Knock Lock with the thethings.iO and Mindstorms NXT

function door()
    
%% CODIGO
      
    COM_CloseNXT all;           % Close all NXT connection 
    h=COM_OpenNXT();            % Open NXT connection
    COM_SetDefaultNXT(h);       % Default value
    OpenSound(SENSOR_2, 'DB');  % Open Sound Sensor
   
    while(1)                                % Working loop
        disp('Ready!')
        NXT_PlayTone(800,500,h);            % Play tone to signal ready 
        while GetSound(SENSOR_2) < 1000     % Wait for knock
        end
        secuence = [];                      % Knock secuence array
        secuence = get_secuence();          % Get knock secuence
        secuence                            % Show knock secuence
        if numel(secuence) == 4                 % Only if 4 intervals
            result =check_secuence(secuence);   % secuence can be valid
                                                % and will be checked
        else
            NXT_PlayTone(2000,500,h);           % else it is rejected
            result = 'Wrong Pass!'
        end
        result                                  % Show result
        write_data(result);                     % Write result to thethings.IO
        if not(strcmp(result,'Wrong Pass!'))    % If secuence is valid
            open_door();                     % door is opened
        else 
            NXT_PlayTone(2000,500,h);
        end
        pause(2);                               % Wait 2 sec
    end
 
    %% FUNCTIONS
    
    % Function to read data from thethings.iO (not used)
    function read_data()
        url_read = 'https://api.thethings.io/v2/things/wJqZQR2aIiCb3iluClnkRs1N2hv_lk9_QknvQpnkR5U/resources/user?limit=10';
        webread(url_read)
    end

    % Function to write data to thethings.IO
    function write_data(result)
        options = weboptions('MediaType', 'application/json','ContentType','json');
        url_write = 'https://api.thethings.io/v2/things/wJqZQR2aIiCb3iluClnkRs1N2hv_lk9_QknvQpnkR5U';
        data1 = '{ "values": [ { "key": "user", "value": "';
        data2 = '" } ] }'; 
        data = strcat(data1,result,data2);
        webwrite(url_write,data,options);
    end

    % Function to register and return knock secuence intervals
    function secuence = get_secuence()
        secuence_aux = [];
        valid = 1;
        for i=1:4
            tstart = tic;
            pause(0.15);
            GetSound(SENSOR_2);
            while GetSound(SENSOR_2) < 1000 && toc(tstart) <= 3
            end
            if toc(tstart) < 3
                tstop = toc(tstart);
                secuence_aux = [secuence_aux, tstop];
            else 
                valid = 0
            end
            if valid == 0
                break
            end
            pause(0.15)
        end
        secuence = secuence_aux;
    end

    % Function that compares knock secuences to the validated ones and
    % returns result
    function result = check_secuence(secuence)
        if secuence(1) > 0.5 && secuence(2) > 0.5 && secuence(3) > 0.5 && secuence(4) > 0.5
            result = 'Peter';   % Knock secuence for Peter
        elseif secuence(1) < 0.5 && secuence(2) < 0.5 && secuence(3) < 0.5 && secuence(4) < 0.5
            result = 'Mary';    % Knock secuence for Mary
        elseif secuence(1) > 0.5 && secuence(2) < 0.5 && secuence(3) > 0.5 && secuence(4) < 0.5
            result = 'John';    % Knock secuence for John
        else
            result = 'Wrong Pass!'; % Not an accepted secuence
        end
    end

    % Function to open the door
    function open_door()
        NXT_PlayTone(500,500,h);
        pause(0.5);
        NXT_PlayTone(800,750,h);
        pause(0.75);
        NXT_PlayTone(1000,500,h);
        mA= NXTMotor('A');
        mA.Power=20;
        mA.TachoLimit= 90;
        mA.SendToNXT();
        pause(2);
        mA.Power=-20;
        mA.TachoLimit= 90;
        mA.SendToNXT();
    end        
end