ATxmega256A3B Atmel Corporation, ATxmega256A3B Datasheet - Page 209

• Manufacturer Part Number: ATxmega256A3B
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3B

• 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 Speed: No
• Usb Interface: No
• 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

8077H–AVR–12/09
Figure 19-5. Master Write Transaction
Given that the slave acknowledges the address, the master can start transmitting data (DATA)
and the slave will ACK or NACK (A/A) each byte. If no data packets are to be transmitted, the
master terminates the transaction by issuing a STOP condition (P) directly after the address
packet. There are no limitations to the number of data packets that can be transferred. If the
slave signal a NACK to the data, the master must assume that the slave cannot receive any
more data and terminate the transaction.
Figure 19-6
ing a START condition followed by an address packet with direction bit set to one (ADRESS+R).
The addressed slave must acknowledge the address for the master to be allowed to continue
the transaction.
Figure 19-6. Master Read Transaction
Given that the slave acknowledges the address, the master can start receiving data from the
slave. There are no limitations to the number of data packets that can be transferred. The slave
transmits the data while the master signals ACK or NACK after each data byte. The master ter-
minates the transfer with a NACK before issuing a STOP condition.
Figure 19-7
and write transactions separated by a Repeated START conditions (Sr).
Figure 19-7. Combined Transaction
S
S
S
ADDRESS
Address Packet #1
illustrates the Master Read transaction. The master initiates the transaction by issu-
illustrates a combined transaction. A combined transaction consists of several read
ADDRESS
ADDRESS
Address Packet
Address Packet
R/W
A
Direction
W
R
N Data Packets
DATA
A
A
A/A
Transaction
Transaction
DATA
DATA
Transaction
Data Packet
Data Packet
Sr
ADDRESS
Address Packet #2
N data packets
N data packets
A
A
R/W
A
DATA
DATA
Direction
M Data Packets
DATA
XMEGA A
A/A
A
A/A P
P
P
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