Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-2549-8-bit-AVR-Microcontroller-ATmega640-1280-1281-2560-2561_Summary.pdf 

Highlights: 

• High Performance, Low Power Atmel® AVR® 8-Bit Microcontroller 

• Advanced RISC Architecture 

– 135 Powerful Instructions – Most Single Clock Cycle Execution 

– 32 × 8 General Purpose Working Registers 

– Fully Static Operation 

– Up to 16 MIPS Throughput at 16MHz 

– On-Chip 2-cycle Multiplier 

• High Endurance Non-unstable Memory Segments 

– 64K/128K/256KBytes of In-System Self-Programmable Flash 

– 4Kbytes EEPROM 

– 8Kbytes Internal SRAM 

– Write/Erase Cycles:10,000 Flash/100,000 EEPROM 

– Data maintenance: 20 years at 85C/100 years at 25C 

– Optional Boot Code Section with Independent Lock Bits 

• In-System Programming by On-chip Boot Program 

• True Read-While-Write Operation 

– Programming Lock for Software Security 

• Endurance: Up to 64Kbytes Optional External Memory Space 

• Atmel® QTouch® library bolster 

– Capacitive touch catches, sliders and wheels 

– QTouch and QMatrix securing 

– Up to 64 sense channels 

• JTAG (IEEE® sexually transmitted disease. 1149.1 consistent) Interface 

– Boundary-check Capabilities According to the JTAG Standard 

– Extensive On-chip Debug Support 

– Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface 

• Peripheral Features 

– Two 8-bit Timer/Counters with Separate Prescaler and Compare Mode 

– Four 16-bit Timer/Counter with Separate Prescaler, Compare-and Capture Mode 

– Real Time Counter with Separate Oscillator 

– Four 8-bit PWM Channels 

– Six/Twelve PWM Channels with Programmable Resolution from 2 to 16 Bits 

(ATmega1281/2561, ATmega640/1280/2560) 

– Output Compare Modulator 

– 8/16-channel, 10-bit ADC (ATmega1281/2561, ATmega640/1280/2560) 

– Two/Four Programmable Serial USART (ATmega1281/2561, ATmega640/1280/2560) 

– Master/Slave SPI Serial Interface 

– Byte Oriented 2-wire Serial Interface 

– Programmable Watchdog Timer with Separate On-chip Oscillator 

– On-chip Analog Comparator 

– Interrupt and Wake-up on Pin Change 

• Special Microcontroller Features 

– Power-on Reset and Programmable Brown-out Detection 

– Internal Calibrated Oscillator 

– External and Internal Interrupt Sources 

– Six Sleep Modes: Idle, ADC Noise Reduction, Power-spare, Power-down, Standby, 

what's more, Extended Standby 

• I/O and Packages 

– 54/86 Programmable I/O Lines (ATmega1281/2561, ATmega640/1280/2560) 

– 64-cushion QFN/MLF, 64-lead TQFP (ATmega1281/2561) 

– 100-lead TQFP, 100-ball CBGA (ATmega640/1280/2560) 

– RoHS/Fully Green 

• Temperature Range: 

– - 40C to 85C Industrial 

• Ultra-Low Power Consumption 

– Active Mode: 1MHz, 1.8V: 500µA 

– Power-down Mode: 0.1µA at 1.8V 

• Speed Grade: 

– ATmega640V/ATmega1280V/ATmega1281V: 

• 0 - 4MHz @ 1.8V - 5.5V, 0 - 8MHz @ 2.7V - 5.5V 

– ATmega2560V/ATmega2561V: 

• 0 - 2MHz @ 1.8V - 5.5V, 0 - 8MHz @ 2.7V - 5.5V 

– ATmega640/ATmega1280/ATmega1281: 

• 0 - 8MHz @ 2.7V - 5.5V, 0 - 16MHz @ 4.5V - 5.5V 

– ATmega2560/ATmega2561: 

• 0 - 16MHz @ 4.5V - 5.5V