Questions tagged [testbench]
The testbench tag has no usage guidance.
37
questions
0
votes
2answers
62 views
Ultracapacitor initial voltage drop during discharging
I've been building a test stand for ultracapacitors, with very simple schematic looking like this:
simulate this circuit – Schematic created using CircuitLab
The resistor on the bottom is to ...
6
votes
3answers
887 views
VHDL: What is correct way to model open collector output for FPGA?
I2C uses open collector outputs. FPGAs do not have such outputs. They do have tri state buffers though.
How should open collector output be defined in a VHDL for an FPGA?
How should open collector ...
1
vote
0answers
85 views
VHDL - rand*real(2**32-1) : can this cause an overflow issue?
I'm studying VHDL implementations of multipliers: I found this one and i'm trying to modify it. Default word size is 8 bit and the design is working (both simulation and synthesis) for any size up to ...
0
votes
1answer
63 views
Variable frequency for sine wave in Verilog [duplicate]
I am trying to implement 4 different frequencies at which sine wave is going to be simulated in testbench. I am using a counter to do so. However, it can not toggle clk_out in simulation window. Not ...
2
votes
2answers
109 views
Xilinx's ISE (GSR): The initial block adds a delay of 100 time units to simulation
I'm working on a lab assignment in which I'm supposed to simulate a sequential logic circuit (A ROM device). I'm using xilinx's ISE as IDE.
My implementation works fine and the logic and the data is ...
0
votes
1answer
64 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 ...
0
votes
1answer
604 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,
...
0
votes
0answers
57 views
What is the procedure to use ISCAS-85 benchmark Circuits for testing? [duplicate]
Could you please explain the detailed procedure about using ISCAS-85 benchmark Circuits for testing available at the below link http://web.eecs.umich.edu/~jhayes/iscas.restore/
How do we start, could ...
0
votes
0answers
105 views
VHDL-2008 generic packages for post-fit simulation in QuestaSim
I created a testbench for a VHDL design including integrated circuit models to check interface timing requirements. Within each model, I instantiate a generic package (genpkg) to print detected errors ...
-1
votes
1answer
252 views
Understanding Testbench Waveform for UART module
I have taken the following code for testing a UART module from https://www.nandland.com/vhdl/modules/module-uart-serial-port-rs232.html
Can anyone explain what is happening in the ...
0
votes
1answer
38 views
VHDL Output is Unitiliazed or Zero when simulated
I am new to VHDL and implementing a test bench. I am trying to write code for a simple 2:1 MUX where the output of the MUX enters an active high synchronous LOAD register. Inputs and outputs are 8 ...
-1
votes
1answer
545 views
How do I override generic values in a VHDL testbench?
I am new to VHDL, and I'm working with an off-the-shelf UART block. I'm trying to create a test bench and override the data width, but I get errors saying that my signals are undeclared:
ERROR - C:/...
0
votes
1answer
67 views
Electrical gremlins under high Amp draws
I'm new here so I hope all goes well!
I have used an ATX PSU to create a power bench tester for testing automotive headlights. HID in particular which draw around 8-10amps on startup. I have noticed ...
0
votes
1answer
551 views
Modelsim simulation doesn't work Pleas help
I can't for the life of me figure out why I don't get an output from this testbench and entity that i've created. I've tried it several different ways with the OUTPUT y never making it out. I know ...
0
votes
1answer
48 views
If constraints in SystemVerilog
I have a class of sequence item with rand variables:
class my_seq_item extends uvm_sequence_item;
rand bit a, b, c, d;
I want to generate a random bit for 'd' ...
-1
votes
1answer
410 views
getting outputs in simulation as all high impedance. topic: restoring algorithm for binary division
I am getting outputs of my hardware as all high impedance (ZZZZZ). i tried synthesizing the code and got these warnings. I think there might be a problem in the test bench i am trying to run.
...
0
votes
1answer
346 views
This model of a D-Flip flop with Enable not working as expected
This is a Verilog model of an array of D flip-flops with enable line along with a test bench used in ModelSim Altera:
...
0
votes
0answers
96 views
Adding of frequency divider causes no output VHDL
I'm trying to get the output from this code. The output is not showing after adding the frequency divider. Before the frequency divider, the code worked well and display the output.
This is my code
<...
0
votes
0answers
123 views
Multiple VHDL testbench for Single entity
I have VHDL design of Clock generator entity which require 8 input parameters and as per parameters generates single clock output. I have tested using single VHDL testbench and simulated in Modelsim. ...
-1
votes
1answer
289 views
Error: illegal Verilog output port specification
I am having problems with my verilog test bench. Every time I try to run it, I get the error in the title above for my four switch registers. I have searched this question numerous times but I cannot ...
1
vote
1answer
150 views
1
vote
4answers
440 views
Usage of “initial” in Verilog module description
I'm writting a code and I have 2 dumb questions:
1- Is it a bad practice to use "initial" in the module description?
I'm asking this because I have a frequency divider with 2 signals (clk_in and ...
-1
votes
1answer
235 views
Output internal reg to a .txt in Verilog
I would like to write an internal reg to a txt file.
I have tried something like:
...
2
votes
1answer
162 views
What options exist to verify Avalon-MM slave component?
I am writing an Avalon-MM slave. It shall connect to Nios II as master device. What options exist to write testbench for it? I must be sure that an Avalon-MM master can correctly read/write it.
I ...
0
votes
1answer
297 views
problem with verilog testbench
I have problem with clock signal in Verilog test bench.
I've tried almost every possible ways to create clock, but in the waveform it's U meaning "Unknown".
Here is my code for clock (...
11
votes
3answers
1k views
How do I protect myself when testing a PCB that involves an AC line?
I have to test prototype PCBs that convert household AC into several DC voltage levels.
I concern about my safety when working with AC and would like to know how to properly setup a testbench that, ...
0
votes
2answers
272 views
Load image into VHDL testbench
Is there a standard way to load an image into VHDL testbench so image processing logic output can be tested? Obviously there will be an output from the testbench, also an image that must be possible ...
0
votes
1answer
102 views
designing image debayer block, how should the testbench be written
A debayer block inputs image from a CCD Bayer filter and then estimates the missing color information for each pixel. The data comes from a camera. How should one go about writing a testbench for ...
-1
votes
1answer
287 views
Help needed with verilog testbench
could anyone explain, why the output signal in my verilog testbench isn't changing?
I'm trying to build a module that does tasks on both posedge and negedge.
For testing purposes, I've built a ...
0
votes
1answer
389 views
Verilog counter does not work!
I've written this code for a counter but I don't know why it doesn't work. Actually the output remains at zero and when I change load to 0, output changes to unknown.
Would you please help me to ...
0
votes
2answers
131 views
Designing a testbench for a multi-cycle circuit?
Let's say I have a circuit that performs a function which takes 100 clock cycles to complete. My testbench feeds inputs into the circuit and then checks whether the output is correct.
I'm unsure how ...
0
votes
2answers
2k views
VHDL: Using internal signals in testbench
I'm trying to use one of my design's internal signals in my testbench. I already know how I would do it in Verilog:
...
3
votes
1answer
224 views
Simulating a thermopile on the bench — is this a reasonable/reasonably accurate way to do it?
Primer
Most people know about 24V HVAC control systems, as that's what's commonly found on furnaces, heat pumps, central air conditioners, and other such systems. If you have electric unit or ...
0
votes
1answer
291 views
How to model devices external to FPGA in a testbench?
FPGA could connect to lot of devices like memory devices (SRAM, SDRAM, DDR RAMs), data converters and various other complex ICs. Is it a normal practice to model them in a testbench to make ...
3
votes
2answers
2k views
Temporary PCB connections for testing
I want to be able to perform tests on assembled PCBs with a custom tool. the test would take seconds, and would be done manually by connecting a cable between the tool and PCB.
My question is what ...
0
votes
1answer
85 views
I need to derive a lower frequency clock from the main clock and sample it in verilog
I have been successful in deriving the clock, but am unable to sample and check the results in the test bench. Attaching the code and the written test bench. Need to find a way to do away with the ...
5
votes
3answers
833 views
Writing synthesizable testbenches
I'm just starting to learn SystemVerilog and work with FPGAs, and so far I haven't found a satisfactory way to test my code. I'm coming from a software background, and I have always been writing ...
