Datasheet

261
2466T–AVR–07/10
ATmega16(L)
Notes: 1. The default value of SUT1..0 results in maximum start-up time. SeeTable 10 on page 29 for
details.
2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 1 MHz. See Table 2 on
page 25 for details.
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 ATmega16 the signature bytes are:
1. $000: $1E (indicates manufactured by Atmel)
2. $001: $94 (indicates 16 Kbytes Flash memory)
3. $002: $03 (indicates ATmega16 device when $001 is $94)
Calibration Byte The ATmega16 stores four different calibration values for the internal RC Oscillator. These bytes
resides in the signature row High Byte of the addresses 0x0000, 0x0001, 0x0002, and 0x0003
for 1 MHz, 2 MHz, 4 MHz, and 8 Mhz respectively. During Reset, the 1 MHz value is automati-
cally loaded into the OSCCAL Register. If other frequencies are used, the calibration value has
to be loaded manually, see “Oscillator Calibration Register – OSCCAL” on page 30 for details.
Table 106. Fuse Low Byte
Fuse Low
Byte
Bit
No. Description Default Value
BODLEVEL 7 Brown-out Detector trigger level 1 (unprogrammed)
BODEN 6 Brown-out Detector enable 1 (unprogrammed, BOD disabled)
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 0 (programmed)
(2)
CKSEL0 0 Select Clock source 1 (unprogrammed)
(2)