Datasheet

Table 30-8 Explanation of Different Variables Used in Figure and the Mapping to the Z-pointer, ATmega64A
(3)
Variable Corresponding Z-
value
(1)
Description
(2)
PCMSB 14 Most significant bit in the program counter. (The program
counter is 15 bits PC[14:0])
PAGEMSB 6 Most significant bit which is used to address the words
within one page (128 words in a page requires 7 bits PC
[6:0]).
ZPCMSB Z15
(1)
Bit in Z-register that is mapped to PCMSB. Because Z0
is not used, the ZPCMSB equals PCMSB + 1.
ZPAGEMSB Z7 Bit in Z-register that is mapped to PAGEMSB. Because
Z0 is not used, the ZPAGEMSB equals PAGEMSB + 1.
PCPAGE PC[14:7] Z15
(1)
: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)
Note:
1. Z0: should be zero for all SPM commands, byte select for the LPM instruction.
2. See Addressing the Flash During Self-Programming on page 371 for details about the use of Z-
pointer during self-programming.
30.9. Register Description
Atmel ATmega64A [DATASHEET]
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