Features: 

• 1.8-5.5V operating range
• Up to 20MHz
• Part: ATMEGA328P-AU
• 32kB Flash program memory
• 1kB EEPROM
• 2kB Internal SRAM
• 2 8-bit Timer/Counters
• 1 16-bit Timer/Counter
• RTC with separate oscillator
• 6 PWM Channels
• 8 Channel 10-bit ADC
• Serial USART
• Master/Slave SPI interface
• 2-wire (I2C) interface
• Watchdog timer
• Analog comparator
• 23 IO lines
• Data retention: 20 years at 85C/ 100 years at 25C
• 32TQFP

Documents:

• Datasheet
• Atmel Product Page