ATMEGA8_08 Datasheet, PDF (221/308 Pages) ATMEL Corporation – 8-bit with 8K Bytes In-System Programmable Flash

ATmega8(L)
Note: The different BOOTSZ Fuse configurations are shown in Figure 102.
Table 83. Read-While-Write Limit
Section
Pages Address
Read-While-Write section (RWW)
96
0x000 - 0xBFF
No Read-While-Write section (NRWW)
32
0xC00 - 0xFFF
For details about these two section, see “NRWW – No Read-While-Write Section” on page 210
and “RWW – Read-While-Write Section” on page 210
Table 84. Explanation of Different Variables used in Figure 103 and the Mapping to the Z-
pointer
Variable
Corresponding
Z-value⁽¹⁾
Description
PCMSB
11
Most significant bit in the Program Counter.
(The Program Counter is 12 bits PC[11:0])
PAGEMSB
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)
Note:
1. Z15:Z13: always ignored
Z0: should be zero for all SPM commands, byte select for the LPM instruction.
See “Addressing the Flash During Self-Programming” on page 214 for details about the use of
Z-pointer during Self-Programming.
2486T–AVR–05/08
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