Datasheet

149
8024A–AVR–04/08
ATmega8HVA/16HVA
27. Memory Programming
27.1 Program And Data Memory Lock Bits
The ATmega8HVA/16HVA provides two Lock bits which can be left unprogrammed (“1”) or can
be programmed (“0”) to obtain the additional features listed in Table 27-2. The Lock bits can only
be erased to “1” with the Chip Erase command.
Note: 1. “1” means unprogrammed, “0” means programmed
Notes: 1. Program the Fuse bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed.
27.2 Fuse Bits
The ATmega8HVA/16HVA has two Fuse bytes. Table 27-4 and Table 27-3 describe briefly the
functionality of all the fuses and how they are mapped into the Fuse byte. Note that the fuses are
read as logical zero, “0”, if they are programmed.
Table 27-1. Lock Bit Byte
Lock Bit Byte Bit No Description Default Value
(1)
7 – 1 (unprogrammed)
6 – 1 (unprogrammed)
5 – 1 (unprogrammed)
4 – 1 (unprogrammed)
3 – 1 (unprogrammed)
2 – 1 (unprogrammed)
LB2 1 Lock bit 1 (unprogrammed)
LB1 0 Lock bit 1 (unprogrammed)
Table 27-2. Lock Bit Protection Modes
(1)(2)
Memory Lock Bits Protection Type
LB Mode LB2 LB1
1 1 1 No memory lock features enabled.
210
The Fuse bits are locked, and further programming of the
Flash and EEPROM is disabled in Programming mode.
(1)
300
The Fuse bits are locked, and further programming and
verification of the Flash and EEPROM is disabled in
Programming mode.
(1)