Datasheet

Table Of Contents

21. RTC – Real-Time Counter

21.1 Overview

The Real-Time Counter (RTC) is a 32-bit counter with a 10-bit programmable prescaler that typically runs

continuously to keep track of time. The RTC can wake up the device from sleep modes using the alarm/

compare wake up, periodic wake up, or overflow wake up mechanisms, or from the wake inputs.

The RTC can generate periodic peripheral events from outputs of the prescaler, as well as alarm/compare

interrupts and peripheral events, which can trigger at any counter value. Additionally, the timer can trigger

an overflow interrupt and peripheral event, and can be reset on the occurrence of an alarm/compare

match. This allows periodic interrupts and peripheral events at very long and accurate intervals.

The 10-bit programmable prescaler can scale down the clock source. By this, a wide range of resolutions

and time-out periods can be configured. With a 32.768kHz clock source, the minimum counter tick

interval is 30.5µs, and time-out periods can range up to 36 hours. For a counter tick interval of 1s, the

maximum time-out period is more than 136 years.

21.2 Features

• 32-bit counter with 10-bit prescaler

• Multiple clock sources

• 32-bit or 16-bit counter mode

• Two 32-bit or four 16-bit compare values

• Clock/Calendar mode

– Time in seconds, minutes, and hours (12/24)

– Date in day of month, month, and year

– Leap year correction

• Digital prescaler correction/tuning for increased accuracy

• Overflow, alarm/compare match and prescaler interrupts and events

– Optional clear on alarm/compare match

• 8 backup registers with retention capability

• Tamper Detection

– Timestamp on event or up to 5 inputs with debouncing

– Active layer protection

SAM D5x/E5x Family Data Sheet

RTC – Real-Time Counter

Datasheet

DS60001507E-page 283