Datasheet

331
2549O–AVR–05/12
ATmega640/1280/1281/2560/2561
Notes: 1. Z0: should be zero for all SPM commands, byte select for the (E)LPM instruction.
2. See “Addressing the Flash During Self-Programming” on page 322 for details about the use of
Z-pointer during Self-Programming.
3. The Z-register is only 16 bits wide. Bit 16 is located in the RAMPZ register in the I/O map.
29.6.16 ATmega2560/2561 Boot Loader Parameters
In Table 29-13 through Table 29-15 on page 332, the parameters used in the description of the
Self-Programming are given.
Note: 1. The different BOOTSZ Fuse configurations are shown in Figure 29-2 on page 320.
PAG EM SB 6
Most significant bit which is used to address the
words within one page (128 words in a page
requires seven bits PC [6:0]).
ZPCMSB Z16
(3)
Bit in Z-pointer that is mapped to PCMSB. Because
Z0 is not used, the ZPCMSB equals PCMSB + 1.
ZPAGEMSB Z7
Bit in Z-pointer that is mapped to PCMSB. Because
Z0 is not used, the ZPAGEMSB equals PAGEMSB +
1.
PCPAGE PC[15:7] Z16
(3)
:Z8
Program Counter page address: Page select, for
Page Erase and Page Write
PCWORD PC[6:0] Z7:Z1
Program Counter word address: Word select, for
filling temporary buffer (must be zero during Page
Write operation)
Table 29-12. Explanation of different variables used in Figure 29-3 on page 322 and the map-
ping to the Z-pointer, ATmega1280/1281 (Continued)
Variable
Corresponding
Z-value
(2)
Description
(1)
Table 29-13. Boot Size Configuration, ATmega2560/2561
(1)
BOOTSZ1 BOOTSZ0 Boot Size Pages Appli-cation Flash Section Boot Loader Flash Section End Application Section Boot Reset Address (Start Boot Loader Section)
11
512
words
4
0x00000 -
0x1FDFF
0x1FE00 -
0x1FFFF
0x1FDFF 0x1FE00
10
1024
words
8
0x00000 -
0x1FBFF
0x1FC00 -
0x1FFFF
0x1FBFF 0x1FC00
01
2048
words
16
0x00000 -
0x1F7FF
0x1F800 -
0x1FFFF
0x1F7FF 0x1F800
00
4096
words
32
0x00000 -
0x1EFFF
0x1F000 -
0x1FFFF
0x1EFFF 0x1F000