Tutorial: Custom AVR8 Soft Processor for use with Arduino IDE. (V1.2) Posted on March 21, 2011 by Jack Gassett Posted in Papilio This screencast provides instructions for downloading and synthesizing a custom AVR8 soft processor for use with a version of the Arduino IDE that has been modified for use with the Papilio. Prerequisites: AVR8 Source Code Arduino IDE modified for the Papilio. Xilinx ISE free “Webpack” version. Part 1: Downloading the AVR8 source code. Selecting only the peripherals you need. Part 2 Copying the custom AVR8 core to the Arduino IDE. Using the custom AVR8 in the Arduino IDE.