Datasheet

Z0: should be zero for all SPM commands, byte select for the LPM instruction.
Please refer to 31.7 Addressing the Flash During Self-Programming for details about the use of Z-pointer
during Self-Programming.
31.8.15 ATmega168PA Boot Loader Parameters
The following tables are the parameters used in the description of the self programming are given.
Table 31-9. Boot Size Configuration, ATmega168PA
BOOTSZ1 BOOTSZ0 Boot
Size
Pages Application
Flash Section
Boot
Loader
Flash
Section
End
Application
Section
Boot Reset
Address
(Start Boot
Loader
Section)
1 1 128
words
2 0x0000 -
0x1F7F
0x1F80 -
0x1FFF
0x1F7F 0x1F80
1 0 256
words
4 0x0000 -
0x1EFF
0x1F00 -
0x1FFF
0x1EFF 0x1F00
0 1 512
words
8 0x0000 -
0x1DFF
0x1E00 -
0x1FFF
0x1DFF 0x1E00
0 0 1024
words
16 0x0000 -
0x1BFF
0x1C00 -
0x1FFF
0x1BFF 0x1C00
Note: The different BOOTSZ Fuse configurations are shown in Figure 31-2.
Table 31-10. Read-While-Write Limit, ATmega168PA
Section Pages Address
Read-While-Write section (RWW) 112 0x0000 - 0x1BFF
No Read-While-Write section (NRWW) 16 0x1C00 - 0x1FFF
For details about these two section, please refer to 31.4.2 No Read-While-Write (NRWW) Section and
31.4.1 Read-While-Write (RWW) Section.
Table 31-11. Explanation of Different Variables used in Figure 31-3, ATmega168PA
Variable Corresponding
Z-value
(1)
Description
PCMSB 12 Most significant bit in the Program Counter. (The Program
Counter is 13 bits PC[12:0])
PAGEMSB 5 Most significant bit which is used to address the words within
one page (64 words in a page requires 6 bits PC [5:0])
ZPCMSB Z13 Bit in Z-register that is mapped to PCMSB. Because Z0 is not
used, the ZPCMSB equals PCMSB + 1.
ATmega48PA/88PA/168PA
Boot Loader Support – Read-While-Write Self-...
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DS40002011A-page 360