Datasheet

260
2466T–AVR–07/10
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.
BLB1 Mode BLB12 BLB11
111
No restrictions for SPM or LPM accessing the Boot Loader
section.
2 1 0 SPM is not allowed to write to the Boot Loader section.
300
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.
401
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)
7 Enable OCD 1 (unprogrammed, OCD disabled)
JTAGEN
(5)
6 Enable JTAG 0 (programmed, JTAG enabled)
SPIEN
(1)
5
Enable SPI Serial Program and
Data Downloading
0 (programmed, SPI prog. enabled)
CKOPT
(2)
4 Oscillator options 1 (unprogrammed)
EESAVE 3
EEPROM memory is preserved
through the Chip Erase
1 (unprogrammed, EEPROM not
preserved)
BOOTSZ1 2
Select Boot Size (see Table 100
for details) 0 (programmed)
(3)
BOOTSZ0 1
Select Boot Size (see Table 100
for details) 0 (programmed)
(3)
BOOTRST 0 Select reset vector 1 (unprogrammed)