ATmega32U2 datasheet(247/314 Pages) ATMEL

247 / 314 page

247

7799B–AVR–07/09

ATmega8U2/16U2/32U2

Notes:

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

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

25.2

Fuse Bits

The ATmega8U2/16U2/32U2 has four Fuse bytes. Table 25-3 - Table 25-5 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 267 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 25-2.

Lock Bit Protection Modes

(1)(2) (Continued)

Memory Lock Bits

Protection Type

Table 25-3.

Extended Fuse Byte

Fuse Low Byte

Bit No

Description

Default Value : 0xF4

–7

–

–6

–

–5

–

–4

–

HWBE

Hardware Boot Enable

0 (programmed)

BODLEVEL2(1)

Brown-out Detector trigger level

1 (unprogrammed)

BODLEVEL1(1)

Brown-out Detector trigger level

0 (programmed)

BODLEVEL0(1)

Brown-out Detector trigger level

0 (programmed)

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