Rainbow Electronics ATmega128RFA1 - Manual (Page 464)

464
8266A-MCU Wireless-12/09
ATmega128RFA1
31 Memory Programming
31.1 Program And Data Memory Lock Bits
The ATmega128RFA1 provides six Lock bits which can be left un-programmed (“1”) or
can be programmed (“0”) to obtain the additional features listed in
Table 31-2 below .
The Lock bits can only be erased to “1” with the Chip Erase command.
Table 31-1. Lock Bit Byte
(1)
Lock Bit Byte Bit No Description Default Value
− 7 − 1 (un-programmed)
− 6 − 1 (un-programmed)
BLB12 5 Boot Lock bit 1 (un-programmed)
BLB11 4 Boot Lock bit 1 (un-programmed)
BLB02 3 Boot Lock bit 1 (un-programmed)
BLB01 2 Boot Lock bit 1 (un-programmed)
LB2 1 Lock bit 1 (un-programmed)
LB1 0 Lock bit 1 (un-programmed)
Note: 1. “1” means un-programmed, “0” means programmed.
Table 31-2. Lock Bit Protection Modes
(1)(2)
Memory Lock Bits Protection Type
LB Mode LB2 LB1
1 1 1 No memory lock features enabled.
2 1 0
Further programming of the Flash and EEPROM is
disabled in Parallel and Serial Programming mode.
The Fuse bits are locked in both Serial and Parallel
Programming mode.
(1)
3 0 0
Further programming and verification of the Flash and
EEPROM is disabled in Parallel and Serial
Programming mode. The Boot Lock bits and Fuse bits
are locked in both Serial and Parallel Programming
mode.
(1)
BLB0 Mode BL02 BL01
1 1 1
No restrictions for SPM or (E)LPM accessing the
Application section.
2 1 0 SPM is not allowed to write to the Application section.
3 0 0
SPM is not allowed to write to the Application section,
and (E)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.
4 0 1
(E)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.