#27 Digital simulation with more than few inputs

closed
Stefan Jahn
None
5
2010-05-10
2009-10-17
Anonymous
No

Simulation a component with f.e. 20 inputs 1 output does not work (in more or less real time):
1) Truth table simulation:
1.1) hangs in step "running VCD conversion... " with qucsconv.exe running. Aborting the simulation does not stop qucsconv.exe.
1.2) or stops after simulation with an error message about "out of memory" in log.
2) TimeList simulation stops with an error message "Unknown time unit .04858e+07
Unknown command 'ns'. Type h for help." in log.

Discussion

  • TimeList simulation netlist

     
    Attachments
  • Stefan Jahn
    Stefan Jahn
    2009-10-21

    Hello! Can you please provide the schematic for easier bug finding? Also: which version of qucs and freehdl are you using?

     
  •  gatisg
    gatisg
    2009-11-03

    QUCS v0.0.15 (Win). FreeHDL latest (IMHO v0.0.7?) - seems like FreeHDL has no command line option to get version info.
    On adding a comment there is no way to add attach - see previously attached netlist.txt

     
  • Stefan Jahn
    Stefan Jahn
    2010-03-29

    Hello! I was now able to reproduce the problem. Let's see what I can do about it.

     
  • Stefan Jahn
    Stefan Jahn
    2010-03-29

    • assigned_to: nobody --> ela
     
  • Stefan Jahn
    Stefan Jahn
    2010-04-14

    Hello there!

    I just changed the VCD converter in CVS. The VCD processing is now much faster. I tested with 18 and 19 bit truthtables and this is working now fine. It is a bit unusual with so many inputs for a truthtable. Technically speaking it is difficult with so many inputs; just consider with 18 inputs you have 256k table entries with 19 samples even 512k table entries. Is this number of table entries (or even more) still useful?

    Nevertheless I'll be checking if I can reduce memory consumption (speed is not a problem anymore) a little. Now, with 2^19 truthtable entries, approx. 1GB is required...

    Best regards, Stefan.

     
  •  gatisg
    gatisg
    2010-04-19

    Should be fine. Every tool has its limits, so truth table too. Nice enough to have it more than 17 bits :)
    Thank You!

     
  • Stefan Jahn
    Stefan Jahn
    2010-05-10

    • status: open --> closed
     
  • Stefan Jahn
    Stefan Jahn
    2010-05-10

    Hello! For now I consider this issue fixed, agreed?