MEGA128CAN Datasheet, PDF (324/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

Table 121. Explanation of Different Variables Used in Figure 155 and the Mapping to
the Z-Pointer/RAMPZ⁽³⁾
Variable
Corresponding
Z-value
Description⁽²⁾
PCMSB
15
Most significant bit in the program counter.
(The program counter is 16 bits PC[15:0])
PAGEMSB
6
Most significant bit which is used to address the
words within one page (128 words in a page
requires 7 bits PC [6:0]).
ZPCMSB
Z16⁽¹⁾
Bit in Z-register that is mapped to PCMSB.
Because Z0 is not used, the ZPCMSB equals
PCMSB + 1.
ZPAGEMSB
Bit in Z-register that is mapped to PAGEMSB.
Z7
Because Z0 is not used, the ZPAGEMSB
equals PAGEMSB + 1.
PCPAGE
PC[15:7]
Z16⁽¹⁾:Z7
Program counter page address: Page select,
for Page Erase and Page Write.
PCWORD
PC[6:0]
Z7:Z1
Program counter word address: Word select,
for filling temporary buffer (must be zero during
PAGE WRITE operation).
Notes:
1. The Z-register is only 16 bits wide. Bit 16 is located in the RAMPZ register in the I/O
map.
2. Z0: should be zero for all SPM commands, byte select for the (E)LPM instruction.
3. See “Addressing the Flash During Self-Programming” on page 317 for details about
the use of Z-pointer/RAMPZ during self-programming.
324 AT90CAN128
4250E–CAN–12/04