Circuit Documentation

Summary

This circuit is designed to measure the pH level of a solution and display the value on an LCD screen. It also includes a visual indicator system using LEDs: a yellow LED lights up for acidic solutions (pH < 5), a green LED for neutral to slightly alkaline solutions (pH 5-8), and a blue LED for alkaline solutions (pH > 8). Upon powering up, the system displays a welcome message on the LCD. The core of the circuit is an Arduino UNO microcontroller, which reads the pH level from a pH meter sensor, processes the data, and controls the LCD and LEDs accordingly.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• Provides the main control and processing for the circuit

LED: Two Pin (yellow)

• Visual indicator for acidic solutions (pH < 5)

LED: Two Pin (green)

• Visual indicator for neutral to slightly alkaline solutions (pH 5-8)

LED: Two Pin (blue)

• Visual indicator for alkaline solutions (pH > 8)

PH Meter

• Sensor for measuring the pH level of a solution
• Outputs an analog signal proportional to the pH level

LCD 16x2 (Wokwi Compatible)

• Alphanumeric liquid crystal display for showing messages and pH values

I2C Module

• Interface module for the LCD to communicate with the Arduino UNO via I2C protocol

Wiring Details

Arduino UNO

• 3.3V connected to I2C Module VCC
• 5V connected to PH Meter VCC
• GND connected to PH Meter GND, I2C Module GND, and all LED cathodes
• A0 connected to PH Meter Signal
• A4 (SDA) connected to I2C Module SDA
• A5 (SCL) connected to I2C Module SCL
• D1 connected to Yellow LED anode
• D2 connected to Green LED anode
• D3 connected to Blue LED anode

LED: Two Pin (yellow)

• cathode connected to common ground
• anode connected to Arduino UNO D1

LED: Two Pin (green)

• cathode connected to common ground
• anode connected to Arduino UNO D2

LED: Two Pin (blue)

• cathode connected to common ground
• anode connected to Arduino UNO D3

PH Meter

• Signal connected to Arduino UNO A0
• VCC connected to Arduino UNO 5V
• GND connected to common ground

LCD 16x2 (Wokwi Compatible)

• Connected via I2C Module using the following pins:
  • VSS to I2C Module VSS
  • VDD to I2C Module VDD
  • V0 to I2C Module VO
  • RS to I2C Module RS
  • RW to I2C Module RW
  • E to I2C Module E
  • D0-D7 to I2C Module DB0-DB7
  • A to I2C Module LEDA
  • K to I2C Module LEDK

I2C Module

• VCC connected to Arduino UNO 3.3V
• GND connected to common ground
• SDA connected to Arduino UNO A4
• SCL connected to Arduino UNO A5
• All other pins connected to corresponding pins on the LCD 16x2

Documented Code

/*
 * Alat pengukur pH air dengan output nilai pH pada LCD.
 * Lampu kuning menyala jika pH < 5.
 * Lampu hijau menyala jika pH 5-8.
 * Lampu biru menyala jika pH > 8.
 * Saat alat dinyalakan, tampilkan pesan selamat datang.
 */

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

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int yellowLED = 1; // Pin connected to the anode of the yellow LED
const int greenLED = 2;  // Pin connected to the anode of the green LED
const int blueLED = 3;   // Pin connected to the anode of the blue LED
const int phSensorPin = A0; // Pin connected to the pH meter sensor

void setup() {
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(blueLED, OUTPUT);
  lcd.begin(); // Initialize the LCD
  lcd.backlight(); // Turn on the backlight
  // Display welcome message
  lcd.setCursor(0, 0);
  lcd.print("pH meter ");
  lcd.setCursor(0, 1);
  lcd.print("Arduino");
  delay(2000); // Wait for 2 seconds
  lcd.clear(); // Clear the display
  // Display group information
  lcd.setCursor(0, 0);
  lcd.print("Pend Kimia 5-A");
  lcd.setCursor(0, 1);
  lcd.print("Kelompok 07");
  delay(2000); // Wait for 2 seconds
  lcd.clear(); // Clear the display
  // Display motivational message
  lcd.setCursor(0, 0);
  lcd.print("Semangat");
  delay(2000); // Wait for 2 seconds
  lcd.clear(); // Clear the display
}

void loop() {
  int phValue = analogRead(phSensorPin); // Read the pH sensor value
  float voltage = phValue * (5.0 / 1023.0); // Convert to voltage
  float ph = 7 - ((2.5 - voltage) / 0.18); // Calculate pH value
  // Display the pH value on the LCD
  lcd.setCursor(0, 0);
  lcd.print("pH: ");
  lcd.print(ph);
  // Control the LEDs based on the pH value
  if (ph < 5) {
    digitalWrite(yellowLED, HIGH);
    digitalWrite(greenLED, LOW);
    digitalWrite(blueLED, LOW);
  } else if (ph >= 5 && ph <= 8) {
    digitalWrite(yellowLED, LOW);
    digitalWrite(greenLED, HIGH);
    digitalWrite(blueLED, LOW);
  } else {
    digitalWrite(yellowLED, LOW);
    digitalWrite(greenLED, LOW);
    digitalWrite(blueLED, HIGH);
  }
  delay(1000); // Wait for 1 second before the next reading
}

This code is responsible for initializing the system, reading the pH sensor data, calculating the pH value, displaying the value on the LCD, and controlling the LEDs based on the pH level. It also includes a startup sequence with welcome and group messages.