ATmega16 datasheet(260/357 Pages) ATMEL

260 / 357 page

260

2466S–AVR–05/09

ATmega16(L)

Notes:

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

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

Fuse Bits

The ATmega16 has two fuse bytes. Table 105 and Table 106 describe briefly the functionality of

all the fuses and how they are mapped into the fuse bytes. Note that the fuses are read as logi-

cal 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 100 on page 257.

4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of Lock bits

and the JTAGEN Fuse. A programmed OCDEN Fuse enables some parts of the clock system

to be running in all sleep modes. This may increase the power consumption.

5. If the JTAG interface is left unconnected, the JTAGEN fuse should if possible be disabled. This

to avoid static current at the TDO pin in the JTAG interface.

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 104. Lock Bit Protection Modes (Continued)

Memory Lock Bits(2)

Protection Type

Table 105. 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 100

for details)

0 (programmed)(3)

BOOTSZ0

Select Boot Size (see Table 100

for details)

0 (programmed)(3)

BOOTRST

Select reset vector

1 (unprogrammed)

ATmega16 Datasheet(PDF) 260 Page - ATMEL Corporation

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