Coin Acceptor false pulse

[bingbongfx]

Hi, im building a cigar vendo however when im about to insert a coin and it makes contact on the surface of coin acceptor cover, it's giving a false pulse. It does it when Im not touching the actual vending cointainer, but when im touching the container itself it works fine. It fixes the issue if i attach a grounding wire, I dont want to keep the grounding wire just to make it work. What can I do?

Im using a ground bus for common ground,

-(disregard servo wire connection from image. Currently using 5v separate power supply for it)

[Railroader]

What's wrong with the grounding wire?
Where is that wire in the picture?
Give the servo an extternal power supply. Controllers are designed to supply power.

[jim-p]

Seems like we already went through this with your other topic for this coin acceptor.

Why do I keep on frying my uno board?

with the same code and diagram, what is the probable cause of unwanted pulse like this video below?

[bingbongfx]

Unfortunately it comes and go. Maybe when i thought it was working already. I was holding the container while inserting the coins

[jim-p]

@bingbongfx

m using a ground bus for common ground,

What do you mean by "bus"
I thought you soldered everything together but you still show a solderless breadboard.

[jim-p]

Post your code

[bingbongfx]

#include <Servo.h>
#include <Arduino.h>
#include <EEPROM.h>
#include <LiquidCrystal_I2C.h>

Servo brand0Servo;

const int brand0ButtonPin = 4;
const int coinPin = 2;
const int ledPin = 6;  // Red LED
const int insufficientLedPin = 7;  // Green LED
const int irSensorPin = 8;
const int buzzerPin = 10;  // Pin for the buzzer

volatile int impulsCount = 0;
float totalAmount = 0.0;
float coinValue;

const char *brand0Name = "Cigar";
const int brand0Price = 8;

const int coinPulses[] = {1, 2, 5, 10};
const float coinValues[] = {1.0, 2.0, 5.0, 10.0};

LiquidCrystal_I2C lcd(0x27, 16, 2);

unsigned long previousMillis = 0;
const unsigned long interval = 3000;
int messageState = 0;
bool transactionActive = false;
bool outOfStockDisplayed = false;
bool messageUpdated = false;  // Flag to track message updates
unsigned long ledBlinkMillis = 0;
bool ledState = false;  // For blinking LED

float lookup(int pulses) {
    for (int i = 0; i < sizeof(coinPulses) / sizeof(coinPulses[0]); i++) {
        if (pulses == coinPulses[i]) {
            return coinValues[i];
        }
    }
    return -1;
}

void setup() {
    pinMode(brand0ButtonPin, INPUT_PULLUP);
    pinMode(coinPin, INPUT);
    pinMode(ledPin, OUTPUT);
    pinMode(insufficientLedPin, OUTPUT);
    pinMode(irSensorPin, INPUT);
    pinMode(buzzerPin, OUTPUT);  // Set buzzer pin as output

    attachInterrupt(digitalPinToInterrupt(coinPin), coinInterrupt, FALLING);

    brand0Servo.attach(9);
    brand0Servo.write(60);

    lcd.init();
    lcd.clear();
    lcd.backlight();
    
    Serial.begin(9600);

    checkStockOnBoot();  // Check stock on boot and handle initial state
}

void coinInterrupt() {
    impulsCount++;
}

void checkStockOnBoot() {
    if (digitalRead(irSensorPin) == LOW) {  // Stock available
        resetDisplay();
        outOfStockDisplayed = false;
        messageUpdated = false;  // Allow message toggling
    } else {  // Stock out
        handleOutOfStock();  // Handle out-of-stock state
    }
}

void handleOutOfStock() {
    lcd.clear();
    lcd.setCursor(4, 0);
    lcd.print("OUT OF");
    lcd.setCursor(5, 1);
    lcd.print("STOCK");
    totalAmount = 0.0;
    outOfStockDisplayed = true;
    beepOutOfStock();  // Beep for out of stock
}

void monitorStock() {
    if (digitalRead(irSensorPin) == LOW) {  // Stock available
        if (outOfStockDisplayed) {
            resetDisplay();  // Reset display if stock is replenished
            outOfStockDisplayed = false;
        }
    } else {  // Stock out
        if (!outOfStockDisplayed) {
            handleOutOfStock();  // Handle out-of-stock state
        }
    }
}

bool checkStockBeforeDispense() {
    if (digitalRead(irSensorPin) == LOW) {  // Stock available
        outOfStockDisplayed = false;
        return true;
    } else {  // Stock out
        if (!outOfStockDisplayed) {
            handleOutOfStock();
        }
        return false;
    }
}

void loop() {
    unsigned long currentMillis = millis();

    // Continuously monitor stock availability
    monitorStock();

    // Handle LED blinking when stock is out
    if (outOfStockDisplayed) {
        if (currentMillis - ledBlinkMillis >= 200) {  // Toggle LED every 500ms
            ledBlinkMillis = currentMillis;
            ledState = !ledState;
            if (ledState) {
                digitalWrite(ledPin, HIGH);  // Turn on red LED
                digitalWrite(insufficientLedPin, LOW);  // Turn off green LED
            } else {
                digitalWrite(ledPin, LOW);  // Turn off red LED
                digitalWrite(insufficientLedPin, HIGH);  // Turn on green LED
            }
        }
    } else {
        // Reset the LED to the balance state after transaction
        if (totalAmount <= 7) {
            digitalWrite(ledPin, HIGH);  // Red LED on
            digitalWrite(insufficientLedPin, LOW);  // Green LED off
        } else {
            digitalWrite(ledPin, LOW);  // Red LED off
            digitalWrite(insufficientLedPin, HIGH);  // Green LED on
        }
    }

    // Only update the message after the interval has passed and the message has not been updated
    if (!transactionActive && currentMillis - previousMillis >= interval && !messageUpdated) {
        previousMillis = currentMillis;
        messageState = (messageState + 1) % 2;
        messageUpdated = true;  // Set flag to indicate the message has been updated
        resetDisplay();
    }

    if (impulsCount > 0) {
        coinValue = lookup(impulsCount);
        if (coinValue > 0) {
            totalAmount += coinValue;
            transactionActive = true;
            beepCoinInserted();  // Beep when a coin is inserted
        }

        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("  YOUR BALANCE");
        lcd.setCursor(0, 1);
        lcd.print("   Php ");
        lcd.print(totalAmount, 2);

        impulsCount = 0;
    }

    // LED Behavior: Turn on red if insufficient funds, green if sufficient funds
    if (totalAmount >= brand0Price) {
        digitalWrite(ledPin, LOW);  // Turn off red LED
        digitalWrite(insufficientLedPin, HIGH);  // Turn on green LED
    } else {
        digitalWrite(ledPin, HIGH);  // Turn on red LED
        digitalWrite(insufficientLedPin, LOW);  // Turn off green LED
    }

    if (digitalRead(brand0ButtonPin) == LOW) {
        if (totalAmount == 0) {
            displayMessage("Insert Coin", 2000);
            beepInsufficientFunds();  // Beep if insufficient funds
        } else if (totalAmount < brand0Price) {
            displayMessage("Add More Coins", 2000);
            beepInsufficientFunds();  // Beep if insufficient funds
        } else if (outOfStockDisplayed) {
            // If stock is out and button is pressed, show "COME BACK LATER"
            displayMessage("  COME BACK", 1000);
            displayMessage("    LATER", 1000);
        }
    }

    if (digitalRead(brand0ButtonPin) == LOW && totalAmount >= brand0Price && !outOfStockDisplayed) {
        dispenseCigar(brand0Servo, brand0Name, brand0Price);
        beepSufficientFunds();  // Beep when the item is dispensed
    }

    // Reset messageUpdated flag after user interaction to allow toggling
    if (digitalRead(brand0ButtonPin) == LOW || impulsCount > 0) {
        messageUpdated = false;  // Allow message to toggle again after user action
    }
}

void displayMessage(const char *message, int duration) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print(message);
    delay(duration);
    resetDisplay();
}

void beepCoinInserted() {
    tone(buzzerPin, 4000, 200);  // Short beep when a coin is inserted
}

void beepSufficientFunds() {
    tone(buzzerPin, 3000, 2000);  // Long beep if funds are sufficient
}

void beepInsufficientFunds() {
    for (int i = 0; i < 3; i++) {
        tone(buzzerPin, 3000, 200);  // Beep 3 times if insufficient funds
        delay(200);
    }
}

void beepOutOfStock() {
    for (int i = 0; i < 50; i++) {
        tone(buzzerPin, 5000, 150);  // Beep 10 times if out of stock
        delay(150);
    }
}

void resetDisplay() {
    if (messageState == 0) {
        lcd.clear();  // Clear display only if necessary
        lcd.setCursor(0, 0);
        lcd.print("  EXACT AMOUNT");
        lcd.setCursor(0, 1);
        lcd.print("      ONLY!");
    } else {
        lcd.clear();  // Clear display only if necessary
        lcd.setCursor(0, 0);
        lcd.print("  CIGAR VENDO");
        lcd.setCursor(0, 1);
        lcd.print("   NO MINORS!");
    }
}

void dispenseCigar(Servo &servo, const char *brandName, int price) {
    int cigars = totalAmount / price;

    for (int i = cigars; i > 0; i--) {
        if (!checkStockBeforeDispense()) {  // Check stock before dispensing
            return;
        }

        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Dispensing ");
        lcd.setCursor(0, 1);
        lcd.print(String(brandName) + " " + String(i));

        servo.write(0);
        delay(300);
        servo.write(30);
        delay(300);
        servo.write(0);
        delay(300);
        servo.write(30);
        delay(300);
        servo.write(0);
        delay(300);
        servo.write(30);
        delay(300);
        servo.write(60);
        delay(300);
    }

    totalAmount = 0.0;
    transactionActive = false;
    digitalWrite(ledPin, LOW);
    digitalWrite(insufficientLedPin, LOW);

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("   THANK YOU!");
    delay(2000);
    resetDisplay();
}

not really into electronics, please bear with my diagram

[jim-p]

@bingbongfx

It fixes the issue if i attach a grounding wire, I dont want to keep the grounding wire just to make it work.

Sounds like it may be a static electricity problem. I suggest you keep the ground wire connected. The ground wire provides a path for the static electricity so that it does not create a pulse. You may also try decreasing the 10K pullup to maybe 3.3K

[the_com3_port]

IINM, it seems like the cover is floating, which can of course create mishaps like that. did you check that the cover is grounded from the accepter ground?

[bingbongfx]

all modules are in the common ground, If I add extra wire from ground to earth, it works fine, without it, it gives false pulse.

[the_com3_port]

ooh it's 220V then

[bingbongfx]

the cover is plastic, I dont see any reason why it should be grounded

[the_com3_port]

it is plastic? hmmm

[bingbongfx]

those three dc's are connected in a one 3 gang outlet to 220v

[the_com3_port]

could you specify what dcs or 3 gang means? excuse my bad english (i'm turkish)

[bingbongfx]

@the_com3_port

it is plastic?

yes it is

@the_com3_port

dcs or 3 gang means

I dont know the global term too, but locally we call it that way,
dc adapters, and 3 gang outlet,where you can technically plug 3 different devices

[jim-p]

@bingbongfx

all modules are in the common ground, If I add extra wire from ground to earth, it works fine, without it, it gives false pulse.

See post #10

[jim-p]

@bingbongfx

the cover is plastic, I dont see any reason why it should be grounded

If it looks like this, then it is metalized plastic.

[bingbongfx]

10k is what most people with the same projects recommend, but I'll try to lower the resistance and see if it works

[jim-p]

It will help increase the noise immunity and make it harder for static to generate a pulse.