35
8331B–AVR–03/12
Atmel AVR XMEGA AU
4.16.6 LOCKBITS – Lock Bit register
• Bit 7:6 – BLBB[1:0]: Boot Lock Bit Boot Loader Section
These lock bits control the software security level for accessing the boot loader section. The
BLBB bits can only be written to a more strict locking. Resetting the BLBB bits is possible by
executing a chip erase command.
• Bit 5:4 – BLBA[1:0]: Boot Lock Bit Application Section
These lock bits control the software security level for accessing the application section. The
BLBA bits can only be written to a more strict locking. Resetting the BLBA bits is possible by
executing a chip erase command.
Bit 76543210
+0x07 BLBB[1:0] BLBA[1:0] BLBAT[1:0] LB[1:0] LOCKBITS
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value 1 1 1 1 1 1 1 1
Table 4-9. Boot lock bit for the boot loader section.
BLBB[1:0] Group Configuration Description
11 NOLOCK
No lock – no restrictions for SPM and (E)LPM accessing
the boot loader section.
10 WLOCK
Write lock – SPM is not allowed to write the boot loader
section.
01 RLOCK
Read lock – (E)LPM executing from the application
section is not allowed to read from the boot loader
section.
If the interrupt vectors are placed in the application
section, interrupts are disabled while executing from the
boot loader section.
00 RWLOCK
Read and write lock – 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 the interrupt vectors are placed in the application
section, interrupts are disabled while executing from the
boot loader section.
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