ATXMEGA384C3_14 Datasheet, PDF (13/125 Pages) ATMEL Corporation – 8/16-bit Atmel XMEGA C3 Microcontroller

The production signature row also contains an ID that identifies each microcontroller device type and a serial number for
each manufactured device. The serial number consists of the production lot number, wafer number, and wafer
coordinates for the device. The device ID for the available devices is shown in Table 7-1.
The production signature row cannot be written or erased, but it can be read from application software and external
programmers.
Table 7-1. Device ID Bytes
Device
ATxmega384C3
Byte 2
45
Device ID bytes
Byte 1
98
Byte 0
1E
7.3.5
User Signature Row
The user signature row is a separate memory section that is fully accessible (read and write) from application software
and external programmers. It is one flash page in size, and is meant for static user parameter storage, such as calibration
data, custom serial number, identification numbers, random number seeds, etc. This section is not erased by chip erase
commands that erase the flash, and requires a dedicated erase command. This ensures parameter storage during
multiple program/erase operations and on-chip debug sessions.
7.4 Fuses and Lock Bits
The fuses are used to configure important system functions, and can only be written from an external programmer. The
application software can read the fuses. The fuses are used to configure reset sources such as brownout detector and
watchdog, and startup configuration.
The lock bits are used to set protection levels for the different flash sections (that is, if read and/or write access should be
blocked). Lock bits can be written by external programmers and application software, but only to stricter protection levels.
Chip erase is the only way to erase the lock bits. To ensure that flash contents are protected even during chip erase, the
lock bits are erased after the rest of the flash memory has been erased.
An unprogrammed fuse or lock bit will have the value one, while a programmed fuse or lock bit will have the value zero.
Both fuses and lock bits are reprogrammable like the flash program memory.
7.5 Data Memory
The data memory contains the I/O memory, internal SRAM, optionally memory mapped EEPROM, and external memory
if available. The data memory is organized as one continuous memory section, see Figure 7-2 on page 13. To simplify
development, I/O Memory, EEPROM and SRAM will always have the same start addresses for all Atmel AVR XMEGA
devices.
Figure 7-2. Data Memory Map (hexadecimal address)
Byte address
0
FFF
ATxmega384C3
I/O registers (4K)
XMEGA C3 [DATASHEET]
13
Atmel-8361F-AVR-ATxmega384C3-Datasheet–11/2014