ATxmega256A3U Atmel Corporation, ATxmega256A3U Datasheet - Page 240

• Manufacturer Part Number: ATxmega256A3U
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3U

• 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: 50
• Ext Interrupts: 50
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 10
• Twi (i2c): 2
• Uart: 7
• 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

20.7
20.7.1
8331A–AVR–07/11
Multi-packet transfers
For input endpoints
Figure 20-8. Ping-Pong operation overview
Multi-packet transfer enables a data payload exceeding the maximum data payload size of an
endpoint to be transferred as multiple packets without any software intervention. This reduces
interrupts and software intervention to higher level USB transfer, and free up significant CPU
time. Multi-packet transfer is identical to the IN and OUT transactions described above unless
otherwise noted in this section.
The application software provides the size and address of the SRAM buffer to be proceeded by
the USB module for a specific endpoint, and the USB module will then split the buffer in the
required USB data transfer.
Figure 20-9. Multi-packet overview
The total number of data bytes to be sent is written to CNT as for normal operation. The Auxiliary
Data register (AUXDATA) is used to store the number of bytes that are sent, and must be written
to zero for a new transfer.
With multipacket
Without multipacket
With Ping-Pong
Without Ping-Pong
Transfer Complete Interrupt and data processing
USB data packet
Available time for data processing by CPU to avoid NACK
Atmel AVR XMEGA AU
t
t
Double bank
single bank
Endpoint
Endpoint
Bank0
Bank1
240