ATxmega64A3 Atmel Corporation, ATxmega64A3 Datasheet - Page 216

• Manufacturer Part Number: ATxmega64A3
• Manufacturer: Atmel Corporation

Specifications of ATxmega64A3

• Flash (kbytes): 64 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): 4
• 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: 7
• Output Compare Channels: 22
• Input Capture Channels: 22
• Pwm Channels: 22
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

19.6.1.1
19.6.1.2
19.6.1.3
19.6.1.4
19.6.2
19.6.3
19.7
8077H–AVR–12/09
Enabling External Driver Interface
Receiving Data Packets
Transmitting Data Packets
Case 1: Address packet accepted - Direction bit set
Case 2: Address packet accepted - Direction bit cleared
Case 3: Collision
Case 4: STOP condition received.
The R/W Direction flag reflects the direction bit received with the address. This can be read by
software to determine the type of operation currently in progress.
Depending on the R/W direction bit and bus condition one of four distinct cases (1 to 4) arises
following the address packet. The different cases must be handled in software.
If the R/W Direction flag is set, this indicates a master read operation. The SCL line is forced
low, stretching the bus clock. If ACK is sent by the slave, the slave hardware will set the Data
Interrupt Flag indicating data is needed for transmit. If NACK is sent by the slave, the slave will
wait for a new condition and address match.
If the R/W Direction flag is cleared this indicates a master write operation. The SCL line is forced
low, stretching the bus clock. If ACK is sent by the slave, the slave will wait for data to be
received. Data, Repeated START or STOP can be received after this. If NACK is indicated the
slave will wait for a new START condition and address match.
If the slave is not able to send a high level or NACK, the Collision flag is set and it will disable the
data and acknowledge output from the slave logic. The clock hold is released. A START or
repeated START condition will be accepted.
Operation is the same as case 1 or 2 above with one exception. When the STOP condition is
received, the Slave Address/Stop flag will be set indicating that a STOP condition and not an
address match occurred.
The slave will know when an address packet with R/W direction bit cleared has been success-
fully received. After acknowledging this, the slave must be ready to receive data. When a data
packet is received the Data Interrupt Flag is set, and the slave must indicate ACK or NACK.
After indicating a NACK, the slave must expect a STOP or Repeated START condition.
The slave will know when an address packet, with R/W direction bit set, has been successfully
received. It can then start sending data by writing to the Slave Data register. When a data packet
transmission is completed, the Data Interrupt Flag is set. If the master indicates NACK, the slave
must stop transmitting data, and expect a STOP or Repeated START condition.
An external drivers interface can be enabled. When this is done the internal TWI drivers with
input filtering and slew rate control are bypassed. The normal I/O pin function is used and the
direction must be configured by the user software. When this mode is enabled an external TWI
compliant tri-state driver is needed for connecting to a TWI bus.
By default port pin 0 (Pn0) and 1 (Pn1) is used for SDA and SCL. The external driver interface
uses port pin 0 to 3 for the signals SDA_IN, SCL_IN, SDA_OUT and SCL_OUT.
XMEGA A
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