atmega323l ATMEL Corporation, atmega323l Datasheet - Page 181

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Setting the Boot Loader Lock
Bits by SPM
1457G–AVR–09/03
Table 61. Boot Lock Bit0 Protection Modes (Application Section)
Note:
Table 62. Boot Lock Bit1 Protection Modes (Boot Loader Section)
Note:
To set the Boot Loader Lock bits, write the desired data to R0, write “00001001” to
SPMCR and execute SPM within four clock cycles after writing SPMCR. The only
accessible Lock bits are the Boot Lock bits that may prevent the Application and Boot
Loader section from any software update by the MCU.
If bits 5..2 in R0 are cleared (zero), the corresponding Boot Lock Bit will be programmed
if an SPM instruction is executed within four cycles after BLBSET and SPMEN are set in
SPMCR.
Bit
R0
BLB0 Mode
BLB1 mode
1
2
3
4
1
2
3
4
1. “1” means unprogrammed, “0” means programmed
1. “1” means unprogrammed, “0” means programmed
7
1
BLB02
BLB12
1
1
0
0
1
1
0
0
6
1
BLB01
BLB11
1
0
0
1
1
0
0
1
BLB12
5
Protection
No restrictions for SPM or LPM accessing the Application
section.
SPM is not allowed to write to the Application section.
SPM is not allowed to write to the Application section, and
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.
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.
Protection
No restrictions for SPM or LPM accessing the Boot Loader
section.
SPM is not allowed to write to the Boot Loader section.
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.
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.
BLB11
4
BLB02
3
BLB01
2
ATmega323(L)
(1)
1
1
(1)
0
1
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