Atmel’s ATMega328P 8‑Bit Proces­sor in 28 pin DIP pack­age. It’s like the ATmega168, with dou­ble the flash space. 32K of pro­gram space. 23 I/O lines, 6 of which are chan­nels for the 10-bit ADC. Runs up to 20MHz with exter­nal crys­tal. Pack­age can be pro­grammed in cir­cuit. 1.8V to 5V oper­at­ing volt­age!Doc­u­ments:DatasheetLow Pow­er Mode Tuto­r­i­al