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vpwlf source and bus signals

Dmitry Babin

Hi all,

I'd like to drive a bus-type signal (let's name it net<3:0> for clarity) using data from a text file. I have two options in mind:

 

1) There is a single text file in the following format:

time1  bit3_value1  bit2_value1 bit1_value1 bit0_value1

time2  bit3_value2  bit2_value2 bit1_value2 bit0_value2

etc.

I suppose there is no built-in support for such a format. I can start implementing such a source in VerilogA, but I like the functionality provided by the VPWLF built-in source (like time/voltage scaling, repetitions, etc.), and it seems a complex task to duplicate all this in VerilogA.

 

2) There is a text file for each bit (filename_bit0.txt, filename_bit1.txt, etc.), each one in the format suitable for VPWLF. I put a bunch of VPWLF sources (per # of bits) in a schematic and create a symbol for it. This approach allown me to use all the features of VPWLF, but it also has disadvantages: a) I have to generate the N files; b) if I want to switch to another input stimulus, I have to edit each VPWLF instance manually and change the file path and/or name (can't do it in one touch)

 

Can anyone suggest a better way?

Is there any simple way to implement the case 1 functionality?

Is there any workaround for the case 2, b problem (like maybe defining some property in the top symbol, containing the beginning of the file path/name, and concatenating it with suitable postfix in each VPWLF source inside)?

 

Thanx all,

Dmitry.

  • If this is for digital vector input, I would suggest you look at using either a VCD or Vector file input (these are in ADE under Setup->Simulation Files). Type "spectre -h vector" for a short description on these, but they are covered in more detail in the full manuals.

    Regards,

    Andrew.

  •  I had to deal with a very similar situation recently. I managed it by starting a schematic and setting the values I am interested in on a single vpwlf instance. I then exported to edif. Using the data from the exported edif file it was quite straightforward to write some simple C code to generate a new edif file with an array of vpwlf. Import the edif and you're good to go.

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