ii
8025I–AVR–02/09
ATmega48P/88P/168P/328P
6.6Calibrated Internal RC Oscillator .............................................................................33
6.7128 kHz Internal Oscillator ......................................................................................33
6.8External Clock .........................................................................................................34
6.9Clock Output Buffer .................................................................................................35
6.10Timer/Counter Oscillator ........................................................................................35
6.11System Clock Prescaler ........................................................................................35
6.12Register Description ..............................................................................................37
7 Power Management and Sleep Modes ................................................. 39
7.1Sleep Modes ............................................................................................................39
7.2BOD Disable ............................................................................................................40
7.3Idle Mode .................................................................................................................40
7.4ADC Noise Reduction Mode ....................................................................................40
7.5Power-down Mode ...................................................................................................41
7.6Power-save Mode ....................................................................................................41
7.7Standby Mode .........................................................................................................41
7.8Extended Standby Mode .........................................................................................41
7.9Power Reduction Register .......................................................................................42
7.10Minimizing Power Consumption ............................................................................42
7.11Register Description ..............................................................................................44
8 System Control and Reset ....................................................................46
8.1Resetting the AVR ...................................................................................................46
8.2Reset Sources .........................................................................................................46
8.3Power-on Reset .......................................................................................................47
8.4External Reset .........................................................................................................48
8.5Brown-out Detection ................................................................................................48
8.6Watchdog System Reset .........................................................................................49
8.7Internal Voltage Reference ......................................................................................49
8.8Watchdog Timer ......................................................................................................50
8.9Register Description ................................................................................................54
9 Interrupts ................................................................................................ 57
9.1Interrupt Vectors in ATmega48P .............................................................................57
9.2Interrupt Vectors in ATmega88P .............................................................................59
9.3Interrupt Vectors in ATmega168P ...........................................................................62
9.4Interrupt Vectors in ATmega328P ...........................................................................65
9.5Register Description ................................................................................................68