Internal Signals and other questions with ModelSim XE/II Starter 5.7g VHDL Testbench

[Martin Maurer]

Hello,

i am trying to learn how to use ModelSim with a VHDL Testbench, but i don't
find any answers on a few of my answers.
At the moment i start ModelSim always via "Simulate Post-Translate VHDL"
from Xilinx Project Navigator.

1) I can see all my stimuli, which are mainly the external in- and outputs.
They seems to toggle fine. But how can i display the internal signals ? Is
the only solution to assign a port to an internal signal to see it in
ModelSim. I already tried to simply define new signals, they are drawn in
ModelSim, but it seems they are not connected to the real signals. I think i
was able to add internal signals via "Signal" window, but next time i
simulate the signal was lost again...

2) I am currently can simulate my design once. When i external edit my vhdl
source or testbench i always must close ModelSim and restart it via Xilinx
Projects Manager. If i don't close it, i get an error message, that
"ModelSim is already running". Is there a more convenient way ?

3) I found a few nice commands like "view wave", "add wave *". Is there a
command for full zoom ? Where can i say, that certain commands should be
executed e.g. after drawing of a wave ?

4) Every time when i open ModelSim the wave window is only a small window,
positioned at right/lower corner of my screen. I already edited the wave
window "geometry", saved it to default name modelsim.tcl of my project
directory. But on next restart same windows size and position as before.
Must i move this file to a certain position. Is there a command like "use
preferences" that i can execute like in question 3 ?

5) In my vhdl source file i use a "std_ulogic_vector", because i want to use
tristate pins, for bidirectional data transfer of data. In the testbench the
xilinx tool created a testbench with "std_logic_vector". It compiles fine.
When i change it to "std_ulogic_vector" in testbench, ModelSim brings a
compile error, that source and testbench does not fit together. I already
use 'Z' for assignments and it seems to work. Should i just ignore this or
must i pay attention when doing it this way ? ModelSim can handle tristate
logic ?

6) Is there a FAQ for such questions ?

So enough for now,

Martin Maurer

 

[Mike Treseler]

i am trying to learn how to use ModelSim with a VHDL Testbench, but i don't
find any answers on a few of my answers.

Learn google grooups searches.

1) I can see all my stimuli, which are mainly the external in- and outputs.
They seems to toggle fine. But how can i display the internal signals ? Is
the only solution to assign a port to an internal signal to see it in
ModelSim. I already tried to simply define new signals, they are drawn in
ModelSim, but it seems they are not connected to the real signals. I think i
was able to add internal signals via "Signal" window, but next time i
simulate the signal was lost again...
http://groups.google.com/groups?q=vsim+add+wave

2) I am currently can simulate my design once. When i external edit my vhdl
source or testbench i always must close ModelSim and restart it via Xilinx
Projects Manager. If i don't close it, i get an error message, that
"ModelSim is already running". Is there a more convenient way ?
http://groups.google.com/groups?q=vsim+command+line+vmap

3) I found a few nice commands like "view wave", "add wave *". Is there a
command for full zoom ? Where can i say, that certain commands should be
executed e.g. after drawing of a wave ?
http://www.google.com/search?q=vsim+wave+zoom


4) Every time when i open ModelSim the wave window is only a small window,
positioned at right/lower corner of my screen. I already edited the wave
window "geometry", saved it to default name modelsim.tcl of my project
directory. But on next restart same windows size and position as before.
Must i move this file to a certain position. Is there a command like "use
preferences" that i can execute like in question 3 ?

Don't know. I size windows manually.

5) In my vhdl source file i use a "std_ulogic_vector", because i want to use
tristate pins, for bidirectional data transfer of data. In the testbench the
xilinx tool created a testbench with "std_logic_vector". It compiles fine.
When i change it to "std_ulogic_vector" in testbench, ModelSim brings a
compile error, that source and testbench does not fit together. I already
use 'Z' for assignments and it seems to work. Should i just ignore this or
must i pay attention when doing it this way ? ModelSim can handle tristate
logic ?
http://groups.google.com/groups?q=vhdl+oe_demo

6) Is there a FAQ for such questions ?

http://www.model.com/
http://www.vhdl.org/vi/comp.lang.vhdl/FAQ1.html

-- Mike Treseler

 

[Charles Bailey]

Hello,

i am trying to learn how to use ModelSim with a VHDL Testbench, but i don't
find any answers on a few of my answers.
At the moment i start ModelSim always via "Simulate Post-Translate VHDL"
from Xilinx Project Navigator.

1) I can see all my stimuli, which are mainly the external in- and outputs.
They seems to toggle fine. But how can i display the internal signals ? Is
the only solution to assign a port to an internal signal to see it in
ModelSim. I already tried to simply define new signals, they are drawn in
ModelSim, but it seems they are not connected to the real signals. I think i
was able to add internal signals via "Signal" window, but next time i
simulate the signal was lost again...

Under the File menu of the waveform window there are options for saving
the current display format, including the signals you have displayed,
and then restoring it again later.

2) I am currently can simulate my design once. When i external edit my vhdl
source or testbench i always must close ModelSim and restart it via Xilinx
Projects Manager. If i don't close it, i get an error message, that
"ModelSim is already running". Is there a more convenient way ?

Yes. I find ModelSim to be very convenient and friendly.
Define a "project" (read the help text). Add your VHDL files to the
project. After you edit one of the files, click on the Project tab. A
question mark will appear by the file if has been changed since you last
compiled it. Select the file and click the Compile button. At the
ModelSim command prompt enter "restart -f". The simulation will be
restarted and ModelSim will load the newly compiled versions of any
files that have changed.

3) I found a few nice commands like "view wave", "add wave *". Is there a
command for full zoom ?

Click anywhere in the waveform window and press "f". There are also
menu buttons for doing this.

Where can i say, that certain commands should be
executed e.g. after drawing of a wave ?

You can put any sequence of commands you want into a "do" file.

4) Every time when i open ModelSim the wave window is only a small window,
positioned at right/lower corner of my screen. I already edited the wave
window "geometry", saved it to default name modelsim.tcl of my project
directory. But on next restart same windows size and position as before.
Must i move this file to a certain position. Is there a command like "use
preferences" that i can execute like in question 3 ?

Size the windows the way you want them. Click Tools -> Save
Preferences -> Save.

5) In my vhdl source file i use a "std_ulogic_vector", because i want to use
tristate pins, for bidirectional data transfer of data. In the testbench the
xilinx tool created a testbench with "std_logic_vector". It compiles fine.
When i change it to "std_ulogic_vector" in testbench, ModelSim brings a
compile error, that source and testbench does not fit together. I already
use 'Z' for assignments and it seems to work. Should i just ignore this or
must i pay attention when doing it this way ? ModelSim can handle tristate
logic ?

You should use std_logic_vector, not std_ulogic_vector, for
bidirectional buses.
You can connect std_logic to std_ulogic, but you can't connect
std_logic_vector to std_ulogic_vector without using a conversion
function. The ieee.std_logic_1164 package comes with functions for
doing these conversions. Look in the package.