Atmel XMEGA A3 series

34
8068C–AVR–06/08
XMEGA A3
18. RTC - Real-Time Counter
18.1 Features
• 16-bit Timer
• Flexible Tick resolution ranging from 1 Hz to 32.768 kHz
• One Compare register
• One Period register
• Clear timer on Overflow or Compare Match
• Overflow or Compare Match event and interrupt generation
18.2 Overview
The XMEGA A3 includes a 16-bit Real-time Counter (RTC). The RTC can be clocked from an
accurate 32.768 kHz Crystal Oscillator, the 32.768 kHz Calibrated Internal Oscillator, or from the
32 kHz Ultra Low Power Internal Oscillator. The RTC includes both a Period and a Compare
register. For details, see Figure 18-1.
A wide range of Resolution and Time-out periods can be configured using the RTC. With a max-
imum resolution of 30.5 µs, time-out periods range up to 2000 seconds. With a resolution of 1
second, the maximum time-out period is over 18 hours (65536 seconds).
Figure 18-1. Real-time Counter overview
10-bit
prescaler
Counter
Period
Compare
=
=
Overflow
Compare Match
1 kHz
32 kHz