
143
8048C–AVR–02/12
ATtiny43U
Notes:
2. The default value of SUT[1:0] results in maximum start-up time for the default clock source.
3. The default setting of CKSEL[3:0] results in internal RC Oscillator @ 8.0 MHz. See
Table 6-4Note that fuse bits are locked if Lock Bit 1 (LB1) is programmed. Fuse bits should be pro-
grammed before lock bits. The status of fuse bits is not affected by chip erase.
19.2.1
Latching of Fuses
Fuse values are latched when the device enters programming mode and changes to fuse values
have no effect until the part leaves programming mode. This does not apply to the EESAVE
Fuse which will take effect once it is programmed. Fuses are also latched on power-up.
19.3
Device Signature Imprint Table
The device signature imprint table is a dedicated memory area used for storing miscellaneous
device information, such as the device signature and oscillator calibaration data. Most of this
memory segment is reserved for internal use, as outlined in
Table 19-6.Notes:
Table 19-5.
Fuse Low Byte
Fuse Low Byte
Bit No
Description
Default Value
7
Divide clock by 8
0 (programmed)
CKOUT
6
Clock Output Enable
1 (unprogrammed)
SUT1
5
Select start-up time
SUT0
4
Select start-up time
CKSEL3
3
Select Clock source
CKSEL2
2
Select Clock source
CKSEL1
1
Select Clock source
CKSEL0
0
Select Clock source
Table 19-6.
Contents of Device Signature Imprint Table.
Address
High Byte
0x00
0x01
Calibration data for internal oscillator
(2)0x02
0x03
Reserved for internal use
0x04
0x05 ... 0x2A
Reserved for internal use