S
spectrallypure
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.
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.