Circuit Documentation

Summary

This circuit is designed to measure and display the water flow rate using a Water Flow Rate Sensor YF-S401 and a 16x2 I2C LCD. The Arduino UNO microcontroller is used to process the sensor data and control the display. The system also includes a buzzer and LEDs to provide alerts based on the flow rate.

Component List

Arduino UNO

• Description: A microcontroller board based on the ATmega328P.
• Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

Water Flow Rate Sensor YF-S401

• Description: A sensor used to measure the flow rate of water.
• Pins: GND negative, IN positive, OUT signal output

16x2 I2C LCD

• Description: A 16x2 character LCD with I2C interface.
• Pins: GND, VCC, SDA, SCL

Wiring Details

Arduino UNO

• 5V: Connected to VCC of the 16x2 I2C LCD and IN positive of the Water Flow Rate Sensor YF-S401
• GND: Connected to GND of the 16x2 I2C LCD and GND negative of the Water Flow Rate Sensor YF-S401
• A4: Connected to SDA of the 16x2 I2C LCD
• A5: Connected to SCL of the 16x2 I2C LCD
• D2: Connected to OUT signal output of the Water Flow Rate Sensor YF-S401

Water Flow Rate Sensor YF-S401

• GND negative: Connected to GND of the Arduino UNO
• IN positive: Connected to 5V of the Arduino UNO
• OUT signal output: Connected to D2 of the Arduino UNO

16x2 I2C LCD

• GND: Connected to GND of the Arduino UNO
• VCC: Connected to 5V of the Arduino UNO
• SDA: Connected to A4 of the Arduino UNO
• SCL: Connected to A5 of the Arduino UNO

Code Documentation

#define buzzer A2
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
#define ledg A1
#define ledr A0

volatile int flow_frequency; // Measures flow sensor pulses
float vol = 0.0, l_minute;
unsigned char flowsensor = 2; // Sensor Input
float fvol; // Flow volume in liters
float limitValue = 0.0; // Limit value entered from keypad
float flowRate;

unsigned long currentTime;
unsigned long cloopTime;

LiquidCrystal_I2C lcd(0x27, 16, 2);

const byte ROWS = 4; // Four rows
const byte COLS = 4; // Three columns

char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},     // D - Enter, C - Unused, B - Backspace
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}      // * - Decimal Point
};

byte rowPins[ROWS] = {13, 12, 11, 10};
byte colPins[COLS] = {9, 8, 7, 6};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
String input = ""; // Variable to store input as it is typed
bool monitoring = true; // Flag to control operation

void flow() { 
  flow_frequency++; 
} // Interrupt function for flow sensor

void setup() {
  pinMode(flowsensor, INPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(ledg, OUTPUT);
  pinMode(ledr, OUTPUT);

  digitalWrite(flowsensor, HIGH); // Optional Internal Pull-Up
  Serial.begin(9600);

  digitalWrite(ledg, LOW);
  digitalWrite(ledr, LOW);

  attachInterrupt(digitalPinToInterrupt(flowsensor), flow, RISING); // Setup Interrupt
  lcd.init();
  lcd.backlight();

  lcd.setCursor(3, 0);
  lcd.print("WELCOME TO");
  lcd.setCursor(0, 1);
  lcd.print("WATER FLOW METER");
  delay(3000);
  lcd.clear();

  lcd.setCursor(0, 0);
  lcd.print("Press C for");
  lcd.setCursor(0, 1);
  lcd.print("Limit 0.5 L");
  delay(2000);
  lcd.clear();

  // Check if the user presses 'C' at the start
  lcd.setCursor(0, 0);
  lcd.print("Set Limit:");
  lcd.setCursor(0, 1);
  lcd.print("Press 'C'...");
  
  while (true) {
    char key = keypad.getKey();
    if (key == 'C') {
      limitValue = 0.5; // Set limit to 0.5
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Limit Set To:");
      lcd.setCursor(0, 1);
      lcd.print("0.5 L");
      delay(2000);
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Monitoring...");
      break;
    } else if (key == 'D') { // Proceed to set custom limit
      setLimitPrompt();
      break;
    }
  }
}

void loop() {
  char key = keypad.getKey();

  if (key) {
    if (monitoring) {
      handleMonitoringKey(key);
    } else {
      handlePostLimitKey(key);
    }
  }

  if (monitoring) {
    checkFlowRate();
  }
}

void handleMonitoringKey(char key) {
  // Handle 'B' for backspace
  if (key == 'B') {
    if (input.length() > 0) {
      input.remove(input.length() - 1); // Remove last character
      updateLCD();
    }
  }
  // Handle 'D' for enter key
  else if (key == 'D') {
    // Convert input to float and store in limitValue as the threshold
    limitValue = input.toFloat();
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Limit Set To:");
    lcd.setCursor(0, 1);
    lcd.print(limitValue); // Display the entered limit
    Serial.print("Limit value set to: ");
    Serial.println(limitValue); // Debugging output
    delay(2000);
    input = ""; // Clear input buffer
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Monitoring...");
  }
  // Handle '*' for decimal point
  else if (key == '*') {
    if (input.indexOf('.') == -1) {
      input += '.';
      updateLCD();
    }
  }
  // Handle regular characters
  else {
    input += key;
    updateLCD();
  }
}

void handlePostLimitKey(char key) {
  if (key == '#') {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Operation Stopped");
    Serial.println("Operation Stopped"); // Debugging output
    monitoring = false; // Stop further monitoring
  } else if (key == 'A') {
    vol = 0.0; // Reset volume
    fvol = 0.0;
    setLimitPrompt();
    monitoring = true; // Restart monitoring
  }
}

void checkFlowRate() {
  currentTime = millis();
  if (currentTime >= (cloopTime + 1000)) {
    cloopTime = currentTime; // Updates cloopTime
    if (flow_frequency != 0) {
      l_minute = (flow_frequency / 7.5) / 60.0; // L/min to L/sec
      flowRate = l_minute * 1000; // Flow rate in mL/sec

      vol += l_minute; // Accumulate volume in L
      fvol = vol / 10; // Convert to liters if needed

      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Rate:");
      lcd.print(flowRate);
      lcd.print(" mL/S");

      lcd.setCursor(0, 1);
      lcd.print("Vol:");
      lcd.print(fvol);
      lcd.print(" L");

      flow_frequency = 0; // Reset Counter

      Serial.print("Current flow rate: ");
      Serial.println(flowRate);
      Serial.print("Total volume: ");
      Serial.println(fvol);

      // Control LED based on flow
      if (flowRate > 0) {
        digitalWrite(ledg, HIGH);
      } else {
        digital