ATmega16A datasheet(265/352 Pages) ATMEL

265 / 352 page

265

8154B–AVR–07/09

ATmega16A

Notes:

1. Program the Fuse bits before programming the Lock bits.

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

26.2

Fuse Bits

The ATmega16A has two fuse bytes. Table 26-3 and Table 26-4 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.

Notes:

1. The SPIEN Fuse is not accessible in SPI Serial Programming mode.

2. The CKOPT Fuse functionality depends on the setting of the CKSEL bits. See See “Clock

Sources” on page 25. for details.

3. The default value of BOOTSZ1:0 results in maximum Boot Size. See Table 25-6 on page 262.

LPM executing from the Boot Loader section is not allowed to

read from the Application section. If interrupt vectors are placed

in the Boot Loader section, interrupts are disabled while

executing from the Application section.

BLB1 Mode

BLB12

BLB11

No restrictions for SPM or 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 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.

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 26-2.

Lock Bit Protection Modes (Continued)

Memory Lock Bits(2)

Protection Type

Table 26-3.

Fuse High Byte

Fuse High

Byte

Bit No.

Description

Default Value

OCDEN(4)

Enable OCD

1 (unprogrammed, OCD disabled)

JTAGEN(5)

Enable JTAG

0 (programmed, JTAG enabled)

SPIEN(1)

Enable SPI Serial Program and

Data Downloading

0 (programmed, SPI prog. enabled)

CKOPT(2)

Oscillator options

1 (unprogrammed)

EESAVE

EEPROM memory is preserved

through the Chip Erase

1 (unprogrammed, EEPROM not

preserved)

BOOTSZ1

Select Boot Size (see Table 25-6

for details)

0 (programmed)(3)

BOOTSZ0

Select Boot Size (see Table 25-6

for details)

0 (programmed)(3)

BOOTRST

Select reset vector

1 (unprogrammed)

ATmega16A Datasheet(PDF) 265 Page - ATMEL Corporation

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