
160
2543L–AVR–08/10
ATtiny2313
Note:
1. The default value of SUT1..0 results in maximum start-up time for the default clock source.
2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 8 MHz.
The 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.
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.
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 ATtiny2313 the signature bytes are:
1. 0x000: 0x1E (indicates manufactured by Atmel).
2. 0x001: 0x91 (indicates 2KB Flash memory).
3. 0x002: 0x0A (indicates ATtiny2313 device when 0x001 is 0x91).
Calibration Byte
Signature area of ATtiny2313 has one byte of calibration data for the internal RC Oscillator. This
byte resides in the high byte of address 0x0000. During reset, this byte is automatically written
into the OSCCAL Register to ensure correct frequency of the calibrated RC Oscillator. See
Page Size
Table 68. Fuse Low Byte
Fuse Low Byte
Bit No
Description
Default Value
CKDIV8
7
Divide clock by 8
0 (programmed)
CKOUT
6
Output Clock on CKOUT pin
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 69. No. of Words in a Page and No. of Pages in the Flash
Flash Size
Page Size
PCWORD
No. of Pages
PCPAGE
PCMSB
1K words (2K bytes)
16 words
PC[3:0]
64
PC[9:4]
9
Table 70. No. of Words in a Page and No. of Pages in the EEPROM
EEPROM Size
Page Size
PCWORD
No. of Pages
PCPAGE
EEAMSB
128 bytes
4 bytes
EEA[1:0]
32
EEA[6:2]
6