AT90USB646 datasheet(369/434 Pages) ATMEL

369 / 434 page

369

7593A–AVR–02/06

AT90USB64/128

Notes:

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

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

29.2 Fuse Bits

The AT90USB64/128 has four Fuse bytes. Table 29-3 - Table 29-5 describe briefly the function-

ality 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 Table 8-2 on page 61 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 29-2.

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

Memory Lock Bits

Protection Type

Table 29-3.

Extended Fuse Byte

Fuse Low Byte

Bit No

Description

Default Value

–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

1 (unprogrammed)

BODLEVEL0(1)

Brown-out Detector trigger level

1 (unprogrammed)

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