
204
ATmega8A [DATASHEET]
8159E–AVR–02/2013
; SPM timed sequence
out
SPMCR, spmcrval
spm
; restore SREG (to enable interrupts if originally enabled)
out
SREG, temp2
ret
24.8.13
Boot Loader Parameters
In
Table 24-6 through
Table 24-8, the parameters used in the description of the self programming are given.
Note:
The different BOOTSZ Fuse configurations are shown in
Figure 24-2.Table 24-6.
Boot Size Configuration
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 24-7.
Read-While-Write Limit
Section
Pages
Address
Read-While-Write section (RWW)
96
0x000 - 0xBFF
No Read-While-Write section (NRWW)
32
0xC00 - 0xFFF
Table 24-8.
Explanation of Different Variables used in
Figure 24-3 and the Mapping to the Z-pointer
Variable
Corresponding
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)