Water Vending Machine

[kathy15]

Hello I am planning on making a water vending Machine but instead of coins I will use plastic bottles (small, medium, larger) but the problem is :(I am using tinkerCad)

• the LCD is not showing any texts

This is the circuit:

Here is the code:

#include <Wire.h>
#include <LiquidCrystal.h>  // Include standard LCD library
#include <Servo.h>

// Initialize the LCD (using new pins)
LiquidCrystal lcd(10, 11, 12, 3, 4, 13);  // Adjust pins according to your wiring

// Pin Definitions
const int trigPin = 9;        // Ultrasonic trigger
const int echoPin = 8;        // Ultrasonic echo
const int redLedPin = 7;      // Red LED for scanning
const int greenLedPin = 6;    // Green LED for "Okay"
const int buttonPin = 5;      // Push button for starting
const int servoPin = 2;       // Servo motor for water valve

// Servo object
Servo waterValve;

// Bottle Sizes (in cm)
#define SMALL_BOTTLE_DIST 50  // Distance thresholds in cm
#define MEDIUM_BOTTLE_DIST 70
#define LARGE_BOTTLE_DIST 100

// Timing
unsigned long waterTime = 0;  // Time to keep servo valve open
bool isButtonPressed = false;

void setup() {
  // Start Serial communication for debugging
  Serial.begin(9600);

  // Initialize I/O pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(redLedPin, OUTPUT);
  pinMode(greenLedPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP); // Using internal pull-up resistor for the button

  // Initialize the Servo motor
  waterValve.attach(servoPin);
  waterValve.write(0);  // Keep valve closed (0 degrees)

  // Initialize the LCD
  lcd.begin(16, 2);
  lcd.print("Water Vending");
  lcd.setCursor(0, 1);
  lcd.print("Insert Bottle");

  // Display initial message in the serial monitor
  Serial.println("System Ready");
}

void loop() {
  // Measure distance to detect bottle
  float distance = getDistance();

  // Determine bottle type based on distance
  String bottleType;
  if (distance <= SMALL_BOTTLE_DIST) {
    bottleType = "Small";
    waterTime = 5000;  // 5 seconds of water
  } else if (distance <= MEDIUM_BOTTLE_DIST) {
    bottleType = "Medium";
    waterTime = 7000;  // 7 seconds of water
  } else if (distance <= LARGE_BOTTLE_DIST) {
    bottleType = "Large";
    waterTime = 10000; // 10 seconds of water
  } else {
    bottleType = "No Bottle";
  }

  // Display bottle type on the LCD
  lcd.clear();
  lcd.setCursor(0, 0);  // Set cursor at the top left
  lcd.print("Bottle Type:");
  lcd.setCursor(0, 1);  // Move to the next line
  lcd.print(bottleType);

  // Output bottle type to Serial Monitor
  Serial.print("Bottle Type: ");
  Serial.println(bottleType);

  // Scanning: Turn red LED on during detection
  digitalWrite(redLedPin, HIGH);

  // Check if a bottle is detected and button is pressed
  if (bottleType != "No Bottle" && digitalRead(buttonPin) == LOW) {
    isButtonPressed = true;
  }

  if (isButtonPressed) {
    // Turn off red LED and turn on green LED to indicate water dispensing
    digitalWrite(redLedPin, LOW);
    digitalWrite(greenLedPin, HIGH);

    // Open the water valve by rotating the servo to 90 degrees
    waterValve.write(90);
    delay(waterTime);  // Keep valve open for the set amount of time

    // Close the valve by rotating the servo back to 0 degrees
    waterValve.write(0);
    digitalWrite(greenLedPin, LOW);

    // Reset the button state
    isButtonPressed = false;

    // Display the countdown on LCD during dispensing
    for (int i = waterTime / 1000; i > 0; i--) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Dispensing Water");
      lcd.setCursor(0, 1);
      lcd.print("Time Left: ");
      lcd.print(i);
      lcd.print(" s");
      delay(1000);
    }
  }
}

// Function to measure distance using ultrasonic sensor (returns cm)
float getDistance() {
  // Trigger the sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the echo
  long duration = pulseIn(echoPin, HIGH);

  // Calculate distance in cm
  float distance = duration * 0.034 / 2;  // Convert to cm

  return distance;
}

[alto777]

Does it print

  // Display initial message in the serial monitor
  Serial.println("System Ready");
}

but show nothing on the LCD?

Remove from setup() anything that has nothing to do with the LCD, and stop the code executing at the end of setup(), a long delay will do

  // Display initial message in the serial monitor
  Serial.println("System Ready");

  delay(60000);
}

These steps are to isolate the LCD problem until you can fix it.

An alternate would be to use a sketch provided somewhere as a simple example of putting text on an LCD.

Working from simlpe code, or better yet a perfect and small example sketch you did not write or mess with is a good way to get each little part of your projext working , and gives you an opportunity to learn about those little parts.

Then using them and combining them will be its own challenge, but as least you'll know the separate parts all work.

a7

[kathy15]

It doesn't print anything and also the LCD has no backlight is there something wrong with the connection?

[alto777]

Since you are using a simulation, we can expect that you have a wiring issue.

Does the simulation need a contrast potentialometer?

Have you examined closely an example for using the simulated LCD in the simulator you have chosen?

a7

[kathy15]

Yes I already saw the example and it uses a potentiometer

[J-M-L]

does this print anything ?

#include <LiquidCrystal.h>  // Include standard LCD library
LiquidCrystal lcd(10, 11, 12, 3, 4, 13);  // Adjust pins according to your wiring

void setup() {
  lcd.begin(16, 2);
  lcd.clear();
  lcd.print("Water Vending");
}

void loop() {}

if not double check that 10, 11, 12, 3, 4, 13 are in the right order / at the right place. They should go respectively to rs, enable, d0, d1, d2, d3

[kathy15]

I checked it and it is the right order but still no texts

[J-M-L]

@J-M-L

LiquidCrystal.h

if you rewire using the pins from the HelloWorld example

examples/HelloWorld/HelloWorld.ino

does it work?

[kathy15]

I saw the problem already it needs a potentiometer. By the way, thank you and it works now

[LarryD]

@kathy15

LCD has no backlight