atxmega128a3-mu ATMEL Corporation, atxmega128a3-mu Datasheet - Page 5

• Manufacturer Part Number: atxmega128a3-mu
• Description: 8/16-bit Xmega Microcontroller
• Manufacturer: ATMEL Corporation

6. AVR CPU
6.1
6.2
8068A–AVR–02/08
Features
Overview
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The XMEGA A3 uses an 8/16-bit AVR CPU. The main function of the CPU core is to ensure cor-
rect program execution. The CPU must therefore be able to access memories, perform
calculations and control peripherals. Interrupt handling is described in a separate section.
6-1 on page 5
Figure 6-1.
The AVR uses a Harvard architecture - with separate memories and buses for program and
data. Instructions in the program memory are executed with a single level pipeline. While one
instruction is being executed, the next instruction is pre-fetched from the program memory. This
concept enables instructions to be executed in every clock cycle. The program memory is In-
System Re-programmable Flash memory.
8/16-bit high performance AVR RISC Architecture
32x8-bit registers directly connected to the ALU
Stack in RAM
Stack Pointer accessible in I/O memory space
Direct addressing of up to 16M bytes of program and data memory.
True 16/24-bit access to 16/24-bit I/O registers
Support for 8-, 16- and 32-bit Aritmetic’s
Configuration Change Protection of system critical features.
– 139 instructions
– Hardware multiplier
shows the CPU block diagram.
CPU block diagram
PERIPHERAL
Instruction
MODULE 1
Program
Program
Register
Memory
Counter
FLASH
PERIPHERAL
MODULE n
Direct Addressing
Indirect Addressing
Instruction
DATA BUS
Decoder
SRAM
DATA BUS
Data
I/O LINES
EEPROM
32 x 8 General
CONTROL
Registers
STATUS/
Purpose
ALU
ATxmega A3
PMIC
Figure
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