Project Documentation

Arduino Nano Battery Monitor with Bluetooth and LCD Display

Circuit Documentation

Summary

This circuit is designed to monitor the voltage of a 12V battery and display the voltage and charge percentage on an LCD screen. It also uses an Arduino Nano to control multiple LEDs and a piezo buzzer. The Bluetooth HC-06 module is used for wireless communication, allowing the battery status to be sent to a remote device.

Component List

Arduino Nano
- Description: Microcontroller board based on the ATmega328P.
- Pins: D1/TX, D0/RX, RESET, GND, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11/MOSI, D12/MISO, VIN, 5V, A7, A6, A5, A4, A3, A2, A1, A0, AREF, 3V3, D13/SCK
Bluetooth HC-06
- Description: Bluetooth module for wireless communication.
- Pins: VCC, GND, TXD, RXD
Piezo Buzzer
- Description: Sound-producing device.
- Pins: pin 1, pin 2
LED: Two Pin (red)
- Description: Red LED.
- Pins: cathode, anode
LED: Two Pin (green)
- Description: Green LED.
- Pins: cathode, anode
LED: Two Pin (blue)
- Description: Blue LED.
- Pins: cathode, anode
LED: Two Pin (yellow)
- Description: Yellow LED.
- Pins: cathode, anode
LED: Two Pin (orange)
- Description: Orange LED.
- Pins: cathode, anode
Resistor (220 Ohms)
- Description: Resistor with 220 Ohms resistance.
- Pins: pin1, pin2
Resistor (10k Ohms)
- Description: Resistor with 10k Ohms resistance.
- Pins: pin1, pin2
Resistor (2k Ohms)
- Description: Resistor with 2k Ohms resistance.
- Pins: pin1, pin2
12V 200Ah Battery
- Description: Power source.
- Pins: GND, 12V
LCD screen 16x2 I2C
- Description: LCD screen with I2C interface.
- Pins: SCL, SDA, VCC, GND

Wiring Details

Arduino Nano

D1/TX connected to Bluetooth HC-06 RXD
D0/RX connected to Bluetooth HC-06 TXD
GND connected to:
- Piezo Buzzer pin 1
- Resistor pin2 (multiple resistors)
- Bluetooth HC-06 GND
- LCD screen 16x2 I2C GND
D2 connected to LED: Two Pin (blue) anode
D3 connected to LED: Two Pin (green) anode
D4 connected to LED: Two Pin (yellow) anode
D5 connected to LED: Two Pin (orange) anode
D6 connected to LED: Two Pin (red) anode
D7 connected to Piezo Buzzer pin 2
5V connected to:
- Bluetooth HC-06 VCC
- LCD screen 16x2 I2C VCC
A5 connected to LCD screen 16x2 I2C SCL
A4 connected to LCD screen 16x2 I2C SDA
A0 connected to:
- Resistor pin1 (2k Ohms)
- Resistor pin2 (10k Ohms)

Bluetooth HC-06

RXD connected to Arduino Nano D1/TX
TXD connected to Arduino Nano D0/RX
GND connected to Arduino Nano GND
VCC connected to Arduino Nano 5V

Piezo Buzzer

pin 1 connected to Arduino Nano GND
pin 2 connected to Arduino Nano D7

LED: Two Pin (red)

anode connected to Arduino Nano D6
cathode connected to Resistor pin1 (220 Ohms)

LED: Two Pin (green)

anode connected to Arduino Nano D3
cathode connected to Resistor pin1 (220 Ohms)

LED: Two Pin (blue)

anode connected to Arduino Nano D2
cathode connected to Resistor pin1 (220 Ohms)

LED: Two Pin (yellow)

anode connected to Arduino Nano D4
cathode connected to Resistor pin1 (220 Ohms)

LED: Two Pin (orange)

anode connected to Arduino Nano D5
cathode connected to Resistor pin1 (220 Ohms)

Resistor (220 Ohms)

pin1 connected to LED cathode
pin2 connected to Arduino Nano GND

Resistor (10k Ohms)

pin1 connected to 12V 200Ah Battery 12V
pin2 connected to Resistor pin1 (2k Ohms)

Resistor (2k Ohms)

pin1 connected to Arduino Nano A0
pin2 connected to 12V 200Ah Battery GND

12V 200Ah Battery

GND connected to Resistor pin2 (2k Ohms)
12V connected to Resistor pin1 (10k Ohms)

LCD screen 16x2 I2C

SCL connected to Arduino Nano A5
SDA connected to Arduino Nano A4
VCC connected to Arduino Nano 5V
GND connected to Arduino Nano GND

Code Documentation

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SoftwareSerial.h>

// Initialize the LCD with I2C address 0x27, 16 columns, and 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Bluetooth module connections
SoftwareSerial BTSerial(0, 1); // RX, TX

// Define pin numbers
const int ledPins[] = {2, 3, 4, 5, 6};
const int buzzerPin = 7;
const int batteryPin = A0;  // Analog pin to read battery voltage

void setup() {
  // Initialize LED pins as outputs
  for (int i = 0; i < 5; i++) {
    pinMode(ledPins[i], OUTPUT);
  }
  // Initialize buzzer pin as output
  pinMode(buzzerPin, OUTPUT);
  // Initialize serial communication for Bluetooth
  BTSerial.begin(9600);
  // Initialize serial communication for debugging
  Serial.begin(9600);
  // Initialize the LCD
  lcd.begin();
  lcd.backlight();
}

void loop() {
  int batteryLevel = analogRead(batteryPin);
  float voltage = batteryLevel * (5.0 / 1023.0) * ((10.0 + 2.0) / 2.0);  // Convert to voltage
  
  // Map voltage to percentage (assuming 20V to 28V range)
  int percentage = map(voltage, 20, 28, 0, 100);

  Serial.print("Battery Voltage: ");
  Serial.print(voltage);
  Serial.print("V, Percentage: ");
  Serial.print(percentage);
  Serial.println("%");

  // Send data over Bluetooth
  BTSerial.print("Battery Voltage: ");
  BTSerial.print(voltage);
  BTSerial.print("V, Percentage: ");
  BTSerial.print(percentage);
  BTSerial.println("%");

  // Display data on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Voltage: ");
  lcd.print(voltage);
  lcd.print("V");
  lcd.setCursor(0, 1);
  lcd.print("Charge: ");
  lcd.print(percentage);
  lcd.print("%");

  // Determine LED states based on percentage
  for (int i = 0; i < 5; i++) {
    if (percentage > (i + 1) * 20) {
      digitalWrite(ledPins[i], HIGH);
    } else {
      digitalWrite(ledPins[i], LOW);
    }
  }

  // Sound buzzer if battery level is below 30%
  if (percentage < 30) {
    for (int i = 0; i <