ATxmega128B1 Atmel Corporation, ATxmega128B1 Datasheet - Page 202

• Manufacturer Part Number: ATxmega128B1
• Manufacturer: Atmel Corporation

Specifications of ATxmega128B1

• Flash (kbytes): 128 Kbytes
• Pin Count: 100
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 53
• Ext Interrupts: 53
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Segment Lcd: 160
• 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
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 8
• Eeprom (bytes): 2048
• 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: 3
• Output Compare Channels: 10
• Input Capture Channels: 10
• Pwm Channels: 10
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

17. RTC — Real-Time Counter
17.1
17.2
8291A–AVR–10/11
Features
Overview
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The 16-bit real-time counter (RTC) is a counter that typically runs continuously, including in low-
power sleep modes, to keep track of time. It can wake up the device from sleep modes and/or
interrupt the device at regular intervals.
The reference clock is typically the 1.024kHz output from a high-accuracy crystal of 32.768kHz,
and this is the configuration most optimized for low power consumption. The faster 32.768kHz
output can be selected if the RTC needs a resolution higher than 1ms. The RTC can also be
clocked from an external clock signal, the 32.768kHz internal oscillator or the 32kHz internal
ULP oscillator.
The RTC includes a 10-bit programmable prescaler that can scale down the reference clock
before it reaches the counter. A wide range of resolutions and time-out periods can be config-
ured. With a 32.768kHz clock source, the maximum resolution is 30.5µs, and time-out periods
can range up to 2000 seconds. With a resolution of 1s, the maximum timeout period is more
than18 hours (65536 seconds). The RTC can give a compare interrupt and/or event when the
counter equals the compare register value, and an overflow interrupt and/or event when it
equals the period register value.
Figure 17-1. Real-time counter overview.
16-bit resolution
Selectable clock source
Programmable 10-bit clock prescaling
One compare register
One period register
Clear counter on period overflow
Optional interrupt/event on overflow and compare match
– 32.768kHz external crystal
– External clock
– 32.768kHz internal oscillator
– 32kHz internal ULP oscillator
TOSC1
TOSC2
32.768kHz Crystal Osc
32kHz int ULP (DIV32)
32.768kHz Int. Osc
External Clock
RTCSRC
prescaler
10-bit
clk
RTC
Atmel AVR XMEGA B
COMP
PER
CNT
=
=
Compare
Overflow
”match”/
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