
190
8008H–AVR–04/11
ATtiny48/88
Note:
1. The default value of SUT[1:0] results in maximum start-up time for the default clock source.
2. The default setting of CKSEL[1:0] results in internal oscillator @ 8 MHz. See
Table 6-1 onThe status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are locked if
Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.
20.2.1
Latching of Fuses
The fuse values are latched when the device enters programming mode and changes of the
fuse values will 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. The fuses are also latched on
Power-up in Normal mode.
20.3
Signature Bytes
All Atmel microcontrollers have a three-byte signature code which identifies the device. This
code can be read in both serial and parallel mode, also when the device is locked. The three
bytes reside in a separate address space. For the ATtiny48/88 the signature bytes are given in
20.4
Calibration Byte
The ATtiny48/88 has a byte calibration value for the internal oscillator. This byte resides in the
high byte of address 0x000 in the signature address space. During reset, this byte is automati-
cally written into the OSCCAL Register to ensure correct frequency of the calibrated oscillator.
Table 20-5.
Fuse Low Byte
Fuse Low Byte
Bit No
Description
Default Value
7
Divide clock by 8
0 (programmed)
6
Clock output
1 (unprogrammed)
SUT1
5
Select start-up time
SUT0
4
Select start-up time
-
3
-
-
2
-
CKSEL1
1
Select Clock source
CKSEL0
0
Select Clock source
Table 20-6.
Device ID
Part
Signature Bytes Address
0x000
0x001
0x002
ATtiny48
0x1E
0x92
0x09
ATtiny88
0x1E
0x93
0x11