attiny24v ATMEL Corporation, attiny24v Datasheet - Page 159

• Manufacturer Part Number: attiny24v
• Description: 8-bit Avr Microcontroller With 2/4/8k Bytes Insystem Programmable Flash
• Manufacturer: ATMEL Corporation

19. Memory Programming
19.1
8006H–AVR–10/09
Program And Data Memory Lock Bits
This section describes the different methods for programming 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
erased to “1” with the Chip Erase command.
The device 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.
Program memory can be read out via the debugWIRE interface when the DWEN fuse is pro-
grammed, even if lock bits are set. Thus, when lock bit security is required, debugWIRE should
always 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
Memory Lock Bits
1
2
3
“1” means unprogrammed, “0” means programmed.
1. Program fuse bits before programming LB1 and LB2.
2. “1” means unprogrammed, “0” means programmed
Lock Bit
Lock Bit Byte
Lock Bit Protection Modes.
LB2
1
1
0
(1) (2)
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.
Description
–
–
–
–
–
–
Lock bit
Lock bit
(1)
Table
debugWire is disabled.
“Reading Lock, Fuse and Signature
19-2. The lock bits can only be
Default Value
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
1 (unprogrammed)
ATtiny24/44/84
(1)
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