Circuit Simulator (WinSpice and Matlab, improved interface)

function [Rac] = WS_RC_low_pass(x)
% Create and save the file 'param.cir' to be included in 
% another file to be run by WinSpice3.
% The built-in function 'num2str' is used to modify parameters
% wherever it is convenient.
p = ['.param RES1=' num2str(x(1)) ' CAP1=' num2str(x(2))];
dlmwrite('param.cir', p, 'delimiter',''); 

% Run WinSpice
% Make sure wspice3.exe and .cir files are available 
% in this directory
! wspice3 RC_LP_filter.cir 

% Read data saved in .csv files
% (assuming name termination _ac_out.csv)
[Rac] = getWSpicedata2('RC_LP_filter'); 

Compare the simplicity of this code against the previously developed code.
We eliminated the need to re-build the complete '.cir' file with Matlab, and we concentrate only on the relevant parameters.

There is an important portion of additional code to read the .csv files.

function [Rac] = getWSpicedata2(WSpiceBaseFile)
% Read csv files generated by a 'write' in a 'WSpiceBaseFile' (.cir file)
% Rac{1} = Frequency Points
% Rac{2} = AC response 

ac = fopen([WSpiceBaseFile '_ac_out.csv']);
Rac = textscan(ac, '%f %*f %f %*f', 'delimiter',',','headerLines', 1);
fclose('all');

clear; clc; close all 

% We try some initial components
R1 = 10e3;
C1 = 1e-9;
x = [R1 C1];
[Ra] = WS_RC_low_pass(x); 

figure(1)
semilogx(Ra{1},Ra{2})
grid on 

% We try another cutoff frequency by modifying the resistor
R1 = 1e3;
x = [R1 C1];
[Ra] = WS_RC_low_pass(x); 

figure(2)
semilogx(Ra{1},Ra{2})
grid on