Rainbow Electronics ATtiny861_V - Manual (Page 168)

168
2588B–AVR–11/06
ATtiny261/461/861
22. Memory Programming
This section describes the different methods for Programming the ATtiny261/461/861 memories.
22.1 Program And Data Memory Lock Bits
The ATtiny261/461/861 provides two Lock bits which can be left unprogrammed (“1”) or can be
programmed (“0”) to obtain the additional security listed in
Table 22-2 . The Lock bits can only be
erased to “1” with the Chip Erase command. The ATtiny261/461/861 has no separate Boot
Loader section. The SPM instruction is enabled for the whole Flash, if the SELFPROGEN fuse is
programmed (“0”), otherwise it is disabled.
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 22-1. 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 22-2. Lock Bit Protection Modes (1)(2)
Memory Lock Bits Protection Type
LB Mode LB2 LB1
1 1 1 No memory lock features enabled.
2 1 0
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)
3 0 0
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)