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.

Standard simulation - simulation is controlled directly from gschem (see examples), gsim contains a set of predefined components

• for simple graphic output directly from gschem - instant graphic components a.e.
  • amplitude-phase characteristic plotter
  • 4 channel analog scope
  • 2 channel analog recorder
  • 2D xy parametric scope
  • 3D xyz parametric scope
  • 4 channel digital recorder
  • 8 channel digital recorder
• 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.

Python scripting - simulation is controlled from Python language/enviroments (eg. IPython, Geany ), gsim contains a set of predefined Python scripts

• 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

Additional functions

• 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

Example - original line from Spice netlist file for D flip-flop

A4 6 4 5 5 7 6 D_DFF

Part of expanded netlist by gsim for XSpice simulation, based on gschem D_DFF 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 ) 

Download - Version (verzia 0.03)

• 100330_py_003.zip - python scripts
• 100330_sym_003.zip - gschem symbol library
• 100330_model_003.zip - basic models

Examples - Small set of gsim examples - analog,digital, mixed, hybrid

Component library - Selected set of Spice and Xspice components.

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