Arduino to Matlab – Read in sensor data!

Posted by Erin, the RobotGrrl on Friday, January 15th, 2010

Matlab is by far the best software I have ever seen when it comes to plotting data and showing it in a visual format. I figured it would be awesome if I could get Arduino and Matlab to work together!

Here’s the code that I came up with that works reasonably fast. It doesn’t wait for the buffer to be filled to then store it to a variable. Here, it is asynchronous communication. ^_^

This is a basic screenshot of what you will get, minus the green stars.

matlabscreenshot

Here is the code. Let me know if you use, it would be neat to see what everyone would come up with!
*Note: The code highlighting for Matlab was buggy, so the below is using C code highlighting. Once you paste it into Matlab, it will be fine.

  1. % Basic Arduino and Matlab
  2. % Communication with an external hardware device
  3. % ———————————————-
  4. %
  5. % Erin Kennedy
  6. % Jan. 18, 2010
  7. %
  8.  
  9.  
  10. clear all; clc; close all;
  11.  
  12.  
  13. % Try-catch is to prevent Matlab from crashing when the program is finished
  14. try
  15.  
  16.    
  17. % Initialize serial port
  18. s = serial(‘/dev/tty.usbserial-A4001lVG’);
  19. %set(s, ‘ Terminator’, ‘LF’); % Default terminator is \n
  20. set(s,‘BaudRate’, 9600);
  21. set(s,‘DataBits’, 8);
  22. set(s,‘StopBits’, 1);
  23. fopen(s);
  24. s.ReadAsyncMode = ‘continuous’;
  25.  
  26.  
  27. % Various variables
  28. numberOfDatas = 50;
  29. data = zeros(1, numberOfDatas);
  30. i = 1;
  31.  
  32.  
  33. % Main graph figure
  34. figure(1);
  35. hold on;
  36. title(‘Incomming Data from External Device’);
  37. xlabel(‘Data Number’);
  38. ylabel(‘Analog Voltage (0-1023)’);
  39.  
  40.  
  41. % Start asynchronous reading
  42. readasync(s);
  43.  
  44.  
  45. while(i<=numberOfDatas)  
  46.    
  47.    
  48.     % Get the data from the serial object
  49.     data(i) = fscanf(s, ‘%d’);
  50.    
  51.     % Plot the data
  52.     figure(1);
  53.     plot(i, data(i), ‘m*’);
  54.    
  55.     % Ensure there are always 10 tick marks on the graph
  56.     if(i>10)
  57.        xlim([i-10 i]);
  58.        set(gca,‘xtick’,[i-10 i-9 i-8 i-7 i-6 i-5 i-4 i-3 i-2 i-1 i])
  59.     end
  60.    
  61.     % Draw and flush
  62.     drawnow;
  63.    
  64.     %Increment the counter
  65.     i=i+1;
  66.    
  67.    
  68. end
  69.  
  70.  
  71. % Give the external device some time…
  72. pause(3);
  73.  
  74. return;
  75.  
  76. catch
  77.  
  78. % Some of these crash the program – it depends. The serial port is left
  79. % open, which is not good.                                              
  80. stopasync(s);
  81. fclose(s); % bad
  82. %delete(s);
  83. %clear s;
  84.  
  85. fprintf(1, ‘Sorry, you"re going to have to close out of Matlab to close the serial port\n‘);
  86.  
  87. return
  88.  
  89. end

The code for the Arduino is this:

  1. //
  2. // BubbleBoy -> Matlab
  3. // ——————-
  4. //
  5. // Read LDR data, print them to Serial (where Matlab will receive them)
  6. //
  7.  
  8. int LDRpin = 0;
  9.  
  10. void setup() {
  11.  
  12.   Serial.begin(9600);
  13.   pinMode(LDRpin, INPUT);
  14.  
  15. }
  16.  
  17. void loop() {
  18.  
  19.  int photocellReading = analogRead(LDRpin);
  20.  
  21.  Serial.println(photocellReading, DEC);
  22.  delay(200);
  23.  
  24. }

Enjoy, happy matlabbing!

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5 Responses to “Arduino to Matlab – Read in sensor data!”

  1. boolscott Says:
    February 20th, 2010 at 2:19 AM

    I’m used to specifying which serial port the program must use for Processing apps, is that done automatically here?

    Is that what the “s = serial(‘/dev/tty.usbserial-A4001lVG’);” is about?

  2. Send Arduino data to Matlab | Embedded projects from around the web Says:
    February 21st, 2010 at 3:01 PM

    [...] Here you can find simple and fast asynchronous Arduino to Matlab communication sources. It can be handy for fast sensor data displaying in convenient graph and even do some analysis. [...]

  3. Joe Lotz Says:
    February 24th, 2010 at 3:02 PM

    Awesome! I can’t wait to try this tonight.

  4. Seb Says:
    March 4th, 2010 at 4:06 AM

    Awesome post, this was just what I was looking for – thank you! (Tho I’m using a PC, and to answer boolscott’s question, replace the contents of serial() with “COMX” where X is the number of your com port the Arduino is connected to)

  5. boolscott Says:
    March 5th, 2010 at 4:51 AM

    Thanks Seb

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