Need help with sequential fault simulation in Tetramax!!!

Discussion in 'VHDL' started by spectrallypure, Mar 28, 2007.

  1. Hi all. I am experiencing a very annoying problem while trying to run
    a sequential fault simulation with Tetramax, using external patterns
    saved (via a VCD dump) from a back-annotated simulation done in
    ModelSim. The problem is that when I load the VCD dump file in
    Tetramax and simulate it, the tool produces wrong simulation results,
    exhibiting an akward behavior. The caption in the following link
    explains the whole situation:
    h**p://images.elektroda.net/37_1175093373.jpg

    ****[Upper part of image: Modelsim 5.8b simulation - Results: OK, as
    expected]****
    Notice the timing of the clocks PAD_EMTCK and PAD_CLK. At the
    beginning they have periods of 40 and 20 ns, respectively. Then, @
    27,240ns, signal PAD_SCAN_EN goes up and PAD_CLK assumes also a 40 ns
    period (the other clock remains unaffected). Notice also the 40ns-wide
    pulses appearing on signals PAD_SCAN_IN1...3.

    ****[Lower part of image: Tetramax Z-2007.03 simulation - Results:
    WRONG]****
    This is Tetramax's simulation as obtained through the reading of
    modelsim's vcd dump through the following command:"set patterns
    external my_dump.vcd -sensitive -strobe period 40 ns -strobe offset 37
    ns" (note that this command implies the sampling of the test patterns
    at periodic intervals of 40ns, with a suitable offset of 37ns that
    should allow for an appropriate sampling of stable values in all
    waveforms).
    Notice now the awful part: at the beginning Tetramax seems to get it
    right, and defines the test patterns at regular intervals 40ns apart.
    But then misfortune happens: after the edge of PAD_SCAN_EN, Tetramax
    incredibily does two wrong things:
    1. Contrary of what was specified in the "set patterns" command, it
    starts to sample the test patterns EVERY 20ns!!!!
    2. It starts mis-simulating everything: the periods of both clocks
    switch to 20ns, the pulses appearing in PAD_SCAN_IN1...3 are 20ns-
    wide ,etc.

    Therefore, since the dumped file is not appropiately simulated by
    Tetramax, I cannot perform the desired fault simulation, which I
    desperately need.
    I would be the most grateful if anybody could please give a clue to
    what is going wrong here. Why doesn't Tmax respect the 40ns-period
    samping? Am I missing something in the "set patterns" command? I have
    struggled for 2 weeks with this problem without success. I have even
    tried using other versions of Tmax, and also giving different values
    to the "offset" parameter, without any luck. I have also verified the
    vcd dump file's correctness with a third tool, with positive results.
    Any suggestions are really, really welcome!!!

    Thanks in advance!!!
    Regards, JL.
    spectrallypure, Mar 28, 2007
    #1
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. D Jensen
    Replies:
    5
    Views:
    488
    steve
    May 5, 2005
  2. Ray Leon
    Replies:
    25
    Views:
    1,590
    John W Kennedy
    Jul 13, 2008
  3. KellyB
    Replies:
    4
    Views:
    1,086
    KellyB
    Aug 26, 2008
  4. Smartfood

    Non-sequential shuffle help

    Smartfood, Oct 21, 2008, in forum: Java
    Replies:
    0
    Views:
    276
    Smartfood
    Oct 21, 2008
  5. jasperng
    Replies:
    0
    Views:
    1,307
    jasperng
    Nov 27, 2008
Loading...

Share This Page