Datasheet

281
2545T–AVR–05/11
ATmega48/88/168
27.8.13 Atmel ATmega88 boot loader parameters
In Table 27-6 through Table 27-8, the parameters used in the description of the self program-
ming are given.
Note: The different BOOTSZ Fuse configurations are shown in Figure 27-2 on page 272.
For details about these two section, see “NRWW – No read-while-write section” on page 270
and “RWW – Read-while-write section” on page 270
Note: 1. Z15:Z13: Always ignored.
Z0: Should be zero for all SPM commands, byte select for the LPM instruction.
Table 27-6. Boot size configuration, ATmega88.
BOOTSZ1 BOOTSZ0
Boot
size Pages
Application
flash
section
Boot
loader
flash
section
End
application
section
Boot reset
address (start
boot loader
section)
11
128
words
4
0x000 -
0xF7F
0xF80 -
0xFFF
0xF7F 0xF80
10
256
words
8
0x000 -
0xEFF
0xF00 -
0xFFF
0xEFF 0xF00
01
512
words
16
0x000 -
0xDFF
0xE00 -
0xFFF
0xDFF 0xE00
00
1024
words
32
0x000 -
0xBFF
0xC00 -
0xFFF
0xBFF 0xC00
Table 27-7. Read-while-write limit, ATmega88.
Section Pages Address
Read-while-write section (RWW) 96 0x000 - 0xBFF
No read-while-write section (NRWW) 32 0xC00 - 0xFFF
Table 27-8. Explanation of different variables used in Figure 27-3 on page 275 and the map-
ping to the Z-pointer, ATmega88.
Variable
Corresponding
Z-value
(1)
Description
PCMSB 11
Most significant bit in the Program Counter. (The
program counter is 12 bits PC[11:0])
PAG EM SB 4
Most significant bit which is used to address the
words within one page (32 words in a page requires
5 bits PC [4:0]).
ZPCMSB Z12
Bit in Z-register that is mapped to PCMSB. Because
Z0 is not used, the ZPCMSB equals PCMSB + 1.
ZPAGEMSB Z5
Bit in Z-register that is mapped to PAGEMSB.
Because Z0 is not used, the ZPAGEMSB equals
PAGEMSB + 1.
PCPAGE PC[11:5] Z12:Z6
Program counter page address: Page select, for
page erase and page write
PCWORD PC[4:0] Z5:Z1
Program counter word address: Word select, for
filling temporary buffer (must be zero during page
write operation)