DETAILED DESCRIPTIONThe DS1302 trickle-charge timekeeping chip contains a real-time clock/calendar and 31 bytes of static RAM. Itcommunicates with a microprocessor via a simple serial interface. The real-time clock/calendar provides seconds,minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted formonths with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or12-hour format with an AM/PM indicator.Interfacing the DS1302 with a microprocessor is simplified by using synchronous serial communication. Only threewires are required to communicate with the clock/RAM: CE, I/O (data line), and SCLK (serial clock). Data can betransferred to and from the clock/RAM 1 byte at a time or in a burst of up to 31 bytes. The DS1302 is designed tooperate on very low power and retain data and clock information on less than 1μW.The DS1302 is the successor to the DS1202. In addition to the basic timekeeping functions of the DS1202, theDS1302 has the additional features of dual power pins for primary and backup power supplies, programmabletrickle charger for VCC1, and seven additional bytes of scratchpad memory.