at43usb320a ATMEL Corporation, at43usb320a Datasheet - Page 9

• Manufacturer Part Number: at43usb320a
• Description: Full-speed Usb Microcontroller With An Embedded Hub
• Manufacturer: ATMEL Corporation

X-, Y- and Z-
Registers
ALU – Arithmetic
Logic Unit
Program Memory
1443E–USB–4/04
Registers R26..R31 contain some added functions to their general-purpose usage. These reg-
isters are address pointers for indirect addressing of the Data Space. The three indirect
address registers X, Y, and Z are defined as:
In the different addressing modes these address registers have functions as fixed displace-
ment, automatic increment and decrement (see the descriptions for the different instructions).
The high-performance AVR ALU operates in direct connection with all 32 general purpose
working registers. Within a single clock cycle, ALU operations between registers in the register
file are executed. The ALU operations are divided into three main categories – arithmetic, log-
ical and bit-functions.
The AT43USB320A operates from an external program memory. Since all instructions are 16-
or 32-bit words, the program memory is organized as X16. The AT43USB320A Program
Counter (PC) is 16 bits wide, thus addressing the 64K program memory addresses.
Constant tables can be allocated within the entire program memory address space (see the
LPM - Load Program Memory instruction description).
X-register
Z-register
Y-register
15
7
15
7
15
7
R29 ($1D)
R27 ($1B)
R30 ($1F)
YH
XH
ZH
0
0
0
7
7
7
AT43USB320A
R26 ($1A)
R28 ($1C)
R31 ($1E)
XL
YL
ZL
0
0
0
0
0
0
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