Simulation and Verification

[kmacc]

There are a number of objects which isim won't let me view. I'm using ISE 11.1. One of the object is a big array of busses. Others are the contents of ramblocks.

Does have a clue why I can't view these traces? I could view them in 10.1.

Thanks,

Kenneth.

[eilert]

Hi Kenneth,

These kinds of data are difficult do display in a useful way.

While ISIM is still a new tool with some quirks, even modelsim gives you trouble.

Example: Displaying the contents of a ramblock. (Busarrrays should be similar)

Let's even assume we want to display a memory of 16x16 Bits, Modelsim would put something liker this in the Waveform:

(I already use hexadecimal radix here)

{  0000, 1234, 3333, ABCD,  0000, 1234, 3333, ABCD, 0000, 1234, 3333,  ABCD,0000, 1234, 3333, ABCD}

So, even in HEX one value needs about half of your screen.

Of course there are means in Modelsim to pick out specific words, but that needs a lot of manual manipulation.

I'm not sure if this already exists in Modelsim, but for this type of data a window with an array view of the memory would be nice.

Cold be made with some tcl/tk.

Have a nice simulation

  Eilert 

[kmacc]

Hi Eilert,

Thanks for the help. One of the objects I can't trace is an array which is used in a way which infers block ram. I used to be able to view this array in 10.1.

Another object that I can't trace is a simple wiring array:

wire [31:0] g[499:0];

I used to be able to view this as a long list of traces which was fine.

Cheers,

Kenneth.

[kmacc]

I just reduced the size of the wire array;

It worked fine for:

[31:0] g[101:0];

I'll now keep making it bigger until it poops.

[kmacc]

I just tried a bunch of different array sizes.

The largest I could do was 128 elements:

wire [31:0] g[127:0];

Is anyone aware of this limitation or whether it can be changed?

Cheers,

Kenneth.

[kdeepak · Accepted solution]

Dear ISim users,

In 11.1, the maximum size (total number of bits in all dimensions) of array that can be traced for viewing in waveform is limited to 4096 by default -- mainly to help avoid inadvertent performance penalty as array tracing can slow down simulation and may not be useful for many users.

But, the maximum traceable size can be changed by the user using "isim set" command easily.

On the Tcl Console of ISim, run:

ISim> isim get maxtraceablesize

You will see 4096 for 11.1 and 65536 for 11.2 (we increased the default in 11.2). This tells you current (default) settings.

If you want to change it to a bigger number (say 200000), you can do that easily by running:

ISim> isim set maxtraceablesize  200000

Now if you run "isim get maxtraceablesize" on Tcl Console it should print 200000 for you.

Note that the maximum size (number of bits) of array that can be displayed in Objects Window is also limited. You can right click on your array object in the Objects Window and select "Show All Elements" in case you wanted to see values of all the elements of an array object.