
19
8018P–AVR–08/10
ATmega169P
6.8.1
The X-register, Y-register, and Z-register
The registers R26..R31 have some added functions to their general purpose usage. These reg-
isters are 16-bit address pointers for indirect addressing of the data space. The three indirect
address registers X, Y, and Z are defined as described in
Figure 6-5.
Figure 6-5.
The X-, Y-, and Z-registers
In the different addressing modes these address registers have functions as fixed displacement,
automatic increment, and automatic decrement (see the instruction set reference for details).
15
XH
XL
0
X-register
70
7
0
R27 (0x1B)
R26 (0x1A)
15
YH
YL
0
Y-register
70
7
0
R29 (0x1D)
R28 (0x1C)
15
ZH
ZL
0
Z-register
7
070
R31 (0x1F)
R30 (0x1E)