Minor revision update 2.1

* Added help for data properties

* Implemented newDataFcn callback property

After new data is received and handled in addData, onNewData() is
called. This new method calls newDataFcn if it is set.

* Removed test... identified the invisible bug.

The "bug" in Myo Connect doesn't exist. I conclude that it was caused by
an issue in old myo_mex.cpp code related to DataCollector in global
scope and "clear myo_mex" not being called in MATLAB. This results in
DataCollector remaining in memory after "myo_mex delete" and stale Myo*
hanging on DataCollector.

* Added descriptive comments to class members

* Added test for bug in Myo Connect

Sometimes myo::Hub passes two unique myo::Myo* pointers into
myo::DeviceListener callbacks IFF there is currently one Myo connected
in Myo Connect, but there were previously two Myos connected.

* Bugfixes, features, change behavior of EMG streaming when countMyos>1

* Formatting

* Updates for release 2.1

* Final update for release 2.1

MyoMex/MyoMex.m

@@ -33,26 +33,30 @@
   % data out of the FIFO. The timer callback then calls back into the
   % MyoMex property myoData (a MyoData object) to provide it with the
   % latest batch of samples.
-
+
+  properties
+    newDataFcn
+  end
   properties (SetAccess = private)
     % myo_data  Data objects for physical Myo devices
-    myoData;
+    myoData
   end
   properties (Dependent,Hidden=true)
-    currTime;
+    currTime
   end
   properties (Access=private,Hidden=true)
     timerStreamingData
     nowInit
     DEFAULT_STREAMING_FRAME_TIME = 0.040
+    NUM_INIT_SAMPLES = 4
   end
 
   methods
 
     %% --- Object Management
     function this = MyoMex(countMyos)
       % MyoMex  Construct a MyoMex object
-      %   
+      %
       % Inputs:
       %   countMyos - Number of Myos
       %     Numerical scalar specifying the number of physical Myo devices
@@ -66,7 +70,7 @@
       %     variable throughout the lifecycle of MyoMex and then explicitly
       %     call the delete() method on the object when finished.
       assert(nargout==1,...
-        'MyoMex must be assigned to an output variable.');      
+        'MyoMex must be assigned to an output variable.');
 
       if nargin<1, countMyos = 1; end
 
@@ -87,22 +91,15 @@
       end
 
       % call into myo_mex init
-      [fail,emsg,countMyosInit] = this.myo_mex_init();
+      [fail,emsg] = this.myo_mex_init(countMyos);
       if fail
         if strcmp(emsg,'Myo failed to init!') % extra hint
           warning('Myo will fail to init if it is not connected to your system via Myo Connect.');
         end
+        this.myo_mex_clear();
         error('MEX-file ''myo_mex'' failed to initialize with error:\n\t''%s''',emsg);
       end
 
-      % error out if myo_mex failed to initialize with desired countMyos
-      if countMyosInit ~= countMyos
-        this.myo_mex_delete(); % clean up myo_mex internal state
-        this.myo_mex_clear(); % clean up mex file myo_mex
-        error('MyoMex failed to initialize %d Myos. myo_mex initialized to %d Myos instead.',...
-          countMyos,countMyosInit);
-      end
-
       this.myoData = MyoData(countMyos);
 
       % at this point, myo_mex should be alive!
@@ -121,6 +118,14 @@ function delete(this)
       MyoMex.myo_mex_clear();
     end
 
+    %% --- Setters
+    function set.newDataFcn(this,val)
+      assert(isempty(val)||(isa(val,'function_handle')&&(2==nargin(val))),...
+        'Property newDataFcn must be the empty matrix when not set, or a function handles conforming to the signature newDataFcn(source,eventdata,...) when set.');
+      this.newDataFcn = val;
+    end
+
+    %% --- Dependent Getters
     function val = get.currTime(this)
       val = (now - this.nowInit)*24*60*60;
     end
@@ -139,7 +144,7 @@ function startStreaming(this)
         'executionmode','fixedrate',...
         'name','MyoMex-timerStreamingData',...
         'period',this.DEFAULT_STREAMING_FRAME_TIME,...
-        'startdelay',this.DEFAULT_STREAMING_FRAME_TIME,...
+        'startdelay',this.DEFAULT_STREAMING_FRAME_TIME*this.NUM_INIT_SAMPLES,...
         'timerfcn',@(src,evt)this.timerStreamingDataCallback(src,evt));
       [fail,emsg] = this.myo_mex_start_streaming();
       if fail
@@ -182,8 +187,13 @@ function timerStreamingDataCallback(this,~,~)
         'myo_mex get_streaming_data failed with message\n\t''%s''\n%s',emsg,...
         sprintf('MyoMex has been cleaned up and destroyed.'));
       this.myoData.addData(data,this.currTime);
+      this.onNewData();
+    end
+    function onNewData(this)
+      if ~isempty(this.newDataFcn)
+        this.newDataFcn(this,[]);
+      end
     end
-
   end
 
   %% --- Wrappers for myo_mex Interface
@@ -192,11 +202,12 @@ function timerStreamingDataCallback(this,~,~)
   % the single quotes
   methods (Static=true,Access=private,Hidden=true)
 
-    function [fail,emsg,data] = myo_mex_init()
+    function [fail,emsg] = myo_mex_init(countMyos)
+      assert( (nargin==1) && isnumeric(countMyos) && isscalar(countMyos) && any(countMyos==[1,2]),...
+        'Input countMyos must be a numeric scalar in [1,2].');
       fail = false; emsg = [];
-      data = [];
       try
-        data = myo_mex('init');
+        myo_mex('init',countMyos);
       catch err
         fail = true; emsg = err.message;
       end

MyoMex/example/MyoMexExample_DataContinuity.m

@@ -0,0 +1,118 @@
+%% MyoMexExample_DataContinuity
+% In this script, we log samples from countMyos devices and then inspect
+% the data to detect cases in which data may have been lost. Since missing
+% data is interpolated by zero order hold, we can only say for sure if no
+% samples have been missed.
+
+
+%% Log Data
+% Configure |TIME_DURATION| (10 seconds is a good choice) and |countMyos|
+% before running this script.
+
+TIME_DURATION = 20; % seconds
+countMyos = 2;
+
+fprintf('Collecting data from %d Myos for roughly %5.2f[s] ... ',...
+  countMyos,TIME_DURATION);
+mm = MyoMex(countMyos);
+tic;
+m = mm.myoData;
+pause(TIME_DURATION-toc);
+mm.delete();
+fprintf('Done!\n\n');
+
+%%  Test Data for Missed Samples
+% Anonymous function returns logical scalar representing the validity of
+% samples. It returns true if no two consecutive rows have the same values
+% in all columns. Otherwise it returns false.
+
+hasDataContinuity = @(x)~any(all((~diff(x))'));
+
+flags = [];
+for ii = 1:countMyos
+  flags = [flags,hasDataContinuity(m(ii).quat_log)];
+  flags = [flags,hasDataContinuity(m(ii).gyro_log)];
+  flags = [flags,hasDataContinuity(m(ii).accel_log)];
+  if countMyos == 1
+    flags = [flags,hasDataContinuity(m(ii).emg_log)];
+  end
+  fprintf('Estimated sample rate (Myo %d):\n\tIMU: %5.2f[Hz]\tEMG: %5.2f[Hz]\n',...
+    ii,length(m(ii).timeIMU_log)/TIME_DURATION,length(m(ii).timeEMG_log)/TIME_DURATION);
+end
+fprintf('\n');
+
+fprintf('Data continuity test result:\n\t');
+if all(flags)
+  fprintf('PASS: No samples were missed\n\n');
+else
+  fprintf('FAIL: At least one sample was missed\n\n');
+end
+
+
+%% Plot Duplicate Samples
+% Usually we find that the duplicates are in up to about 15% of the
+% quaternion samples. It may be that the quaternion estimate is acually
+% updated less frquently than it is sampled. Over many 60 second trials, I
+% seldom witness lost data in gyro, accel, or emg. This leads me to believe
+% that we're not actually missing quaternion data.
+
+idDuplicates = @(x)all((~diff(x))');
+
+tIMU1 = m(1).timeIMU_log(2:end);
+qd1 = idDuplicates(m(1).quat_log);
+gd1 = idDuplicates(m(1).gyro_log);
+ad1 = idDuplicates(m(1).accel_log);
+
+if countMyos == 2
+  tIMU2 = m(2).timeIMU_log(2:end);
+  qd2 = idDuplicates(m(2).quat_log);
+  gd2 = idDuplicates(m(2).gyro_log);
+  ad2 = idDuplicates(m(2).accel_log);
+elseif countMyos==1
+  tEMG1 = m(1).timeEMG_log(2:end);
+  ed1 = idDuplicates(m(1).emg_log);
+end
+
+figure;
+if countMyos == 2, subplot(2,1,1); end
+plot(tIMU1,1*qd1,'r',tIMU1,2*gd1,'g',tIMU1,3*ad1,'b'); legCell = {'quat','gyro','accel'};
+if countMyos == 1, hold on; plot(tEMG1,4*ed1,'k'); legCell{4} = 'emg'; end 
+legend(legCell);
+if countMyos == 2
+  subplot(2,1,2);
+  plot(tIMU2,1*qd2,'r',tIMU2,2*gd2,'g',tIMU2,3*ad2,'b');
+  legend('quat','gyro','accel');
+end
+
+%% Plot Acceleration Magnitude
+% If logging from two Myos, plot the 2 norm of kinematic acceleration to
+% inspect the time-synchronization of signals. You may choose to perform
+% similar motions on the two Myos to visualize the results.
+
+if countMyos == 2
+  figure;
+  an1 = sqrt(sum((m(1).accel_log.^2)'))-1;
+  an2 = sqrt(sum((m(2).accel_log.^2)'))-1;
+  plot(...
+    m(1).timeIMU_log,...
+    an1-mean(an1),'r',...
+    m(2).timeIMU_log,...
+    an2-mean(an2),'b');
+  legend('|a|_1','|a|_2');
+end
+
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