Serial communications issues.

Development Tools IDE 1.x
1

Symptoms:

  1. I cannot upload simple sketches. For example, I tried to upload the example ‘Blink’ sketch. It compiles, but stalls on upload.
  2. Running Arduino from the Applications window displays “Unable to load Java Runtime Environment”.
  3. Running the same Arduino from the downloads folder allows the program to start. However, the serial interface doesn’t work.

System:
Mac El capitan
Arduino Uno (Make Special Edition)

Troubleshooting:

  1. The same Arduino module works fine on my PC using the same USB cable.
  2. Tried logout, restart.
  3. I carefully went through the process below:
  4. https://www.arduino.cc/en/Guide/MacOSX
  5. Arduino 1.6.8
  6. I used the Mac OS X 10.7 Lion or newer download.
  7. I made sure to use the Arduino board selection in the IDE.
  8. The only serial port I see is .cu.usbmodem1A21 (Arduino / Genduino Uno). Sometimes I see the TTY port. Neither work.
  9. I’m using Java Version 8 Update 73 (build 1.8.0_73_b02)
  10. I’m using Java Runtime environment 1.8.0_73
  11. The loopback test failed (Loop-Back Test Instructions - Installation & Troubleshooting - Arduino Forum)
  12. I tried the trick : csrutil enable —without kext
  13. Tried the FTDI solution: Arduino in OS X 10.9 Mavericks - Serial Port Issues - Installation & Troubleshooting - Arduino Forum
  14. I tried using Arduino 1.0.6. It opens, but serial doesn’t work either. I get the following errors though I’ve logged out and back in just before running Arduino IDE:
  15. This report would have more information with
  16. "Show verbose output during compilation"
  17. enabled in File > Preferences.
  18. Arduino: 1.0.6 (Mac OS X), Board: "Arduino Uno"
  19. Binary sketch size: 1,082 bytes (of a 32,256 byte maximum)
  20. processing.app.SerialException: Serial port '/dev/tty.usbmodem1A21' already in use. Try quiting any programs that may be using it.
  21. at processing.app.Serial.(Serial.java:171)
  22. at processing.app.Serial.(Serial.java:77)
  23. at processing.app.debug.Uploader.flushSerialBuffer(Uploader.java:77)
  24. at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:175)
  25. at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
  26. at processing.app.Sketch.upload(Sketch.java:1666)
  27. at processing.app.Sketch.exportApplet(Sketch.java:1622)
  28. at processing.app.Sketch.exportApplet(Sketch.java:1594)
  29. at processing.app.Editor$DefaultExportHandler.run(Editor.java:2382)
  30. at java.lang.Thread.run(Thread.java:695)
  31. processing.app.debug.RunnerException: Serial port '/dev/tty.usbmodem1A21' already in use. Try quiting any programs that may be using it.
  32. at processing.app.debug.Uploader.flushSerialBuffer(Uploader.java:101)
  33. at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:175)
  34. at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
  35. at processing.app.Sketch.upload(Sketch.java:1666)
  36. at processing.app.Sketch.exportApplet(Sketch.java:1622)
  37. at processing.app.Sketch.exportApplet(Sketch.java:1594)
  38. at processing.app.Editor$DefaultExportHandler.run(Editor.java:2382)
  39. at java.lang.Thread.run(Thread.java:695)

I'd appreciate some help. Thanks in advance.