VCD file generation

[sunil]

Hi,
I want to generate VCD for my design. Can anybody tell me how to
generate for VHDl design. After loading the design, which commandas i
have to execute. I am not using any test bench, i am giving values by
forcing.
thanking you all.

 

[Ajeetha Kumari]

Sunil,
Depends on your simulator, as VCD is not defined in VHDL LRM,
rather it is part of Verilog LRM. I know that NCSIm & Modelsim
supports VCD dumping for VHDL too. In NCSIm you could do:

database -vcd -open my_dump -default
probe -create -vcd tb_top -depth all

Check your simulator's documentation for more.

HTH,
Ajeetha,
http://www.noveldv.com
Co-Author: Using PSL/SUGAR for Formal and Dynamic Verification 2nd
Edition.

 

[Andy Botterill]

Hi,
I want to generate VCD for my design. Can anybody tell me how to

Using ModelSim do file commands :-

vcd file page_test000_tb.vcd # Creates a standard VCD file
vcd add -ports /test000_tb/u0/* # This only adds the names signals.
# For bi-directionals you may need to
# store the control signals.

ModelSim can create extended VCD files. If you want to create one of
these then the syntax is similar to above. Chapter 13 gives a reasonable
explanation of how to create VCD files.

Here is a *rough* website covering VCD files. It was written from a
verilog perspective. The techniques and checks shouldn't be much
different for VHDL.
http://www.plymouth2.demon.co.uk/vcd_pages/vcdtoc.htm
Constructive criticism will be appreciated.

What are you trying to do? For viewing waveforms the above information
is OK. If you are going to extract test vectors then you need to check
that the waveforms are suitable for the tester.

If anyone knowledge of the VHDL equivalents of the verilog system tasks
dumpfile and dumpvars then I would be interested.

generate for VHDl design. After loading the design, which commandas i
have to execute. I am not using any test bench, i am giving values by
forcing.

It'll be easier to write a testbench surely.

 

[sunil]

Hi,
thanks for u r replies. I required VCd file for power calculation
in FPGA. I used commnads vcd file sun.vcd
vcd dumpports -file sun.vcd /totalunit/*.

It is loading signals. But accorind to format it is not coming. I want
to load all the switching rates of all signals in my design. It is not
loading all signals.

 

[Andy Botterill]

Hi,
thanks for u r replies. I required VCd file for power calculation
in FPGA. I used commnads vcd file sun.vcd
vcd dumpports -file sun.vcd /totalunit/*.

It is loading signals. But accorind to format it is not coming. I want

If you add a -r the command recursively travels the whole of the design.

vcd add -r /totalunit/* -file sun.vcd

to load all the switching rates of all signals in my design. It is not
loading all signals.

If the design is of any size the resultant extended VCD file will be
huge.

 

[sunil]

Hi,
Thanks for u r help. That commnad is working,. I ahve one doubt.
Whether we have run the program for the real values which we are going
to use. And How much time it is required to get propoer acitivity
rates.
Once again thanks.