AT43USB325E-AU Atmel, AT43USB325E-AU Datasheet - Page 10

• Manufacturer Part Number: AT43USB325E-AU
• Description: IC USB KEYBOARD CTRLR 64LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB325E-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: SRAM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: SPI, 3-Wire Serial
• Number Of I /o: 42
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.1
3.2
3.3
10
X-, Y- and Z- Registers
Arithmetic Logic Unit (ALU)
Program Memory
AT43USB325
Registers R26..R31 contain some added functions to their general-purpose usage. These regis-
ters 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 displacement,
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 work-
ing 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, logical
and bit-functions.
The AT43USB325E contains 16K bytes on-chip downloadable memory for program storage
while the AT43USB325M has a masked programmable ROM. Since all instructions are 16- or
32-bit words, the program memory is organized as 8K x 16. The AT43USB325 Program Counter
(PC) is 13 bits wide, thus addressing the 8,192 program memory addresses.
Constant tables can be allocated within the entire program memory address space (see the LPM
- Load Program Memory instruction description).
The program memory of the AT43USB325E is automatically written with data stored in an exter-
nal serial EEPROM during the chip's power on reset sequence. The power on reset is the only
way the on-chip program memory of the AT43USB325E will be written or modified.
The two versions of the AT43USB325 are binary compatible. A firmware written for the
AT43USB325E will work unaltered on the AT43USB325M. The only functional difference
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
R26 ($1A)
R28 ($1C)
R31 ($1E)
XL
YL
ZL
3355C–USB–4/05
0
0
0
0
0
0