ATMEGA 328P is a high performing register which is for general purpose working. It consists of broad range of working features. Some of these are; Fully static operation, 2- cycle multiplier, Up to 20 MIPS throughout the operation at 20 MHz, Erase/write cycles are also sufficiently large, etc. The peripheral features of this register includes two 8-bit counter, one 16 bit counter, a real time counter having separate oscillators. In its datasheet, the pin configurations are described in detail. It includes various pins ( 4 in total). You can download the ATMEGA328P DATASHEET from the link given above.