Parsing packet from openEEG EEG-SMT in Matlab

Hi all,



I have been trying to continuously take data from the Olimex EEG-SMT board
and parse the data coming from the serial port in Matlab, but so far have
been unsuccessful..



I have the code currently reading in a specified amount of data, parsing it
and giving me 6 channels of data. However, I want to be able to
continuously read in data and plot the data in real-time until a user
interrupt occurs. And I can't figure out how to adapt my code for this.



My logic for parsing the data is as follows..



Each packet starts with the 2 byte sync sequence 165, 90. Followed by
version number byte, then packet number byte and then the 6 channels of raw
EEG data (2 bytes each) and finally 1 byte of button state. Which gives 17
bytes per packet.





So, I open my serial connection, read in X number of samples..

% Find all the points where 165 is followed by 90, using something like

             index = find(rawData == 165);

             if (index(1)+1 ==90)

                     firstPacketStart = index(1);

             end



% Build a matrix of all the packetStarts like this..

             packetStarts = (0:(N-1))'*17 + firstPacketStart;



% Build a X row, 6 column matrix with the start samples of each packet + 4
to get to the first channel of actual data.

             indicesMatrix = 4 + repmat(packetStarts, 1, 6) +
repmat(0:2:10, length(packetStarts), 1);



% Fill indicesMatrix with rawData.

             eegData = (rawdata(indicesMatrix)*256 + rawdata(indicesMatrix
+ 1)) - 512;



% Extract channel 1.

             channel1 = eegData(:,1);

Any help with code/documentation or anything with regard to parsing the
EEG-SMT serial data in matlab or continuous plotting of the EEG channel
would be very much appreciated!!

Best regards,

Mark O'Sullivan

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