Plotting Data Continuously From Arduino Serial

I am currently attempting to read in data from an alcohol sensor in Arduino. The code works with a for loop, with the data being stored as a vector.

I would like to plot this data against time, for an infinite amount of time. I have tried using an infinite while loop, but it failed to update the graph each time (no points show up).

The Code looks like this:

arduino= serial('/dev/cu.usbserial-DA01P0H8', 'BaudRate', 9600); fopen(arduino);

pause on;

x = 0; y = 1;

while 1 == 1

    alcohol = fscanf(arduino, '%f');
    time = x;
    plot(x, alcohol);
    pause(5);
    x = x + 5;
    y = y + 1;
end

Any help would be appreciated! Thanks :)

[Technical]

Why it is coming like this?

Answer 1

[Nick]

This is an old code I had before Arduino had a support package so I'm getting data from the Arduino a different way but this will plot until you stop it.

%This is a script that will plot Arduino analogRead values in real time
%Modified from http://billwaa.wordpress.com/2013/07/10/matlab-real-time-serial-data-logger/
%The code from that site takes data from Serial 

clear
clc

%User Defined Properties 
a = arduino('Com13')             % define the Arduino Communication port
plotTitle = 'Arduino Data Log';  % plot title
xLabel = 'Elapsed Time (s)';     % x-axis label
yLabel = 'Temperature (C)';      % y-axis label
legend1 = 'Temperature Sensor 1'
legend2 = 'Temperature Sensor 2'
legend3 = 'Temperature Sensor 3'
yMax  = 40                           %y Maximum Value
yMin  = 0                       %y minimum Value
plotGrid = 'on';                 % 'off' to turn off grid
min = 0;                         % set y-min
max = 40;                        % 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,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')

[Jacob Schoeb]

How do you get a.analogRead. It keeps having an error at that step

Answer 2

[Tommy Fu]

Nick's program works. But when run the MATLAB program, it seems MATLAB will write something into the Arduino board to override the Arduino program in the board. I would like to consult that how I can solve this problem. Thank you!

[Akash Kalghatgi]

For this, you have to update the following lines

device = serialport("com9", 115200)
data = readline(device) %if your device uses serial print
%OR
data = read(device,1,"double") %if your device uses serial write