User Manual

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ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
8271E–AVR–07/2012
Table of Contents
Features .....................................................................................................1
1 Pin Configurations ...................................................................................2
1.1Pin Descriptions .........................................................................................................3
2 Overview ...................................................................................................5
2.1Block Diagram ...........................................................................................................5
2.2Comparison Between Processors .............................................................................6
3 Resources .................................................................................................7
4 Data Retention ..........................................................................................7
5 About Code Examples .............................................................................7
6 Capacitive Touch Sensing .......................................................................7
7 AVR CPU Core ..........................................................................................8
7.1Overview ....................................................................................................................8
7.2ALU – Arithmetic Logic Unit .......................................................................................9
7.3Status Register ..........................................................................................................9
7.4General Purpose Register File ................................................................................10
7.5Stack Pointer ...........................................................................................................12
7.6Instruction Execution Timing ...................................................................................13
7.7Reset and Interrupt Handling ...................................................................................13
8 AVR Memories ........................................................................................ 16
8.1Overview ..................................................................................................................16
8.2In-System Reprogrammable Flash Program Memory .............................................16
8.3SRAM Data Memory ................................................................................................18
8.4EEPROM Data Memory ..........................................................................................19
8.5I/O Memory ..............................................................................................................20
8.6Register Description ................................................................................................21
9 System Clock and Clock Options .........................................................26
9.1Clock Systems and their Distribution .......................................................................26
9.2Clock Sources .........................................................................................................27
9.3Low Power Crystal Oscillator ...................................................................................28
9.4Full Swing Crystal Oscillator ....................................................................................29
9.5Low Frequency Crystal Oscillator ............................................................................31
9.6Calibrated Internal RC Oscillator .............................................................................32