ATXMEGA8E5 datasheet(19/153 Pages) MICROCHIP

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Data Sheet Complete

DS40002059A-page 19

ATxmega32E5/16E5/8E5

corresponding peripheral registers from software. For details on calibration conditions, refer to “Electrical Characteristics”

on page 78.

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 8-1.

The production signature row cannot be written or erased, but it can be read from application software and external

programmers.

Table 8-1.

Device ID Bytes for AVR XMEGA E5 Devices

8.3.5

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 com-

mands that erase the flash, and requires a dedicated erase command. This ensures parameter storage during multiple

program/erase operations and on-chip debug sessions.

8.4

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, startup configuration, etc.

The lock bits are used to set protection levels for the different flash sections (i.e., 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 un-programmed 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.

Device

Device ID bytes

Byte 2

Byte 1

Byte 0

ATxmega32E5

ATxmega16E5

ATxmega8E5

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