ATMEGA48V_11 ATMEL [ATMEL Corporation], ATMEGA48V_11 Datasheet - Page 288

• Manufacturer Part Number: ATMEGA48V_11
• Description: 8-bit Atmel Microcontroller with 4/8/16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

28.2.1
28.3
28.4
2545T–AVR–05/11
Signature bytes
Calibration byte
Latching of fuses
Table 28-7.
Note:
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.
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.
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 Atmel ATmega48/88/168 the signature bytes
are given in
Table 28-8.
The ATmega48/88/168 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.
Low fuse byte
CKDIV8
CKOUT
SUT1
SUT0
CKSEL3
CKSEL2
CKSEL1
CKSEL0
Part
ATmega48
ATmega88
ATmega168
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 @ 8MHz. See
3. The CKOUT fuse allows the system clock to be output on PORTB0. See
4. See
(3)
(4)
See
page 34
on page 35
Table
Fuse low byte.
Device ID.
Table 9-9 on page 34
“System clock prescaler” on page 36
28-8.
for details.
for details.
Bit no.
7
6
5
4
3
2
1
0
0x000
0x1E
0x1E
0x1E
for details.
Description
Divide clock by 8
Clock output
Select start-up time
Select start-up time
Select clock source
Select clock source
Select clock source
Select clock source
Signature bytes address
for details.
0x001
0x92
0x93
0x94
ATmega48/88/168
Default value
0 (programmed)
1 (unprogrammed)
1 (unprogrammed)
0 (programmed)
0 (programmed)
0 (programmed)
1 (unprogrammed)
0 (programmed)
“Clock output buffer”
0x002
0x0A
0x05
0x06
(1)
(2)
(2)
(2)
Table 9-8 on
(1)
(2)
288