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ATtiny40 [DATASHEET]
8263B–AVR–01/2013
19.3.3
Configuration Section
ATtiny40 has one configuration byte, which resides in the configuration section. See
Table 19-4.Table 19-5 briefly describes the functionality of all configuration bits and how they are mapped into the configura-
tion byte.
Notes:
Configuration bits are not affected by a chip erase but they can be cleared using the configuration section erase
Volatile Lock Bit 1 (NVLB1) is programmed.
19.3.3.1
Latching of Configuration Bits
All configuration bits are latched either when the device is reset or when the device exits the external programming
mode. Changes to configuration bit values have no effect until the device leaves the external programming mode.
19.3.4
Signature Section
The signature section is a dedicated memory area used for storing miscellaneous device information, such as the
device signature. Most of this memory section is reserved for internal use, as shown in
Table 19-6.
Table 19-4.
Configuration bytes
Configuration word address
Configuration word data
High byte
Low byte
0x00
Reserved
Configuration Byte 0
0x01 ... 0x1F
Reserved
Table 19-5.
Configuration Byte 0
Bit
Bit Name
Description
Default Value
7
–
Reserved
1 (unprogrammed)
6
Brown-out Detector trigger level
1 (unprogrammed)
5
Brown-out Detector trigger level
1 (unprogrammed)
4
Brown-out Detector trigger level
1 (unprogrammed)
3
–
Reserved
1 (unprogrammed)
2
CKOUT
System Clock Output
1 (unprogrammed)
1
WDTON
Watchdog Timer always on
1 (unprogrammed)
0
RSTDISBL
External Reset disable
1 (unprogrammed)
Table 19-6.
Signature bytes
Signature word address
Signature word data
High byte
Low byte
0x00
Device ID 1
Manufacturer ID
0x01
Reserved for internal use
Device ID 2
0x02 ... 0x3F
Reserved for internal use