Work with an ADXL345 acelerometer and NI845x borad using I2C Protocol. i write down my script anybody can help me ? the value the i plot are strenge

Hi

for my projet i have to work with an ADXL345 acelerometer and NI845x borad using I2C Protocol.

now i have to plot the aceleration of the three axis this is my script:

function [Xvalue,Yvalue,Zvalue]=aceleration

fs_I2C= 100; acq_time=10; g_range=16; resolucion='full';

array_fs_I2C =[3200,1000,400,100];

i2cInfo = instrhwinfo ('i2c', 'ni845x');%ensure tha NI is installed

% Direccion del registro accelerometerAddress = hex2dec('53');%ok i2cInterface = i2c('ni845x', 0, accelerometerAddress);%ok fopen(i2cInterface);%ok

i2cInterface.BitRate = fs_I2C;%I2C speed not the ADXL Bit Rate

%Inicialización

freqSelectRegisterAddress = hex2dec('2C'); % 2C is the addres of rate and power mode control (ADXL345) valueToWrite = bin2dec('00001010');

fwrite(i2cInterface, [freqSelectRegisterAddress valueToWrite]);

%stand by mode

powerControlRegisterAddress = hex2dec('2D');% 2D is the addres of power saving feastures control register valueToWrite = bin2dec('00001000'); %measure mode fwrite(i2cInterface, [powerControlRegisterAddress valueToWrite]);

%CONVERSION DIRECCIONES REGISTROS

XregLow=hex2dec('32'); XregHigh=hex2dec('33'); YregLow=hex2dec('34'); YregHigh=hex2dec('35'); ZregLow=hex2dec('36'); ZregHigh=hex2dec('37');

%DATA FORMAT

dataFormatRegisterAddress = hex2dec('31');

switch (g_range)

    case 2

        if  strcmp(resolucion,'10bit')

            valueToWrite = bin2dec('00000000');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0039;
            factor_de_resolucion = 6; 
        else

            valueToWrite = bin2dec('00001000');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0039;
            factor_de_resolucion = 6;
        end

    case 4

        if strcmp(resolucion,'10bit')

            valueToWrite = bin2dec('00000001');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0078;
            factor_de_resolucion = 6;
        else

            valueToWrite = bin2dec('00001001');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0039;
            factor_de_resolucion = 5;
        end

    case 8

        if strcmp(resolucion,'10bit')

            valueToWrite = bin2dec('00000010');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0156;
            factor_de_resolucion = 6;

        else

            valueToWrite = bin2dec('00001010');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0039;
            factor_de_resolucion = 4;
        end

    case 16

        if strcmp(resolucion,'10bit')

            valueToWrite = bin2dec('00000011');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0312;
            factor_de_resolucion = 6;
        else

            valueToWrite = bin2dec('00001011');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0039;
            factor_de_resolucion = 5;

        end

    otherwise %default i put g_range 2g y resolucion 10bit

        if  strcmp(resolucion,'10bit')

            valueToWrite = bin2dec('00000000');
            fwrite(i2cInterface, [dataFormatRegisterAddress valueToWrite]);

            factor_de_conversion = 0.0039;
            factor_de_resolucion = 6;

        end

end

%PLOT

nW=acq_time*fs_I2C; %number of samples

for i=1:nW

    % X

    fwrite(i2cInterface, XregLow);
    XregisterValueLow = fread(i2cInterface, 1, 'uint8'); 

    fwrite(i2cInterface, XregHigh);
    XregisterValueHigh = fread(i2cInterface, 1, 'uint8');

    Xlow = dec2bin(XregisterValueLow);
    Xhigh = dec2bin(XregisterValueHigh);
    XhighT = num2str(Xhigh);
    nBitsKeep = 8-(factor_de_resolucion); 

    if length(XhighT)>nBitsKeep
        XhighT = XhighT(end-nBitsKeep+1:end);
    end

    Xhigh = str2num(XhighT);

    % Y

    fwrite(i2cInterface, YregLow);
    YregisterValueLow = fread(i2cInterface, 1, 'uint8');

    fwrite(i2cInterface, YregHigh);
    YregisterValueHigh = fread(i2cInterface, 1, 'uint8');

    Ylow = dec2bin(XregisterValueLow);
    Yhigh = dec2bin(XregisterValueHigh);
    YhighT = num2str(Xhigh);
    nBitsKeep = 8-(factor_de_resolucion); % Mirar mejor qué bits necesitamos del registro alto (depende resol??)

    if length(YhighT)>nBitsKeep
        YhighT = YhighT(end-nBitsKeep+1:end);
    end

    Yhigh = str2num(YhighT);

    % Z

    fwrite(i2cInterface, ZregLow);
    ZregisterValueLow = fread(i2cInterface, 1, 'uint8');

    fwrite(i2cInterface, ZregHigh);
    ZregisterValueHigh = fread(i2cInterface, 1, 'uint8');

    Zlow = dec2bin(XregisterValueLow);
    Zhigh = dec2bin(XregisterValueHigh);
    ZhighT = num2str(Xhigh);
    nBitsKeep = 8-(factor_de_resolucion); 

    if length(ZhighT)>nBitsKeep
        ZhighT = ZhighT(end-nBitsKeep+1:end);
    end

    Zhigh = str2num(ZhighT);

    Xvalue(i)=XregisterValueHigh*(2^8)+XregisterValueLow;
    Xvalueg(i)=Xvalue(i)*factor_de_conversion;    % value in g
    Xvalue(i)=Xvalueg(i)*9.81;  % value in m/s^2 , 1g = 9.81m/s^2 ,

    Yvalue(i)=YregisterValueHigh*(2^8)+ YregisterValueLow;
    Yvalueg(i)=Yvalue(i)*factor_de_conversion;   % value in g
    Yvalue(i)=Yvalueg(i)*9.81;  % value in m/s^2

    Zvalue(i)=ZregisterValueHigh*(2^8)+ZregisterValueLow;
    Zvalueg(i)=Zvalue(i)*factor_de_conversion;  
    Zvalue(i)=Zvalueg(i)*9.81; % value in m/s^2

    % pause(1/fs);

end t=(0:length(Zvalue)-1)/fs_I2C;

%PLOT

figure

subplot(3,1,1); plot(t,Xvalueg); xlabel('tiempo (s)') ylabel('Acel x (g)')

subplot(3,1,2); plot(t,Yvalueg); xlabel('tiempo (s)') ylabel('Acel y (g)')

subplot(3,1,3); plot(t,Zvalueg); xlabel('tiempo (s)') ylabel('Acel z (g)')

delete(i2cInterface); clear('i2cInterface');