Reading Serial Data from arduino and plotting it continuously vs time

Right now I am using an arduino uno to read analog serial data from a GSR(skin conductance) sensor. I have a code in arduino IDE that alters the serial data, so I am hoping to take this data directly from the IDE and use it with matlba continously. Also, Arduino Uno has a circuit that automaticaly converts the voltage into a digital value from 0-1024, but when I do readVoltage() it will read the analog signal. I borrowed this code from some ones in the answers page, but every time I run the code I get an error:

"No appropriate method, property, or field 'analogRead' for class 'arduino'.
Error in ArduinoSerial (line 36)
        dat = a.analogRead(0);   %* 0.48875855327; %Data from the arduino"

Is the a.analogRead in the download support package or do i need to make my own?

clear
clc
%User Defined Properties 
a = arduino('/dev/cu.usbmodem1411','uno');            % define the Arduino Communication port
plotTitle = 'Arduino Data Log';  % plot title
xLabel = 'Elapsed Time (s)';     % x-axis label
yLabel = 'Skin Conductance';      % y-axis label
legend1 = 'Measured Skin Conductance';
% legend2 = 'Temperature Sensor 2';
% legend3 = 'Temperature Sensor 3';
yMax  = 1000;                          %y Maximum Value
yMin  = 0;                     %y minimum Value
plotGrid = 'on';                 % 'off' to turn off grid
min = 0;                         % set y-min
max = 1000;                        % set y-max
delay = .01;                     % make sure sample faster than resolution 
%Define Function Variables
time = 0;
data = 0;
data1 = 0;
data2 = 0;
count = 0;
%Set up Plot
plotGraph = plot(time,data,'-r' );  % every AnalogRead needs to be on its own Plotgraph
hold on                            %hold on makes sure all of the channels are plotted
% plotGraph1 = plot(time,data1,'-b');
% plotGraph2 = plot(time, data2,'-g' );
title(plotTitle,'FontSize',15);
xlabel(xLabel,'FontSize',15);
ylabel(yLabel,'FontSize',15);
legend(legend1)% legend(legend1,legend2,legend3)
axis([yMin yMax min max]);
grid(plotGrid);
tic
while ishandle(plotGraph) %Loop when Plot is Active will run until plot is closed
        dat = a.analogRead(0);   %* 0.48875855327; %Data from the arduino
%          dat1 = a.analogRead(2)* 0.48875855327; 
%          dat2 = a.analogRead(4)* 0.48875855327;       
         count = count + 1;    
         time(count) = toc;    
         data(count) = dat(1);         
%          data1(count) = dat1(1)
%          data2(count) = dat2(1)
         %This is the magic code 
         %Using plot will slow down the sampling time.. At times to over 20
         %seconds per sample!
         set(plotGraph,'XData',time,'YData',data);
%          set(plotGraph1,'XData',time,'YData',data1);
%          set(plotGraph2,'XData',time,'YData',data2);
          axis([0 time(count) min max]);
          %Update the graph
          pause(delay);
 end
delete(a);
disp('Plot Closed and arduino object has been deleted')

[Lokeshwaran S]

Thanks @Walter Roberson

The syntax is different from arduino to MATLAB.

Solution:

Take a look at the following example code to read the analog voltage value from the arduino and use according to your need.

a = arduino;

readVoltage(a,'A4')

So the change needed to be done is:

dat = readVoltage(a,'A0');

If you dont want to print the dat value in the above code which keeps scrolling at my screen, insert ; at the end of that line.

Answer 1

[Walter Roberson]

analogRead() is for the legacy arduino package; https://www.mathworks.com/matlabcentral/fileexchange/32374-legacy-matlab-and-simulink-support-for-arduino

https://www.mathworks.com/matlabcentral/answers/217451-no-appropriate-method-property-or-field-analogread-for-class-arduino#answer_179567

[Jacob Schoeb]

I download it and it is still popping up with the same error. I think it is only compatible for some older versions of Matlab. IS there any suggestions on solutions to this?

[Walter Roberson]

The solution is to rewrite using readVoltage