Common board pinout references
A list of simplified board pinout schematics found online. Pinouts from BQ Boards Arduino UNO, source Arduino Mega, source Arduino Micro, source Arduino Leonardo, source Arduino MiniPro, source Arduino Nano, source BQ Zum, source AtTiny, source Peripherals Document describing multiple setups for peripherals on Arduino (source): Full document (without microcontrollers) LCD screen (Hitachi 44780 compatible), source RS232 connector, source SD Card, source