Datasheet

149
2586D–AVR–02/06
ATtiny25/45/85
23. Memory Programming
This section describes the different methods for Programming the ATtiny25/45/85 memories.
23.1 Program And Data Memory Lock Bits
The ATtiny25/45/85 provides two Lock bits which can be left unprogrammed (“1”) or can be pro-
grammed (“0”) to obtain the additional security listed in Table 23-2. The Lock bits can only be
erased to “1” with the Chip Erase command.
Program memory can be read out via the debugWIRE interface when the DWEN fuse is pro-
grammed, even if the Lock Bits are set. Thus, when Lock Bit security is required, should always
debugWIRE be disabled by clearing the DWEN fuse.
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
Table 23-1. Lock Bit Byte
(1)
Lock Bit Byte Bit No Description Default Value
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 23-2. Lock Bit Protection Modes
(1)(2)
Memory Lock Bits Protection Type
LB Mode LB2 LB1
1 1 1 No memory lock features enabled.
210
Further programming of the Flash and EEPROM is disabled in
High-voltage and Serial Programming mode. The Fuse bits are
locked in both Serial and High-voltage Programming mode.
(1)
debugWire is disabled.
300
Further programming and verification of the Flash and EEPROM
is disabled in High-voltage and Serial Programming mode. The
Fuse bits are locked in both Serial and High-voltage
Programming mode.
(1)
debugWire is disabled.