Rainbow-electronics ATmega161L Manual do Utilizador descarregar pdf (Página 116)

116

ATmega161(L)

1228C–AVR–08/02

Program Memory

Lock bits

The ATmega161 MCU provides six Lock bits that can be left unprogrammed (“1”)orcan

be programmed (“0”) to obtain the additional features listed in Table 40. The Lock bits

canonlybeerasedto“1” with the Chip Erase command.

Note: 1. Program the Fuse bits before programming the Lock bits.

Fuse bits The ATmega161 has six Fuse bits: BOOTRST, SPIEN, SUT, and CKSEL [2:0].

• When BOOTRST is programmed (“0”), the Reset Vector is set to address $1E00,

which is the first address location in the Boot Loader section of the Flash. If the

BOOTRST is unprogrammed (“1”), the Reset Vector is set to address $0000.

Default value is unprogrammed (“1”).

• When the SPIEN Fuse is programmed (“0”), Serial Program and Data Downloading

is enabled. Default value is programmed (“0”). The SPIEN Fuse is not accessible in

Serial Programming mode.

• The SUT Fuse changes the start-up times. Default value is unprogrammed (“1”).

Table 40. Lock Bit Protection Modes

(1)

Memory Lock bits

Protection TypeLB Mode LB1 LB2

1 1 1 No memory lock features enabled

2 0 1 Further programming of the Flash and EEPROM is

disabled in parallel and Serial Programming modes. The

Fuse bits are locked in both Serial and Parallel

Programming modes.

(1)

3 0 0 Further programming and verification of the Flash and

EEPROM is disabled in parallel and Serial Programming

modes. The Fuse bits are locked in both Serial and

Parallel Programming modes.

(1)

BLB0 Mode BLB02 BLB01

1 1 1 No restrictions for SPM, LPM accessing the Application

Code section

2 1 0 SPM is not allowed to write to the Application Code

section.

3 0 0 SPM is not allowed to write to the Application Code

section and LPM executing from Boot Loader section is

not allowed to read from the Application Code section.

4 0 1 LPM executing from the Boot Loader section is not

allowed to read from the Application Code section.

BLB1 Mode BLB12 BLB11

1 1 1 No restrictions for SPM, LPM accessing the Boot Loader

section

2 1 0 SPM is not allowed to write the Boot Loader section.

3 0 0 SPM is not allowed to write to the Boot Loader section and

LPM executing from the Application Code section is not

allowed to read from the Boot Loader section.

4 0 1 LPM executing from the Application Code section is not

allowed to read from the Boot Loader section.

1 2 ... 111 112 113 114 115 116 117 118 119 120 121 ... 158 159

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