Rainbow-electronics ATmega8515L Instrukcja Użytkownika Pobierz pdf (Strona 164)

164

ATmega8515(L)

2512A–AVR–04/02

Figure 72. Memory Sections

(1)

Note: 1. The parameters in the figureabove are given in Table 78onpage 173.

Boot Loader Lock Bits If no Boot Loadercapability is needed, the entire Flash is available for application code.

The Boot Loaderhas two separate sets ofBoot Lock bitswhich can be set indepen-

dently.This gives theuser aunique flexibility to select different levels ofprotection.

Theusercan select:

•Toprotectthe entire Flash from a softwareupdate by the MCU.

•Toprotectonly the Boot LoaderFlash section from a softwareupdate by the MCU.

•Toprotectonly theApplication Flash section from a softwareupdate by the MCU.

•Allowsoftwareupdateinthe entire Flash.

See Table 74and Table 75 forfurtherdetails.The Boot Lock bitscan be set in software

and in Serial or Parallel Programming mode,but theycan be clearedbya ChipErase

command only.The generalWrite Lock (Lock Bit mode2)does not control the program-

ming of the Flash memory by SPM instruction. Similarly, thegeneral Read/Write Lock

(Lock Bit mode1)does not controlreading norwriting 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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