Codeserialport

Matlab code to use serial port to communicate with the CNI tablet.

NOTE: on Linux, you may need to create a symbolic link for matlab to find the port location; see here for more info http://www.mathworks.com/support/solutions/en/data/1-3ZT8GP/index.html?product=ML&solution=1-3ZT8GP

   % Code to use CNI Tablet using serial port
   % Aim: Simply outputs x and y coordinates from the tablet.  
   % Written by Manish Saggar (saggar@stanford.edu) on 3/26/2012
   function tabletCodeSerialPort()
      % change the path below for location of tablet mount, usually in
      % /dev/...
      s = serial('/dev/cu.usbmodem12341','BaudRate',57600);
      fopen(s);     
      c = onCleanup(@()letscleanup(s));
      % screen resolution
      theRect = [0 0 1200 800];
      while(1)
         ln = fgets(s);
         if size(ln,2) ~=18 || ln(3) == 'N'
           continue;
         end            
         x = str2double(ln(3:5));
         y = str2double(ln(9:11));
         b = str2double(ln(15));
         if x <= 0 || y <= 0
           continue;
         end 
         x = floor((x/(850+180))*theRect(3))
         y = floor((y/(800+230))*theRect(4))
      end
      fclose(s); delete(s); clear s; 
   end
   % if Ctrl+C is used this function clears up the pointer of the tablet.
   % Otherwise Matlab crashes or you need to quit matlab every time. 
   function letscleanup(s)
      % clear serial port
      fclose(s); delete(s); clear s; 
      Screen('CloseAll');
      ShowCursor;
      psychrethrow(psychlasterror);
   end