Automatic Tea Vending Machine Model with IoT Sales Monitoring

Vending machines are one of the clearest examples of a mechatronic system students can build end to end: payment input, a timed dispensing sequence, fluid handling, level sensing and a sales log all have to work together reliably. Commercial machines hide this machinery; this project makes it visible. A tabletop model dispenses tea on demand — coin or QR payment triggers an Arduino-controlled sequence that runs a 12 V DC pump and solenoid valves for calibrated durations, mixing hot water with milk and tea concentrate into a waiting cup. An ultrasonic cup-presence sensor prevents dispensing without a cup, and float sensors watch tank levels. Every transaction is pushed by an ESP32 to a cloud dashboard, so the owner sees cups sold, revenue and refill alerts — the IoT layer that turns a machine into a manageable business.

1. The buyer inserts a coin or confirms a QR payment; the Arduino registers the credit and arms the dispense cycle.
2. The ultrasonic sensor checks for a cup under the nozzle — if none is found, the machine beeps and refunds the state.
3. The firmware runs the calibrated sequence: hot-water pump on, milk valve open for its timed share, tea concentrate valve for its share, then a short stir/mix pause.
4. The finished cup is signaled with a buzzer and the LCD shows "Enjoy your tea"; the machine returns to idle.
5. The ESP32 posts the transaction (timestamp, drink type, amount) to the cloud dashboard, updating cups-sold and revenue counters.
6. Float sensors continuously report tank levels; when any tank runs low, the dashboard flags a refill alert and the LCD shows which ingredient is needed.
7. The owner views daily sales charts and refill history on the dashboard, demonstrating the complete machine-plus-IoT business loop.

Tech stack:

• Arduino Uno (sequence controller)
• ESP32 (IoT telemetry)
• 12 V DC pump + solenoid valves
• Coin acceptor / QR input
• Ultrasonic + float level sensors
• Cloud dashboard (MQTT/HTTP)
• 16x2 LCD display
• Thermostat heater band

• [Calibrated dispensing sequence] Arduino-timed pump and solenoid valve actuation delivers repeatable tea volumes — water, milk and concentrate each dispensed for firmware-set durations.
• [Coin and QR payment input] A coin acceptor (or QR-scan confirmation) unlocks the dispense cycle, demonstrating real payment-gated automation.
• [Cup-presence safety interlock] An ultrasonic sensor confirms a cup is under the nozzle before dispensing; the cycle aborts with an alert if the cup is missing.
• [Ingredient level monitoring] Float sensors in the water, milk and concentrate tanks warn when a refill is due, both on the local LCD and the cloud dashboard.
• [IoT sales dashboard] Every sale is logged by the ESP32 — cups sold, revenue estimate, time of day — visible as live charts for the owner.
• [Temperature hold] A thermostat-controlled heater band keeps the water tank near serving temperature, with the setpoint shown on the display.
• [Hygiene-first fluid path] Food-grade tubing and a documented cleaning-flush procedure in the report address the real operational concern of a beverage machine.

• Tabletop vending machine cabinet with tanks, pumps and valves fitted
• Arduino + ESP32 electronics (assembled, programmed)
• Cloud sales dashboard setup with refill alerts
• Complete firmware source code with dispense-time calibration guide
• Wiring diagram and fluid-path plumbing guide
• Cleaning and maintenance procedure document
• Project report PDF (background, mechatronics design, firmware, results)
• PPT presentation for final review
• Viva Q&A preparation document (timing control, sensors, IoT telemetry)

• This is a tabletop demonstration model, not a food-safety-certified commercial machine — the report states the hygiene and certification limits plainly.
• Dispense volumes are calibrated by timing, so they drift as pump wear or voltage changes; recalibration is a buyer-run procedure documented in the guide.
• The coin acceptor is a basic pulse-type unit; it does not validate counterfeit coins.
• Milk and concentrate need daily refrigeration and cleaning in real use — the report's maintenance section covers this honestly.
• Hot water is held near serving temperature by a simple thermostat band, not a precision boiler.
• Cloud sales logging needs Wi-Fi; the machine still dispenses offline, it just queues the sale record locally.