PIC12F1840 + I2C DS1307 RTC

The DS1307 IC is a serial I2C Real Time Clock (RTC) and calendar plus 56 bytes of SRAM.


  • I2C (SCL max frequency is 100 KHz).
  • Counts: Seconds, minutes, hours, date of the month, month, day of the week and year (with leap compensation valid up to 2100).
  • Can operate in either the 24-hour or 12-hour with AM/FM format.
  • Date and Time is in BCD format.
  • 56 Bytes general purpose SRAM (Battery backed).
  • Automatic power-fail detect and switch circuitry to a battery source.
  • Programmable square wave out signal.
  • Operating voltage: 5.0V


Typical operating circuit:

Function block diagram:

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