The LilyPad Arduino 328 Main Board is a sewable microcontroller designed for integration into e-textiles and wearable electronic systems. It is based on the ATmega328 with the Arduino bootloader and uses a simplified circuit layout to maintain a compact, lightweight profile. The board operates from 2 V to 5 V and features large conductive pads for reliable stitching and connection using conductive thread. With the exception of the power pins, each pad can interface with standard input and output components, enabling practical development of embedded wearable applications.