ATxmega256A3B Atmel Corporation, ATxmega256A3B Datasheet - Page 10

• Manufacturer Part Number: ATxmega256A3B
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3B

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 47
• Ext Interrupts: 49
• Usb Speed: No
• Usb Interface: No
• Spi: 8
• Twi (i2c): 2
• Uart: 6
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 16
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 4
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

3.9.1
8077H–AVR–12/09
The X-, Y- and Z- Registers
Figure 3-4.
Most of the instructions operating on the Register File have direct access to all registers, and
most of them are single cycle instructions.
The Register File is located in a separate address space, so the registers are not accessible as
data memory.
The registers R26..R31 have added functions besides their general-purpose usage.
These registers can form 16-bit address pointers for addressing of the Data Memory. The three
address registers is called the X-, Y-, and Z-register. The Z-register can also be used as an
address pointer to read from and/or write to the Flash Program Memory, Signature Rows, Fuses
and Lock Bits.
Figure 3-5.
The lowest register address holds the least significant byte (LSB). 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).
Bit (individually)
X-register
Bit (X-register)
Bit (individually)
Y-register
Bit (Y-register)
Bit (individually)
Z-register
Bit (Z-register)
AVR CPU General Purpose Working Registers
The X-, Y- and Z-registers
Registers
Purpose
General
Working
7
15
7
15
7
15
R27
R29
R31
XH
YH
ZH
7
R13
R14
R15
R16
R17
R26
R27
R28
R29
R30
R31
R0
R1
R2
…
…
0
0
8
0
8
0
8
7
7
7
7
7
7
Addr.
0x0D
0x0E
0x0F
0x1A
0x1B
0x1C
0x1D
0x1E
0x1F
0x00
0x01
0x02
0x10
0x11
X-register High Byte
Y-register High Byte
Z-register High Byte
X-register Low Byte
Y-register Low Byte
Z-register Low Byte
R26
R28
R30
XL
YL
ZL
XMEGA A
10
0
0
0
0
0
0