Datasheet

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321
ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]
2549Q–AVR–02/2014
29.6.15 ATmega1280/1281 Boot Loader Parameters
In Table 29-10 and Table 29-11, 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 29-10. Boot Size Configuration, ATmega1280/1281
(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 0x0000 - 0xFDFF 0xFE00 - 0xFFFF 0xFDFF 0xFE00
1 0 1024 words 8 0x0000 - 0xFBFF 0xFC00 - 0xFFFF 0xFBFF 0xFC00
0 1 2048 words 16 0x0000 - 0xF7FF 0xF800 - 0xFFFF 0xF7FF 0xF800
0 0 4096 words 32 0x0000 - 0xEFFF 0xF000 - 0xFFFF 0xEFFF 0xF000
Table 29-11. Read-While-Write Limit, ATmega1280/1281
Section
(1)
Pages Address
Read-While-Write section (RWW) 480 0x0000 - 0xEFFF
No Read-While-Write section (NRWW) 32 0xF000 - 0xFFFF
Table 29-12. Explanation of different variables used in Figure 29-3 on page 314 and the mapping to the Z-pointer,
ATmega1280/1281
Variable
Corresponding
Z-value
(2)
Description
(1)
PCMSB 15
Most significant bit in the Program Counter. (The Program Counter is 16
bits PC[15:0])
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 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)