Triple-A: Alternative AVR (Arduino) Library
Lightweight library for people using AVR Libc and Makefiles for their Atmel development. Work in progress and not really in usable state yet.
Macro implementations of digital_write(), digital_read(), analog_write() and analog_read() functions.
Redirects STDIN and STDOUT to UART so you can use printf() and friends for debugging.
Hardware SPI helpers.
Bitbanged shift_in() and shit_out() functions.
Hardware timer helpers.
Code for driving led matrices with MAX7219.