165
ATmega8515(L)
2512A–AVR–04/02
Note: 1. “1” means unprogrammed, “0” meansprogrammed
Note: 1. “1” means unprogrammed, “0” meansprogrammed
Entering the Boot Loader
Program
Entering the Boot Loader takesplace by a jump orcall from theapplication program.
This maybe initiatedbyatriggersuch as a commandreceived via USART, orSPI inter-
face. Alternatively, the Boot Reset Fuse can be programmedsothat theReset Vector is
pointing to the Boot Flash startaddress after a reset. Inthiscase, the Boot Loader is
started after a reset. After theapplication codeisloaded, the program can startexecut-
ing theapplication code. Note that the fusescannot be changedbythe MCU itself.This
means that oncethe Boot Reset Fuseisprogrammed, theReset Vectorwill always
point to the Boot Loader Reset and the fuse can only be changed through the Serial or
Parallel Programming interface.
Note: 1. “1” means unprogrammed, “0” meansprogrammed
Table 74. Boot Lock Bit0 Protection Modes(Application Section)
(1)
BLB0 Mode BLB02 BLB01 Protection
111
No restrictionsforSPM orLPM accessing theApplication
section.
210SPM is not allowed to write to theApplication section.
3 00
SPM is not allowed to writetotheApplication section, and
LPM executing from the Boot Loadersection is not
allowed to readfrom theApplication section. If Interrupt
Vectors are placed in the Boot Loadersection, interrupts
are disabledwhileexecuting from theApplication section.
401
LPM executing from the Boot Loadersection is not
allowed to readfrom theApplication section. If Interrupt
Vectors are placed in the Boot Loadersection, interrupts
are disabledwhileexecuting from theApplication section.
Table 75. Boot Lock Bit1 Protection Modes(Boot LoaderSection)
(1)
BLB1 Mode BLB12 BLB11 Protection
111
No restrictionsforSPM orLPM accessing the Boot Loader
section.
210SPM is not allowed to write to the Boot Loadersection.
3 00
SPM is not allowed to write to the Boot Loadersection,
andLPM executing from theApplication section is not
allowed to readfrom the Boot Loadersection. If Interrupt
Vectors are placed in theApplication section, interrupts
are disabledwhileexecuting from the Boot Loadersection.
401
LPM executing from theApplication section is not allowed
to readfrom the Boot Loadersection. If InterruptVectors
are placed in theApplication section, interrupts are
disabledwhileexecuting from the Boot Loadersection.
Table 76. Boot Reset Fuse
(1)
BOOTRST Reset Address
1Reset Vector=Application Reset (address $0000)
0Reset Vector=Boot Loader Reset (see Table 78onpage 173)
(24 strony)
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