PIR Sensor for Smart Vending Machines

Introduction

Vending machines are becoming smarter. PIR sensors play a key role in detecting approaching customers, waking up the machine, and powering down when no one is around.

Applications in Vending

Customer Detection

When a person approaches, the machine can:

• Light up the display.
• Activate the touch screen.
• Play a welcoming message.
• Start the payment system.

Energy Saving

Vending machines consume significant energy for lighting, cooling, and displays. By powering down when no customers are present, energy savings of 30-50% are achievable.

Security

Detect tampering or vandalism after hours.

Customer Counting

Track how many people approach vs. make purchases to analyze conversion rates.

Sensor Requirements

• Wide detection angle: To cover the area in front of the machine.
• Adjustable range: Typically 2-5 meters.
• Outdoor capability: For outdoor machines (weatherproof).
• Low power: If battery-powered or to minimize standby consumption.

Implementation

A typical smart vending machine uses:

• PIR sensor mounted on front panel.
• Microcontroller to process detection.
• Relay to control lights and display power.
• Timer to turn off after no motion for set period.

Code Example

int pirPin = 2;
int relayPin = 3;
unsigned long lastMotion = 0;
const unsigned long timeout = 30000; // 30 seconds

void setup() {
    pinMode(pirPin, INPUT);
    pinMode(relayPin, OUTPUT);
    digitalWrite(relayPin, LOW); // Start with everything off
}

void loop() {
    if (digitalRead(pirPin) == HIGH) {
        lastMotion = millis();
        digitalWrite(relayPin, HIGH); // Turn on display/lights
    }
    
    if (millis() - lastMotion > timeout) {
        digitalWrite(relayPin, LOW); // Turn off after timeout
    }
}

Case Study: Coca-Cola Smart Vending

Coca-Cola deployed smart vending machines with PIR sensors. The machines reduced energy consumption by 35% and increased customer engagement with interactive displays that only activated when someone approached.

Challenges

• False triggers: People walking past without stopping. Use hold time to ensure genuine approach.
• Environmental factors: Outdoor machines face sun, rain, temperature extremes.
• Cleaning: Lens must stay clean in dusty environments.

Integration with Payment Systems

The PIR sensor can also wake up the payment terminal (card reader, cash acceptor) only when needed, saving power.

Conclusion

PIR sensors make vending machines smarter and more energy-efficient. They are a low-cost addition that pays for itself through energy savings.