Datasheet

293
8021G–AVR–03/11
ATmega329P/3290P
Note: 1. For details about these two section, see ”NRWW – No Read-While-Write Section” on page 282 and ”RWW – Read-While-
Write Section” on page 282.
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 286 for details about the use of Z-pointer during Self-Programming.
Table 26-7. Read-While-Write Limit (ATmega329P/3290P)
(1)
Section Pages Address
Read-While-Write section (RWW) 224 0x0000 - 0x37FF
No Read-While-Write section (NRWW) 32 0x3800 - 0x3FFF
Table 26-8. Explanation of different variables used in Figure 26-3 and the mapping to the Z-pointer
(ATmega329P/3290P)
(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)