How to substract bussed analog signals ?

Edit : It works when one of the bus is replaced by a single waveform.

/Guillaume.

Forgot to mention : getVersion(t) -> "sub-version ICADVM20.1-64b.500.29 "

/Guillaume

Hi Guillaume,

The trick is to use the function in this article of mine - it explains why this is a challenge and provides a function to adapt the bus-indexed waveforms so that you can do operations that work on buses of different signals: How can I measure the delay between each bit of two analog buses in the ViVA calculator? (the title may not be obvious that it's related - perhaps I should try to generalise the title).

Regards,

Andrew

Hi Andrew,

It works perfectly. Thanks a lot !

However, I still have some trouble with the result of [ abBusToIndex(BusP<2:0>)-abBusToIndex(BusN<2:0>) ].

Let me explain. Please consider the following outputs :

• Test0 = vtime('tran "/lo_pmos_msb<2:0>")
• Test1 = (abBusToIndex(vtime('tran "/lo_pmos_msb<2:0>")) - abBusToIndex(vtime('tran "/MSB<2:0>/local_vss")))
• Test2 = (abBusToIndex(vtime('tran "/lo_pmos_msb<2:0>") t) - abBusToIndex(vtime('tran "/MSB<2:0>/local_vss") t))
• Test3_p = abBusToIndex(vtime('tran "/lo_pmos_msb<2:0>"))
• Test3_m = abBusToIndex(vtime('tran "/MSB<2:0>/local_vss"))
• Test3_p_m = Test3_p - Test3_m
• Test4_p = abBusToIndex(vtime('tran "/lo_pmos_msb<2:0>") t)
• Test4_m = abBusToIndex(vtime('tran "/MSB<2:0>/local_vss") t)
• Test4_p_m = Test4_p - Test4_m

Note that :

• Each of them should include 3 waveforms.
• Test2 = Test1 but with [ abBusToIndex(vtime('tran "xxxxx"<2:0>")) ] replaced by [ abBusToIndex(vtime('tran "xxxxx"<2:0>") t) ]. Just a trial.
• Same as point #2 above from [ Test3_* ] to [ Test4_* ]. Same trial.

Then, please have a look at the screen-shot below and the following observations.

• Test0 is 3 waveforms as expected, with each waveform perfectly identified. But no calculation can be made on it w.r.t. another bus, as already known.
• Test1 and test2 seem (?) to be one waveform only ???
• Test3_p and Test3_m are 3 waveforms as expected, but no clear information about which one is e.g. bit <2>.
• Test3_p_m seems (?) to be one waveform only ???
• Same for Test4_*. In other words, using the t) doesn't help.

My questions : 

• Are the observation above correct ?
• How to proceed to plot Tests 1* -> 4* as they should be ?

I'm not familiar with the bitNum which appears only when using abBusToIndex(). There may be a 'dedicated' way to plot in such cases, but I couldn't find info on it.

Thanks.

/Guillaume