![](http://datasheet.mmic.net.cn/30000/MR80C32-20-D_datasheet_2377239/MR80C32-20-D_266.png)
266
8154B–AVR–07/09
ATmega16A
4. Never ship a product with the OCDEN Fuse programmed regardless of the setting of Lock bits
and the JTAGEN Fuse. A programmed OCDEN Fuse enables some parts of the clock system
to be running in all sleep modes. This may increase the power consumption.
5. If the JTAG interface is left unconnected, the JTAGEN fuse should if possible be disabled. This
to avoid static current at the TDO pin in the JTAG interface.
Notes:
details.
2. The default setting of CKSEL3:0 results in internal RC Oscillator @ 1MHz. See
Table 8-1 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.
26.2.1
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.
26.3
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 ATmega16A the signature bytes are:
1.
$000: $1E (indicates manufactured by Atmel)
2.
$001: $94 (indicates 16KB Flash memory)
3.
$002: $03 (indicates ATmega16A device when $001 is $94)
26.4
Calibration Byte
The ATmega16A 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, 2, 4, and 8 Mhz respectively. During Reset, the 1 MHz value is automatically
loaded into the OSCCAL Register. If other frequencies are used, the calibration value has to be
Table 26-4.
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
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