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8210C–AVR–09/11
Atmel AVR XMEGA D
4.
Memories
4.1
Features
•
Flash program memory
– One linear address space
– In-system programmable
– Self-programming and boot loader support
– Application section for application code
– Application table section for application code or data storage
– Boot section for application code or bootloader code
– Separate read/write protection lock bits for all sections
– Built in fast CRC check of a selectable flash program memory section
•
Data memory
– One linear address space
– Single-cycle access from CPU
– SRAM
– EEPROM
Byte and page accessible
Optional memory mapping for direct load and store
– I/O memory
Configuration and status registers for all peripherals and modules
4 bit-accessible general purpose registers for global variables or flags
•
Production signature row memory for factory programmed data
– ID for each microcontroller device type
– Serial number for each device
– Calibration bytes for factory calibrated peripherals
•
User signature row
– One flash page in size
– Can be read and written from software
– Content is kept after chip erase
4.2
Overview
This section describes the different memories in XMEGA AU devices. The AVR architecture has
two main memory spaces, the program memory and the data memory. Executable code can
reside only in the program memory, while data can be stored in the program memory and the
data memory. The data memory includes the internal SRAM, and EEPROM for nonvolatile data
storage. All memory spaces are linear and require no memory bank switching. Nonvolatile mem-
ory (NVM) spaces can be locked for further write and read/write operations. This prevents
unrestricted access to the application software.
A separate memory section contains the fuse bytes. These are used for configuring important
system functions, and can only be written by an external programmer.
4.3
Flash Program Memory
The XMEGA AU devices contain on-chip in-system reprogrammable flash memory for program
storage. The flash memory can be accessed for read and write from an external programmer
through the PDI or from application software running in the device.