ATMEGA8U2_14 Datasheet, PDF (303/310 Pages) ATMEL Corporation – 125 Powerful Instructions – Most Single Clock Cycle Execution

ATmega8U2/16U2/32U2
Table of Contents
Features ..................................................................................................... 1
1 Pin Configurations ................................................................................... 2
1.1Disclaimer ..................................................................................................................2
2 Overview ................................................................................................... 3
2.1Block Diagram ...........................................................................................................3
2.2Pin Descriptions .........................................................................................................4
3 Resources ................................................................................................. 6
4 Code Examples ........................................................................................ 6
5 Data Retention .......................................................................................... 6
6 AVR CPU Core .......................................................................................... 7
6.1Introduction ................................................................................................................7
6.2Architectural Overview ...............................................................................................7
6.3ALU – Arithmetic Logic Unit .......................................................................................8
6.4Status Register ..........................................................................................................8
6.5General Purpose Register File ................................................................................10
6.6Stack Pointer ...........................................................................................................11
6.7Instruction Execution Timing ...................................................................................12
6.8Reset and Interrupt Handling ...................................................................................13
7 AVR Memories ........................................................................................ 16
7.1In-System Reprogrammable Flash Program Memory .............................................16
7.2SRAM Data Memory ................................................................................................17
7.3EEPROM Data Memory ..........................................................................................18
7.4I/O Memory ..............................................................................................................19
7.5Register Description ................................................................................................20
8 System Clock and Clock Options ......................................................... 26
8.1Clock Systems and their Distribution .......................................................................26
8.2Clock Switch ............................................................................................................27
8.3Clock Sources .........................................................................................................29
8.4Low Power Crystal Oscillator ...................................................................................30
8.5Full Swing Crystal Oscillator ....................................................................................32
8.6Calibrated Internal RC Oscillator .............................................................................33
8.7External Clock .........................................................................................................35
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7799D–AVR–11/10