https://www.raspberrypi.org/ Raspberry Pi

http://kicad-pcb.org/ KiCad

http://www.nongnu.org/avr-libc/ AVR LIBC (manual)

https://www.obdev.at/products/vusb/index.html VUSB
http://codeandlife.com/2012/01/29/avr-attiny-usb-tutorial-part-3/ VUSB Tutorial

https://www.dcf77logs.de DCF77

http://elm-chan.org/fsw/ff/00index_e.html FatFs for uCs