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

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Nicola Benenati
Nicola Benenati 2015-4-15
编辑： Nicola Benenati 2015-4-15
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');

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