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

1. 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

2. Bluetooth HC-06

   • Description: Bluetooth module for wireless communication.
   • Pins: VCC, GND, TXD, RXD

3. Piezo Buzzer

   • Description: Sound-producing device.
   • Pins: pin 1, pin 2

4. LED: Two Pin (red)

   • Description: Red LED.
   • Pins: cathode, anode

5. LED: Two Pin (green)

   • Description: Green LED.
   • Pins: cathode, anode

6. LED: Two Pin (blue)

   • Description: Blue LED.
   • Pins: cathode, anode

7. LED: Two Pin (yellow)

   • Description: Yellow LED.
   • Pins: cathode, anode

8. LED: Two Pin (orange)

   • Description: Orange LED.
   • Pins: cathode, anode

9. Resistor (220 Ohms)

   • Description: Resistor with 220 Ohms resistance.
   • Pins: pin1, pin2

10. Resistor (10k Ohms)

    • Description: Resistor with 10k Ohms resistance.
    • Pins: pin1, pin2

11. Resistor (2k Ohms)

    • Description: Resistor with 2k Ohms resistance.
    • Pins: pin1, pin2

12. 12V 200Ah Battery

    • Description: Power source.
    • Pins: GND, 12V

13. 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 <