30.8.14 Boot Loader Parameters

In the following tables, the parameters used in the description of the self programming are given.

Table 30-6. Boot Size Configuration
BOOTSZ1BOOTSZ0Boot SizePagesApplication Flash SectionBoot Loader Flash SectionEnd Application Section Boot Reset Address (Start Boot Loader Section)
11256 words40x0000 - 0x3EFF0x3F00 - 0x3FFF0x3EFF0x3F00
10512 words80x0000 - 0x3DFF0x3E00 - 0x3FFF0x3DFF0x3E00
011024 words160x0000 - 0x3BFF0x3C00 - 0x3FFF0x3BFF0x3C00
002048 words320x0000 - 0x37FF0x3800 - 0x3FFF0x37FF0x3800
Note: The different BOOTSZ Fuse configurations are shown in Figure 30-2
Table 30-7. Read-While-Write Limit
SectionPagesAddress
Read-While-Write section (RWW)2240x0000 - 0x37FF
No Read-While-Write section (NRWW)320x3800 - 0x3FFF
Note: For details about these two section, see NRWW – No Read-While-Write Section and RWW – Read-While-Write Section.
Table 30-8. Explanation of Different Variables used in Figure and the Mapping to the Z-pointer
Variable Corresponding Variable (1)Description
PCMSB13 Most significant bit in the Program Counter. (The Program Counter is 14 bits PC[13:0])
PAGEMSB5 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 Z14Bit in Z-register that is mapped to PCMSB. Because Z0 is not used, the ZPCMSB equals PCMSB + 1.
ZPAGEMSB Z6Bit in Z-register that is mapped to PAGEMSB. Because Z0 is not used, the ZPAGEMSB equals PAGEMSB + 1.
PCPAGEPC[13:6]Z[14:7]Program counter page address: Page select, for page erase and page write
PCWORDPC[5:0]Z[6:1]Program counter word address: Word select, for filling temporary buffer (must be zero during page write operation)
Note:
  1. Z[15]: always ignored. Z0: should be zero for all SPM commands, byte select for the LPM instruction.

    See Addressing the Flash During Self-Programming for details about the use of Z-pointer during Self- Programming.