ATxmega256A3BU Atmel Corporation, ATxmega256A3BU Datasheet - Page 293

• Manufacturer Part Number: ATxmega256A3BU
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3BU

• 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 Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• 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

Table 23-1.
Note:
23.3.2
8331A–AVR–07/11
Operating Mode
Asynchronous normal
speed mode (CLK2X = 0)
Asynchronous double
speed mode (CLK2X = 1)
Synchronous and master
SPI mode
1. The baud rate is defined to be the transfer rate in bits per second (bps)
External Clock
Equations for calculating baud rate register settings.
For BSEL=0, all baud rates be achieved by changing BSEL instead of setting BSCALE:
BSEL = (2
External clock (XCK) is used in synchronous slave mode operation. The XCK clock input is sam-
pled on the peripheral clock frequency (f
limited by the following:
For each high and low period, XCK clock cycles must be sampled twice by the peripheral clock.
If the XCK clock has jitter, or if the high/low period duty cycle is not 50/50, the maximum XCK
clock speed must be reduced accordingly.
f
XCK
Conditions
BSCALE ≥ 0
BSCALE < 0
BSCALE ≥ 0
BSCALE < 0
f
f
f
f
f
BAUD
BAUD
BAUD
BAUD
BAUD
<
BSCALE
f
---------- -
PER
4
≤
≤
≤
≤
<
f
---------- -
f
---------- -
f
---------- -
f
---------- -
f
---------- -
1
2
3
4
5
6
7
PER
PER
PER
PER
PER
16
16
8
8
2
BSCALE-1
)
BSEL
f
f
BAUD
BAUD
f
f
BAUD
0
0
0
0
0
0
0
BAUD
Baud Rate
=
=
f
=
BAUD
=
------------------------------------------------------------------ -
16((2
--------------------------------------------------------------- -
8((2
-------------------------------------------------------------- -
2
------------------------------------------------------------- -
2
BSCALE
BSCALE
BSCALE
=
PER
BSCALE
(1)
→
→
→
→
→
→
→
------------------------------------ -
2
Calculation
), and the maximum XCK clock frequency (f
⋅
⋅
f
(
⋅
f
PER
f
8
BSEL
f
PER
16(
PER
⋅
PER
f
⋅
⋅
PER
BSEL )
(
BSEL )
BSEL
BSEL
Atmel AVR XMEGA AU
+
1
BSCALE
+
)
+
+
+
1)
1
1)
1)
0
0
0
0
0
0
0
)
BSEL
BSEL
BSEL
BSEL
BSEL Value Calculation
BSEL
=
=
=
BSEL
1
3
7
15
31
63
127
=
---------------------
2
------------------------------------------------ 1
2
---------------------
2
-------------------------------------------- - 1
2
BSCALE
BSCALE
BSCALE
BSCALE
1
=
1
------------------ - 1
2f
f
f
f
BAUD
PER
PER
PER
⎛
⎝
⋅
⎛
⎝
--------------------- - 1
16f
⋅ f
16
------------------ - 1
8f
8
f
f
BAUD
PER
PER
f
BAUD
BAUD
BAUD
–
–
–
–
–
XCK
⎞
⎠
⎞
⎠
293
)is