How to plot the real time data from arduino?

I have an Arduino program loaded to the Arduino. I want to plot the real time data from arduino in the MATLAB too. My MATLAB program can get the data from the Arduino board and plot successfully. However, it seems the MATLAB will write something to the Arduino board to override the Arduino program. Is it true? If the answer is positive, may I have a help that how can I get the data from Arduino without affecting the Arduino program? (P.S. both Arduino program and MATLAB program will read the same pin such as A0). Many thanks!

Answer 1

[Arun Kumar]

Hi Tommy,

Your observation is correct.

When you do a=arduino, an arduino server is built and is deployed to the hardware.

If you already have code running on arduino, I would suggest using serial read to read the data from serial port for plotting. Refer this page for details about reading data from com port.

https://in.mathworks.com/help/matlab/matlab_external/writing-and-reading-data.html

[Tommy Fu]

Many thanks Arun Kumar. My MATLAB program is used serial to read the data by 'readVoltage' command. Please see my code as below which modified from https://www.mathworks.com/matlabcentral/answers/333946-how-to-plot-the-real-time-data-from-arduino-in-matlab

Thus, how I can to use fscanf based on the given reference link to read the analog value for a specific Arduino pin such as pin A0, A1, etc?

%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('Com14','Nano3'); % define the Arduino Communication port

b = arduino('Com15','Nano3');

c = arduino('Com15','Nano3');

plotTitle = 'Arduino Data Log'; % plot title

xLabel = 'Elapsed Time (s)'; % x-axis label

yLabel = 'Power (W)'; % y-axis label

legend1 = 'Perturb & Observe';

legend2 = 'Fractional Open Circuit Voltage';

legend3 = 'Fractional short Circuit Current';

yMax = 20; %y Maximum Value

yMin = 0; %y minimum Value

plotGrid = 'on'; % 'off' to turn off grid

min = 0; % set y-min

max = 20; % 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 = readVoltage(a,'A0')* 0.029296875 * readVoltage(a,'A1')*0.026393581; %Data from the arduino

dat1 = readVoltage(b,'A0')* 0.029296875 * readVoltage(b,'A1')*0.026393581;

dat2 = readVoltage(c,'A0')* 0.029296875 * readVoltage(c,'A1')*0.026393581;

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');

[Arun Kumar]

Hi,

I can see that in your code you are connecting to arduino object using a=arduino, which will program a arduino server code to the device. In which case, the existing code on arduino will be overwritten.

In order to read values from Analog pin, you can do either of these:

1. Continue with the existing code which you are using. You can read analog values from arduino but the existing program will be overwritten.
2. Write the analog read function using arduino IDE so that arduino sends the analog values over serial. And read those values using serial object. In this case you can have other algorithms running on your arduino.
3. There is one more way of doing this which uses simulink. You can implement your existing algorithm in simulink and can use Analog read blocks along with serial transmit blocks to read and transmit analog values.

HTH

Thanks.

[Tommy Fu]

Thank You! I tried a simple code as below. The program in Arduino can run properly right now. However, no data is obtained at Matlab. May I have a help on this?

// ---- Arduino Code ----

void setup()

{

Serial.begin(9600);

}

void read_loop()

{

if(Serial.available()>0)

{

Serial.println(sol_amps);

}

}

% ----- MATLAB Code -----

s=serial('COM14','BaudRate',9600);

fopen(s);

go = true;

while go

readData=fscanf(s);

fprintf(s,readData);

end

fclose(s);

delete(s);

[anil simsek]

I have Arduino code, I want to draw it instantly in matlab. Can you help me

Answer 2

[Sylvain]

With a bit of delay, the issue is in your Arduino code:

Serial.available will return the number of bytes you can read. So you are telling your arduino to scan arriving signals:

https://www.arduino.cc/reference/en/language/functions/communication/serial/available/

use the instruction if(Serial) instead: https://www.arduino.cc/reference/en/language/functions/communication/serial/ifserial/

Answer 3

[anil simsek]

Hi. I have an arduino code like this. this code prints the number of passes of this object on the screen when an object passes in front of the sensor.I also have to create an instant graphical simulation in Matlab that instantly shows the total number of passes of the object.how do i do this in matlab? can you help me?

[anil simsek]

this is my arduino code;

//===============================

int ledpin=12;

bool turn=0;

int sayac=0;

void setup() {

Serial.begin(9600);

pinMode(2,INPUT);

pinMode(ledpin,OUTPUT);

attachInterrupt(0,kesme,RISING);

Serial.println("Started!!!");

}

void loop() {

digitalWrite(ledpin,LOW);

Serial.println(sayac);

turn =0;

}

void kesme() {

digitalWrite(ledpin,HIGH);

if(!turn)

sayac++;

while( digitalRead (2)==1){turn=1; }

Serial.println(sayac);

}

//===========================