This application note describes the features of the real-time clock (RTC) controller embedded in medium density STM8L15x and medium+ and high density STM8L15x/16x devices microcontrollers, together with the steps required to configure the RTC for use with the calendar, alarm, periodic wakeup unit, tamper detection and chronometer. Five applicative examples are provided with useful configuration information to allow the user to quickly and correctly configure the RTC for calendar, alarm, periodic wakeup unit, tamper detection and chronometer applications.