Datasheet
241
ATmega48/88/168 Automotive [DATASHEET]
7530K–AVR–07/14
24.7.14 ATmega168 Boot Loader Parameters
In Table 24-9 through Table 24-11, the parameters used in the description of the self programming are given.
For details about these two section, see Section 24.3.2 “NRWW – No Read-While-Write Section” on page 230 and
Section 24.3.1 “RWW – Read-While-Write Section” on page 230.
Table 24-9. Boot Size Configuration, ATmega168
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 24-2 on page 231.
Table 24-10. Read-While-Write Limit, ATmega168
Section Pages Address
Read-while-write section (RWW) 112 0x0000 - 0x1BFF
No read-while-rite section (NRWW) 16 0x1C00 - 0x1FFF
Table 24-11. Explanation of Different Variables used in Figure 24-3 and the Mapping to the Z-pointer, ATmega168
Variable Corresponding Z-value
(1)
Description
PCMSB 12
Most significant bit in the program counter. (The program
counter is 12 bits PC[11:0])
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.
ZPAGEMSB Z6
Bit in Z-register that is mapped to PAGEMSB. Because Z0 is
not used, the ZPAGEMSB equals PAGEMSB + 1.
PCPAGE PC[12:6] Z13:Z7
Program counter page address: page select, for page erase
and page write
PCWORD PC[5:0] Z6:Z1
Program counter word address: Word select, for filling
temporary buffer (must be zero during page write operation)
Note: 1. Z15:Z14: always ignored
Z0: should be zero for all SPM commands, byte select for the LPM instruction. See Section 24.6 “Addressing
the Flash During Self-Programming” on page 234 for details about the use of Z-pointer during
self-Programming.