ATtiny2313

• High-performance and Low-power RISC Architecture
• 120 Powerful Instructions – Most Single Clock Cycle Execution
• 32 x 8 General Purpose Working Registers
• Data and Non-volatile Program and Data Memories
• 2K Bytes of In-System Self Programmable Flash
• 128 Bytes In-System Programmable EEPROM
• 128 Bytes Internal SRAM
• Programming Lock for Flash Program and EEPROM Data Security
• One 8-bit Timer/Counter with Separate Prescaler and Compare Mode
• One 16-bit Timer/Counter with Separate Prescaler, Compare and Capture Modes
• Four PWM Channels
• On-chip Analog Comparator
• Programmable Watchdog Timer with On-chip Oscillator
• Universal Serial Interface
• Full Duplex USART
• In-System Programmable via SPI Port
• External and Internal Interrupt Sources
• Low-power Idle, Power-down, and Standby Modes
• Enhanced Power-on Reset Circuit
• Programmable Brown-out Detection Circuit
• Internal Calibrated Oscillator
• 18 Programmable I/O Lines
• 20-pin PDIP, 20-pin SOIC, 20-pad QFN/MLF
  

Details can be found
http://www.atmel.com/dyn/resources/prod_documents/doc2543.pdf