Atmel XMEGA B, User Manual

Page: 377 / 415

377 XMEGA B [DATASHEET]
8291B–AVR–01/2013
30. Memory Programming
30.1 Features

Read and write access to all memory spaces from

External programmers

Application software self-programming

Self-programming and boot loader support

Read-while-write self-programming

CPU can run and execute code while flash is being programmed

Any communication interface can be used for program upload/download

External programming

Support for in-system and production programming

Programming through serial PDI or JTAG interface

High security with separate boot lock bits for:

External programming access

Boot loader section access

Application section access

Application table access

Reset fuse to select reset vector address to the start of the

Application section, or

Boot loader section
30.2 Overview
This section describes how to program the nonvolatile memory (NVM) in Atmel AVR XMEGA devices, and covers both
self-programming and external programming. The NVM consists of the flash program memory, user signature and
production signature rows, fuses and lock bits, and EEPROM data memory. For details on the actual memories, how
they are organized, and the register description for the NVM controller used to access the memories, refer to
“Memories”
on page 20 .
The NVM can be accessed for read and write from application software through self-programming and from an external
programmer. Accessing the NVM is done through the NVM controller, and the two methods of programming are similar.
Memory access is done by loading address and/or data to the selected memory or NVM controller and using a set of
commands and triggers that make the NVM controller perform specific tasks on the nonvolatile memory.
From external programming, all memory spaces can be read and written, except for the production signature row, which
can only be read. The device can be programmed in-system and is accessed through the PDI using the PDI or JTAG
physical interfaces.
“External Programming” on page 390 describes PDI and JTAG in detail.
Self-programming and boot loader support allows application software in the device to read and write the flash, user
signature row and EEPROM, write the lock bits to a more secure setting, and read the production signature row and
fuses. The flash allows read-while-write self-programming, meaning that the CPU can continue to operate and execute
code while the flash is being programmed.
“Self-programming and Boot Loader Support” on page 381 describes this in
detail.
For both self-programming and external programming, it is possible to run a CRC check on the flash or a section of the
flash to verify its content after programming.
The device can be locked to prevent reading and/or writing of the NVM. There are separate lock bits for external
programming access and self-programming access to the boot loader section, application section, and application table
section.
30.3 NVM Controller
Access to the nonvolatile memories is done through the NVM controller. It controls NVM timing and access privileges,
and holds the status of the NVM, and is the common NVM interface for both external programming and self-