BCD Adder Using Logisim

This repository contains the design and simulation of a BCD (Binary-Coded Decimal) adder circuit using Logisim. BCD is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of binary digits, usually four or eight.

Overview

A BCD adder is a circuit that adds two BCD numbers and produces a BCD result. The BCD adder handles each decimal digit separately and ensures that the sum of each digit pair does not exceed 9 (which is the highest digit in BCD).

Features

• BCD Addition Logic: The circuit includes the logic to handle the addition of two BCD digits.
• Correction Logic: When the sum of two digits exceeds 9, the circuit adds 6 (0110) to the result to correct it.
• Carry Handling: The circuit correctly handles carries between decimal digits.

Components

The BCD adder is constructed using the following components in Logisim:

• 4-Bit Binary Adders: To add the binary representations of the BCD digits.
• AND, OR, and NOT Gates: To implement the correction logic.
• Multiplexers: To select the correct sum and carry outputs based on the correction logic.

Design Steps

1. Basic 4-Bit Adder: Create a basic 4-bit binary adder using Logisim to handle the addition of two 4-bit numbers.
2. BCD Correction Logic: Implement the correction logic to handle cases where the sum of two BCD digits exceeds 9.
3. Carry Logic: Add logic to handle the carry out from the addition of two BCD digits.
4. Simulation: Simulate the BCD adder circuit in Logisim to verify its functionality with various inputs.

Simulation

The Logisim project file (BCDadderCircuit.circ) contains the complete design and can be used to simulate the BCD adder. The simulation allows you to input BCD numbers and observe the output sum and carry.

Getting Started

Prerequisites

• Logisim: Download and install Logisim from the official website.

Running the Simulation

1. Clone the Repository:

   git clone https://github.com/jubayer98/BCD-Adder-Using-Logisim.git
   cd BCD-Adder-Using-Logisim

2. Open the Project:

   • Launch Logisim.
   • Open the BCDadderCircuit.circ file in Logisim.

3. Simulate:

   • Use the input pins to enter BCD numbers.
   • Observe the output sum and carry to verify the correct operation of the BCD adder.

Usage Example

1. Input: BCD numbers 0101 (5) and 0110 (6).
2. Output: Sum 0001 (1) with carry 0001 (carry of 1), resulting in 11 (correct BCD result for 5 + 6).

Contributing

Contributions are welcome! If you have any suggestions or improvements, feel free to fork the repository, make your changes, and submit a pull request.

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Enjoy designing and simulating the BCD adder using Logisim!