The IECDevice library for the Arduino IDE provides a simple interface to connect microcontrollers to the Commodore IEC bus used on the C64, C128 and VIC20 computers. The library is developed by David Hansel, and is tested on the following microcontrollers: Arduino Uno R3, Mega, Mini, Micro, Leonardo, Uno R4, Due, ESP32 and the Raspberry Pi Pico.