AT32UC3A3256AU Atmel Corporation, AT32UC3A3256AU Datasheet - Page 553

• Manufacturer Part Number: AT32UC3A3256AU
• Manufacturer: Atmel Corporation

Specifications of AT32UC3A3256AU

• Flash (kbytes): 256 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 66 MHz
• Cpu: 32-bit AVR
• # Of Touch Channels: 32
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 110
• Ext Interrupts: 110
• Usb Transceiver: 1
• Usb Speed: Hi-Speed
• Usb Interface: Device + OTG
• Spi: 6
• Twi (i2c): 2
• Uart: 4
• Lin: 4
• Ssc: 1
• Sd / Emmc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 16
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 128
• Self Program Memory: YES
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.0 to 3.6
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 6
• Output Compare Channels: 18
• Input Capture Channels: 12
• Pwm Channels: 12
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

25.6.3
25.6.3.1
32072G–11/2011
Synchronous and Asynchronous Modes
Transmitter Operations
The user can disable the receiver/transmitter by writing a one to either the Receiver Disable, or
Transmitter Disable bit (CR.RXDIS, or CR.TXDIS). If the receiver is disabled during a character
reception, the USART will wait for the current character to be received before disabling. If the
transmitter is disabled during transmission, the USART will wait until both the current character
and the character stored in the Transmitter Holding Register (THR) are transmitted before dis-
abling. If a timeguard has been implemented it will remain functional during the transaction.
The transmitter performs equally in both synchronous and asynchronous operating modes
(MR.SYNC). One start bit, up to 9 data bits, an optional parity bit, and up to two stop bits are
successively shifted out on the TXD pin at each falling edge of the serial clock. The number of
data bits is selected by the Character Length field (MR.CHRL) and the MR.MODE9 bit. Nine bits
are selected by writing a one to MODE9, overriding any value in CHRL. The parity bit configura-
tion is selected in the MR.PAR field. The Most Significant Bit First bit (MR.MSBF) selects which
data bit to send first. The number of stop bits is selected by the MR.NBSTOP field. The 1.5 stop
bit configuration is only supported in asynchronous mode.
Figure 25-5. Character Transmit
The characters are sent by writing to the Character to be Transmitted field (THR.TXCHR). The
transmitter reports status with the Transmitter Ready (TXRDY) and Transmitter Empty
(TXEMPTY) bits in the Channel Status Register (CSR). TXRDY is set when THR is empty.
TXEMPTY is set when both THR and the transmit shift register are empty (transmission com-
plete). Both TXRDY and TXEMPTY are cleared when the transmitter is disabled. Writing a
character to THR while TXRDY is zero has no effect and the written character will be lost.
Figure 25-6. Transmitter Status
Baud Rate
TXEMPTY
Baud Rate
Example: 8-bit, Parity Enabled One Stop
TXRDY
Clock
Write
TXD
THR
Clock
TXD
Start
Bit
Start
Bit
D0
D1
D0
D2
D3
D1
D4
D5
D2
D6
D7
D3
Parity
Bit
Stop
Bit
D4
Start
Bit
D0
D5
D1
D2
D6
D3
D4
D7
D5
D6
Parity
Bit
D7
Parity
Bit
Stop
Bit
Stop
Bit
553