Rainbow-electronics ATmega32L Bedienungsanleitung PDF herunterladen (Seite 244)

244

ATmega32(L)

2503C–AVR–10/02

Figure 125. Memory Sections

(1)

Note: 1. The parameters in the figure above are given in Table 100 on page 253.

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 96 and Table 97 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.

$0000

Flashend

Program Memory

BOOTSZ = '11'

Application Flash Section

Boot Loader Flash Section

Flashend

Program Memory

BOOTSZ = '10'

$0000

Program Memory

BOOTSZ = '01'

Program Memory

BOOTSZ = '00'

Application Flash Section

Boot Loader Flash Section

$0000

Flashend

Application Flash Section

Flashend

End RWW

Start NRWW

Application flash Section

Boot Loader Flash Section

End RWW

Start NRWW

End RWW

Start NRWW

$0000

End RWW, End Application

Start NRWW, Start Boot Loader

Application Flash SectionApplication Flash Section

Application Flash Section

Read-While-Write SectionNo Read-While-Write Section

Read-While-Write SectionNo Read-While-Write SectionRead-While-Write SectionNo Read-While-Write Section

End Application

Start Boot Loader

End Application

Start Boot Loader

End Application

Start Boot Loader

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