(typically this will be on pins 11-13, similar to an Arduino)

This is the SPI library, formerly known as 'SPI'.

To use this library to support SPI commnication on the ATXMega, you merely need to

    #include <XSPI.h>

in your application in lieu of 'SPI.h'. So long as your '~/sketchbook/libraries' directory contains the 'XSPI' sub-directory tree, you should be able to make use of it exactly as the standard SPI library from the Arduino IDE.

NOTE: this code is from the 1.05 version of Arduino. It should be forward compatible, but may not be backward compatible.