Arduino real time clock with DS1307

This post shows a simple real time clock and calendar example using an Arduino UNO board and DS1307 RTC chip where time and calendar are displayed on 1602 LCD screen and it can be set with two push buttons.

The DS1307 is an IC (integrated circuit) which has only 8 pins, it’s low cost, easy to use and it has the ability to count time and date in real time (more details are in the datasheet).

Hardware Required:

Arduino real time clock with DS1307 circuit:

In the circuit there are 2 push buttons (B1 & B2) connected to pins 8 and 9 respectively, the two push buttons are used to set time date parameters (minutes, hours, date, month and year). Button B1 selects the parameter and B2 increments the selected parameter.

Arduino real time clock with DS1307 code: The Arduino code below doesn’t use any library for the DS1307 RTC, the Wire library is for the communication between the Arduino and the DS1307 using I2C protocol.

The DS1307 works with BCD format only and to convert the BCD to decimal and vise versa I used the 2 lines below (example for minute): // Convert BCD to decimal minute = (minute >> 4) * 10 + (minute & 0x0F);

// Convert decimal to BCD minute = ((minute / 10)