A Real Time Clock(RTC) used to keep the track of accurate current date & time for an Embedded System. RTC is present in every time based Embedded System. A real-time clock (RTC) is a battery-powered clock as it keeps on tracking Data & Time in Power Down. Most often, a IC based hardware is used to manage the RTC, but there are many microcontrollers which, comes with in-built RTC. A microcontroller use I2C or SPI port to communicate with external RTC device.