ATxmega256A3 Atmel Corporation, ATxmega256A3 Datasheet - Page 225

• Manufacturer Part Number: ATxmega256A3
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3

• 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 Speed: No
• Usb Interface: No
• 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

XMEGA A
• Bit 7 - DIF: Data Interrupt Flag
The Data Interrupt Flag (DIF) is set when a data byte is successfully received, i.e. no bus error
or collision occurred during the operation. Writing a one to this bit location will clear the DIF.
When this flag is set the slave forces the SCL line low, stretching the TWI clock period. Clearing
the interrupt flags will release the SCL line.
This flag is also automatically cleared when writing a valid command to the CMD bits in the
CTRLB register
• Bit 6 - APIF: Address/Stop Interrupt Flag
The Address/Stop Interrupt Flag (APIF) is set when the slave detects that a valid address has
been received, or when a transmit collision is detected. If the PIEN bit in the CTRLA register is
set a STOP condition on the bus will also set APIF. Writing a one to this bit location will clear the
APIF. When this flag is set the slave forces the SCL line low, stretching the TWI clock period.
Clearing the interrupt flags will release the SCL line.
The flag is also automatically cleared for the same condition as DIF.
• Bit 5 - CLKHOLD: Clock Hold
The slave Clock Hold (CLKHOLD) flag is set when the slave is holding the SCL line low.This is a
status flag, and a read only bit that is set when the DIF or APIF is set. Clearing the interrupt flags
and releasing the SCL line, will indirectly clear this flag.
• Bit 4 - RXACK: Received Acknowledge
The Received Acknowledge (RXACK) flag contains the most recently received acknowledge bit
from the master. This is a read only flag. When read as zero the most recent acknowledge bit
from the maser was ACK, and when read as one the most recent acknowledge bit was NACK.
• Bit 3 - COLL: Collision
The slave Collision (COLL) flag is set when slave is not been able to transfer a high data bit or a
NACK bit. If a collision is detected, the slave will commence its normal operation, disable data
and acknowledge output, and no low values will be shifted out onto the SDA line. Writing a one
to this bit location will clear the COLL flag.
The flag is also automatically cleared when a START or Repeated START condition is detected.
• Bit 2 - BUSERR: TWI Slave Bus Error
The slave Buss Error (BUSERR) flag is set when an illegal bus condition has occurs during a
transfer. An illegal bus condition occurs if a Repeated START or STOP condition is detected,
and the number of bits from the previous START condition is not a multiple of nine. Writing a one
to this bit location will clear the BUSERR flag.
For bus errors to be detected, the bus state logic must be enabled. This is done by enable TWI
master.
• Bit 1 - DIR: Read/Write Direction
The Read/Write Direction (DIR) flag reflects the direction bit from the last address packet
received from a master. When this bit is read as one, a Master Read operation is in progress.
When read as zero a Master Write operation is in progress.
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