Datasheet

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322
ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]
2549Q–AVR–02/2014
29.6.16 ATmega2560/2561 Boot Loader Parameters
In Table 29-13 through Table 29-15, 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 312.
Note: 1. For details about these two section, see NRWWNo Read-While-Write Section” on page 311 and “RWW – Read-
While-Write Section” on page 311.
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 314 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.
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)
1 1 512 words 4 0x00000 - 0x1FDFF 0x1FE00 - 0x1FFFF 0x1FDFF 0x1FE00
1 0 1024 words 8 0x00000 - 0x1FBFF 0x1FC00 - 0x1FFFF 0x1FBFF 0x1FC00
0 1 2048 words 16 0x00000 - 0x1F7FF 0x1F800 - 0x1FFFF 0x1F7FF 0x1F800
0 0 4096 words 32 0x00000 - 0x1EFFF 0x1F000 - 0x1FFFF 0x1EFFF 0x1F000
Table 29-14. Read-While-Write Limit, ATmega2560/2561
Section
(1)
Pages Address
Read-While-Write section (RWW) 992 0x00000 - 0x1EFFF
No Read-While-Write section (NRWW) 32 0x1F000 - 0x1FFFF
Table 29-15. Explanation of different variables used in Figure 29-3 on page 314 and the mapping to the Z-pointer,
ATmega2560/2561
Variable
Corresponding
Z-value
(2)
Description
(1)
PCMSB 16
Most significant bit in the Program Counter. (The Program Counter is 17 bits
PC[16:0]).
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 Z17: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[16:7] Z17
(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).