ATxmega256A3BU Atmel Corporation, ATxmega256A3BU Datasheet - Page 291

• Manufacturer Part Number: ATxmega256A3BU
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3BU

• 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 Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• 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

8331A–AVR–07/11
Figure 23-1. USART block diagram.
The clock generator includes a fractional baud rate generator that is able to generate a wide
range of USART baud rates from any system clock frequencies. This removes the need to use
an external crystal oscillator with a specific frequency to achieve a required baud rate. It also
supports external clock input in synchronous slave operation.
The transmitter consists of a single write buffer (DATA), a shift register, and a parity generator.
The write buffer allows continuous data transmission without any delay between frames.
The receiver consists of a two-level receive buffer (DATA) and a shift register. Data and clock
recovery units ensure robust synchronization and noise filtering during asynchronous data
reception. It includes frame error, buffer overflow, and parity error detection.
When the USART is set in master SPI mode, all USART-specific logic is disabled, leaving the
transmit and receive buffers, shift registers, and baud rate generator enabled. Pin control and
interrupt generation are identical in both modes. The registers are used in both modes, but their
functionality differs for some control settings.
An IRCOM module can be enabled for one USART to support IrDA 1.4 physical compliant pulse
modulation and demodulation for baud rates up to 115.2kbps. For details, refer to
Communication Module” on page 312
CTRLA
TRANSMIT SHIFT REGISTER
RECEIVE SHIFT REGISTER
BAUD RATE GENERATOR
FRACTIONAL DIVIDE
.
DATA (Transmit)
DATA (Receive)
BSEL [H:L]
CTRLB
Atmel AVR XMEGA AU
GENERATOR
SYNC LOGIC
RECOVERY
RECOVERY
CHECKER
PARITY
CLOCK
PARITY
DATA
OSC
Clock Generator
CONTROL
CONTROL
CONTROL
CONTROL
CONTROL
Transmitter
PIN
PIN
PIN
TX
RX
Receiver
CTRLC
XCK
RxD
TxD
”IRCOM - IR
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