Serial port with ESP-32 not working.

We're having some difficulties with a project. Apparently an "error using serialport", matlab says it can connect to port 'COM8', but that is indeed the right port. We don't know if it makes any difference, but the following is what we have as com8: USB-SERIAL CH340(COM8)

The code is as follows:

%% nettoyage de l'environnement
clear
close
close all;
clear all
%% liste de toutes les matrices
EDF_mes=[];
EDF_cmd=[];
temperature_mat=[];
P_atm=[];
P_mes=[];
P_mes_new=[];
P_est=[];
Q_mes=[];
Q_est=[];
reg_mes=[];
reg_cmd=[];
U_DC=[];
I_DC=[];
Pow_DC=[];
I_15V=[];
cmd=[];
RPM_mes=[];
D_I=[];
D_O=[];
sample=[];
temps=[];
Fontsize = 12
hypothese=3

p_estime=0
q_estime=0

%% adresses modbus

adress_tension = 2;
adress_speed = 3;
adress_U_DC = 4;
adress_I_DC = 5;
adress_Power = 6;

%% initialisation de l'UI
fig = uifigure('Name','test_manuel',"Position",[100 100 800 800]);
graphical_window = uigridlayout(fig);
%graphical_window.RowHeight = {'1x','1x'};
%graphical_window.ColumnWidth = {'1x','fit','1x'};
fig.UserData=1; % utilisé pour mettre fin a la boucle principale
fig.CloseRequestFcn = @(src,event)my_closereq(src);

%% initialisation sliders cmd

cmd_edf = uislider(graphical_window);  % Slider tension
cmd_edf.Limits = [80 260];  % I3
cmd_edf.Value=123;
cmd_edf.Layout.Row = 1;
cmd_edf.Layout.Column = [4];
cmd_edf.UserData="fdsf";

cmd_moteur =uislider(graphical_window);  % Puissance moteur
cmd_moteur.Limits = [0 6500];
cmd_moteur.Value=3000;
cmd_moteur.Layout.Row = 5;
cmd_moteur.Layout.Column = [4];
cmd_moteur.UserData="fdsf";

cmd_registre=uislider(graphical_window); % Papillon
cmd_registre.Limits = [0 10];
cmd_registre.Value=7;
cmd_registre.Layout.Row = 3;
cmd_registre.Layout.Column = [4];
cmd_registre.UserData="fdsf";

%% initialisation des graphes
grapheQ = uiaxes(graphical_window);
grapheQ.Layout.Row = [1 3];
grapheQ.Layout.Column = [1 3];
%plot(grapheQ,sample,D_I)
grapheQ.Title.String=("débit en fonction du temps");
grapheQ.YLabel.String = 'Débit en m3/h';
grapheQ.XLabel.String = 'nb échantillons';
%legend('Q_est','Q_mes');
%grapheQ.Legend('Q_est','Q_mes')

grapheP = uiaxes(graphical_window);
grapheP.Layout.Row = [4 6];
grapheP.Layout.Column = [1 3];
%plot(grapheP,sample,D_I)
grapheP.Title.String=("Pression en fonction du temps");
grapheP.YLabel.String = 'Pression en Pa';
grapheP.XLabel.String = 'nb échantillons';

graphe_EDF = uiaxes(graphical_window);
graphe_EDF.Layout.Row = 2;
graphe_EDF.Layout.Column = 4;
%plot(graphe_EDF,sample,D_I)
graphe_EDF.Title.String=("Tension EDF");
graphe_EDF.YLabel.String = 'Tension en Vac';
graphe_EDF.XLabel.String = 'nb échantillons';

graphe_cmd = uiaxes(graphical_window);
graphe_cmd.Layout.Row = 6;
graphe_cmd.Layout.Column = 4;
%plot(graphe_cmd,sample,D_I)
graphe_cmd.Title.String=("commande moteur mV");
graphe_cmd.YLabel.String = 'cmd mV';
graphe_cmd.XLabel.String = 'nb échantillons';

graphe_rpm = uiaxes(graphical_window);
graphe_rpm.Layout.Row = 7;
graphe_rpm.Layout.Column = 4;
%plot(graphe_rpm,sample,D_I)
graphe_rpm.Title.String=("RPM moteur");
graphe_rpm.YLabel.String = 'RPM';
graphe_rpm.XLabel.String = 'nb échantillons';

graphe_registre = uiaxes(graphical_window);
graphe_registre.Layout.Row = 4;
graphe_registre.Layout.Column = 4;
%plot(graphe_registre,sample,D_I)
graphe_registre.Title.String=("position registre");
graphe_registre.YLabel.String = 'position';
graphe_registre.XLabel.String = 'nb échantillons';

graphe_registre2 = uiaxes(graphical_window);
graphe_registre2.Layout.Row = 7;
graphe_registre2.Layout.Column = [1 3];
%plot(graphe_registre2,sample,D_I)
graphe_registre2.Title.String=("position registre");
graphe_registre2.YLabel.String = 'position';
graphe_registre2.XLabel.String = 'nb échantillons';

disp(123)

%% DAQ :
% DAQ general parameters
disp("initialistion device_daq")
device_daq = daq("ni");
time_offset = 0; % s
rate = 10; % Hz - communication rate with NI
device_daq.Rate = 1/(1/rate-time_offset);
disp('DAQ input')
%% Initialisation new pressure
newPressureDevice = serialport("COM8", 9600);

% DAQ input:
read_pressure = addinput(device_daq,"Dev1","ai8","Voltage");
read_pressure.TerminalConfig = "SingleEnded";
%
read_flow_rate = addinput(device_daq,"Dev1","ai1","Voltage");
read_flow_rate.TerminalConfig = "SingleEnded";
%
read_valva_position = addinput(device_daq,"Dev1","ai3","Voltage");
read_valva_position.TerminalConfig = "SingleEnded";

% daq output:
%controle du registre
write_motor_signal = addoutput(device_daq,"Dev1","ao1","Voltage");
write_motor_signal.Range = [-10  10];
disp(146)
%% initialistion modbus
disp("initialistion modbus")
moteur_modbus = modbus("serialrtu","COM5");
disp("modbus: ok")
%% controle de la tension d'alimentation
% commande servo moteur de l'autotransformateur (arduino usb + servo
% moteur)

cmd_autotransfo=serialport("COM7",9600);  % Vérifier la BAUD
position_autotransfo = 260;


consigne_position=90;
position_autotransfo_str=int2str(position_autotransfo);
write(cmd_autotransfo, position_autotransfo_str, "uint8");
configureTerminator(cmd_autotransfo,"CR/LF")
disp("autotransfo arduino connecté")

% voltmetre USB (visa)
visausb = visadev("USB0::0x0957::0x0607::MY47011181::0::INSTR");
visausb.Timeout=3;
visausb.write("CONF:VOLT:AC")
visausb.write("CONF:VOLT:AC BAND 20")
tension_entree=visausb.writeread("READ?");
%tension_voulue = (tension_voulue_init);
disp(165)


%% mesure de la température ambiante

comserie_temp=serialport("COM3",9600);
configureTerminator(comserie_temp,"CR/LF");

%% boucle principale
 % Integration UI
toto=0;
i=0;
visausb.Timeout=2;
while fig.UserData<2
    %% condition de sortie de la boucle et compteur de boucle
    %fig.UserData=fig.UserData+1
    %pause(0.1)
    toto=toto+1;
    %

    %% get data

    % Vedf
    var_temp=visausb.writeread("READ?");
    var_temp=str2double (var_temp);
    EDF_mes=[EDF_mes;var_temp];
    EDF_cmd=[EDF_cmd ;cmd_edf.Value];

    % temperature
    %var_temp=readline(comserie_temp);
    %var_temp=str2double (var_temp);
    temperature_mat=[temperature_mat ; var_temp];

    % données du DAQ
    inScanData = read(device_daq);

    pressure = table2array(inScanData(:,1));
    % pressure_convert=(pressure-2)*62.5;
    pressure_convert=(pressure*20);
    P_mes=[P_mes;pressure_convert];

    flow_rate = table2array(inScanData(:,2));
    flow_rate_convert=(flow_rate*63.375)-126.75;
    Q_mes=[Q_mes;flow_rate_convert];

    var_temp=table2array(inScanData(:,3));
    reg_mes=[reg_mes;var_temp];

    %% New pressor sensor
    new_pressure = readline(newPressureDevice);
    new_num = str2double(new_pressure);
    disp(new_pressure);
    P_mes_new=[P_mes_new;new_pressure];
    disp('DONE')
    pause(0.5)
    %% pression obtenue sur internet
    try
        webb = webread("https://www.allosurf.net/meteo/live/toulouse-blagnac-station-meteo-lfbo-5386.html");
        k = strfind(webb, 'hPa');
        releve = webb(k(1)-5: k(1)-2);
    catch
        releve = '0000';
    end
    releve=str2num(releve);
    P_atm=[P_atm;releve];



    % données modbus
    modbus_data = read(moteur_modbus,"holdingregs",17,7);
    U_DC=[U_DC; modbus_data(4)* 0.1];
    I_DC=[I_DC; modbus_data(5)* 0.1];
    Pow_DC=[Pow_DC; modbus_data(6)* 0.1];
    I_15V=[I_15V; modbus_data(7)* 0.1];
    cmd=[cmd; modbus_data(2)];
    RPM_mes=[RPM_mes; modbus_data(3)];

    if toto==1
        D_I=[D_I; 0];
        D_O=[D_O; 0];
    else
        D_I=[D_I;I_DC(end)-I_DC(end-1)];% 0];
        D_O=[D_O;RPM_mes(end)-RPM_mes(end-1)];% 0];
    end

    % données estimées
    %p_estime=pressure_06_14_2023_15_14(RPM_mes(end),U_DC(end),I_DC(end),D_O(end),D_I(end))*0.4+0.6*p_estime;%(rpm,udc,idc,delta_rpm, delta_idc)
    %q_estime=flow_06_14_2023_15_14(RPM_mes(end),U_DC(end),I_DC(end),D_O(end),D_I(end))*0.4+0.6*q_estime;
    if hypothese==1
        q_estime=flow_hyp_1deg8(RPM_mes(end),U_DC(end),I_DC(end))
        p_estime=pressure_hyp_1deg8(RPM_mes(end),U_DC(end),I_DC(end))
    end

    if hypothese==2
        q_estime=flow_hyp_2deg7(RPM_mes(end),U_DC(end),I_DC(end),D_I(end))
        p_estime=pressure_hyp_2deg7(RPM_mes(end),U_DC(end),I_DC(end),D_I(end))
    end
    if hypothese==3
        q_estime=flow_hyp_3deg6(RPM_mes(end),U_DC(end),I_DC(end),D_O(end))
        p_estime=pressure_hyp_3deg6(RPM_mes(end),U_DC(end),I_DC(end),D_O(end))
    end

    if hypothese==4
        q_estime=flow_hyp_4deg7(RPM_mes(end),U_DC(end),I_DC(end),D_I(end),D_O(end))
        p_estime=pressure_hyp_4deg7(RPM_mes(end),U_DC(end),I_DC(end),D_I(end),D_O(end)) 
    end

    if p_estime<0
        p_estime=0
    end
    if p_estime>600
        p_estime=600
    end
    if q_estime<0
        q_estime=0
    end
    if q_estime>600
        q_estime=600
    end
    
    P_est=[P_est;p_estime];
    Q_est=[Q_est;q_estime];

    % données sliders
    reg_cmd=[reg_cmd;cmd_registre.Value];

    % echantillonage
    sample=[sample ;toto];
    temps=[temps;now];


    %% asservissements

    %registre
    
    write(device_daq,cmd_registre.Value);

    %commande VMC
    var_temp=double(round(cmd_moteur.Value));
    disp(var_temp)
    disp(278);
    i=var_temp%i+100
    i=mod(i,6000)
    if i<3000
        i=3000
    end
    disp('cmd')
    disp(i)
    disp(cmd_moteur.Value)
    disp(cmd(end))
    write(moteur_modbus,'holdingregs',2,i);
    disp(280);


    %% plot des graphes
     plot(graphe_cmd,sample,cmd,'--b')%,sample,RPM_mes,'.r')
    lgd_cmd=legend(graphe_cmd, 'cmd moteur (mV)', 'Location','northwest') ;
    lgd_cmd.FontSize = Fontsize;
    
    plot(graphe_EDF,sample,EDF_cmd,'--b',sample,EDF_mes,'.r');
    lgd_EDF=legend(graphe_EDF, 'EDF_cmd','EDF_mes', 'Location','northwest') ;
    lgd_EDF.FontSize= Fontsize;

    plot(graphe_registre,sample,reg_cmd,'--b',sample,reg_mes,'.r');
    lgd_registre=legend(graphe_registre, 'reg_cmd','reg_mes', 'Location','northwest');
    lgd_registre.FontSize= Fontsize;

    plot(graphe_registre2,sample,reg_cmd,'--b',sample,reg_mes,'.r');
    lgd_registre2=legend(graphe_registre, 'reg_cmd','reg_mes', 'Location','northwest');
    lgd_registre2.FontSize=Fontsize;

    plot(graphe_rpm,sample,RPM_mes,'--b');%,sample,RPM_mes,'.r')
    lgd_rpm=legend(graphe_rpm, 'RPM_mes', 'Location','northwest');
    lgd_rpm.FontSize=Fontsize;

    plot(grapheP,sample,P_est,'--b',sample,P_mes,'.r', sample, P_mes_new);
    lgd_P=legend(grapheP, 'P_est','P_mes','P_mes_new', 'Location','northwest');
    lgd_P.FontSize=Fontsize;
        
    plot(grapheQ,sample,Q_est,'--b',sample,Q_mes,'.r');
    lgd_Q=legend(grapheQ, 'Q_est','Q_mes', 'Location','northwest');
    lgd_Q.FontSize=Fontsize;

    %%sauvegarde des données en matrice
    save_matrix=[EDF_mes,EDF_cmd,temperature_mat,P_atm,P_mes,P_est,Q_mes,Q_est,reg_mes,reg_cmd,U_DC,I_DC,Pow_DC,I_15V,cmd,RPM_mes,D_I,D_O,sample,temps];
    pause(0.2)
    if P_mes>500
        fig.UserData=3
    end
    % -------------------------------------------------Integration panne_UI
    %
    %% on convertit les volts en degre
    % récupère la consigne du slider
    consigne_edf=cmd_edf.Value;
    % on mesure la sortie
    sortie=EDF_mes(end);
    % on calcul l'erreur
    erreur = sortie-consigne_edf;
    % on met une consigne de position qui prends en compte l'erreur et la
    % consigne du slider
    Kp=-0.6;% correcteur proportionnel;
    consigne_position=consigne_position+Kp*erreur;
    consigne_position=round(consigne_position);
    
    if consigne_position>180
        consigne_position=180
    end
    if consigne_position<0
        consigne_position=0
    end    
    

    position_autotransfo_str=int2str(consigne_position);
    disp(position_autotransfo_str)
    
    write(cmd_autotransfo, position_autotransfo_str, "uint8");
        %
    %pause(0.5)
    % -------------------------------------------------Integration panne_UI
end

%% procedure de fermeture
currentDateTime = datestr(now, 'mm-dd-yyyy_HH-MM'); % Format YYYY-MM-DD_HH-MM-SS
fileName = strcat('Repetabilite_var_position_', currentDateTime, '.csv');
%matrice= [RPM_mes,cmd];
writematrix (save_matrix,fileName,"Delimiter",';')
% exportapp(fig,['filename.jpg'])
disp(fig.UserData)
delete(fig)

write(moteur_modbus,'holdingregs',2,0);
write(device_daq,0);
disp("Fin du test");

function my_closereq(fig)
selection = uiconfirm(fig,'Close the figurewindow?',...
    'Confirmation');

switch selection
    case 'OK'
        %exportapp(fig,['filename'])
        fig.UserData=201 %delete(fig)
    case 'Cancel'
        return
end
end

The specific parts of the code that have been causing this problem are:

%% Initialisation new pressure
newPressureDevice = serialport("COM8", 9600);

And...

%% New pressor sensor
    new_pressure = readline(newPressureDevice);
    new_num = str2double(new_pressure);
    disp(new_pressure);
    P_mes_new=[P_mes_new;new_pressure];
    disp('DONE')
    pause(0.5)

If anyone has any idea please share.

Thanks in advance

Answer 1

[Raj]

Hello Gerson,

I understand you are facing an error while using serial port when you connecting your ESP-32 with your laptop.

There may be several reasons responsible for this-

• Incorrect port might be selected. You can use the "serialportlist” function to list all available serial ports and verify that the ESP-32 is connected to the expected port.
• Check if there are any driver issues and the support packages for ESP-32 are installed and up-to date.
• Check if all serial ports are not already in use in ESP-32. Since ESP-32 has 3 serial ports, atleast one of them should be available while you connect ESP-32 to MATLAB.

You can also refer to the documentation from MathWorks regarding how to troubleshoot serial port connection issues-

• https://www.mathworks.com/help/instrument/troubleshooting-serial-port-interface.html
• https://www.mathworks.com/help/matlab/import_export/resolve-serial-port-connection-errors.html

I hope this resolves your query and you are able to proceed further!