Getting Processing to listen to Arduino

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Currently with OSX Lion there seems to be a problem with Processing talking to Arduino, it turns out it’s a mismatch of RXTX libraries.
When running my Processing sketch the following error can occur:

WARNING: RXTX Version mismatch
Jar version = RXTX-2.2pre1
native lib Version = RXTX-2.2pre2

1. Download the latest RXTX library from

2. Find the files librxtxSerial.jnilib and RXTXcomm.jar in the unzipped folder structure: MACOSX_IDE/ForPackageMaker/Install/Java/Extensions

3. Copy the 2 files into the folder: Harddrive/Library/Java/Extensions

4. Close down Processing and right-click on the application in the “Applications”-folder and select “Show Package Contents”. Go to folder “Contents/Resources/Java/modes/java/libraries/serial/library”. Replace the old RXTXcomm.jar with the new file in this folder.

5. Replace the file librxtxSerial.jnilib with the new file in the “macosx” folder “Contents/Resources/Java/modes/java/libraries/serial/library/macosx”.

6. In order for this to work properly also follow these steps taken from here:

  1. Under Finder click on the “Go” Menu
  2. Select “Go to Folder…”
  3. Type “/var/”
  4. Finder will open var folder.
  5. Right click on folder named “lock” and select “Get info”
    If your version of OSX doesn’t have a folder called “lock”, create one by running – sudo mkdir /var/lock/ in the Terminal.
  6. Open drop arrow titled “Sharing & Permissions”
  7. I set all privileges to: “Read & Write”
  8. Close Info
  9. Go to the Var folder on the finder and open the “spool” folder
  10. Right click on folder named “uucp” and select “Get info”
  11. Open drop arrow titled “Sharing & Permissions”
  12. I set all privileges to: “Read & Write”
  13. Close Info
  14. DONE

7. Restart your computer and Processing. The output you should see is:

Stable Library
Native lib Version = RXTX-2.1-7
Java lib Version = RXTX-2.1-7

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1 Comment. Leave new

  • has also worked for me (osx lion 10.7.4, processing 1.5.1 & arduino 1.01). thanks.

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