ESP32 DS1307 Real-Time Clock (RTC)

Code Examples

Below you can find code examples of DS1307 Real-Time Clock (RTC) with ESP32 in several frameworks:

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

If you encounter issues while using the DS1307 Real-Time Clock (RTC), check the Common Issues Troubleshooting Guide.

ESP32 DS1307 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the DS1307 Real-Time Clock (RTC):

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

RTC_DS1307 rtc;

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

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 use the DS1307 RTC module for timekeeping. The RTClib library simplifies I2C communication and RTC management. The rtc.adjust() function initializes the DS1307 with a specific date and time if it is not already running. In the loop(), the current date and time are fetched using the rtc.now() method and displayed on the Serial Monitor.

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 DS1307 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the DS1307 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 "ds1307.h"

#define I2C_MASTER_SCL_IO 22
#define I2C_MASTER_SDA_IO 21

void app_main(void) {
    i2c_config_t 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, &config);
    i2c_driver_install(I2C_NUM_0, I2C_MODE_MASTER, 0, 0, 0);

    ds1307_init(I2C_NUM_0);
    ds1307_set_datetime(2023, 12, 4, 14, 30, 0);

    while (1) {
        ds1307_datetime_t now;
        ds1307_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 configure I2C for communication with the DS1307 RTC. The I2C pins (SDA: GPIO21, SCL: GPIO22) are configured, and the RTC is initialized. The ds1307_set_datetime() function sets the initial date and time, while the ds1307_get_datetime() function retrieves the current time and date in a loop, displaying them on the console.

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 DS1307 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the DS1307 Real-Time Clock (RTC)

i2c:
  sda: GPIO21
  scl: GPIO22

sensor:
  - platform: ds1307
    id: ds1307_time
    update_interval: 1s

text_sensor:
  - platform: custom
    lambda: |-
      auto my_sensor = new DS1307Sensor(id(ds1307_time));
      return {my_sensor};
    sensors:
      - name: "DS1307 Date and Time"

The ESPHome configuration for the DS1307 RTC sets up the I2C interface with SDA on GPIO21 and SCL on GPIO22. The sensor platform is used to periodically fetch the date and time, which are displayed with an update interval of 1 second.

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

ESP32 DS1307 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 DS1307 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the DS1307 Real-Time Clock (RTC):

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

RTC_DS1307 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.isrunning()) {
        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 use the DS1307 RTC with I2C communication (SDA: GPIO21, SCL: GPIO22). The code initializes the RTC, sets the initial date and time if required, and fetches the current time and date in a loop, displaying 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 DS1307 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the DS1307 Real-Time Clock (RTC) with your ESP32.

from machine import I2C, Pin
import time

# DS1307 I2C address
DS1307_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), decimal_to_bcd(month), decimal_to_bcd(year - 2000)]
    i2c.writeto_mem(DS1307_ADDRESS, 0x00, bytes(data))
    # Start the clock by ensuring the CH (clock halt) bit is cleared
    control = i2c.readfrom_mem(DS1307_ADDRESS, 0x00, 1)[0] & 0x7F
    i2c.writeto_mem(DS1307_ADDRESS, 0x00, bytes([control]))

def get_time(i2c):
    data = i2c.readfrom_mem(DS1307_ADDRESS, 0x00, 7)
    second = bcd_to_decimal(data[0] & 0x7F)
    minute = bcd_to_decimal(data[1])
    hour = bcd_to_decimal(data[2] & 0x3F)
    day = bcd_to_decimal(data[4])
    month = bcd_to_decimal(data[5])
    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 DS1307 RTC over I²C using SDA (GPIO21) and SCL (GPIO22). The set_time() function initializes the DS1307 with the provided date and time, ensuring the clock is running by clearing the CH (clock halt) bit. The get_time() function reads the current time and date from the DS1307, decodes the BCD values into integers, and returns them. The main loop continuously retrieves the current date and time and prints them every second.

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