ATMEGA640 datasheet(326/436 Pages) MICROCHIP

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

Notes: 1. Program the Fuse bits and Boot Lock bits before programming the LB1 and LB2.

2. “1” means unprogrammed, “0” means programmed.

30.2 Fuse Bits

The ATmega640/1280/1281/2560/2561 has three Fuse bytes. Table 30-3 through Table 30-5 on page 327

describe briefly the functionality of all the fuses and how they are mapped into the Fuse bytes. Note that the fuses

are read as logical zero, “0”, if they are programmed.

Note:

1. See “System and Reset Characteristics” on page 360 for BODLEVEL Fuse decoding.

BLB1 Mode

BLB12

BLB11

No restrictions for SPM or (E)LPM accessing the Boot Loader section.

SPM is not allowed to write to the Boot Loader section.

SPM is not allowed to write to the Boot Loader section, and (E)LPM executing from

the Application section is not allowed to read from the Boot Loader section. If

Interrupt Vectors are placed in the Application section, interrupts are disabled while

executing from the Boot Loader section.

(E)LPM executing from the Application section is not allowed to read from the Boot

Loader section. If Interrupt Vectors are placed in the Application section, interrupts

are disabled while executing from the Boot Loader section.

Table 30-2.

Lock Bit Protection Modes(1)(2) (Continued)

Memory Lock Bits

Protection Type

Table 30-3.

Extended Fuse Byte

Bit No

Description

Default Value

–7

–

–6

–

–5

–

–4

–

–3

–

BODLEVEL2(1)

Brown-out Detector trigger level

1 (unprogrammed)

BODLEVEL1(1)

Brown-out Detector trigger level

1 (unprogrammed)

BODLEVEL0(1)

Brown-out Detector trigger level

1 (unprogrammed)

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