He has a Embedded Systems Programming Blog where you can read and learn programming for the small SBCs and Testing Chips on "USB Stick SBCs" that are now a standard.
Code and Life - Joonas Pihlajamaa
He has useful tutorials on V-USB which is a software-only implementation of a low-speed USB device for 's AVR microcontrollers.
He also has many ideas on PC Interface Hardware and Code that may help Home Automation Projects. He reviews embedded starter evaluation boards. Many ideas on Audio and Video using these uC boards.
Arduino Uno and Raspberry Pi to talk to each other
"All that was needed between the two devices was some jumper wire and two 1 kOhm resistors to form a voltage divider between Arduino TX pin and Pi RX pin – Arduino understands Pi’s 3.3V signal levels just fine so Pi TX to Arduino RX needed no voltage shifting at all."