I want to interface with the DHT11 sensor in matlab.But program give this error Subscripted assignment dimension mismatch. Error in Untitled (line 27) Humi(i)=st​r2num(out(​5:9)); Can you help me?

clc
clear all

delete(instrfindall);
close(instrfindall);


s = serial('COM3');
time=100;
i=1;
while(i<time)

    fopen(s)
    fprintf(s, 'Your serial data goes here')
    out = fscanf(s)
    
    Temp(i)=str2num(out(1:4));
    subplot(211);
    plot(Temp,'g');
    axis([0,time,20,50]);
    title('Parameter: DHT11 Temperature');
    xlabel('---> time in x*0.02 sec');
    ylabel('---> Temperature');
    grid
    
    
    Humi(i)=str2num(out(5:9));
    subplot(212);
    plot(Humi,'m');
    axis([0,time,25,100]);
    title('Parameter: DHT11 Humidity');
    xlabel('---> time in x*0.02 sec');
    ylabel('---> % of Humidity ');
    grid
    
    fclose(s)
    i=i+1;
    drawnow;
end
delete(s)
clear s

[Geoff Hayes]

Erhan - why 5:9 in

Humi(i)=str2num(out(5:9));

? Perhaps out isn't exactly what you think it is. I recommend using the MATLAB debugger to check to see what out is and what out(5:9) becomes. It could be two numbers (separated by a space?) that creates an array of two or more elements via str2num.

[Erhan erhnbgdtl]

https://www.youtube.com/watch?v=oGPGIaicfAA in this video the same program is working

smoothly. Why my program isn't working ?

[Geoff Hayes]

What is the out variable set to? Either use the MATLAB debugger to determine the value or print it out with

out = fscanf(s)
fprintf('out is set to : %s\n', out);

[Erhan erhnbgdtl]

[Erhan erhnbgdtl]

Answer 1

[Geoff Hayes]

Erhan - so the out variable is a string with value '23.00derece'. Your line of code

Humi(i)=str2num(out(5:9));

extracts chracters 5 through 9 which is

0dere

and then converts it to a number which, because of the non-numeric characters, is an empty array. What are you expecting in characters 5 through 9?

[Sebastián Terán]

Codigo de arduino:

#include <DHT.h>

#define DHTPIN 2

#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

void setup() {

Serial.begin(9600);

delay(2000);

dht.begin(); // initialise DHT11 sensor

}

void loop() {

float temp = dht.readTemperature(); //read temperature data

float humi = dht.readHumidity(); //read temperature data

Serial.print(temp);

Serial.print(humi);

delay(1000);

}

Mal:

Serial.println(temp);

Serial.println(humi);

Bien:

Serial.print(temp);

Serial.print(humi);

Answer 2

[Erhan erhnbgdtl]

Answer 3

[Erhan erhnbgdtl]

Ohh my good. Problem is arduino code. Serial.println("derece"). Thank you so so much.