add function to wait for fMRI trigger

demos/CPP_wait4TriggerDemo.m

@@ -0,0 +1,11 @@
+cd ..
+
+cfg.device = 'Scanner';
+
+cfg.numTriggers = 4; 
+
+cfg.triggerKey = 'space';
+
+KbName('UnifyKeyNames');
+
+wait4Trigger(cfg)

pressSpace4me.m

@@ -1,18 +1,16 @@
 function pressSpace4me
 % Use that to stop your script and only restart when the space bar is pressed.
 
-fprintf('\npress space to continue\n');
+fprintf('\nPress space to continue.\n');
 
 while 1
 
     WaitSecs(0.1);
 
     [~, keyCode, ~] = KbWait(-1);
 
-    responseKey = KbName(find(keyCode));
-
-    if strcmp(responseKey,'space')
-        fprintf('starting the experiment....\n');
+    if strcmp(KbName(find(keyCode)), 'space')
+        fprintf('starting the experiment...\n');
         break
     end
 

wait4Trigger.m

@@ -0,0 +1,61 @@
+function wait4Trigger(cfg)
+
+triggerCounter = 0;
+
+if strcmp(cfg.device, 'Scanner')
+
+    msg = 'Waiting for trigger';
+    talkToMe(cfg, msg)
+
+    while triggerCounter < cfg.numTriggers
+
+        keyCode = []; %#ok<NASGU>
+
+        [~, keyCode] = KbPressWait(-1);
+
+        if strcmp(KbName(keyCode), cfg.triggerKey)
+
+            triggerCounter = triggerCounter + 1 ;
+
+            msg = sprintf(' Trigger %i', triggerCounter);
+            talkToMe(cfg, msg)
+
+            pauseBetweenTriggers(cfg)
+
+        end
+    end
+end
+end
+
+
+function talkToMe(cfg, msg)
+
+fprintf([msg , ' \n']);
+
+if isfield(cfg, 'win')
+
+    DrawFormattedText(cfg.win, msg,...
+        'center', 'center', cfg.textColor);
+
+    Screen('Flip', cfg.win);
+
+end
+
+end
+
+
+function pauseBetweenTriggers(cfg)
+% we pause between triggers for half a repetition time or 500 ms if no RT
+% is specified.
+% we do this otherwise KbWait and KbPressWait might be too fast and could
+% catch several triggers in one go.
+
+if isfield(cfg, 'repetitionTime')
+    waitTime = cgf.repetitionTime / 2;
+else
+    waitTime = .5;
+end
+
+WaitSecs(waitTime);
+
+end