Rainbow Electronics ATmega64L - Manual (Page 252)

252
ATmega16(L)
2466B–09/01
Note: 1. The different BOOTSZ fuse configurations are shown in Figure 126
Note: 1. For details about these two section, see “NRWW - No Read-While-Write section” on
page 241 and “RWW - Read-While-Write section” on page 241
Note: 1. Z15:Z14: 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 246 for details about
the use of Z-pointer during self-programming.
Table 100. Boot Size Configuration (1)
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
$0000 -
$1F7F $1F80 -
$1FFF
$1F7F $1F80
1 0
256
words
4
$0000 -
$1EFF $1F00 -
$1FFF
$1EFF $1F00
0 1
512
words
8
$0000 -
$1DFF $1E00 -
$1FFF
$1DFF $1E00
0 0
1024
words
16
$0000 -
$1BFF $1C00 -
$1FFF
$1BFF $1C00
Table 101. Read-While-Write Limit (1)
Section Pages Address
Read-While-Write section (RWW) 112 $0000 - $1BFF
No Read-While-Write section (NRWW) 16 $1C00 - $1FFF
Table 102. Explanation of Different Variables used in Figure 127 and the Mapping to
the Z-Pointer
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.
ZPAGEMSB
Z6 Bit in Z-register that is mapped to PCMSB.
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)