px4-firmware/apps/sdlog/mfile.template

%% Import logfiles

if (exist ('OCTAVE_VERSION', 'builtin'))
    % Octave
    graphics_toolkit ("fltk")
else
    % Matlab
end

% define log file and GPSs
logfileFolder = 'logfiles';
fileName = 'all';
fileEnding = 'px4log';

numberOfLogTypes = length(logTypes);

path = [fileName,'.', fileEnding];
fid = fopen(path, 'r');

% get file length
fseek(fid, 0,'eof');
fileLength = ftell(fid);
fseek(fid, 0,'bof');

% get length of one block
blockLength = 4; % check: $$$$
for i=1:numberOfLogTypes
    blockLength = blockLength + logTypes{i}.type_bytes*logTypes{i}.number_of_array;
end

% determine number of entries
entries = fileLength / blockLength;


% import data
offset = 0;
for i=1:numberOfLogTypes
    
    data.(genvarname(logTypes{i}.data)).(genvarname(logTypes{i}.variable_name)) = transpose(fread(fid,[logTypes{i}.number_of_array,entries],[num2str(logTypes{i}.number_of_array),'*',logTypes{i}.type_name,'=>',logTypes{i}.type_name],blockLength-logTypes{i}.type_bytes*logTypes{i}.number_of_array));
    offset = offset + logTypes{i}.type_bytes*logTypes{i}.number_of_array;
    fseek(fid, offset,'bof');
    
    progressPercentage = i/numberOfLogTypes*100;
    fprintf('%3.0f%%',progressPercentage);
end


%% Plots

figure
plot(data.sensors_raw.timestamp,data.sensors_raw.gyro_raw)

figure
plot(data.sensors_raw.timestamp,data.sensors_raw.accelerometer_raw)

%% Check for lost data

% to detect lost frames (either when logging to sd card or if no new data is
% data is available for some time)
diff_counter = diff(data.sensors_raw.gyro_raw_counter);
figure
plot(diff_counter)

% to detect how accurate the timing was
diff_timestamp = diff(data.sensors_raw.timestamp);

figure
plot(diff_timestamp)

%% Export to file for google earth


if(isfield(data.gps,'lat') && isfield(data.gps,'lon') && isfield(data.gps,'alt'))

    % extract coordinates and height where they are not zero
    maskWhereNotZero = ((data.gps.lon ~= 0 & data.gps.lat ~= 0 ) & data.gps.alt ~= 0);

    % plot
    figure
    plot3(data.gps.lon(maskWhereNotZero),data.gps.lat(maskWhereNotZero),data.gps.alt(maskWhereNotZero))


    % create a kml file according to https://developers.google.com/kml/documentation/kml_tut
    % also see https://support.google.com/earth/bin/answer.py?hl=en&answer=148072&topic=2376756&ctx=topic

    % open file and overwrite content
    fileId = fopen('gps_path.kml','w+');

    % define strings that should be written to file
    fileStartDocumentString = ['<?xml version="1.0" encoding="UTF-8"?><kml xmlns="http://www.opengis.net/kml/2.2"><Document><name>Paths</name><description>Path</description>'];

    fileStyleString = '<Style id="blueLinebluePoly"><LineStyle><color>7fff0000</color><width>4</width></LineStyle><PolyStyle><color>7fff0000</color></PolyStyle></Style>';

    filePlacemarkString = '<Placemark><name>Absolute Extruded</name><description>Transparent blue wall with blue outlines</description><styleUrl>#blueLinebluePoly</styleUrl><LineString><extrude>1</extrude><tessellate>1</tessellate><altitudeMode>absolute</altitudeMode><coordinates>';

    fileEndPlacemarkString = '</coordinates></LineString></Placemark>';
    fileEndDocumentString = '</Document></kml>';

    % start writing to file
    fprintf(fileId,fileStartDocumentString);

    fprintf(fileId,fileStyleString);
    fprintf(fileId,filePlacemarkString);

    
    lonTemp = double(data.gps.lon(maskWhereNotZero))/1E7;
    latTemp = double(data.gps.lat(maskWhereNotZero))/1E7;
    altTemp = double(data.gps.alt(maskWhereNotZero))/1E3 + 100.0; % in order to see the lines above ground

    % write coordinates to file
    for k=1:length(data.gps.lat(maskWhereNotZero))
        if(mod(k,10)==0)
            fprintf(fileId,'%.10f,%.10f,%.10f\\n',lonTemp(k),latTemp(k),altTemp(k));
        end
    end

    % write end placemark
    fprintf(fileId,fileEndPlacemarkString);

    % write end of file
    fprintf(fileId,fileEndDocumentString);

    % close file, it should now be readable in Google Earth using File -> Open
    fclose(fileId);

end

if(isfield(data.position,'lat') && isfield(data.position,'lon') && isfield(data.position,'alt'))

    % extract coordinates and height where they are not zero
    maskWhereNotZero = ((data.position.lon ~= 0 & data.position.lat ~= 0 ) & data.position.alt ~= 0);
    
    % plot
    figure
    plot3(data.position.lon(maskWhereNotZero),data.position.lat(maskWhereNotZero),data.position.alt(maskWhereNotZero))
end