Datasheet

35
8068U–AVR–06/2013
XMEGA A3
Not recommended for new designs -
Use XMEGA A3U series
19. RTC - Real-Time Counter
19.1 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
19.2 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 19-1.
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 19-1. Real-time Counter overview
10-bit
prescaler
Counter
Period
Compare
=
=
Overflow
Compare Match
1.024 kHz
32.768 kHz