Datasheet

345

7766F–AVR–11/10

ATmega16/32U4

Note: 1. Z0: should be zero for all SPM commands, byte select for the (E)LPM instruction.

Note: See “Addressing the Flash During Self-Programming” on page 337 for details about the use of Z-

pointer during Self-Programming.

Table 27-10. Explanation of different variables used in Figure 27-4 and the mapping to the Z-

pointer

Variable

Corresponding

Z-value

(1)

Description

PCMSB 13

Most significant bit in the Program Counter. (The

Program Counter is 14 bits PC[13:0])

PAG EM SB 6

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 Z14

Bit in Z-pointer that is mapped to PCMSB. Because

Z0 is not used, the ZPCMSB equals PCMSB + 1.

ZPAGEMSB Z7

Bit in Z-pointer that is mapped to PCMSB. Because

Z0 is not used, the ZPAGEMSB equals PAGEMSB +

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)