301
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
27.2.1
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.
27.3
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 Atmel ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P the signature bytes
27.4
Calibration byte
The ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P has a byte calibration value
for the internal RC Oscillator. This byte resides in the high byte of address 0x000 in the signa-
ture address space. During reset, this byte is automatically written into the OSCCAL Register to
ensure correct frequency of the calibrated RC Oscillator.
27.5
Page Size
Table 27-6.
Device and JTAG ID.
Part
Signature bytes address
JTAG
0x000
0x001
0x002
Part number
Manufacture ID
ATmega164A
0x1E
0x94
0x0F
940A
0x1F
ATmega164PA
0x1E
0x94
0x0A
940A
0x1F
ATmega324A
0x1E
0x95
0x15
9511
0x1F
ATmega324PA
0x1E
0x95
0x11
9511
0x1F
ATmega644A
0x1E
0x96
0x09
960A
0x1F
ATmega644PA
0x1E
0x96
0x0A
960A
0x1F
ATmega1284
0x1E
0x97
0x06
9705
0x1F
ATmega1284P
0x1E
0x97
0x05
9705
0x1F
Table 27-7.
Number of words in a page and number of pages in the flash.
Device
Flash size
Page size
PCWORD
No. of pages
PCPAGE
PCMSB
ATmega164A/ATmega164PA
8K words (16KBytes)
64 words
PC[5:0]
128
PC[12:6]
12
ATmega324A/ATmega324PA
16K words (32KBytes)
64 words
PC[5:0]
256
PC[13:6]
13
ATmega644A/ATmega644PA
32K words (64KBytes)
128 words
PC[6:0]
256
PC[14:6]
14
ATmega1284/ATmega1284P
64K words (128KBytes)
128 words
PC[6:0]
512
PC[15:7]
15