🛗 Smart Elevator Control System (Embedded C)

📌 Project Overview

This project is a Smart Elevator Control System developed for the 8051 Microcontroller (C8051F020). It features a complete logic implementation for a 5-floor building, incorporating Safety Mechanisms (Overload protection), Smart Scheduling (SCAN Algorithm), and Real-time Sensor Monitoring.

The system simulates a realistic elevator environment where inputs are polled via Timer Interrupts to ensure responsiveness, and passenger flow is tracked using IR sensors.

⚙️ Key Features

• Bi-Directional Scheduling (SCAN Algorithm): The system optimizes movement by servicing all requests in the current direction (UP) before switching to the opposite direction (DOWN), similar to modern elevator logic.
• Safety & Overload Protection:
  • Monitors passenger count using Infrared (IR) Sensors.
  • Triggers an Overload Alarm and prevents door closing if capacity > 4 persons.
• Interrupt-Driven Logic:
  • Utilizes Timer0 Interrupts to periodically poll buttons and sensors, ensuring that user requests are never missed during motor operation.
• Hardware Interfacing:
  • Direct control of H-Bridge for Motor Direction (Up/Down).
  • 7-Segment Display multiplexing for Floor Indication.

🛠️ Hardware Architecture

The code interacts directly with the MCU registers for low-level control:

Component	Logic Function
IR Sensors	Passenger counting (Entry/Exit sequence detection)
Timer 0	Periodic Interrupt Generation (~240ms tick)
Port 1	7-Segment Display Output
Port 2	Motor Control & Safety LEDs
Port 5	External Floor Call Buttons

🚀 How it Works (Logic Flow)

1. Initialization: Configures Crossbar, Watchdog Timer, and System Clock (2MHz).
2. Polling (ISR): Timer0 triggers every 240ms to check:
   • Floor Buttons (Internal Panel).
   • Call Buttons (External per floor).
   • Door Open Requests.
3. Main Loop (Scheduler):
   • Sweep UP: Moves motor UP if there are requests above current floor. Checks for intermediate stops dynamically.
   • Sweep DOWN: Moves motor DOWN if there are requests below current floor.
4. Door Sequence: * Checks IR sensors continuously while door is open.
   • Updates passenger count.
   • Checks for Overload before closing.

📂 File Structure

├── include/ │ └── C8051F020.h # Register/bit definitions for the C8051F020 MCU ├── src/ │ └── elevatorsystem.c # Main application logic, ISRs, and scheduler ├── docs/ │ └── Elevator.pdf # Project documentation and schematics └── README.md # This file

👨‍💻 Skills Demonstrated

• Embedded C Programming.
• Interrupt Service Routines (ISR) handling.
• Sensor Fusion (IR + Switches).
• State Machine Implementation.
• Algorithmic Logic Design.