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MEGSynch

MEGSynch provides an interface for National Instruments PCI 6503 card used to capture all pulses (scanner synch pulse and button pulses alike) when using MATLAB.

For more information, type in MATLAB

help MEGSynchClass

N.B.: National Instruments PCI 6503 card does not monitor pulses in the background, so you have to make sure that you wait for any pulse before it comes!

Any problems, report them to Johan Carlin.

Obtain MEGSynch

  • MEGSynch is already available on MEG stimulus PC. You can check out a personal copy for testing from our github repo.

Using MEGSynch

Initialise

  • Default. Use only in MEG lab!
  • MEG = MEGSynchClass;
    
    Default button mapping:

    Button

    Button name in MATLAB

    Channel

    'Left Yellow'

    'LY'

    'S3'

    'Right Blue'

    'RB'

    'S4'

    'Right Yellow'

    'RY'

    'S5'

    'Right Green'

    'RG'

    'S6'

    'Right Red'

    'RR'

    'S7'

  • To change button mapping:
  • MEG = MEGSynchClass({'B1','S4';'B2','S5'}); % specify button names "B1" and "B2" and maps them to S4 and S5
    
  • Emulation:
  • MEG = MEGSynchClass(1);   % full emulation
    

Close

MEGSynchClass has a destructor, which is automatically triggered if the object is deleted (e.g. clear, returning function). If you use a script, however, it does not perform any auto-clear, so you have to destroy the object manually:

  • MEG.delete;
    

Send trigger

  • for v = 0:255  % send triggers 0 to 255 ...
        pause(0.1) % ... in every 100ms
        MEG.SendTrigger(v)
    end
    

Capture button presses

  • MEG.SetButtonReadoutTime(0.5);      % block individual buttons for 0.5s after button press so we will not detect the same button press twice
    % MEG.SetButtonBoxReadoutTime(0.5); % block the whole buttonbox for 0.5s after button press
    % MEG.Keys = {'f1','f2','f3','f4'}; % emulation Buttons #1-#4 with F1-F4
    n = 0;
    % MEG.BBoxTimeout = 1.5;            % Wait for button press for 1.5s
    % MEG.BBoxTimeout = -1.5;           % Wait for button press for 1.5s even in case of response
    MEG.ResetClock;
    while n ~= 10 rButtonRelease;     % Wait for any button to be   released
        % MEG.WaitFo                      % polls 10 button presses
        MEG.WaitForButtonPress;         % Wait for any button to be pressed
        % MEG.WaitForButtonPress([],2); % Wait for Button #2
        % MEG.WaitForButtonPress(2);    % Wait for any button for 2s (overrides MEG.BBoxTimeout only for this event)
        % MEG.WaitForButtonPress(-2);   % Wait for any button for 2s even in case of response (overrides MEG.BBoxTimeout only for this event)
        % MEG.WaitForButtonPress(2,2);  % Wait for Button #2 for 2s (overrides MEG.BBoxTimeout only for this event)
        % MEG.WaitForButtonPress(-2,2); % Wait for Button #2 for 2s even in case of response (overrides MEG.BBoxTimeout only for this event)
        n = n + 1;
        fprintf('At %2.3fs, ',MEG.Clock);
        fprintf('Button %d ',MEG.LastButtonPress);
        fprintf('pressed: %2.3fs\n',MEG.TimeOfLastButtonPress);
    end