Datasheet

293
8018P–AVR–08/10
ATmega169P
Note: 1. For details about these two section, see ”NRWW – No Read-While-Write Section” on page
281 and ”RWW – Read-While-Write Section” on page 281.
Note: 1. Z15:Z14: 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 286 for details about the use of
Z-pointer during Self-Programming.
Table 26-7. Read-While-Write Limit
(1)
Section Pages Address
Read-While-Write section (RWW) 112 0x0000 - 0x1BFF
No Read-While-Write section (NRWW) 16 0x1C00 - 0x1FFF
Table 26-8. Explanation of different variables used in Figure 26-3 on page 286 and the map-
ping to the Z-pointer
(1)
Variable
Corresponding
Z-value Description
PCMSB 12
Most significant bit in the Program Counter. (The
Program Counter is 13 bits PC[12:0])
PAGEMSB 5
Most significant bit which is used to address the words
within one page (64 words in a page requires six bits PC
[5:0]).
ZPCMSB Z13
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[12:6] Z13: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)