ATA8741_14 Datasheet, PDF (161/215 Pages) ATMEL Corporation – Microcontroller with UHF ASK/FSK Transmitter

28. Memory Programming
This section describes the different methods for programming the Atmel^® ATtiny24/44/84 memories.
28.1
Program And Data Memory Lock Bits
The Atmel ATtiny24/44/84 provides two lock bits which can be left unprogrammed (“1”) or can be programmed (“0”) to obtain
the additional security listed in Table 28-2 on page 161. 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 programmed, even if the lock bits
are set. Thus, when lock bit security is required, should always debugWIRE be disabled by clearing the DWEN fuse.
Table 28-1. Lock Bit Byte⁽¹⁾
Lock Bit Byte
Bit No
Description
7
–
6
–
5
–
4
–
3
–
2
–
LB2
1
Lock bit
LB1
0
Lock bit
Notes: 1. “1” means unprogrammed, “0” means programmed.
Default Value
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
Table 28-2. Lock Bit Protection Modes⁽¹⁾⁽²⁾
Memory Lock Bits
Protection Type
LB Mode
LB2
LB1
1
1
1
No memory lock features enabled.
Further programming of the flash and EEPROM is disabled in high-voltage
2
1
0
and serial programming mode. The fuse bits are locked in both serial and
high-voltage programming mode⁽¹⁾. debugWire is disabled.
Further programming and verification of the flash and EEPROM is disabled in
3
0
0
high-voltage and serial programming mode. The fuse bits are locked in both
serial and high-voltage programming mode⁽¹⁾. debugWire is disabled.
Notes: 1. Program the Fuse bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed
ATA8741 [DATASHEET] 161
9140E–INDCO–09/14