ATxmega256A3B Atmel Corporation, ATxmega256A3B Datasheet - Page 197

• 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

18. RTC32 - 32-bit Real Time Counter
18.1
18.2
Features
Overview
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The 32-bit Real Time Counter is a 32-bit counter, counting reference clock cycles and giving an
event and/or an interrupt request when it reaches a configurable compare and/or top value. The
reference clock is generated from a high accuracy 32.768 kHz crystal, and the design is opti-
mized for low power consumption. The Real Time Counter (RTC) typically operates in low power
sleep modes, keeping track of time and waking up the device at regular intervals.
The RTC input clock can be taken from a 1.024 kHz or 1 Hz prescaled output from the 32.768
kHz reference clock. The RTC will give a compare interrupt request and/or event when the coun-
ter value equals the Compare register value. The RTC will give an overflow interrupt request
and/or event when the counter value equals the Period register value. Counter overflow will also
reset the counter value to zero.
The RTC can generate both compare and overflow interrupt request and/or events.
Figure 18-1. 32-bit Real Time Counter Overview
32-bit resolution
Selectable clock reference
One Compare register
One Period register
Clear Timer on overflow
Optional Interrupt/ Event on overflow and compare match
Isolated V
– 1.024 kHz
– 1 Hz
BAT
power domain with dynamic switch over from/to V
1.024 kHz
1 Hz
32-bit Compare
32-bit Counter
=
=
32-bit Period
Overflow
Compare Match
CC
power domain