Datasheet

i
8023F–AVR–07/09
ATmega325P/3250P
Table of Contents
Features ..................................................................................................... 1
1 Pin Configurations ................................................................................... 2
1.1Disclaimer ..................................................................................................................3
2 Overview ................................................................................................... 3
2.1Block Diagram ...........................................................................................................4
2.2Comparison between ATmega325P and ATmega3250P ..........................................5
2.3Pin Descriptions ........................................................................................................6
3 Resources ................................................................................................. 9
4 Data Retention ........................................................................................ 10
5 About Code Examples ........................................................................... 10
6 AVR CPU Core ........................................................................................ 11
6.1Overview .................................................................................................................11
6.2Architectural Overview ............................................................................................11
6.3ALU – Arithmetic Logic Unit ....................................................................................12
6.4AVR Status Register ...............................................................................................13
6.5General Purpose Register File ................................................................................14
6.6Stack Pointer ...........................................................................................................15
6.7Instruction Execution Timing ...................................................................................16
6.8Reset and Interrupt Handling ..................................................................................17
7 AVR Memories ........................................................................................ 19
7.1Overview .................................................................................................................19
7.2In-System Reprogrammable Flash Program Memory .............................................19
7.3SRAM Data Memory ...............................................................................................20
7.4EEPROM Data Memory ..........................................................................................21
7.5I/O Memory ..............................................................................................................22
7.6Register Description ................................................................................................23
8 System Clock and Clock Options ......................................................... 29
8.1Clock Systems and their Distribution .......................................................................29
8.2Clock Sources .........................................................................................................30
8.3Default Clock Source ...............................................................................................30
8.4Crystal Oscillator .....................................................................................................31
8.5Low-frequency Crystal Oscillator .............................................................................32