ATxmega256A3BU Atmel Corporation, ATxmega256A3BU Datasheet - Page 217

• 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

18.3
18.3.1
8331A–AVR–07/11
Register Descriptions
CTRL – Control Register
• Bit 7:3 – Reserved
These bits are unused and reserved for future use. For compatibility with future devices, always
write these bits to zero when this register is written.
• Bit 2:0 – PRESCALER[2:0]: Clock Prescaling factor
These bits define the prescaling factor for the RTC clock according to
Table 18-1.
Bit
+0x00
Read/Write
Initial Value
PRESCALER[2:0]
000
001
010
011
100
101
110
111
R
7
–
0
Real-time counter clock prescaling factor.
R
6
–
0
Group Configuration
5
–
R
0
DIV1024
DIV256
DIV16
DIV64
DIV1
DIV2
DIV8
OFF
4
–
R
0
Atmel AVR XMEGA AU
R
3
–
0
RTC Clock Prescaling
No clock source, RTC stopped
RTC clock / 1 (no prescaling)
RTC clock / 2
RTC clock / 8
RTC clock / 16
RTC clock / 64
RTC clock / 256
RTC clock / 1024
R/W
2
0
PRESCALER[2:0]
Table 18-1 on page
R/W
1
0
R/W
0
0
CTRL
217.
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