E11 Lab 3 (MatLab Snippets)

Useful Matlab Code Snippets
E11 Lab 3
2008

Loop for 10 seconds
Initialize DAQ
Close DAQ
Set P0.0 low (or high)
Read from Channel 0 (or 1)
Plot blue circle, but keep axes consistent

Note: this code is (for the most part) uncommented. If you choose to use any of it, please add comments, as appropriate, before turning it in.

Loop for 10 seconds:

Method 1

start_tm = clock();
loopTime = 10;
while etime(clock(),start_tm)<loopTime,

    %... Put your code in here ...

end

Method 2 (note: this is less accurate and only works if your code takes very little time).

dt=0.1;
loopTime=10;
for i=1:(loopTime/dt),

    %... Put your code in here ...

    pause(dt);
end

Initialize DAQ

%1) Create a data acquistion object
% (and specify single-ended inputs)
daqInfo=daqhwinfo('nidaq');
ai=analoginput('nidaq',daqInfo.InstalledBoardIds{1});
ai.InputType='SingleEnded';

%2) Add channels 0 and 1 (analog input channels);
ch=addchannel(ai,[0:1]);

%3) Change Properties to suit our needs
ai.SampleRate=10000;		%10000 points per second
ai.SamplesPerTrigger=2;		%Collect 2 points per channel (this is a minimum)

%4) Create a digital i/o object
dio=digitalio('nidaq',daqInfo.InstalledBoardIds{1});
addline(dio,0,0,'Out','P0.0');	%P0.0 is an output pin

Close DAQ

delete(dio);
clear dio;
delete(ai);
clear ai;

Note: this code assumes aio and dio exist.

Set P0.0 low (or high)

putvalue(dio,0);
% or putvalue(dio,1);

Note: this code assumes dio exists and consists of P0.0

Read from Channel 0 (or 1)

start(ai);
wait(ai,1);
data=getdata(ai);
val=mean(data(:,chan+1));  %where chan=0 or chan=1...

Plot blue circle, but keep axes consistent

plot(x,y,'bo');
axis([0 5 0 5]);