Digital Voltmeter using Arduino

This project demonstrates how to build a digital voltmeter using an Arduino board and an LCD display. The voltmeter is capable of monitoring the voltage of a battery in real-time.

Hardware Required

• Arduino board
• 16x2 LCD display
• Resistors (for the voltage divider circuit)
• Voltage divider circuit components (to reduce the battery voltage to a measurable level for the Arduino's analog input pins)
• 5V reference voltage for the Arduino's analog-to-digital converter (ADC)

Circuit Diagram

Code Explanation

#include "LiquidCrystal.h"

LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

float input_voltage = 0.0;
float temp = 0.0;
float r1 = 5000.0;
float r2 = 1000.0;

void setup()
{
   Serial.begin(9600);     // opens serial port, sets data rate to 9600 bps
   lcd.begin(16, 2);       // set up the LCD's number of columns and rows
   lcd.print("BATTERY VOLTAGE");
}

void loop()
{
   // Conversion formula
   int analog_value = analogRead(A0);
   temp = (analog_value * 5.0) / 1024.0;
   input_voltage = temp / (r2 / (r1 + r2));

   if (input_voltage < 0.1)
   {
     input_voltage = 0.0;
   }

   Serial.print("Voltage: ");
   Serial.println(input_voltage);
   lcd.setCursor(0, 1);
   lcd.print("Voltage=");
   lcd.print(input_voltage);
   lcd.print("V");
   delay(100);
}

1. The code begins by including the LiquidCrystal library, which provides an interface to control the LCD display.
2. The LiquidCrystal object is initialized with the corresponding pin numbers for the LCD display.
3. In the setup() function, the serial port is opened and set to a data rate of 9600 bps. The LCD display is also initialized with the number of columns and rows, and a message is printed to indicate that the voltmeter is monitoring the battery voltage.
4. The loop() function continuously performs the following steps:
   • Reads the analog value from the voltage divider circuit using the analogRead() function.
   • Converts the analog value to voltage using the formula: temp = (analog_value * 5.0) / 1024.0.
   • Calculates the battery voltage using the formula: input_voltage = temp / (r2 / (r1 + r2)).
   • Checks if the input voltage is less than 0.1V, and if so, sets it to 0.0V.
   • Prints the voltage value to the serial monitor.
   • Updates the LCD display with the voltage value.
   • Adds a delay of 100 milliseconds to prevent rapid flickering of the display.

Usage

1. Connect the Arduino board to a power source.
2. The LCD display will show the battery voltage in real-time.
3. You can also monitor the voltage values through the serial monitor in the Arduino IDE.

License

This project is licensed under the MIT License.