A Step-by-Step Raindrop Sensor Project with Real-Time Monitoring

				
					#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
// Define OLED screen parameters
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
// Create OLED object
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
// Pin definition
const int waterLevelPin = A0;  
const int buzzerPin = 7;       
// Alarm threshold (alarm when the value is below this)
const int alarmThreshold = 300;
//  State judgment thresholds
const int highToMediumThreshold = 600;  
const int mediumToLowThreshold = 300;   
// Alarm state variable
bool isAlarming = false;
void setup() {
  // Initialize serial port
  Serial.begin(9600);
  // Configure buzzer pin as output and ensure initial state is off
  pinMode(buzzerPin, OUTPUT);
  digitalWrite(buzzerPin, LOW);  
  //  Initialize OLED
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); 
  } 
  // Initial display
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println(F("Water Level Monitor"));
  display.println(F("Ready"));
  display.display();  
  delay(2000);
}
void loop() {
    // Note: The smaller the value, the larger the raindrops/higher the water level
  int waterLevel = analogRead(waterLevelPin);  
  String waterStatus;
  if (waterLevel < mediumToLowThreshold) {
    waterStatus = "High Level";  
  } else if (waterLevel < highToMediumThreshold) {
    waterStatus = "Medium Level";  
  } else {
    waterStatus = "Low Level";  
  }  
  //  Trigger alarm only when water level is high (value below threshold) and not in alarm state 
  if (waterLevel < alarmThreshold && !isAlarming) {
    triggerAlarm();
  }  
  //  Serial port output information
  Serial.print("Water Level: ");
  Serial.print(waterLevel);
  Serial.print(" - ");
  Serial.println(waterStatus);  
  // OLED display information
  display.clearDisplay();  
  // Title
  display.setTextSize(2);
  display.setCursor(0, 0);
  display.println(F("Water"));
  // Display water level state
  display.setTextSize(1);
  display.setCursor(0, 20);
  display.print(F("Status: "));
  display.println(waterStatus);
  // Display original value
  display.setCursor(0, 35);
  display.print(F("Value: "));
  display.print(waterLevel);
  //  Display voltage value
  float voltage = waterLevel * (5.0 / 1023.0);
  display.setCursor(0, 50);
  display.print(F("Voltage: "));
  display.print(voltage, 2);
  display.print(F("V"));
  // Alarm prompt
  if (isAlarming) {
    display.setCursor(80, 50);
    display.print(F("ALARM!"));
  }
  display.display();
  delay(500);
}
// Alarm function
void triggerAlarm() {
  isAlarming = true;
  unsigned long alarmStartTime = millis();
  // Alarm continuously for 2 seconds
  while (millis() - alarmStartTime < 2000) {
    // Buzzer sounds intermittently
    digitalWrite(buzzerPin, HIGH);
    delay(500);
    digitalWrite(buzzerPin, LOW);
    delay(500);
    
    loop(); 
  }
  digitalWrite(buzzerPin, LOW);
  isAlarming = false;
}