Four-Story Elevator Controller

Atair Rahman Alvi — Arduino Uno + Stepper Motor, simulated in Proteus

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Repository Structure

elevator-controller/
├── src/
│   └── elevator.ino          # Arduino firmware (main source)
├── project_files/
│   ├── elevator.pdsprj       # Proteus simulation project
│   └── elevator.hex          # Compiled HEX (for direct Proteus load)
├── report.pdf                # Project report (2 pages)
└── README.md

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Hardware Overview

Component	Details
MCU	Arduino Uno
Stepper driver	L293D H-bridge
Motor	28BYJ-48 (2048 steps/rev)
Display	16×2 LCD, 4-bit mode (D2–D7)
Floor buttons/LEDs	Multiplexed on D8–D11 (G, 2, 3, 4)
Direction buttons	UP → D12, DOWN → D13
LCD contrast	10 kΩ potentiometer on V0

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How to Run in Proteus

1. Open project_files/elevator.pdsprj in Proteus 8 or later.
2. The HEX file (project_files/elevator.hex) is already linked in the Arduino component. If it isn't, double-click the Arduino Uno component → set Program File to elevator.hex.
3. Press the Play button to start simulation.
4. Interact via the on-screen buttons (UP / DOWN / G / 2 / 3 / 4).
5. Open the Virtual Terminal in Proteus to see serial debug output.

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How to Flash to a Real Arduino

1. Install the Arduino IDE (1.8.x or 2.x).
2. Open src/elevator.ino.
3. Required libraries (both bundled with Arduino IDE):
   • LiquidCrystal
   • Stepper
4. Select Board → Arduino Uno and the correct COM port.
5. Click Upload.

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Firmware Logic Summary

setup()
  └─ zero stepper, blink Ground LED ×3 (ready signal)

loop()
  ├─ display current floor on LCD
  ├─ waitForDirection()   ← 6 s timeout, blinks current-floor LED
  ├─ doorCycle()          ← latches extra floor requests into queue
  ├─ waitForFloorButton() ← 3 s window to pick destination
  └─ moveTo(destination)
       ├─ steps motor floor-by-floor
       ├─ updates LCD each floor
       ├─ turns off indicator LED on arrival
       └─ runs doorCycle() + serves queued floors recursively

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Known Limitation — Stepper Position Drift

After multiple round-trips the motor drifts from true zero. Root cause: the Arduino Stepper library counts 512 integer steps per floor, but the Proteus 28BYJ-48 model registers only ~508 due to its internal gear-reduction ratio. The fractional residual accumulates with every trip.

Workaround (not yet implemented): apply a calibration factor to stepsToMove on each return-to-ground command, e.g.:

// Instead of:
stepsToMove = -totalSteps;

// Use a corrected factor:
const float GEAR_CORRECTION = 508.0 / 512.0;
stepsToMove = (long)(-totalSteps * GEAR_CORRECTION);

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Feature Status

Feature	Status
4-floor motor travel (up/down)	✅ Functional
LCD floor + direction display	✅ Functional
LED indicators (multiplexed)	✅ Functional
Door open/close with queuing	✅ Functional
Multi-floor request queue	✅ Functional
Direction timeout / idle return	✅ Functional
Stepper zero-return accuracy	❌ Drifts