Build Instructions

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• 1

  Finding the Arduino's port number in the NAS

  1. Use SSH to get a command prompt in your NAS.

  2. type the command:    
  

  ls /dev/tty*

  3. Connect the Arduino

  4. type the command:    
  

  ls /dev/tty*

  5. compare the results from step 2 and 4.  The extra device that was added in step 4 is your Arduino.  Make a note of the port name...we'll use that throughout the rest of the project.  It'll probably be ttyACM0 or ttyUSB0
  

  If you don't see your device, you'll need to install a device driver for your device in Linux.  That's beyond the scope of this article.
  

• 2

  Communication testing

  This is a good time to test the linkage between your NAS and the Arduino.

  1. download attached BasicSerialTest.ino into the Arduino
  

  2. connect the Arduino to the NAS

  3. type the command (use your device port name from the previous step):  
  

  screen /dev/ttyUSB0 9600

  4. Review the results for a few minutes.  If the results are regular and predictable ("1234567890" every second), you can skip ahead
  

• 3

  Fixing corrupted communication

  In my case, I got what you see in figure 2 below.
  

  Figure 2:  corrupted communications from the Arduino as seen by the NAS's "screen" command.
  

  We'll cover the causes individually.

  The first cause can be that serial ports can be opened by more than one application simultaneously.  In my case, I used the following command to see what applications had the Arduino's USB port open:   
  

  lsof  /dev/ttyUSB0

  The lsof command showed that an application called "ups_yec" also had the port open.  From what I’ve read, ups_yec is a driver for a brand of UPS and it will attempt to use any USB device with the default VendorID/ProductID provided in the OSEPP Arduino Nano.  It will open the port and remove characters from the USB port’s buffer and it may also be changing the baud rate. 

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