Rainbow Electronics ATmega3290P_V - Manual (Page 270)

270
ATmega329/3290/649/6490
2552H–AVR–11/06
Figure 118. Memory Sections
Note: 1. The parameters in the figure above are given in Table 120 on page 280.
Boot Loader Lock Bits 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:
• 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.
See Table 116 and Table 117 for further details. The Boot Lock bits and general 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 programming of the Flash memory by SPM instruction. Similarly, the gen-
eral Read/Write Lock (Lock Bit mode 1) does not control reading nor writing by
LPM/SPM, if it is attempted.
0x0000
Flashend
Program Memory
BOOTSZ = '11'
Application Flash Section
Boot Loader Flash Section
Flashend
Program Memory
BOOTSZ = '10'
0x0000
Program Memory
BOOTSZ = '01'
Program Memory
BOOTSZ = '00'
Application Flash Section
Boot Loader Flash Section
0x0000
Flashend
Application Flash Section
Flashend
End RWW
Start NRWW
Application Flash Section
Boot Loader Flash Section
Boot Loader Flash Section
End RWW
Start NRWW
End RWW
Start NRWW
0x0000
End RWW, End Application
Start NRWW, Start Boot Loader
Application Flash Section Application Flash Section
Application Flash Section
Read-While-Wr
ite Section
No Read-While-Wr
ite Section
Read-While-Wr
ite Section
No Read-While-Wr
ite Section
Read-While-Wr
ite Section
No Read-While-Wr
ite Section
Read-While-Wr
ite Section
No Read-While-Wr
ite Section
End Application
Start Boot Loader
End Application
Start Boot Loader
End Application
Start Boot Loader