Rainbow Electronics ATmega64M1 - Manual (Page 285)

285
8209A–AVR–08/09
ATmega16M1/32M1/64M1
27.7.15 ATmega32M1 - 32K - Flash Boot Loader Parameters
In Table 27-10 through Table 27-12 , the parameters used in the description of the self programming are given.
Notes: 1. The different BOOTSZ Fuse configurations are shown in Figure 27-2 .
2. 1 word equals 2 bytes.
For details about these two section, see “NRWW – No Read-While-Write Section” on page 273 and “RWW – Read-While-
Write Section” on page 273
Note: 1. Z15:Z13: always ignored
Z0: should be zero for all SPM commands, byte select for the LPM instruction.
See
“Addressing the Flash During Self-Programming” on page 277 for details about the use of Z-pointer during Self-
Programming.
Table 27-10. Boot Size Configuration, ATmega32M1 (32K product)
BOOTSZ1 BOOTSZ0 Boot Size (2) 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 27-11. Read-While-Write Limit
Section Pages Address
Read-While-Write section (RWW) 224 0x0000 - 0x37FF
No Read-While-Write section (NRWW) 32 0x3800 - 0x3FFF
Table 27-12. Explanation of Different Variables used in Figure 27-3 and the Mapping to the Z-pointer
Variable
Corresponding
Z-value (1) Description
PCMSB 13 Most significant bit in the Program Counter. (The Program Counter is 14 bits PC[13:0])
PAGEMSB 5
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 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 PAGEMSB. 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)