ATxmega256A3B Atmel Corporation, ATxmega256A3B Datasheet - Page 84

• Manufacturer Part Number: ATxmega256A3B
• Manufacturer: Atmel Corporation

Specifications of ATxmega256A3B

• 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 Speed: No
• Usb Interface: No
• 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

7.9
7.9.1
7.9.2
8077H–AVR–12/09
Register Description - Clock
CTRL - System Clock Control Register
PSCTRL - System Clock Prescaler 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 - SCLKSEL[2:0]: System Clock Selection
SCLKSEL is used to select the source for the System Clock. See
selections. Changing the system clock source will take 2 clock cycles on the old clock source
and 2 clock cycles on the new clock source. These bits are protected by the Configuration
Change Protection mechanism, for details refer to
tion” on page
SCLKSEL cannot be changed if the new source is not stable.
Table 7-1.
• Bit 7 - Reserved
This bit is reserved and will always be read as zero. For compatibility with future devices, always
write this bit to zero when this register is written.
Bit
+0x00
Read/Write
Initial Value
Bit
+0x01
Read/Write
Initial Value
SCLKSEL[2:0]
000
001
010
011
100
101
110
111
12.
R
7
0
System Clock Selection
-
R
7
0
-
R/W
6
0
6
R
0
-
R/W
5
0
Group Configuration
R
5
0
-
RC32MHz
RC32KHz
PSADIV[4:0]
RC2MHz
XOSC
PLL
R/W
4
0
-
-
-
R
4
0
-
Section 3.12 ”Configuration Change Protec-
R/W
3
0
R
3
0
-
Description
External Oscillator or Clock
Phase Locked Loop
Reserved
Reserved
Reserved
2 MHz Internal RC Oscillator
32 MHz Internal RC Oscillator
32 kHz Internal RC Oscillator
R/W
R/W
2
0
2
0
SCLKSEL[2:0]
Table 7-1
R/W
R/W
1
0
1
0
PSBCDIV
XMEGA A
R/W
for the different
R/W
0
0
0
0
PSCTRL
CTRL
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