Datasheet

Table Of Contents
16
ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]
2549Q–AVR–02/2014
7.6.1 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 7-4. Note
that LPM is not affected by the RAMPZ setting.
Figure 7-4. The Z-pointer used by ELPM and SPM
The actual number of bits is implementation dependent. Unused bits in an implementation will always read as zero.
For compatibility with future devices, be sure to write these bits to zero.
7.6.2 EIND – Extended Indirect Register
For EICALL/EIJMP instructions, the Indirect-pointer to the subroutine/routine is a concatenation of EIND, ZH, and
ZL, as shown in Figure 7-5. Note that ICALL and IJMP are not affected by the EIND setting.
Figure 7-5. The Indirect-pointer used by EICALL and EIJMP
The actual number of bits is implementation dependent. Unused bits in an implementation will always read as zero.
For compatibility with future devices, be sure to write these bits to zero.
7.7 Instruction Execution Timing
This section describes the general access timing concepts for instruction execution. The AVR CPU is driven by the
CPU clock clk
CPU
, directly generated from the selected clock source for the chip. No internal clock division is used.
Figure 7-6 on page 17 shows the parallel instruction fetches and instruction executions enabled by the Harvard
architecture and the fast-access Register File concept. This is the basic pipelining concept to obtain up to 1 MIPS
per MHz with the corresponding unique results for functions per cost, functions per clocks, and functions per
power-unit.
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
(Individually)
707070
EIND ZH ZL
Bit (Indirect-
pointer)
23 16 15 8 7 0