ATxmega16A4U Atmel Corporation, ATxmega16A4U Datasheet - Page 92

• Manufacturer Part Number: ATxmega16A4U
• Manufacturer: Atmel Corporation

Specifications of ATxmega16A4U

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 7
• Twi (i2c): 2
• Uart: 5
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 2
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 3.3
• Eeprom (bytes): 1024
• 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: 5
• Output Compare Channels: 16
• Input Capture Channels: 16
• Pwm Channels: 16
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

7.9.3
7.9.4
8331A–AVR–07/11
LOCK – Clock System Lock Register
RTCCTRL – RTC Control Register
• Bit 7:1 – Reserved
These bits are reserved and will always be read as zero. For compatibility with future devices,
always write these bits to zero when this register is written.
• Bit 0 – LOCK: Clock System Lock
When this bit is written to one, the CTRL and PSCTRL registers cannot be changed, and the
system clock selection and prescaler settings are protected against all further updates until after
the next reset. This bit is protected by the configuration change protection mechanism., For
details, refer to
The LOCK bit can be cleared only by a reset.
• Bit 7:4 – 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 3:1 – RTCSRC[2:0]: RTC Clock Source
These bits select the clock source for the real-time counter according to
Table 7-4.
Bit
+0x03
Read/Write
Initial Value
Bit
+0x02
Read/Write
Initial Value
RTCSRC[2:0]
000
001
010
011
100
101
110
111
7
–
R
0
R
7
–
0
RTC clock source selection.
”Configuration Change Protection” on page
Group Configuration
6
–
R
0
R
6
–
0
RCOSC32
EXTCLK
TOSC32
RCOSC
TOSC
ULP
—
—
R
5
–
0
R
5
–
0
R
4
–
0
R
4
–
0
Description
1kHz from 32kHz internal ULP oscillator
1.024kHz from 32.768kHz crystal oscillator on TOSC
1.024kHz from 32.768kHz internal oscillator
Reserved
Reserved
32.768kHz from 32.768kHz crystal oscillator on TOSC
32.768kHz from 32.768kHz internal oscillator
External clock from TOSC1
R/W
3
0
Atmel AVR XMEGA AU
R
3
–
0
RTCSRC[2:0]
12.
R/W
2
0
R
2
–
0
R/W
1
0
R
1
–
0
Table
RTCEN
7-4.
R/W
LOCK
0
0
R/W
0
0
RTCCTRL
LOCK
92