Datasheet

 2018 Microchip Technology Inc. Data Sheet Complete DS40002061A-page 3
ATmega48A/PA/88A/PA/168A/PA/328/P
Table of Contents
1 Pin Configurations .............................................................................................................. 12
1.1 Pin Descriptions............................................................................................... 13
2Overview .................................................................................................................................... 15
2.1 Block Diagram ................................................................................................. 15
2.2 Comparison Between Processors ................................................................... 16
3 Resources ................................................................................................................................ 17
4 Data Retention ....................................................................................................................... 17
5 About Code Examples ...................................................................................................... 17
6 Capacitive Touch Sensing ............................................................................................. 17
7 AVR CPU Core ....................................................................................................................... 18
7.1 Overview.......................................................................................................... 18
7.2 ALU – Arithmetic Logic Unit............................................................................. 19
7.3 Status Register ................................................................................................ 19
7.4 General Purpose Register File ........................................................................ 20
7.5 Stack Pointer ................................................................................................... 22
7.6 Instruction Execution Timing ........................................................................... 23
7.7 Reset and Interrupt Handling........................................................................... 23
8 AVR Memories ....................................................................................................................... 26
8.1 Overview.......................................................................................................... 26
8.2 In-System Reprogrammable Flash Program Memory ..................................... 26
8.3 SRAM Data Memory........................................................................................ 28
8.4 EEPROM Data Memory .................................................................................. 29
8.5 I/O Memory...................................................................................................... 30
8.6 Register Description ........................................................................................ 31
9 System Clock and Clock Options .............................................................................. 36
9.1 Clock Systems and their Distribution............................................................... 36
9.2 Clock Sources ................................................................................................. 37
9.3 Low Power Crystal Oscillator........................................................................... 38
9.4 Full Swing Crystal Oscillator............................................................................ 39
9.5 Low Frequency Crystal Oscillator.................................................................... 42
9.6 Calibrated Internal RC Oscillator ..................................................................... 43
9.7 128kHz Internal Oscillator ............................................................................... 43