Catatan penting: saya anggap board yang dipakai adalah NodeMCU ESP8266, bukan Arduino Uno biasa. Karena Telegram butuh WiFi, lebih cocok pakai ESP8266 langsung.

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HC-SR04 ECHO ---- R1 1kΩ ----+---- D6 NodeMCU
                             |
                           R2 2kΩ
                             |
                            GND

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NodeMCU Pin ---- Resistor 220Ω ---- Anoda LED
Katoda LED ------------------------ GND

1. ESP8266WiFi
2. WiFiClientSecure
3. UniversalTelegramBot
4. ArduinoJson
5. LiquidCrystal_I2C

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Board: NodeMCU 1.0 ESP-12E Module

1. Buka Telegram.
2. Cari BotFather.
3. Kirim:

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/newbot

4. Ikuti instruksi sampai mendapat BOT TOKEN.
5. Cari bot Anda, tekan Start.
6. Untuk mendapatkan CHAT ID, buka di browser:

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https://api.telegram.org/botTOKEN_BOT_ANDA/getUpdates

Cpp
const char* ssid = "NAMA_WIFI";
const char* password = "PASSWORD_WIFI";
#define BOT_TOKEN "TOKEN_BOT_TELEGRAM"
#define CHAT_ID "CHAT_ID_ANDA"

Cpp
#include <ESP8266WiFi.h>
#include <WiFiClientSecure.h>
#include <UniversalTelegramBot.h>
#include <ArduinoJson.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// ==========================
// WiFi dan Telegram
// ==========================
const char* ssid = "NAMA_WIFI";
const char* password = "PASSWORD_WIFI";

#define BOT_TOKEN "TOKEN_BOT_TELEGRAM"
#define CHAT_ID "CHAT_ID_ANDA"

WiFiClientSecure secured_client;
UniversalTelegramBot bot(BOT_TOKEN, secured_client);

// ==========================
// LCD I2C
// ==========================
LiquidCrystal_I2C lcd(0x27, 16, 2);
// Jika LCD tidak tampil, coba ubah 0x27 menjadi 0x3F

// ==========================
// Pin NodeMCU
// ==========================
#define TRIG_PIN D5
#define ECHO_PIN D6

#define LED_HIJAU D0
#define LED_KUNING D7
#define LED_MERAH D8

#define BUZZER_PIN D3

// ==========================
// Batas Level Air
// ==========================
#define BATAS_WASPADA 30
#define BATAS_BAHAYA 15

// ==========================
// Timer Notifikasi
// ==========================
unsigned long lastTelegramTime = 0;
const unsigned long telegramInterval = 60000; 
// kirim notifikasi maksimal setiap 60 detik

String statusSebelumnya = "";

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

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(LED_HIJAU, OUTPUT);
  pinMode(LED_KUNING, OUTPUT);
  pinMode(LED_MERAH, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);

  digitalWrite(LED_HIJAU, LOW);
  digitalWrite(LED_KUNING, LOW);
  digitalWrite(LED_MERAH, LOW);
  digitalWrite(BUZZER_PIN, LOW);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Pendeteksi");
  lcd.setCursor(0, 1);
  lcd.print("Banjir ESP8266");
  delay(2000);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Connect WiFi...");

  WiFi.begin(ssid, password);

  Serial.print("Menghubungkan WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  secured_client.setInsecure();

  Serial.println();
  Serial.println("WiFi Terhubung");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("WiFi Terhubung");
  lcd.setCursor(0, 1);
  lcd.print(WiFi.localIP());
  delay(2000);

  bot.sendMessage(CHAT_ID, "Sistem pendeteksi banjir ESP8266 aktif.", "");
}

void loop() {
  long jarak = bacaJarakCM();

  String statusAir = tentukanStatus(jarak);

  tampilkanLCD(jarak, statusAir);
  kontrolOutput(statusAir);
  kirimTelegramJikaPerlu(jarak, statusAir);

  Serial.print("Jarak: ");
  Serial.print(jarak);
  Serial.print(" cm | Status: ");
  Serial.println(statusAir);

  delay(1000);
}

long bacaJarakCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long durasi = pulseIn(ECHO_PIN, HIGH, 30000);

  if (durasi == 0) {
    return 999;
  }

  long jarak = durasi * 0.034 / 2;
  return jarak;
}

String tentukanStatus(long jarak) {
  if (jarak <= BATAS_BAHAYA) {
    return "BAHAYA";
  } else if (jarak <= BATAS_WASPADA) {
    return "WASPADA";
  } else {
    return "AMAN";
  }
}

void tampilkanLCD(long jarak, String statusAir) {
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("Jarak: ");
  lcd.print(jarak);
  lcd.print(" cm");

  lcd.setCursor(0, 1);
  lcd.print("Status: ");
  lcd.print(statusAir);
}

void kontrolOutput(String statusAir) {
  if (statusAir == "AMAN") {
    digitalWrite(LED_HIJAU, HIGH);
    digitalWrite(LED_KUNING, LOW);
    digitalWrite(LED_MERAH, LOW);
    digitalWrite(BUZZER_PIN, LOW);
  }

  else if (statusAir == "WASPADA") {
    digitalWrite(LED_HIJAU, LOW);
    digitalWrite(LED_KUNING, HIGH);
    digitalWrite(LED_MERAH, LOW);

    digitalWrite(BUZZER_PIN, HIGH);
    delay(100);
    digitalWrite(BUZZER_PIN, LOW);
  }

  else if (statusAir == "BAHAYA") {
    digitalWrite(LED_HIJAU, LOW);
    digitalWrite(LED_KUNING, LOW);
    digitalWrite(LED_MERAH, HIGH);

    digitalWrite(BUZZER_PIN, HIGH);
    delay(300);
    digitalWrite(BUZZER_PIN, LOW);
    delay(100);
  }
}

void kirimTelegramJikaPerlu(long jarak, String statusAir) {
  unsigned long currentTime = millis();

  bool statusBerubah = statusAir != statusSebelumnya;
  bool sudahLewatInterval = currentTime - lastTelegramTime > telegramInterval;

  if ((statusAir == "WASPADA" || statusAir == "BAHAYA") && 
      (statusBerubah || sudahLewatInterval)) {

    String pesan = "";

    if (statusAir == "WASPADA") {
      pesan += "PERINGATAN BANJIR\n";
      pesan += "Status: WASPADA\n";
    } else if (statusAir == "BAHAYA") {
      pesan += "BAHAYA BANJIR!\n";
      pesan += "Status: BAHAYA\n";
    }

    pesan += "Jarak air dari sensor: ";
    pesan += String(jarak);
    pesan += " cm\n";

    if (statusAir == "WASPADA") {
      pesan += "Air mulai naik. Harap dipantau.";
    } else {
      pesan += "Air sangat tinggi. Segera lakukan tindakan.";
    }

    bot.sendMessage(CHAT_ID, pesan, "");

    lastTelegramTime = currentTime;
  }

  if (statusAir == "AMAN" && statusSebelumnya != "AMAN") {
    String pesan = "Status kembali AMAN.\n";
    pesan += "Jarak air dari sensor: ";
    pesan += String(jarak);
    pesan += " cm";

    bot.sendMessage(CHAT_ID, pesan, "");
  }

  statusSebelumnya = statusAir;
}

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           +----------------------+
           |      NodeMCU ESP8266 |
           |                      |
5V/VIN ----+ VIN              GND +---- GND semua modul
           |                      |
D5 --------+ TRIG                 |
D6 <-------+ ECHO via divider     |
           |                      |
D1 --------+ SCL LCD I2C          |
D2 --------+ SDA LCD I2C          |
           |                      |
D0 --------+ LED Hijau + 220R     |
D7 --------+ LED Kuning + 220R    |
D8 --------+ LED Merah + 220R     |
           |                      |
D3 --------+ Buzzer +             |
           +----------------------+

HC-SR04:
VCC -> VIN/5V
GND -> GND
TRIG -> D5
ECHO -> Divider -> D6

LCD I2C:
VCC -> VIN/5V
GND -> GND
SDA -> D2
SCL -> D1

• Letakkan HC-SR04 di atas permukaan air, menghadap ke bawah.
• Ukur jarak dari sensor ke dasar/permukaan maksimum, lalu sesuaikan nilai:
  • BATAS_WASPADA
  • BATAS_BAHAYA
• Jika LED merah di D8 mengganggu proses upload, cabut sementara saat upload program.
• Pastikan semua GND disatukan.
• Gunakan adaptor 5V minimal 1A untuk supply NodeMCU dan modul.