With applications for Raspberry Pi
notes
by hobbytronics.com
http://www.hobbytronics.co.uk/raspberry-pi-serial-port
C – programming example:
http://stackoverflow.com/questions/6947413/how-to-open-read-and-write-from-serial-port-in-c
An R-Pi thread about connecting Arduino to R-Pi. R-Pi does TTL (3.3 v level and Arduino is rs-232 5v) so you need a level converter for them to communicate.
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=31&t=23873
Another similar example, connecting Arduino and R-pi via USB
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=32&t=28801
The WiringPi library for serial io:
https://projects.drogon.net/raspberry-pi/wiringpi/serial-library/