ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 255

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

2570A–AVR–09/04
Table 106. Explanation of different variables used in Figure 110 and the mapping to the
Z-pointer
Z0: should be zero for all SPM commands, byte select for the LPM instruction.
See “Addressing the Flash During Self-Programming” on page 247 for details about the use of Z-
pointer during Self-Programming.
Variable
PCMSB
PAGEMSB
ZPCMSB
ZPAGEMSB
PCPAGE
PCWORD
()
/14:6/7]
PC[13
[5/6:0]
13/14
5/6
PC
Corresponding
Z14/15:Z7/8
Z-value
Z6/7:Z1
Z14/15
Z6/7
ATmega325/3250/645/6450
Most significant bit in the Program Counter.
(Program Counter is 14/15 bits PC[13/14:0])
Most significant bit which is used to address the
words within one page (64/128 words in a page
requires six/seven bits PC [5/6:0]).
Bit in Z-register that is mapped to PCMSB.
Because Z0 is not used, the ZPCMSB equals
PCMSB + 1.
Bit in Z-register that is mapped to PCMSB.
Because Z0 is not used, the ZPAGEMSB equals
PAGEMSB + 1.
Program Counter page address: Page select,
for Page Erase and Page Write
Program Counter word address: Word select,
for filling temporary buffer (must be zero during
Page Write operation)
Description
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