ATxmega128A4U Atmel Corporation, ATxmega128A4U Datasheet - Page 241

• Manufacturer Part Number: ATxmega128A4U
• Manufacturer: Atmel Corporation

Specifications of ATxmega128A4U

• Flash (kbytes): 128 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 7
• Twi (i2c): 2
• Uart: 5
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 2
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 8
• Eeprom (bytes): 2048
• 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: 5
• Output Compare Channels: 16
• Input Capture Channels: 16
• Pwm Channels: 16
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

20.7.2
20.8
20.9
8331A–AVR–07/11
Auto Zero Length Packet
Transaction Complete FIFO
For output endpoints
When an IN token is received, endpoint CNT and AUXDATA are fetched. If CNT minus AUX-
DATA is less than the endpoint SIZE, endpoint CNT minus endpoint AUXDATA number bytes
are transmitted, otherwise SIZE number of bytes are transmitted. If endpoint CNT is a multiple of
SIZE, the last packet sent will be zero-length, if the Auto Zero Length Packet (AZLP) is enabled.
If a maximum payload size packet was sent (i.e. not the last transaction), AUXDATA is incre-
mented by SIZE. TOGGLE will be toggled if the endpoint is not isochronous after the transaction
has completed. If a short packet was sent (i.e. the last transaction), AUXDATA is incremented by
the data payload. TOGGLE will be toggled if the endpoint is not isochronous, and BUSNACK,
TRNIF and TRNCOMPL0 will be set.
The number of data bytes received is stored in endpoint CNT as for normal operation. Since
endpoint CNT is updated after each transaction, it must be set to zero when setting up a new
transfer. The total number of bytes to be received must be written to AUXDATA. This value must
be a multiple of SIZE, otherwise excess data may be written to SRAM locations used by other
parts of the application.
The TOGGLE management is as for non-isochronous packets, and BUSNACK0/BUSNACK1
management is as for normal operation.
If a maximum payload size packet is received, CNT is incremented by SIZE after the transaction
has completed, and TOGGLE toggles if the endpoint is not isochronous. If the updated endpoint
CNT is equal to AUXDATA, BUSNACK0/BUSNACK1, TRNIF and TRNCOMPL0/TRNCOMPL1
will be set.
If a short or oversized packet is received, endpoint CNT will be incremented by the data payload
after the transaction has completed. TOGGLE will be toggled if the endpoint is not isochronous
and BUSNACK0/BUSNACK1, TRNIF and TRNCOMPL0/TRNCOMPL1 will be set.
Some IN transfer requires a zero length packet to be generated in order to signal end of transfer
to the host. The Auto Zero Length Packet (AZLP) function can be enabled to perform this gener-
ation automatically, thus remove need for application software or CPU intervention to perform
this task.
The Transaction Complete FIFO (FIFO) provides a convenient way to keep track of the end-
points that has completed IN or OUT transactions and needs firmware intervention. It creates a
first come, first serve work queue for the application software.
The FIFO size is (MAXEP[3:0]+1)x4 bytes, and grows downword starting from EPPTR-1. This
SRAM memory is only allocated when the FIFO is enabled.
Atmel AVR XMEGA AU
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