Datasheet

10.4. Full Swing Crystal Oscillator.......................................................................................................46
10.5. Low Frequency Crystal Oscillator...............................................................................................47
10.6. Calibrated Internal RC Oscillator................................................................................................48
10.7. 128kHz Internal Oscillator.......................................................................................................... 49
10.8. External Clock............................................................................................................................ 50
10.9. Timer/Counter Oscillator.............................................................................................................51
10.10. Clock Output Buffer....................................................................................................................51
10.11. System Clock Prescaler............................................................................................................. 51
10.12. Register Description...................................................................................................................52
11. PM - Power Management and Sleep Modes...........................................................56
11.1. Overview.....................................................................................................................................56
11.2. Sleep Modes...............................................................................................................................56
11.3. BOD Disable...............................................................................................................................56
11.4. Idle Mode....................................................................................................................................57
11.5. ADC Noise Reduction Mode.......................................................................................................57
11.6. Power-Down Mode.....................................................................................................................58
11.7. Power-Save Mode......................................................................................................................58
11.8. Standby Mode............................................................................................................................ 59
11.9. Extended Standby Mode............................................................................................................ 59
11.10. Power Reduction Register..........................................................................................................59
11.11. Minimizing Power Consumption................................................................................................. 59
11.12. Register Description................................................................................................................... 61
12. SCRST - System Control and Reset....................................................................... 67
12.1. Resetting the AVR...................................................................................................................... 67
12.2. Reset Sources............................................................................................................................67
12.3. Power-on Reset..........................................................................................................................68
12.4. External Reset............................................................................................................................69
12.5. Brown-out Detection...................................................................................................................69
12.6. Watchdog System Reset............................................................................................................ 70
12.7. Internal Voltage Reference.........................................................................................................70
12.8. Watchdog Timer......................................................................................................................... 71
12.9. Register Description................................................................................................................... 73
13. Interrupts................................................................................................................. 77
13.1. Overview.....................................................................................................................................77
13.2. Interrupt Vectors in ATmega644A...............................................................................................77
13.3. Register Description................................................................................................................... 80
14. External Interrupts................................................................................................... 83
14.1. EXINT - External Interrupts........................................................................................................ 83
15. I/O-Ports.................................................................................................................. 95
15.1. Overview.....................................................................................................................................95
15.2. Ports as General Digital I/O........................................................................................................96
15.3. Alternate Port Functions.............................................................................................................99
15.4. Register Description................................................................................................................. 112
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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