AT32UC3B0256 Atmel Corporation, AT32UC3B0256 Datasheet - Page 300

• Manufacturer Part Number: AT32UC3B0256
• Manufacturer: Atmel Corporation

Specifications of AT32UC3B0256

• Flash (kbytes): 256 Kbytes
• Pin Count: 64
• Max. Operating Frequency: 60 MHz
• Cpu: 32-bit AVR
• # Of Touch Channels: 32
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 44
• Ext Interrupts: 44
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device + OTG
• Spi: 4
• Twi (i2c): 1
• Uart: 3
• Ssc: 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
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 32
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 3.0-3.6 or (1.65-1.95+3.0-3.6)
• Operating Voltage (vcc): 3.0-3.6 or (1.65-1.95+3.0-3.6)
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 10
• Output Compare Channels: 16
• Input Capture Channels: 6
• Pwm Channels: 13
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

21.6
21.6.1
21.6.2
Figure 21-2. Baud Rate Generator
21.6.2.1
32059L–AVR32–01/2012
Functional Description
Selecting Mode
Baud Rate Generator
CLK_USART/DIV
CLK
CLK_USART
Baud Rate in Asynchronous Mode
Reserved
USCLKS
The USART can operate in several modes. The operating mode is selected by writing to the
Mode field in the
mode is selected by writing to the Synchronous Mode Select bit in MR (MR.SYNC).
The baud rate generator provides the bit period clock named the Baud Rate Clock to both
receiver and transmitter. It is based on a 16-bit divider, which is specified in the Clock Divider
field in the Baud Rate Generator Register (BRGR.CD). A non-zero value enables the generator,
and if CD is one, the divider is bypassed and inactive. The Clock Selection field in the Mode
Register (MR.USCLKS) selects clock source between:
If the external CLK clock is selected, the duration of the low and high levels of the signal pro-
vided on the CLK pin must be at least 4.5 times longer than those provided by CLK_USART.
If the USART is configured to operate in an asynchronous mode, the selected clock is divided by
the CD value before it is provided to the receiver as a sampling clock. Depending on the Over-
sampling Mode bit (MR.OVER) value, the clock is then divided by either 8 (OVER=1), or 16
(OVER=0). The baud rate is calculated with the following formula:
This gives a maximum baud rate of CLK_USART divided by 8, assuming that CLK_USART is
the fastest clock possible, and that OVER is one.
0
1
3
2
• CLK_USART (internal clock, refer to Power Manager chapter for details)
• CLK_USART/DIV (a divided CLK_USART, refer to Module Configuration section)
• CLK (external clock, available on the CLK pin)
BaudRate
16-bit Counter
=
“Mode Register”
CD
----------------------------------------------- -
(
8 2 OVER
SelectedClock
(
–
USCLKS= 3
0
SYNC
)CD
)
(MR.MODE). In addition, Synchronous or Asynchronous
CD
>1
0
1
0
1
OVER
Sampling
Divider
FIDI
0
1
SYNC
CLK
BaudRate
Sampling
Clock
Clock
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