XMEGAA datasheet(19/445 Pages) ATMEL

19 / 445 page

8077H–AVR–12/09

XMEGA A

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 setting important sys-

tem functions, and write access is only possible from an external programmer.

4.3

Flash Program Memory

The XMEGA contains On-chip In-System Reprogrammable Flash memory for program storage.

The Flash memory can be accessed for read and write both from an external programmer

through the PDI, or from application software running in the CPU.

All AVR instructions are 16 or 32 bits wide, and each Flash location is 16 bits wide. The Flash

memory in XMEGA is organized in two main sections, the Application Section and the Boot

Loader section, as shown in Figure 4-1 on page 19. The sizes of the different sections are fixed,

but device dependent. These two sections have separate lock bits and can have different level

of protection. The Store Program Memory (SPM) instruction used to write to the Flash from the

application software, will only operate when executed from the Boot Loader Section.

The Application Section contains an Application Table Section with separate lock settings. This

can be used for safe storage of Non-volatile data in the Program Memory.

Figure 4-1.

Flash Memory sections

Application Flash

Section

0x000000

End RWW, End Application

Start NRWW, Start Boot Loader

Flashend

Application Table

Flash Section

Boot Loader Flash

Section

XMEGAA Datasheet(PDF) 19 Page - ATMEL Corporation