VHDL Elevator Controller

A modular, synthesizable elevator control system implemented in VHDL. This project implements a complete elevator controller with configurable floor count, request handling, and 7-segment display output.

Features

• Configurable Floor Count: Supports up to N floors (default: 10)
• Smart Request Resolution: Maintains a queue of floor requests with automatic clearing on arrival
• Direction Memory: Continues in the current direction when multiple requests exist
• Door Control: Automatic 2-second door open timing at each destination
• Edge Detection: Debounced button inputs using dedicated edge detector modules
• 7-Segment Display: Real-time floor number display on common-anode SSD
• Fully Synthesizable: Clean RTL design suitable for FPGA implementation

Architecture Overview

Module Descriptions

1. elevator_ctrl (Top Level)

The top-level entity that instantiates and connects all sub-modules.

2. request_resolver

Manages floor requests by registering new requests and clearing them when the elevator arrives.

• Uses edge detectors for button debouncing
• Registers requests on rising edge of request_btn
• Clears floor bit when door opens at that floor

3. unit_control

The main FSM that controls elevator movement and door operations.

• 4-state FSM: IDLE, MOVING_UP, MOVING_DOWN, DOOR_OPEN
• 2-second timing for floor transitions and door open
• Direction memory for serving requests efficiently
• Shift-based request detection for above/below floors

4. EdgeDetector

A reusable edge detection module for button debouncing.

5. DisplayDecoder

BCD to 7-segment decoder for common-anode display.

State Machine

The unit_control module implements the following FSM:

State Descriptions

State	Description	Duration
IDLE	Waiting for requests	Instant transition
MOVING_UP	Traveling upward	2 seconds per floor
MOVING_DOWN	Traveling downward	2 seconds per floor
DOOR_OPEN	Door open at destination	2 seconds

RTL Diagrams

Request Resolver RTL

Unit Control RTL

Simulation Waveforms

Functional Simulation

Simulation

vsim -do main.do

⚙️ Parameters

Generic	Default	Description
N_FLOORS	10	Number of floors in the building
CLK_FREQ	50,000,000	Clock frequency in Hz

License

This project is licensed under the MIT License.