ATxmega128B1 Atmel Corporation, ATxmega128B1 Datasheet - Page 281

• Manufacturer Part Number: ATxmega128B1
• Manufacturer: Atmel Corporation

Specifications of ATxmega128B1

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 53
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Segment Lcd: 160
• 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
• 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: 3
• Output Compare Channels: 10
• Input Capture Channels: 10
• Pwm Channels: 10
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

21.12 Multiprocessor Communication Mode
21.12.1
21.13 IRCOM Mode of Operation
8291A–AVR–10/11
Using Multiprocessor Communication Mode
A comparison of the USART in master SPI mode and the SPI pins is shown
Table 21-5.
The multiprocessor communication mode effectively reduces the number of incoming frames
that have to be handled by the receiver in a system with multiple microcontrollers communicat-
ing via the same serial bus. In this mode, a dedicated bit in the frames is used to indicate
whether the frame is an address or data frame type.
If the receiver is set up to receive frames that contain five to eight data bits, the first stop bit is
used to indicate the frame type. If the receiver is set up for frames with nine data bits, the ninth
bit is used. When the frame type bit is one, the frame contains an address. When the frame type
bit is zero, the frame is a data frame. If 5-bit to 8-bit character frames are used, the transmitter
must be set to use two stop bits, since the first stop bit is used for indicating the frame type.
If a particular slave MCU has been addressed, it will receive the following data frames as usual,
while the other slave MCUs will ignore the frames until another address frame is received.
The following procedure should be used to exchange data in multiprocessor communication
mode (MPCM):
The process then repeats from step 2.
Using any of the 5-bit to 8-bit character frame formats is impractical, as the receiver must
change between using n and n+1 character frame formats. This makes full-duplex operation dif-
ficult, since the transmitter and receiver must use the same character size setting.
IRCOM mode can be enabled to use the IRCOM module with the USART. This enables IrDA 1.4
compliant modulation and demodulation for baud rates up to 115.2kbps. When IRCOM mode is
enabled, double speed mode cannot be used for the USART.
• Interrupt timing is not compatible
• Pin control differs due to the master-only operation of the USART in SPI master mode
1. All slave MCUs are in multiprocessor communication mode.
2. The master MCU sends an address frame, and all slaves receive and read this frame.
3. Each slave MCU determines if it has been selected.
4. The addressed MCU will disable MPCM and receive all data frames. The other slave
5. When the addressed MCU has received the last data frame, it must enable MPCM
MCUs will ignore the data frames.
again and wait for a new address frame from the master.
USART
XCK
RxD
TxD
N/A
Comparison of USART in master SPI mode and SPI pins.
MOSI
MISO
SCK
SPI
SS
Comment
Master out only
Master in only
Functionally identical
Not supported by USART in master SPI mode
Atmel AVR XMEGA B
Table
21-5.
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