Datasheet

1. Note: The default value of SUT1..0 results in maximum start-up time for the default clock source.
See Table 8-9 on page 31 for details.
2. Note: The default setting of CKSEL3..0 results in internal RC Oscillator @ 8MHz. See Table 8-9
on page 31 for details.
3. Note: The CKOUT Fuse allows the system clock to be output on PORTB0. See “Clock output
buffer” on page 32 for details.
4. Note: See “System clock prescaler” on page 32 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.
28.3.1. 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.
28.4. Signature Bytes
The device have a three-byte signature code. 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 device the
signature bytes are given in the following table.
Table 28-9. Device ID
Part Signature Bytes Address
0x000 0x001 0x002
ATmega16M1 0x1E 0x94 0x84
ATmega32M1 0x1E 0x95 0x84
ATmega64M1 0x1E 0x95 0x84
28.5. Calibration Byte
The device 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.
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
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