4-Bit Gray Code Counter for FPGA

This repository contains the VHDL source code for a 4-bit Gray code counter designed to be implemented on an FPGA. The counter's output is displayed on a 4-digit 7-segment display.

Project Overview

This project was developed for the Digital Systems and Computer Architecture Laboratory Course at Guilan University. It demonstrates a basic digital system design, including a sequential logic circuit (counter), clock management, and input/output handling.

Functionality

The core of the project is a 4-bit counter that cycles through the Gray code sequence. Gray code is a binary numeral system where two successive values differ in only one bit.

The counter has the following features:

• 4-bit Gray Code Sequence: The counter cycles through all 16 Gray code values from "0000" to "1000".
• 7-Segment Display Output: The current 4-bit value of the counter is shown on a 4-digit 7-segment display. Each digit of the display shows one bit of the counter's value (either '0' or '1').
• Push Button Control: A push button is used to start and stop the counter. When the button is pressed, the counter advances through the sequence. When it is not pressed, the counter is paused.

Hardware Setup

To run this project, you will need the following hardware:

• An FPGA development board
• A 4-digit, common anode 7-segment display
• A push button
• Connecting wires

The specific pin connections for the FPGA are defined in the GrayCounter/pins.ucf file. You may need to modify this file to match your specific FPGA board.

Files

• GrayCounter/gray_counter.vhd: The main VHDL source file containing the design for the Gray code counter.
• GrayCounter/pins.ucf: The User Constraints File (UCF) that maps the design's ports to the physical pins of the FPGA.
• README.md: This file.

Usage

1. Synthesize and Implement: Use an FPGA development tool (such as Xilinx ISE or Vivado) to synthesize the VHDL code and implement the design for your target FPGA.
2. Connect Hardware: Connect the 7-segment display and push button to the appropriate pins on your FPGA board, as defined in GrayCounter/pins.ucf.
3. Program FPGA: Upload the generated bitstream file to your FPGA.
4. Operate: Press the push button to cycle through the Gray code sequence. The 4-bit output will be displayed on the 7-segment display.