ATMEGA8L ATMEL [ATMEL Corporation], ATMEGA8L Datasheet - Page 208

• Manufacturer Part Number: ATMEGA8L
• Description: 8-bit AVR with 8K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Boot Loader Lock Bits
208
ATmega8(L)
Figure 102. Memory Sections
Note:
If no Boot Loader capability is needed, the entire Flash is available for application code.
The Boot Loader has two separate sets of Boot Lock Bits which can be set indepen-
dently. This gives the user a unique flexibility to select different levels of protection.
The user can select:
•
•
•
•
See Table 78 and Table 79 for further details. The Boot Lock Bits can be set in software
and in Serial or Parallel Programming mode, but they can be cleared by a chip erase
command only. The general Write Lock (Lock bit mode 2) does not control the program-
ming of the Flash memory by SPM instruction. Similarly, the general Read/Write Lock
(Lock bit mode 3) does not control reading nor writing by LPM/SPM, if it is attempted.
To protect the entire Flash from a software update by the MCU.
To protect only the Boot Loader Flash section from a software update by the MCU.
To protect only the Application Flash section from a software update by the MCU.
Allow software update in the entire Flash.
1. The parameters in the figure are given in Table 82 on page 217.
Boot Loader Flash Section
Boot Loader Flash Section
Application Flash Section
Application Flash Section
Application Flash Section
Application Flash Section
Program Memory
Program Memory
BOOTSZ = '11'
BOOTSZ = '01'
$0000
End RWW
Start NRWW
End Application
Start Boot Loader
Flashend
$0000
End RWW
Start NRWW
End Application
Start Boot Loader
Flashend
(1)
Boot Loader Flash Section
Boot Loader Flash Section
Application Flash Section
Application Flash Section
Application flash Section
Program Memory
Program Memory
BOOTSZ = '10'
BOOTSZ = '00'
$0000
End RWW
Start NRWW
End Application
Start Boot Loader
Flashend
$0000
End RWW, End Application
Start NRWW, Start Boot Loader
Flashend
2486M–AVR–12/03