Rainbow Electronics ATmega8515L - Manual (Page 176)

176
ATmega8515(L)
2512A–AVR–04/02
Notes: 1. Program the Fuse bits before programming the Lock bits.
2. “1” means unprogrammed, “0” means programmed
Fuse Bits The ATmega8515 has two Fuse bytes. Table 83 and Table 84 describe briefly the func-
tionality of all the fuses and how they are mapped into the fuse bytes. Note that the
Fuses are read as logical zero, “0”, if they are programmed.
Notes: 1. See “AT90S4414/8515 Compatibility Mode” on page 4 for details.
2. The SPIEN Fuse is not accessible in serial programming mode.
3. The CKOPT Fuse functionality depends on the setting of the CKSEL bits. See “Clock
Sources” on page 32. for details.
4. The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 78 on
page 173.
BLB1 Mode BLB12 BLB11
1 1 1
No restrictions for SPM or LPM accessing the Boot Loader
section.
2 1 0 SPM is not allowed to write to the Boot Loader section.
3 0 0
SPM is not allowed to write to the Boot Loader section,
and LPM executing from the Application section is not
allowed to read from the Boot Loader section. If Interrupt
Vectors are placed in the Application section, interrupts
are disabled while executing from the Boot Loader section.
4 0 1
LPM executing from the Application section is not allowed
to read from the Boot Loader section. If Interrupt Vectors
are placed in the Application section, interrupts are
disabled while executing from the Boot Loader section.
Table 82. Lock Bit Protection Modes (2) (Continued)
Memory Lock Bits Protection Type
Table 83. Fuse High Byte
Fuse High Byte Bit no Description Default Value
S8515C 7
AT90S4414/8515 compatibility
mode
1 (unprogrammed)
WDTON 6 Watchdog Timer always on 1 (unprogrammed)
SPIEN (1)(2) 5
Enable Serial Program and Data
Downloading 0 (programmed, SPI prog.
enabled)
CKOPT (3) 4 Oscillator options 1 (unprogrammed)
EESAVE 3
EEPROM memory is preserved
through the Chip Erase 1 (unprogrammed,
EEPROM not preserved)
BOOTSZ1 2
Select Boot Size (see Table 78 for
details)
0 (programmed) (4)
BOOTSZ0 1
Select Boot Size (see Table 78 for
details)
0 (programmed) (4)
BOOTRST 0 Select Reset Vector 1 (unprogrammed)