Data Sheet

i
8161D–AVR–10/09
ATmega48PA/88PA/168PA/328P
Table of Contents
Features..................................................................................................... 1
1 Pin Configurations ................................................................................... 2
1.1Pin Descriptions ........................................................................................................3
2 Overview ................................................................................................... 5
2.1Block Diagram ...........................................................................................................5
2.2Comparison Between ATmega48PA, ATmega88PA, ATmega168PA and
ATmega328P 6
3 Resources ................................................................................................. 7
4 Data Retention .......................................................................................... 7
5 About Code Examples ............................................................................. 7
6 AVR CPU Core .......................................................................................... 8
6.1Overview ...................................................................................................................8
6.2ALU – Arithmetic Logic Unit ......................................................................................9
6.3Status Register ..........................................................................................................9
6.4General Purpose Register File ................................................................................11
6.5Stack Pointer ...........................................................................................................12
6.6Instruction Execution Timing ...................................................................................13
6.7Reset and Interrupt Handling ..................................................................................14
7 AVR Memories ........................................................................................ 16
7.1Overview .................................................................................................................16
7.2In-System Reprogrammable Flash Program Memory .............................................16
7.3SRAM Data Memory ...............................................................................................18
7.4EEPROM Data Memory ..........................................................................................19
7.5I/O Memory ..............................................................................................................20
7.6Register Description ................................................................................................21
8 System Clock and Clock Options ......................................................... 26
8.1Clock Systems and their Distribution .......................................................................26
8.2Clock Sources .........................................................................................................27
8.3Low Power Crystal Oscillator ...................................................................................28
8.4Full Swing Crystal Oscillator ....................................................................................30
8.5Low Frequency Crystal Oscillator ............................................................................32
8.6Calibrated Internal RC Oscillator .............................................................................33