Datasheet

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]
2549Q–AVR–02/2014
10.3Clock Sources .......................................................................................................40
10.4Low Power Crystal Oscillator .................................................................................41
10.5Full Swing Crystal Oscillator ..................................................................................42
10.6Low Frequency Crystal Oscillator ..........................................................................43
10.7Calibrated Internal RC Oscillator ...........................................................................45
10.8128kHz Internal Oscillator .....................................................................................45
10.9External Clock .......................................................................................................46
10.10Clock Output Buffer .............................................................................................47
10.11Timer/Counter Oscillator ......................................................................................47
10.12System Clock Prescaler ......................................................................................47
10.13Register Description ............................................................................................48
11 Power Management and Sleep Modes .................................................50
11.1Sleep Modes ..........................................................................................................50
11.2Idle Mode ...............................................................................................................50
11.3ADC Noise Reduction Mode ..................................................................................51
11.4Power-down Mode .................................................................................................51
11.5Power-save Mode ..................................................................................................51
11.6Standby Mode .......................................................................................................51
11.7Extended Standby Mode .......................................................................................51
11.8Power Reduction Register .....................................................................................52
11.9Minimizing Power Consumption ............................................................................52
11.10Register Description ............................................................................................54
12 System Control and Reset ..................................................................... 57
12.1Resetting the AVR .................................................................................................57
12.2Reset Sources .......................................................................................................57
12.3Internal Voltage Reference ....................................................................................60
12.4Watchdog Timer ....................................................................................................61
12.5Register Description ..............................................................................................64
13 I/O-Ports ..................................................................................................67
13.1Introduction ............................................................................................................67
13.2Ports as General Digital I/O ...................................................................................68
13.3Alternate Port Functions ........................................................................................72
13.4Register Description for I/O-Ports ..........................................................................96
14 Interrupts ...............................................................................................101
14.1Interrupt Vectors in ATmega640/1280/1281/2560/2561 ......................................101