Datasheet

Table of Contents
Introduction......................................................................................................................1
Features.......................................................................................................................... 1
1. Pin configurations...................................................................................................... 9
1.1. Pin descriptions.......................................................................................................................... 10
2. Ordering Information ...............................................................................................14
2.1. ATmega16M1............................................................................................................................. 14
2.2. ATmega32M1............................................................................................................................. 14
2.3. ATmega64M1............................................................................................................................. 14
3. Overview..................................................................................................................15
3.1. Block diagram.............................................................................................................................15
3.2. Pin descriptions.......................................................................................................................... 16
4. Resources................................................................................................................18
5. About code examples.............................................................................................. 19
6. Data retention.......................................................................................................... 20
7. AVR CPU Core........................................................................................................ 21
7.1. Overview.....................................................................................................................................21
7.2. ALU – Arithmetic Logic Unit........................................................................................................22
7.3. Status Register...........................................................................................................................22
7.4. General Purpose Register File................................................................................................... 24
7.5. Stack Pointer.............................................................................................................................. 25
7.6. Accessing 16-bit Registers.........................................................................................................28
7.7. Instruction Execution Timing...................................................................................................... 29
7.8. Reset and Interrupt Handling..................................................................................................... 29
8. AVR Memories.........................................................................................................32
8.1. Overview.....................................................................................................................................32
8.2. In-System Reprogrammable Flash Program Memory................................................................32
8.3. SRAM Data Memory...................................................................................................................33
8.4. EEPROM Data Memory............................................................................................................. 36
8.5. I/O Memory.................................................................................................................................37
8.6. Register Description................................................................................................................... 38
9. System Clock and Clock Options............................................................................ 47
9.1. Clock Systems and Their Distribution.........................................................................................47
9.2. Clock Sources............................................................................................................................ 48
9.3. Default Clock Source .................................................................................................................49
9.4. Low Power Crystal Oscillator......................................................................................................49
9.5. Calibrated Internal RC Oscillator................................................................................................51