Table 82. Lock Bit Protection Modes(2) (Continued)
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Memory Lock bits |
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Protection Type |
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1 |
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1 |
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1 |
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No restrictions for SPM or LPM accessing the Boot Loader |
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section. |
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2 |
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1 |
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0 |
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SPM is not allowed to write to the Boot Loader section. |
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SPM is not allowed to write to the Boot Loader section, |
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and LPM executing from the Application section is not |
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3 |
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0 |
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0 |
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allowed to read from the Boot Loader section. If Interrupt |
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Vectors are placed in the Application section, interrupts |
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are disabled while executing from the Boot Loader |
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section. |
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LPM executing from the Application section is not allowed |
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4 |
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0 |
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1 |
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to read from the Boot Loader section. If Interrupt Vectors |
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are placed in the Application section, interrupts are |
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disabled while executing from the Boot Loader section. |
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Notes: 1. Program the Fuse bits before programming the Lock bits. |
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2. “1” means unprogrammed, “0” means programmed |
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Fuse bits |
The ATmega8515 has two Fuse bytes. Table 83 and Table 84 describe briefly the func- |
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tionality of all the fuses and how they are mapped into the fuse bytes. Note that the |
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Fuses are read as logical zero, “0”, if they are programmed. |
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Table 83. Fuse High Byte |
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Fuse High Byte |
Bit no |
Description |
Default Value |
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S8515C |
7 |
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AT90S4414/8515 compatibility |
1 (unprogrammed) |
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mode |
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WDTON |
6 |
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Watchdog Timer always on |
1 (unprogrammed) |
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SPIEN(1)(2) |
5 |
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Enable Serial Program and Data |
0 (programmed, SPI prog. |
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Downloading |
enabled) |
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CKOPT(3) |
4 |
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Oscillator options |
1 (unprogrammed) |
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EESAVE |
3 |
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EEPROM memory is preserved |
1 (unprogrammed, |
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through the Chip Erase |
EEPROM not preserved) |
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BOOTSZ1 |
2 |
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Select Boot Size (see Table 78 for |
0 (programmed)(4) |
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details) |
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BOOTSZ0 |
1 |
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Select Boot Size (see Table 78 for |
0 (programmed)(4) |
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details) |
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BOOTRST |
0 |
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Select Reset Vector |
1 (unprogrammed) |
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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 34. for details.
4.The default value of BOOTSZ1..0 results in maximum Boot Size. See Table 78 on page 175.
178 ATmega8515(L)
2512G–AVR–03/05