Arducam PRO Mini Atmega328 Development Board 5V/16MHz 328 Compatible with Arduino Main Chip: Atmega328P-AU 14 digital input / output port: RX, TX, D2 D13, 8 analog input ports: A0 ~ A7, 1 pair TTL level serial transceiver port: RX / TX, 6 PWM ports: D3, D5, D6, D9, D10, D11 16MHz clock frequency The bootloader is already installe in the board Size:22mm*33mm