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ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller TQFP 100 (14x14) 8-Bit 20 MHz I/O number 69
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268
8023F–AVR–07/09
ATmega325P/3250P
24.8.13 ATmega325P/3250P Boot Loader Parameters
In Table 24-6 through Table 24-8, the parameters used in the description of the Self-Programming are given.
Note: 1. The different BOOTSZ Fuse configurations are shown in Figure 24-2
Note: 1. For details about these two section, see ”NRWW – No Read-While-Write Section” on page 257 and ”RWW – Read-While-
Write Section” on page 257.
Note: 1. Z0: should be zero for all SPM commands, byte select for the LPM instruction. See ”Addressing the Flash During Self-Pro-
gramming” on page 261 for details about the use of Z-pointer during Self-Programming.
Table 24-6. Boot Size Configuration
(1)
BOOTSZ1 BOOTSZ0 Boot Size Pages
Application
Flash Section
Boot Loader
Flash Section
End
Application
Section
Boot Reset
Address
(Start
Boot Loader
Section)
1 1 256 words 4 0x0000-0x3EFF 0x3F00-0x3FFF 0x3EFF 0x3F00
1 0 512 words 8 0x0000-0x3DFF 0x3E00-0x3FFF 0x3DFF 0x3E00
0 1 1024/ words 16 0x0000-0x3BFF 0x3C00-0x3FFF 0x3BFF 0x3C00
0 0 2048 words 32 0x0000-0x37FF 0x3800-0x3FFF 0x37FF 0x3800
Table 24-7. Read-While-Write Limit
(1)
Section Pages Address
Read-While-Write section (RWW) 224 0x0000 - 0x37FF
No Read-While-Write section (NRWW) 32 0x3800 - 0x3FFF
Table 24-8. Explanation of different variables used in Figure 24-3 and the mapping to the Z-pointer
(1)
Variable
Corresponding
Z-value Description
PCMSB 13
Most significant bit in the Program Counter. (Program Counter is 14 bits
PC[13:0])
PAG EM SB 5
Most significant bit which is used to address the words within one page
(64 words in a page requires six/seven bits PC [5:0]).
ZPCMSB Z14
Bit in Z-register that is mapped to PCMSB. Because Z0 is not used, the
ZPCMSB equals PCMSB + 1.
ZPAGEMSB Z6
Bit in Z-register that is mapped to PCMSB. Because Z0 is not used, the
ZPAGEMSB equals PAGEMSB + 1.
PCPAGE PC[13:6] Z14:Z7
Program Counter page address: Page select, for Page Erase and Page
Write
PCWORD PC[5:0] Z6:Z1
Program Counter word address: Word select, for filling temporary buffer
(must be zero during Page Write operation)