DS1302 Real-Time Clock (RTC)

// Requires the esp-idf-lib DS1302 driver from the ESP Component Registry:
//   idf.py add-dependency "esp-idf-lib/ds1302^1.2.0"

#include <stdio.h>
#include <string.h>
#include <time.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "ds1302.h"

#define CE_GPIO   GPIO_NUM_5  // RST, matches the wiring above
#define IO_GPIO   GPIO_NUM_23 // I/O
#define SCLK_GPIO GPIO_NUM_18 // SCLK

void app_main(void)
{
    ds1302_t dev = {
        .ce_pin = CE_GPIO,
        .io_pin = IO_GPIO,
        .sclk_pin = SCLK_GPIO,
    };
    ESP_ERROR_CHECK(ds1302_init(&dev));
    ESP_ERROR_CHECK(ds1302_set_write_protect(&dev, false));

    while (1) {
        struct tm time;
        if (ds1302_get_time(&dev, &time) == ESP_OK)
            printf("%04d-%02d-%02d %02d:%02d:%02d\n",
                   time.tm_year + 1900, time.tm_mon + 1, time.tm_mday,
                   time.tm_hour, time.tm_min, time.tm_sec);
        else
            printf("Could not read time from RTC\n");
        vTaskDelay(pdMS_TO_TICKS(1000));
    }
}

external_components:
  - source: github://trombik/esphome-component-ds1302
    components: [ds1302]

time:
  - platform: ds1302
    id: rtc_time
    cs_pin: GPIO5    # RST/CE, matches the wiring above
    dio_pin: GPIO23  # I/O
    clk_pin: GPIO18  # SCLK
    update_interval: never

text_sensor:
  - platform: template
    name: "DS1302 Date and Time"
    lambda: |-
      char buf[20];
      auto now = id(rtc_time).now();
      if (!now.is_valid()) return {"unknown"};
      now.strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S");
      return {buf};
    update_interval: 1s

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200
lib_deps =
    caligari/Ds1302 @ ^1.1.0

#include <Arduino.h>
#include <Ds1302.h>

// RST (CE) = GPIO5, CLK = GPIO18, DAT (I/O) = GPIO23 - matches the wiring above
Ds1302 rtc(5, 18, 23); // ENA (RST), CLK, DAT

void setup() {
    Serial.begin(115200);
    rtc.init();

    if (rtc.isHalted()) {
        Serial.println("RTC is halted. Setting the time...");
        Ds1302::DateTime dt = {
            .year = 26, .month = Ds1302::MONTH_SEP, .day = 1,
            .hour = 12, .minute = 0, .second = 0,
            .dow = Ds1302::DOW_TUE
        };
        rtc.setDateTime(&dt);
    }
}

void loop() {
    Ds1302::DateTime now;
    rtc.getDateTime(&now);

    Serial.print("Time: ");
    Serial.print(now.hour);
    Serial.print(":");
    Serial.print(now.minute);
    Serial.print(":");
    Serial.println(now.second);
    Serial.print("Date: 20");
    Serial.print(now.year);
    Serial.print("/");
    Serial.print(now.month);
    Serial.print("/");
    Serial.println(now.day);
    delay(1000);
}

# Requires driver: ds1302.py from https://github.com/omarbenhamid/micropython-ds1302-rtc
# Copy it to the board: mpremote cp ds1302.py :
from machine import Pin
from ds1302 import DS1302
import time

# Pins per the wiring above: SCLK=GPIO18, I/O=GPIO23, RST/CE=GPIO5
rtc = DS1302(Pin(18), Pin(23), Pin(5))

# Set the clock once (year, month, day, weekday, hour, minute, second), then comment out
# rtc.date_time([2026, 9, 1, 1, 12, 0, 0])

while True:
    year, month, day, weekday, hour, minute, second = rtc.date_time()
    print("{:04d}-{:02d}-{:02d} {:02d}:{:02d}:{:02d}".format(year, month, day, hour, minute, second))
    time.sleep(1)