==== Serial modification ====

For using the serial line of the Raspberry Pi you have to make some small modifications (just if you hadn't run the alamode setup):

In the file: /boot/cmdline.txt\\
change:\\
  dwc_otg.lpm_enable=0 console=ttyAMA0,11520 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait
to:\\
  dwc_otg.lpm_enable=0 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait

And in the file: /etc/inittab\\
comment out:\\
  2:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100
to: \\
  #2:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100

Because the Arduino IDE is not able to find the tty connection of the serial port (ttyAMA0) you have to mirror it to ttyS0. That is to be done with a file in: /etc/udev/rules.d\\
then name it (the number is according to the order in which the rules were loaded):\\
  85-paperduinopi.rules
and put in the following line:\\
  KERNEL=="ttyAMA0", SYMLINK+="ttyS0",GROUP="dialout",MODE:=0666

More informations:\\
[[http://www.andremiller.net/content/raspberry-pi-and-arduino-via-gpio-uart|www.andremiller.net]]

[[http://codeandlife.com/2012/07/29/arduino-and-raspberry-pi-serial-communication/|www.codeandlife.com]]