ATA5771 ATMEL Corporation, ATA5771 Datasheet - Page 211

• Manufacturer Part Number: ATA5771
• Manufacturer: ATMEL Corporation

19. Memory Programming
19.1
8006G–AVR–01/08
Program And Data Memory Lock Bits
This section describes the different methods for Programming the ATtiny24/44/84 memories.
The ATtiny24/44/84 provides two Lock bits which can be left unprogrammed (“1”) or can be pro-
grammed (“0”) to obtain the additional security listed in
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.
Table 19-1.
Note:
Table 19-2.
Notes:
Lock bits can also be read by device firmware. See section
Data from Software” on page
LB2
LB1
LB Mode
1
2
3
1. “1” means unprogrammed, “0” means programmed
1. Program the Fuse bits before programming the LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed
Lock Bit
Memory Lock Bits
Lock Bit Byte
Lock Bit Protection Modes
LB2
1
1
0
(1)
LB1
155.
1
0
0
Bit No
7
6
5
4
3
2
1
0
Protection Type
No memory lock features enabled.
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.
debugWire is disabled.
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)(2)
Description
–
–
–
–
–
–
Lock bit
Lock bit
(1)
Table 19-2 on page
debugWire is disabled.
“Reading Lock, Fuse and Signature
Default Value
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
ATtiny24/44/84
159. The Lock bits
(1)
159