ATxmega256A3BU Atmel Corporation, ATxmega256A3BU Datasheet - Page 237

• 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

20.4
8331A–AVR–07/11
SRAM Memory Mapping
Figure 20-5. In transaction state machine
The USB module uses internal SRAM to store the:
The Endpoint Pointer Register (EPPTR) is used to set the SRAM address for the endpoint con-
figuration table. The USB frame number (FRAMENUM) and transaction complete FIFO (FIFO)
locations are derived from this. Location of these areas is selectable inside the internal SRAM.
Figure 20-6 on page 238
• Endpoint configuration table
• USB frame number
• Transaction complete FIFO
STALL HANDSHAKE
STALL & NO ISO
gives the relative memory location of each area.
RAM FETCH IN CONFIGURATION TABLE
ENDPOINT STATUS ENABLED ?
ENDPOINT FIELD =< MAXEP ?
ADDRESS MATCH OK ?
DATA : CTRL & STATUS
ISO
DIR : IN ENDPOINT
Set OVF, OVFIF
IDLE
Yes
Yes
Yes
NAK0, set
NAK HANDSHAKE
In token
NO ISO
Atmel AVR XMEGA AU
No
No
ACK not received
No
WAIT ACK
NO ISO
RAM FETCH IN INTERNAL DATA RAM
SEND DATA(s) TO HOST
ACK OK
DATA : POINTER EPDTR
DIR : IN ENDPOINT
TOGGLE TGL IF NO ISO
SET USBTCIF & NAK0
ISO
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