Rainbow Electronics ATmega8515L - Manual (Page 174)

174
ATmega8515(L)
2512A–AVR–04/02
Note: 1. 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 167 for details about
the use of Z-pointer during Self-Programming.
Table 80. Explanation of Different Variables used in Figure 73 and the Mapping to the
Z-pointer
(1)
Variable
Corresponding
Z-value Description
PCMSB 11 Most significant bit in the Program Counter.
(The Program Counter is 12 bits PC[11:0])
PAGEMSB 4 Most significant bit which is used to address
the words within one page (32 words in a page
requires five bits PC [4:0]).
ZPCMSB Z12 Bit in Z-register that is mapped to PCMSB.
Because Z0 is not used, the ZPCMSB equals
PCMSB + 1.
ZPAGEMSB Z5 Bit in Z-register that is mapped to PCMSB.
Because Z0 is not used, the ZPAGEMSB
equals PAGEMSB + 1.
PCPAGE PC[11:5] Z12:Z6 Program Counter page address: Page select,
for Page Erase and Page Write
PCWORD PC[4:0] Z5:Z1 Program Counter word address: Word select,
for filling temporary buffer (must be zero during
Page Write operation)