Arduino real time clock with temperature monitor using DS3231 and SSD1306

In the last post I built an Arduino based real time clock using DS1307 RTC and SSD1306 OLED and in this project I’m going to show how to build a real time clock with temperature monitor using Arduino, DS3231 RTC chip and SSD1306 OLED (128×64 pixel).

The DS3231 is more accurate than the DS1307 due to its built-in temperature sensor. It also (the DS3231) keeps the time running if the main power source is down. It also uses I2C interface to communicate with the master device which is in this case the Arduino. That means the DS3231 and the SSD1306 OLED screen share the same I2C bus. Even they share the same bus but at any time the microcontroller ‘speaks’ with 1 device only depending on the address sent. The DS3231 RTC address is 0x68 (the same address with the DS1307) and the SSD1306 OLED address is 0x3D.
In the circuit there are two push buttons for setting time and date of the real time clock.

Related Projects:
Arduino and DS3231 real time clock
Interfacing Arduino with SSD1306 OLED display
Arduino real time clock using DS1307 and SSD1306 OLED

Hardware Required:

  • Arduino board
  • DS3231 board  —  DS3231 RTC datasheet
  • SSD1306 OLED (I2C mode)
  • 2 x push button
  • 3V coin cell battery
  • Breadboard
  • Jumper wires

Arduino with SSD1306 OLED and DS3231 RTC circuit

The SSD1306 OLED used in this project is configured to work in I2C mode, some SSD1306 OLED boards may require a small hardware modifications (to select between SPI mode or I2C mode) such as soldering, placing jumpers …

In this project I used Adafruit SSD1306 OLED driver and Adafruit GFX library. Both libraries can be downloaded through Arduino IDE Library Manager of manually from the links below (after downloading, unzip the folders and place them in Arduino libraries folder, for example C:\Program Files\Arduino\libraries)
Adafruit SSD1306 OLED library   —   direct link
Adafruit GFX library                  —   direct link

Project circuit:
Project circuit diagram is shown below.

Arduino SSD1306 OLED DS3231 RTC with set buttons

(All grounded terminals are connected together)

The two push buttons B1 and B2 are for setting time and date.

Arduino Code:
SSD1306 OLED and DS3231 RTC share the same I2C bus and the Arduino communicates only with 1 device at a time depending on the address (sent by the Arduino), the SSD1306 address is 0x3D and the DS3231 address is 0x68.

The Arduino code below uses Adafruit SSD1306 OLED driver and Adafruit GFX library. It doesn’t use any library for the DS3231 RTC.

The small video below shows a simple hardware circuit of the project:

and the one below shows the simulation of the project with Proteus (the simulation circuit is not the same as the hardware circuit, the hardware circuit diagram is shown above).

Proteus simulation file download (for version 8.6 or higher):
Arduino + SSD1306 OLED + DS3231

31 thoughts on “Arduino real time clock with temperature monitor using DS3231 and SSD1306”

  1. Dear Madam, Mister,
    We have included a led for the time you change the date/time.
    // Arduino real time clock and temperature monitor with DS3231 and SSD1306 OLED

    // End of code.

  2. Very cool project. I live in the USA and I was able to change the time to 12 hr format (and added “PM”) and I changed temp to Fahrenheit without much trouble. I am a beginner and just followed the help guide and reference code they included.with the Arduino compiler.

  3. Nice project.
    I tried it but it displays only day of week and date.
    I don’t know how to see the time amd temperature.
    Can you explain please?

      1. I tried it to an 0.96″ SSD1306 OLED 128X64
        As i told the first and only screen i get is the day of week with small font and the date in big font.
        The switces works perfect.I can adjust day and date.

        1. Alexander Zheleznov

          I had same problem, also used 4 pin OLED screen, managed to fix it by changing top part of the code (lines 3-24) to below:


          #define SCREEN_WIDTH 128 // OLED display width, in pixels
          #define SCREEN_HEIGHT 64 // OLED display height, in pixels

          // Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
          #define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)
          Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

          #define button1 9 // Button B1 is connected to Arduino pin 9
          #define button2 8 // Button B2 is connected to Arduino pin 8

          void setup() {
          if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128×64
          for(;;); // Don’t proceed, loop forever
          pinMode(button1, INPUT_PULLUP);
          pinMode(button2, INPUT_PULLUP);
          // init done

          // Clear the display buffer.

  4. Hi,
    I copied the code and flashed it. The font is not the same as your pictures. Could you explasin hoe to modify the fonts to come out as you have them displayed please?

  5. ArduinoNano+DS3231clock modul+DHT22 temperature modul+0.96OLED I2C display with 4 pins +2 buttons use. Code how to modifyed? How it use plese?! Can you help me?

      1. The difficulty is that the video and the wiring diagram are other options than
        reality for me. 128×64 pin 0.96 ”OLED display on video and circuit diagram
        is not the same as the OLED version I want to use.
        Both the video and the wiring diagram show a 7 pin model, but my OLED display has only 4 terminals.
        Terminal 7 is CS, DC, RST, D1, D0, VCC, GND. In contrast, the 4 terminals on the display are SDA, SCL, VCC, GND.
        I do not know the reason why this difference is described. New type, new development? What is the reason for the change?
        Can the two types be used interchangeably despite the different designs?
        What changes should be made to this in the circuits and encoding,
        library usage?
        How do I use the 4 pin OLED display instead of the 7 pin OLED display?
        I would like to get directions for modifying the wiring diagram and modifying the encoding,
        why and how to get started.

        1. The 7-pin module can work with either SPI and I2C modes, the 4-pin module can work with I2C mode only!
          The I2C slave address of the 7-pin module is 0x3D when the DC pin is connected to VDD (3.3V or 5V depending on system voltage) and it’s 0x3C when the DC pin is connected to GND.
          The I2C slave address of the 4-pin module is also 0x3D or 0x3C where you can select between the two using a jumper located in the back of the module (may require soldering).

  6. Hello, This is a very beautiful project and I must have it, I have plans on placing several of these throughout my little world but I built this project today and there is no display showing on the oled, nothing shows up. I have changed the display 3 times, I have tried 4 different Arduino Uno’s, I have replaced the hookup wiring with each different Arduino, I tried 3 different DS3231’s. I have even tried 4 different breadboards with each different Arduino. I noticed that the video shows a different hookup than the Fritzig and I hooked it up both ways still nothing showing up on the display. I am wondering if there is anything missing from the code. I am relatively new to these Arduino devices so I would not recognize anything missing. Can you offer any advice that might help because I believe this to be the perfect clock for my needs. Thank you

    1. bet your bottom dollar, the address of oled is wrong, most of the time you may find change the address from 0x3D to 0x3C and that will light up your skies.
      If not, find and run a sketch(google for one) to find I2C loads on your board that will tell you what addresses yours is running on

  7. Thank You Simple Project for providing the code i just needed the blink_parameter part which is now perfectly working for my project.

  8. I am going to build this real time clock and temperature monitor maybe this weekend (with or without the Chicken sound effects) but I can not read the metrics is there a way to convert them to American English?

    1. Simple Projects

      If you mean mm-dd-yyyy arrangement of the calendar, yes you can do that, few modifications to the code are required.

  9. Hi everyone, I have a big question, can it works with a ds1302 instead a ds1306? And if the case is correct, how can I do it?
    I’m new in all these and I don’t know how to do it, or change it.
    Thanks in advice.

    1. Simple Projects

      If you mean DS1302 instead of DS3231 (not DS1306 or SSD1306), no you can’t, because the DS3231 uses I2C protocol (2-wire interface) whereas the DS1302 does use 3-wire interface.

  10. Hi tired this out but i get warnings “warning: ISO C++ forbids converting a string constant to ‘char*’ [-Wwrite-strings”
    and I see only the day (which is small) .and dd/mm/yyyy which is very large I do not see time or TEMPERATURE.
    I’m using the same pcs but my OLED is only blue.
    I can chage the day Monday etc and the dd/mm/yyyy.
    I’m looking but cann’t find the answer ( i’m new to arduino)
    Thanks for any help

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Scroll to Top