Rainbow Electronics Atmega169L - Manual (Page 264)

264
ATmega169V/L
2514A–AVR–08/02
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 257 for details about
the use of Z-pointer during Self-Programming.
Table 115. Explanation of different variables used in Figure 117 and the mapping 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.
ZPAGEMS
B Z6 Bit in Z-register that is mapped to PCMSB.
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)