Description of gsim

gsim is simulation pre/post processor for gschem, ngspice and matplotlib based on Python. Allows easy control of simulation process directly from the circuit in gschem or interactively in Python environment.

gsim contains a set of predefined components for gschem and python scripts

• for simple graphic output directly from gschem - instant graphic components a.e.
  • plotter for amplitude-phase characteristic
  • 2 channel or 4 channel analog scope
  • digital scope, x/y parametric scope
• for input of analog and digital blocks of XSpice simulator. Enables the creation of hybrid models, consisting of discrete, block and logic components and their use as regular components in gschem.
• simple *.sch files parser
  • generates list of a part of the schematics (components, connections...)
• *.net file parser with preferences
  • allow use of real components in the simulation
  • corrects the order of pins for the simulation by real pin name (eg diode - Anode, Anoda, AN, A), eliminates problems with different components for simulation and real proposal of the circuit
  • generates block models for XSpice in their specific format based on the components attributes

Original Spice netlist for D flip-flop

A4 6 4 5 5 7 6 D_DFF

Expanded by gsim, based on component attributes

* >>><<< A4 6 4 5 5 7 6 D_DFF
A4 6 4 5 5 7 6 D_DFF_A4
.MODEL D_DFF_A4 D_DFF (
  + rise_delay=1.0e-9
  + fall_delay=1.0e-9
  + set_load=1.0e-12
  + reset_load=1.0e-12
  + data_load=1.0e-12
  + clk_load=1.0e-12
  + reset_delay=1.0e-12
  + ic=0
  + clk_delay=1.0e-9
  + set_delay=1.0e-9 ) 

• in interactive mode substitutes parameters of components (functions setPAR, setTRAN, setAC …)
• set of referenced classes gsim_PLOT for implementing instant-graphic components
• set of inherited classes for easy data manipulation (simulation results) in the interactive mode

gsim is in an early experimental version, it is intensively tested and continuously developed. Please notice, this is conceptual proposal which will be extended in the future.

Thanks to the authors of gEDA project, ngspice, matplotlib, python, and scipy, only thank to their superior and excellent work, it was possible to integrate all components into a compact system, usable at the present time.

itPK - Team