SECOND
MINUTE
HOUR
DAY
MONTH
YEAR
Alarm
Timer
Alarm
Interrupts
Periodic
Interrupts
Counter
32 kHz
Oscillator
Compensation
DOTW
Oscillator
RTC_XI
Crystal
RTC_XO
Introduction
1320
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Real-Time Clock (RTC)
27.1 Introduction
27.1.1 Purpose of the Peripheral
The real-time clock (RTC) provides a time reference to an application running on the device. The current
date and time is tracked in a set of counter registers that update once per second. The time can be
represented in 12-hour or 24-hour mode. The calendar and time registers are buffered during reads and
writes so that updates do not interfere with the accuracy of the time and date.
Alarms are available to interrupt the CPU at a particular time, or at periodic time intervals, such as once
per minute or once per day. In addition, the RTC can interrupt the CPU every time the calendar and time
registers are updated, or at programmable periodic intervals.
27.1.2 Features
The real-time clock (RTC) provides the following features:
•
100-year calendar (xx00 to xx99)
•
Counts seconds, minutes, hours, day of the week, date, month, and year with leap year compensation
•
Binary-coded-decimal (BCD) representation of time, calendar, and alarm
•
12-hour clock mode (with AM and PM) or 24-hour clock mode
•
Alarm interrupt
•
Periodic interrupt
•
Single interrupt to the CPU
•
Supports external 32.768-kHz crystal or external clock source of the same frequency
•
Isolated power supply
27.1.3 Block Diagram
shows a block diagram of the RTC.
Figure 27-1. Real-Time Clock Block Diagram