A Simple Parallel Port Controller for LED Control

 

The project is a prototype designed to demonstrate the use of a Parallel Port (LPT port) for controlling LEDs. This project bridges the gap between legacy hardware interfaces and practical applications, offering a hands-on approach to understanding hardware-software interactions.

Project Overview

This serves as a demonstration of how the parallel port, an older but versatile hardware interface, can be used to control external devices such as LEDs. This project includes both hardware and software components, providing an interactive way to experiment with digital outputs and understand parallel communication.

Key Features

1. Hardware Integration:

• A prototype board designed (in KiCAD) to connect LEDs to the parallel port pins.
• Simple circuitry to showcase the state of each LED based on parallel port data.

2. Software Control:

• A custom software application to manipulate the LED states by sending data to the parallel port.
• Includes a graphical user interface (GUI) for easy control.

3. Source Code and Executable:

• Open-source software code to learn and modify.
• Ready-to-use executable located in the bin/Debug folder for immediate testing.

Technical Details

Hardware Design

1. Parallel Port Pinout:

• The LPT port uses a standard DB25 connector with 8 data pins (D0-D7) for output control.
• Each pin is connected to an LED through a current-limiting resistor to ensure safe operation.

2. Prototype Board:

• The board consists of:
  • LEDs to represent the state of each data pin.
  • Resistors to limit current and protect the LEDs.
  • A DB25 connector to interface with the computer's parallel port.

Software Functionality

1. Programming Language:

• Written in C# for ease of development and maintainability.

2. Core Features:

• LED State Control: Users can toggle the state of each LED through the GUI.
• Parallel Port Access: Sends binary data to the LPT port, where each bit corresponds to an LED's state.
• Real-Time Feedback: Immediate response on the prototype board as data is sent to the port.

3. Implementation Highlights:

• Accessing the parallel port directly requires low-level system calls or third-party libraries like inpout32.dll for Windows systems.

Dependencies

• inpout32.dll:
• A library used to enable low-level access to parallel port registers on modern operating systems.
• Provides functions like Inp32() for reading and Out32() for writing data.

Steps to Set Up and Run

1. Hardware Setup:

• Connect the LEDs and resistors to the data pins (D0-D7) of the DB25 connector.
• Attach the board to the computer’s parallel port.

2. Software Setup:

• Compile the provided source code or use the precompiled executable in the bin/Debug folder.
• Ensure the inpout32.dll library is in the same directory as the executable.

3. Operation:

• Launch the software.
• Use the GUI to toggle LED states by clicking LED button.

This project offers a hands-on experience with hardware-software interaction, using the parallel port to control LEDs. By combining a simple prototype board with an intuitive software application, this project makes it easy to explore the fundamentals of digital output control and parallel communication.

Whether you’re an electronics enthusiast, a student, or a curious developer, provides a great starting point to dive into the world of legacy hardware interfacing and creative electronics.

Browse Github repositories to explore about more about the project.

KiCAD Prototype Circuit Diagram Project Application Project created in C#