atmega161-4pi ATMEL Corporation, atmega161-4pi Datasheet - Page 116

• Manufacturer Part Number: atmega161-4pi
• Description: 8-bit Microcontroller With 16k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Program Memory
Lock bits
Fuse bits
116
ATmega161(L)
The ATmega161 MCU provides six Lock bits that can be left unprogrammed (“1”) or can
be programmed (“0”) to obtain the additional features listed in Table 40. The Lock bits
can only be erased to “1” with the Chip Erase command.
Table 40. Lock Bit Protection Modes
Note:
The ATmega161 has six Fuse bits: BOOTRST, SPIEN, SUT, and CKSEL [2:0].
•
•
•
BLB0 Mode
BLB1 Mode
LB Mode
When BOOTRST is programmed (“0”), the Reset Vector is set to address $1E00,
which is the first address location in the Boot Loader section of the Flash. If the
BOOTRST is unprogrammed (“1”), the Reset Vector is set to address $0000. Default
value is unprogrammed (“1”).
When the SPIEN Fuse is programmed (“0”), Serial Program and Data Downloading
is enabled. Default value is programmed (“0”). The SPIEN Fuse is not accessible in
Serial Programming mode.
The SUT Fuse changes the start-up times. Default value is unprogrammed (“1”).
1
2
3
1
2
3
4
1
2
3
4
Memory Lock bits
1. Program the Fuse bits before programming the Lock bits.
BLB02
BLB12
LB1
1
0
0
1
1
0
0
1
1
0
0
BLB01
BLB11
LB2
1
1
0
1
0
0
1
1
0
0
1
Protection Type
No memory lock features enabled
Further programming of the Flash and EEPROM is
disabled in parallel and Serial Programming modes. The
Fuse bits are locked in both Serial and Parallel
Programming modes.
Further programming and verification of the Flash and
EEPROM is disabled in parallel and Serial Programming
modes. The Fuse bits are locked in both Serial and
Parallel Programming modes.
No restrictions for SPM, LPM accessing the Application
Code section
SPM is not allowed to write to the Application Code
section.
SPM is not allowed to write to the Application Code
section and LPM executing from Boot Loader section is
not allowed to read from the Application Code section.
LPM executing from the Boot Loader section is not
allowed to read from the Application Code section.
No restrictions for SPM, LPM accessing the Boot Loader
section
SPM is not allowed to write the Boot Loader section.
SPM is not allowed to write to the Boot Loader section and
LPM executing from the Application Code section is not
allowed to read from the Boot Loader section.
LPM executing from the Application Code section is not
allowed to read from the Boot Loader section.
(1)
(1)
(1)
1228D–AVR–02/07