Datasheet

279
4317K–AVR–03/2013
AT90PWM2/3/2B/3B
For details about these two section, see “NRWW – No Read-While-Write Section” on page 267
and “RWW – Read-While-Write Section” on page 267
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 272 for details about the use of
Z-pointer during Self-Programming.
Table 24-8. Explanation of Different Variables used in Figure 24-3 and the Mapping to the Z-
pointer
Variable
Corresponding
Z-value
(1)
Description
PCMSB 11
Most significant bit in the Program Counter. (The
Program Counter is 12 bits PC[11:0])
PAG E MS B 4
Most significant bit which is used to address the
words within one page (32 words in a page requires
5 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 PAGEMSB.
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)