295
7647H–AVR–03/12
Atmel ATmega16/32/64/M1/C1
For details about these two section, see “NRWW – No Read-While-Write Section” on page 280
and “RWW – Read-While-Write Section” on page 280.
Note: 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 285 for details about the use of
Z-pointer during Self-Programming.
Table 24-15. Explanation of Different Variables used in Figure 24-3 and the Mapping to the
Z-pointer
Variable
Corresponding
Z-value
(Note:)
Description
PCMSB 14
Most significant bit in the Program Counter. (The
Program Counter is 15 bits PC[14:0])
PAGE MSB 7
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 Z15
Bit in Z-register that is mapped to PCMSB. Because
Z0 is not used, the ZPCMSB equals PCMSB + 1.
ZPAGEMSB Z8
Bit in Z-register that is mapped to PAGEMSB.
Because Z0 is not used, the ZPAGEMSB equals
PAGEMSB + 1.
PCPAGE PC[14:7] Z15: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)
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