Datasheet

15
ATmega640/1280/1281/2560/2561
2549K–AVR–01/07
RAMPZ – Extended Z-pointer
Register for ELPM/SPM
For ELPM/SPM instructions, the Z-pointer is a concatenation of RAMPZ, ZH, and ZL, as
shown in Figure 8. Note that LPM is not affected by the RAMPZ setting.
Figure 8. The Z-pointer used by ELPM and SPM
The actual number of bits is implementation dependent. Unused bits in an implementa-
tion will always read as zero. For compatibility with future devices, be sure to write these
bits to zero.
EIND – Extended Indirect
Register
For EICALL/EIJMP instructions, the Indirect-pointer to the subroutine/routine is a con-
catenation of EIND, ZH, and ZL, as shown in Figure 9. Note that ICALL and IJMP are
not affected by the EIND setting.
Figure 9. The Indirect-pointer used by EICALL and EIJMP
The actual number of bits is implementation dependent. Unused bits in an implementa-
tion will always read as zero. For compatibility with future devices, be sure to write these
bits to zero.
Bit 765432 1 0
0x3B (0x5B)
RAMPZ7 RAMPZ6 RAMPZ5 RAMPZ4 RAMPZ3 RAMPZ2 RAMPZ1 RAMPZ0
RAMPZ
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value000000 0 0
Bit (
Individually)
707070
RAMPZ ZH ZL
Bit (Z-pointer) 23 16 15 8 7 0
Bit 765432 1 0
0x3C (0x5C) EIND7 EIND6 EIND5 EIND4 EIND3 EIND2 EIND1 EIND0 EIND
Read/Write R/W R/W R/W R/W R/W R/W R/W R/W
Initial Value000000 0 0
Bit (Individual-
ly)
707070
EIND ZH ZL
Bit (Indirect-
pointer)
23 16 15 8 7 0