Rainbow Electronics ATtiny2313 - Manual (Page 162)

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ATtiny2313
2543A–AVR–08/03
Note: 1. The default value of SUT1..0 results in maximum start-up time for the default clock
source. See Table 15 on page 35 for details.
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 The ATtiny2313 has a byte calibration value for the internal RC Oscillator. This byte
resides in the high byte of address 0x000 in the signature address space. During reset,
this byte is automatically written into the OSCCAL Register to ensure correct frequency
of the calibrated RC Oscillator.
Table 69. 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 1 (unprogrammed) (1)
SUT0 4 Select start-up time 0 (programmed) (1)
CKSEL3 3 Select Clock source 0 (programmed) (2)
CKSEL2 2 Select Clock source 0 (programmed) (2)
CKSEL1 1 Select Clock source 1 (unprogrammed) (2)
CKSEL0 0 Select Clock source 0 (programmed) (2)