Datasheet

Memory Lock Bits Protection Type
LB Mode LB2 LB1
4 0 1 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
1 1 1 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.
3 0 0 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.
4 0 1 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.
Note:
1. Program the Fuse Bits before programming the Lock Bits.
2. “1” means unprogrammed, “0” means programmed.
31.2. Fuse Bits
The ATmega64A has three fuse bytes. The tables of this section 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.
Table 31-3 Extended Fuse Byte
Extended Fuse Byte Bit No. Description Default Value
– 7 – 1
– 6 – 1
– 5 – 1
– 4 – 1
– 3 – 1
– 2 – 1
M103C
(1)
1 ATmega103 compatibility mode 0 (programmed)
WDTON
(2)
0 Watchdog Timer always on 1 (unprogrammed)
Note:
1. See ATmega103 and ATmega64A Compatibility for details.
Atmel ATmega64A [DATASHEET]
Atmel-8160E-ATmega64A_Datasheet_Complete-09/2015
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