Get External Signal Data

clear;

Tobii = EyeTrackingOperations();

eyetracker_address = 'Address of the desired device';
% Example:
% eyetracker_address = 'tet-tcp://10.46.32.51';
try
    eyetracker = Tobii.get_eyetracker(eyetracker_address);
catch ME
    if (strcmp(ME.identifier,'EyeTrackerGet:error204'))
        fprintf('Unable to connect eye tracker.\n');
        return
    end
end

% It is possible to check if the eyetracker supports this stream
if ismember(EyeTrackerCapabilities.HasExternalSignal,eyetracker.DeviceCapabilities)
    disp('External Signal Supported');
else
    disp('External Signal Not Supported');
end

% The first call subscribes to the stream and returns either data
% (might be empty if no data has been received yet) or any error that
% happened during the subscription.
% If a flat structure is prefered just use an extra input 'flat'.
% i.e. eyetracker.get_external_signal_data('flat');
eyetracker.get_external_signal_data();
pause(1);
result = eyetracker.get_external_signal_data();

if isa(result,'StreamError')
    fprintf('Error: %s\n',string(result.Error.value));
    fprintf('Source: %s\n',string(result.Source.value));
    fprintf('SystemTimeStamp: %d\n',result.SystemTimeStamp);
    fprintf('Message: %s\n',result.Message);

elseif isa(result,'ExternalSignal')
    % Collect data for 1 seconds.
    pause(1);

    % The subsequent calls return the current values in the stream buffer.
    external_signal_data = eyetracker.get_external_signal_data();

    eyetracker.stop_external_signal_data();

    fprintf('Collected %d data points\n',size(external_signal_data,2));

    % To select the most recent data point simply select the last value of the
    % buffer.
    latest_external_signal_data = external_signal_data(end);

    fprintf('SystemTimeStamp: %d\n',latest_external_signal_data.SystemTimeStamp);
    fprintf('DeviceTimeStamp: %d\n',latest_external_signal_data.DeviceTimeStamp);
    fprintf('Value: %d\n',latest_external_signal_data.Value);
    fprintf('ChangeType: %s\n',string(latest_external_signal_data.ChangeType.value));
end