A-Star 328PB Micro - 3.3V, 8MHz.
The A-Star 328PB Micro is a tiny programmable module featuring the ATmega328PB AVR microcontroller, a backward-compatible replacement for the popular ATmega328P that features more general-purpose I/O and many additional peripherals. This module provides access to all 24 digital input/output pins (of which 9 can be used as PWM outputs and 8 as analog inputs), all on a board measuring only 1.3″ × 0.7″. It ships preloaded with an Arduino-compatible serial bootloader that enables programming through the Arduino IDE via a USB-to-serial adapter, and the ISP pins are accessible for programming with an AVR programmer. This version features an 8 MHz resonator and a 3.3 V regulator that can be powered from 3.8 V to 15 V supplies.