

I was writing Verilog code for an ALU from the nand2tetris course This code compiled without any errors in ModelSim but when I try to start simulation it throws an error Error loading design ...
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1answer
83 views

How do i read the RGB values of an image in Verilog from a hex file generated in Matlab for processing?

I have used Matlab to generate hex file for an image (1200 * 900 resolution). The hex file is like There are such 3240000 rows. How do i read this in verilog to performing some processing (filtering ...
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1answer
493 views

Verilog code for construction of 4x16 decoder using 3x8 decoder [closed]

This is my 3x8 verilog module: ...
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0answers
35 views

Verilog State Diagram Problem

I am trying to implement the SPI_SLAVE ...
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0answers
70 views

Difference in SystemVerilog-2005 HDL simulation behavior between Quartus Prime Lite (20.1) and ModelSim-Intel Starter Edition(2020.1)

A SystemVerilog module using an always@ block with a gated trigger does not compile in Quartus Prime Lite (20.1). Quartus Prime reports the following compiler error message: Error (10170): Verilog ...
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18 views

Testbench for RTL and GLS simulation

I want to do the GLS simulation after the RTL simulation. I was asked to add uut : entity work.eq3(structure) instead of the one specified below used for RTL <...
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0answers
87 views

Simulation of IP Core using ModelSim

I try to use IP core in Xilinx ISE 14.2. When the simulation done with ISim it works fine. Now I need to do the simualtion with ModelSim SE-64 10.7. I compile HDL Simualtion Libraries Fig.1. I run ...
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28 views

Post-synthesis simulation using Nangateopencelllibrary_pdkv1_3_v2010_12

I'm wondering if anyone has used the open-source Nangate library to do synthesis and post-synthesis simulation? I was trying to synthesis my processor and got the netlist verilog file from design ...
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60 views

ModelSim does not run until “$stop” command after editing my testbench

I keep running into this issue where my code stops running before the "@stop" command. This only occurs whenever I add code in Libero and then go back to ModelSim. When I go to simulate in ...
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1answer
110 views

Why is my 8-bit counter only counting until 127?

I recently coded an 8-bit counter in Libero and simulated it in ModelSim using Verilog. When I simulated my design, it only went up to 127. Shouldn't an 8-bit counter go up to 255? Here is my HDL Code:...
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1answer
96 views

Writing to a Register happens one or two clock cycles after asserting write enable?

I am using the code shown here Verilog: Writing to a Register Happens A Clock Cycle Late and that user posted a picture where output would change 2 cycles after asserting write enable. That post got ...
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56 views

error loading design

I am trying to simulate a testbench. I have compiled the testbench and the file it is testing and everything compiles without errors. When I try to simulate the testbench it says "error loading design"...
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344 views

How to use VHDL Entity in logisim evolution?

I'm new in Logisim and VHDL. I'm trying to use VHDL entity-component but the output always is "x". Then I read a document ( this link ) that said Logisim requires ModelSim to use this feature. So I ...
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1answer
227 views

Verilog output is hiZ in testbench

I'm new to verilog and modelsim. I'm having trouble with my AND and OR modules in this particular testbench. The output is always Z(hi impedance) ...
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0answers
17 views

What is the easiest way to simulate and experiment with FPGA using simulated external DDR3?

For a computer architecture school project I have to implement an algorithm in verilog, such design have to input and output a VERY large ammount of data that wouldn't fit in on-chip memory, hence I ...
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1answer
74 views

Help on writing test bench for up counter in verilog

preamble: I think I have enough understanding of logic circuits and enough experience in programming from other languages(C, python, etc.) However, I am very new at Verilog and also have never used ...
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52 views

Why am I getting weird behavior when building 4-bit down counter?

I'm attempting to build a 4-bit modulo-10 down-counter (i.e 9,8,7...,1,0,9,8,7...0). Here is my code so far: ...
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0answers
96 views

Range error during Modelsim simulation of a VHDL user-defined resolved data type

When running a simulation of a testbench involving a user-defined resolved data-type, I get an error report of the form: "** Fatal: (vsim-3734) Index value 1 is out of range 0 to 1" , followed by ...
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0answers
10 views

How to print line coverage for a particular line in a Verilog code, in Modelsim?

The following line gives the line coverage for an instance of a module in Modelsim. ...
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2answers
69 views

Sequential logic in VHDL

Does anyone know of a way I can use sequential statements in VHDL without using the traditional if, case, when statements? I am building an 8 bit word splitter that will then pass a 4 bit nibble to ...
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1answer
107 views

vhdl output pulse

I have another question regarding some VHDL, I am trying to create a pulse of 5ms output for (in my code a_full) however I am struggling to find any information on how to generate this, basically I ...
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2answers
84 views

ModelSim wave window showing zero time transitions

I'm new to verilog and so ModelSim. There's a problem or actually may not be a problem that I have noticed. It seems to me that ModelSim wave window imposes by default a transition at time zero on ...
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1answer
90 views

Input CLK Keeps Showing As Hi-Z on ModelSim

I am writing some basic verilog code that blinks an LED at some frequency. The code for the design file is the following: ...
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1answer
152 views

I am not getting output I want in ModelSim - Altera (perhaps something related to timing requirements not being met?)

I am writing some basic verilog code that blinks an LED at some frequency. The code is the following: ...
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1answer
729 views

My work directory in ModelSim is always empty. How can I resolve this problem?

I'm new to Verilog. I made a new ModelSim project and kept the default directory to work. Then I added .v (Verilog) files to the project. And after that I compiled the files. Compilation was ...
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1answer
384 views

Verilog Missing connection for port

I was creating a circuit using two dual input AND gates into a dual input NOR using three modules and module instantiation. The first module is for the AND inputs and the second module is for the ...
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1answer
1k views

How to come out of the transcript window of Modelsim which is stuck?

I am running a Modelsim script and the transcript window gets stuck. I have tried the following to go to the next line in the transcript window without any success. Simulate > End simulation Simulate ...
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0answers
123 views

Power analysis using Synopsys Design Compiler

I am trying to generate power report using Synopsys DC compiler. At first I have generated VCD file using Modelsim simulator, which I have converted to SAIF file using "vcd2saif" command. Then I ...
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1answer
258 views

Why is this VHDL pseudo random number generator not working as expected?

I'll start off by saying I have about 2 days experience in VHDL so there's a strong chance my code is horrible. I would appreciate any tips on better VHDL practice. I am busy trying to simulate a ...
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1answer
1k views

Removing modelsim error

I am trying to simulate a simple inverter in verilog using modelsim 10.7 version. While compiling the code I am getting the -novopt error (error code 12110). As per user manual page 80; the -novopt ...
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1answer
76 views

Set alternative editor for ModelSim

I want to set an alternative editor in ModelSim. I tried How to configure my favorite editor in ModelSim? and after I set the altEditor I get "unknown command external_editor". Unfortunately my ...
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1answer
96 views

Respecting setup/hold time in RTL design

This question might sound obvious for some, however, I found that I need to understand some VLSI fundamentals. In Functional simulation setup and hold time are equal to zero, so we can simulate the ...
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1answer
331 views

Too many ports expected in verilog? [duplicate]

I get an error saying i have to many port connections when I try to model sim, but clearly I have the right amount. Whats wrong with my design ?? As you can see the error appears in line line 16 of ...
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1answer
232 views

VHDL Procedure - Same variable for input/output parameter

I've written a component where I use the same variable for the input and output parameter of a procedure. A reduced example looks like this: ...
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0answers
61 views

VHDL - Unable to correctly implement complex scheduling of data lines to Inputs of multiplexers

In my design, I have two configurable parameters ...
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1answer
195 views

Why am I getting a red wire for my out?

I am attempting to create an output that goes on for a certain amount of time an then goes low for a certain amount of time and my out simply won't simulate. Attached is my code, test bench, and ...
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1answer
133 views

How add delays to everything in Verilog or SystemVerilog outside of .v or .sv file

All delay documentation I've seen is pretty low level -- add a #5 or whatever and that particular assignment gets a delay. Use this in a module and instantiate, etc, etc. There are variations on ...
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1answer
2k views

error loading design - modelsim

I'm new to modelsim and Verilog and I have got an error in it: # Region: /seqdectorTB # Error loading design 1.3.v: ...
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1answer
3k views

Unknown Formal Identifier in VHDL

I am facing an error with my VHDL code. I am new in it. After putting so much of my time I am even unable to resolve this error. I am using ModelSim software for it. Here is my code: ...
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1answer
577 views

Unable to diagnose StX fault in Modelsim

I'm unable to figure out why Modelsim is giving me a StX fault for this testbench. I'm just creating a counter and simulating a device that returns the MSB of the counter. Any help in figuring out ...
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2answers
471 views

Passing VHDL string generic with spaces via Modelsim command line

Given the following code: entity foo is generic ( VAL : string ); end entity foo; architecture behav of foo is begin end architecture behav; How can I ...
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1answer
266 views

I write this module to arithmetic shift to left and right in verilog

this is my code: module zero(out,A,B); output signed[5:0] out; input signed[5:0] A,B; assign out = A[5:0]<<<2 + B[5:0]>>>1; endmodule ...
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1answer
88 views

Problem in blocking and non-blocking - verilog

I have this code and I am having a problem in the product output, any ideas? I've tried a lot and it doesn't work.
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1answer
192 views

Modelsim: resume simulation future

I have long running simulation in Modelsim for VHDL/Verilog designs. I want to know are there any way to save current simulation progress and resume it somehow in later time?
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1answer
2k views

VHDL: reading integers from a text file, storing them in array, and writing in text format again

In a certain simulation testbench using questasim, I am trying to read the files with integers numbers which looks like, ...
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0answers
139 views

No output with for loop

I have been working on this issue for a couple days and still cannot figure it out. I wonder if someone can help me with this. You can just focus on the video process at the bottom of the code below. ...