... , it causes upgrade from serial to usb connector. the cubage is small, the existed firmwarecan be upgrade as studio changed (handled). Thus ... ,ATmega169 / ATmega169V,ATmega32 / ATmega32L,ATmega323 / ATmega323L,ATmega64 / ATmega64L,ATmega128 / ATmega128L,the scales of working voltage of chips3V~5V(broad voltage)