This library allows an Arduino/Genuino 101 control and use the internal RTC (Real Time Clock). A real-time clock is a clock that keeps track of the current time and that can be used in order to program actions at a certain time. Most RTCs use a crystal oscillator whose frequency is 32.768 kHz (same frequency used in quartz clocks and watches). Namely this the frequency equal to 2^15 cycles per second and so is a convenient rate to use with simple binary counter circuits. Furthermore the RTC can continue to operate in any sleep mode, so it can be used to wake up the device from sleep modes in a programmed way. Every time the board is powered, the RTC is reset and starts from a standard date. To keep the time and the RTC running it is necessary to keep the board powered.
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