Mac OSX Yosemite no serial ports showing for Uno R3 I have a MacBook Pro running OS X Yosemite (10.10.3). I connected my Arduino UNO R3 to my computer for the first time after the Yosemite upgrade - it worked fine before this!

When I opened the Arduino IDE I selected Tools > Board > "Arduino UNO", but when I try to choose a Serial Port the only options are:

/dev/tty.Bluetooth-Incoming-Port
/dev/cu.Bluetooth-Incoming-Port
/dev/tty.Bluetooth-Modem
/dev/cu.Bluetooth-Modem


I have followed several tutorials and threads on how to 'fix' this issue, all to no avail:

I've installed the latest version of the FTDI drivers (even though, from what I recall the UNO doesn't even need them): FTDIUSBSerialDriver_v2_3.dmg

Downgraded to a prev. version of the FTDI driver hoping that would clear it up: /Volumes/FTDIUSBSerialDriver_v2_2_18

I followed a tutorial of how to remove the existing Apple drivers and removed the kext files, etc... 

Tried connecting arduino to both USB ports.

Tried various cables, including the one that a I used before the Yosemite upgrade.

Tried installing updated Silabs drivers:
Arduino compatible&#39;s serial port not showing Mac OSX

Walked through the entire Arduino Mac OSX guide:
http://www.arduino.cc/en/guide/macOSX

After looking into the system info of my Macbook Pro, I can see the USB Controller is Broadcom based, in case that helps. I searched for Broadcom USB drivers but got hits for Silabs one instead.

Under my Tools > Port menu.. I can see these options:

clicking the Serial Ports option doesn't do anything.

Running ls -1 /dev/tty.* or ls -l /dev/tty.usb* from terminal gives me:

/dev/tty.Bluetooth-Incoming-Port
/dev/tty.Bluetooth-Modem


The Board does NOT show up under system networking (as it has for others), so it's not recognized as an incorrect device.

I'm at a complete loss. The board powers up... but I cannot connect to it.

SIDE NOTE: This is a legit Uno R3, not a clone.
Probably, you have Chinese Uno analog which works on CH340 USB-to-serial chip, so you need to install driver for it.

Steps to fix:


Install the CH340 driver
Run the command in Terminal: sudo nvram boot-args="kext-dev-mode=1" (disable kext signing introduced in Mac OS X 10.9 Yosemite)
Reboot


Also you're right according to Uno and FDTI:


  Differences with other boards
  
  The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.