ESP32 DS3231 / AT24C32 Real-Time Clock (RTC)

Code Examples

Below you can find code examples of DS3231 / AT24C32 Real-Time Clock (RTC) with ESP32 in several frameworks:

• Arduino IDE
• ESP-IDF
• ESPHome
• PlatformIO
• MicroPython

If you encounter issues while using the DS3231 / AT24C32 Real-Time Clock (RTC), check the Common Issues Troubleshooting Guide.

ESP32 DS3231 / AT24C32 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the DS3231 / AT24C32 Real-Time Clock (RTC):

#include <Wire.h>
#include <RTClib.h>

RTC_DS3231 rtc;

void setup() {
    Serial.begin(9600);
    Wire.begin();
    if (!rtc.begin()) {
        Serial.println("Couldn't find RTC");
        while (1);
    }
    if (rtc.lostPower()) {
        rtc.adjust(DateTime(2023, 12, 4, 14, 30, 0)); // Set initial date/time
    }
}

void loop() {
    DateTime now = rtc.now();
    Serial.print("Time: ");
    Serial.print(now.hour());
    Serial.print(":");
    Serial.print(now.minute());
    Serial.print(":");
    Serial.println(now.second());
    Serial.print("Date: ");
    Serial.print(now.year());
    Serial.print("/");
    Serial.print(now.month());
    Serial.print("/");
    Serial.println(now.day());
    delay(1000);
}

This Arduino sketch demonstrates how to interface with the DS3231 RTC module using the RTClib library. In the setup() function, the RTC is initialized, and if it has lost power, the date and time are set. The loop() function retrieves the current time and date from the RTC and prints them to the Serial Monitor every second.

Connect your ESP32 to your computer via a USB cable, Ensure the correct Board and Port are selected under Tools, Click the "Upload" button in the Arduino IDE to compile and upload the code to your ESP32.

ESP32 DS3231 / AT24C32 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the DS3231 / AT24C32 Real-Time Clock (RTC), here's how you can set it up and read data from the sensor. Fill in this code in the main ESP-IDF file:

#include <stdio.h>
#include "driver/i2c.h"
#include "ds3231.h"

#define I2C_MASTER_SCL_IO 22
#define I2C_MASTER_SDA_IO 21

void app_main(void) {
    i2c_config_t i2c_config = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = I2C_MASTER_SDA_IO,
        .scl_io_num = I2C_MASTER_SCL_IO,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .master.clk_speed = 100000
    };
    i2c_param_config(I2C_NUM_0, &i2c_config);
    i2c_driver_install(I2C_NUM_0, I2C_MODE_MASTER, 0, 0, 0);

    ds3231_init(I2C_NUM_0);
    ds3231_set_datetime(2023, 12, 4, 14, 30, 0);

    while (1) {
        ds3231_datetime_t now;
        ds3231_get_datetime(&now);
        printf("Time: %02d:%02d:%02d\n", now.hour, now.minute, now.second);
        printf("Date: %04d/%02d/%02d\n", now.year, now.month, now.day);
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

This ESP-IDF example demonstrates how to interface with the DS3231 RTC over I²C. SDA and SCL are connected to GPIO21 and GPIO22, respectively. The RTC is initialized, and the date and time are set using ds3231_set_datetime(). The current time and date are retrieved with ds3231_get_datetime() and displayed on the console every second.

Update the I2C pins (I2C_MASTER_SDA_IO and I2C_MASTER_SCL_IO) to match your ESP32 hardware setup, Use idf.py build to compile the project, Use idf.py flash to upload the code to your ESP32.

ESP32 DS3231 / AT24C32 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the DS3231 / AT24C32 Real-Time Clock (RTC)

i2c:
  sda: GPIO21
  scl: GPIO22

time:
  - platform: ds3231
    id: ds3231_time
    update_interval: 1s

sensor:
  - platform: custom
    lambda: |-
      auto my_sensor = new DS3231Sensor(id(ds3231_time));
      return {my_sensor};
    sensors:
      - name: "DS3231 Date and Time"

The ESPHome configuration sets up I²C communication with the DS3231 RTC using SDA on GPIO21 and SCL on GPIO22. The time platform fetches the date and time at 1-second intervals. A custom sensor processes and displays the time and date in a human-readable format.

Upload this code to your ESP32 using the ESPHome dashboard or the esphome run command.

ESP32 DS3231 / AT24C32 PlatformIO Code Example

Example in PlatformIO Framework

For PlatformIO, make sure to configure the platformio.ini file with the appropriate environment and libraries, and then proceed with the code.

Configure platformio.ini

First, your platformio.ini should look like below. You might need to include some libraries as shown. Make sure to change the board to your ESP32:

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

ESP32 DS3231 / AT24C32 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the DS3231 / AT24C32 Real-Time Clock (RTC):

#include <Wire.h>
#include <RTClib.h>

RTC_DS3231 rtc;

void setup() {
    Serial.begin(115200);
    Wire.begin(21, 22); // SDA: GPIO21, SCL: GPIO22
    if (!rtc.begin()) {
        Serial.println("Couldn't find RTC");
        while (1);
    }
    if (rtc.lostPower()) {
        rtc.adjust(DateTime(2023, 12, 4, 14, 30, 0)); // Set initial date/time
    }
}

void loop() {
    DateTime now = rtc.now();
    Serial.print("Time: ");
    Serial.print(now.hour());
    Serial.print(":");
    Serial.print(now.minute());
    Serial.print(":");
    Serial.println(now.second());
    Serial.print("Date: ");
    Serial.print(now.year());
    Serial.print("/");
    Serial.print(now.month());
    Serial.print("/");
    Serial.println(now.day());
    delay(1000);
}

This PlatformIO code demonstrates how to interface with the DS3231 RTC using I²C. SDA and SCL are connected to GPIO21 and GPIO22, respectively. The RTC is initialized, and if it has lost power, the date and time are set. The loop() retrieves the current time and date and prints them every second.

Upload the code to your ESP32 using the PlatformIO "Upload" button in your IDE or the pio run --target upload command.

ESP32 DS3231 / AT24C32 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the DS3231 / AT24C32 Real-Time Clock (RTC) with your ESP32.

from machine import I2C, Pin
import time

# DS3231 I2C address
DS3231_ADDRESS = 0x68

def bcd_to_decimal(bcd):
    return (bcd >> 4) * 10 + (bcd & 0x0F)

def decimal_to_bcd(decimal):
    return ((decimal // 10) << 4) | (decimal % 10)

def set_time(i2c, year, month, day, hour, minute, second):
    data = [decimal_to_bcd(second), decimal_to_bcd(minute), decimal_to_bcd(hour),
            decimal_to_bcd(day), 0, decimal_to_bcd(month), decimal_to_bcd(year - 2000)]
    i2c.writeto_mem(DS3231_ADDRESS, 0x00, bytes(data))

def get_time(i2c):
    data = i2c.readfrom_mem(DS3231_ADDRESS, 0x00, 7)
    second = bcd_to_decimal(data[0])
    minute = bcd_to_decimal(data[1])
    hour = bcd_to_decimal(data[2])
    day = bcd_to_decimal(data[4])
    month = bcd_to_decimal(data[5] & 0x1F)
    year = bcd_to_decimal(data[6]) + 2000
    return year, month, day, hour, minute, second

# Initialize I2C
i2c = I2C(0, scl=Pin(22), sda=Pin(21))

# Set initial time
set_time(i2c, 2023, 12, 4, 14, 30, 0)

# Loop to read time
while True:
    year, month, day, hour, minute, second = get_time(i2c)
    print(f"Time: {hour:02}:{minute:02}:{second:02}, Date: {year:04}/{month:02}/{day:02}")
    time.sleep(1)

This MicroPython script interfaces with the DS3231 RTC over I²C using SDA (GPIO21) and SCL (GPIO22). The set_time() function sets the date and time on the DS3231 by writing BCD-encoded values to its memory. The get_time() function reads the current date and time from the DS3231, decodes the BCD values into integers, and returns them in a human-readable format. The main loop continuously fetches the current time and date from the DS3231 and prints them every second.

Upload this code to your ESP32 using a MicroPython-compatible IDE, such as Thonny, uPyCraft, or tools like ampy.