🔋 Arduino Voltmeter with LCD Display

This project measures the input voltage using an Arduino Uno and displays it on a 16x2 I2C LCD screen.
It uses a simple voltage divider circuit to safely read voltages up to 12V.

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🧠 Overview

The Arduino reads an analog value from pin A0, converts it into a real voltage using a scaling factor, and displays the voltage on an I2C LCD display.

The circuit is safe, low-cost, and perfect for beginners learning how to measure analog voltages using Arduino.

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⚙️ Hardware Requirements

Component	Quantity	Description
Arduino Uno	1	Microcontroller board
16x2 LCD (I2C)	1	Display for showing voltage
Resistor 7.2kΩ	1	Used in voltage divider
Resistor 4.8kΩ	1	Used in voltage divider
Breadboard	1	For connections
Jumper wires	As needed	For wiring
Power Source (max 12V)	1	Input voltage to measure

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🔌 Circuit Connections

LCD Pin	Arduino Pin
VCC	5V
GND	GND
SDA	A4
SCL	A5

Voltage Divider	Arduino Pin
Output (middle node)	A0
GND	GND
Input (12V max)	From source

⚠️ Note: Never connect voltages higher than 5V directly to A0 — use a proper voltage divider.

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🧮 Formula Used

V_in = (AnalogValue / 1023) × V_ref × ScalingFactor Where:

• AnalogValue → ADC reading (0–1023)
• V_ref → 5V (Arduino reference voltage)
• ScalingFactor → (R1 + R2) / R2 = 2.4 in this project

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💻 Arduino Code

The main code is in the file VoltMeter.ino.
It reads the analog pin and updates the voltage on the LCD every 0.5 seconds.

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📚 Required Libraries

Install these libraries in Arduino IDE or VS Code:

• Wire.h (usually pre-installed)
• LiquidCrystal_I2C.h

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🧪 How It Works

1. The voltage divider scales down the input voltage (max 12V) to below 5V.
2. The Arduino reads the analog signal using its 10-bit ADC.
3. The code calculates the actual input voltage using the scaling factor.
4. The LCD displays the voltage in real time.

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📁 Project Structure

Arduino_Voltmeter_LCD/ │ ├── voltmeter.ino # Main Arduino sketch ├── README.md # Full project documentation ├── components.txt # List of all electronic components ├── connections.txt # Wiring connections for circuit ├── LICENSE # MIT License for open-source use └── .gitignore # Files/folders to exclude from Git tracking

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🧠 Future Improvements

Add OLED or 7-segment display support.

Include max/min voltage tracking.

Display battery status using bar graph.

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🧑‍💻 Author

Jayanti
🎓 Information Science & Engineering Student
💡 Passionate about IoT, Arduino, and electronics projects.

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🪪 License

This project is open-source under the MIT License.
You’re free to use, modify, and share it with credit.