Project Documentation

Arduino UNO Power Meter with I2C LCD Display and Current/Voltage Sensors

Circuit Documentation

Summary

This circuit is designed to measure voltage, current, and power using an Arduino UNO, a 16x2 I2C LCD, a voltage sensor, and a current sensor. The measured values are displayed on the LCD and can also be monitored via the Arduino's serial monitor.

Component List

16x2 I2C LCD
- Pins: GND, VCC, SDA, SCL
- Description: A 16x2 character LCD display with I2C interface.
- Purpose: To display voltage, current, and power measurements.
LED: Two Pin (red)
- Pins: cathode, anode
- Description: A standard red LED.
- Purpose: Visual indicator.
Resistor
- Pins: pin1, pin2
- Description: A resistor with a resistance of 390 Ohms.
- Purpose: Current limiting for the LED.
9V Battery
- Pins: -, +
- Description: A 9V battery.
- Purpose: Power supply for the circuit.
ACS712 Current Sensor 5A 20A 30A
- Pins: 1, 2, GND, OUT, VCC
- Description: A current sensor capable of measuring up to 30A.
- Purpose: To measure the current flowing through the circuit.
Voltage Sensor DC 25V
- Pins: +, -, output, gnd, vcc
- Description: A voltage sensor capable of measuring up to 25V.
- Purpose: To measure the voltage in the circuit.
Arduino UNO
- Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0
- Description: A microcontroller board based on the ATmega328P.
- Purpose: To process sensor data and control the LCD display.

Wiring Details

16x2 I2C LCD

GND connected to GND of Arduino UNO
VCC connected to 5V of Arduino UNO
SDA connected to A4 of Arduino UNO
SCL connected to A5 of Arduino UNO

LED: Two Pin (red)

cathode connected to gnd of Voltage Sensor DC 25V
anode connected to pin1 of Resistor

Resistor

pin1 connected to anode of LED
pin2 connected to vcc of Voltage Sensor DC 25V and 1 of ACS712 Current Sensor

9V Battery

- connected to 2 of ACS712 Current Sensor
+ connected to gnd of Voltage Sensor DC 25V and cathode of LED

ACS712 Current Sensor 5A 20A 30A

1 connected to pin2 of Resistor
2 connected to - of 9V Battery
GND connected to - of Voltage Sensor DC 25V and GND of Arduino UNO
OUT connected to A1 of Arduino UNO
VCC connected to + of Voltage Sensor DC 25V and 5V of Arduino UNO

Voltage Sensor DC 25V

+ connected to VCC of ACS712 Current Sensor and 5V of Arduino UNO
- connected to GND of ACS712 Current Sensor and GND of Arduino UNO
output connected to A0 of Arduino UNO
gnd connected to cathode of LED and + of 9V Battery
vcc connected to pin2 of Resistor and 1 of ACS712 Current Sensor

Arduino UNO

5V connected to VCC of 16x2 I2C LCD, VCC of ACS712 Current Sensor, and + of Voltage Sensor DC 25V
GND connected to GND of 16x2 I2C LCD, GND of ACS712 Current Sensor, and - of Voltage Sensor DC 25V
A0 connected to output of Voltage Sensor DC 25V
A1 connected to OUT of ACS712 Current Sensor
A4 connected to SDA of 16x2 I2C LCD
A5 connected to SCL of 16x2 I2C LCD

Code Documentation

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

// I2C LCD Initialization
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Sensor Pins
const int VOLTAGE_SENSOR = A0;
const int CURRENT_SENSOR = A1;

// Calibration values
const float VOLTAGE_FACTOR = 5.0 / 1024.0; // 5V reference / 1024 steps
const float VOLTAGE_DIVIDER_RATIO = 4.964;  // HW-067
const float CURRENT_SENSITIVITY = 1.33985;    // Sensitivity for ACS712 5A
const float VOLTAGE_OFFSET = 2.5;         
const int SAMPLES = 100;                    // Number of samples for averaging
const float CURRENT_THRESHOLD = 0.013;     // Ignore readings below 13mA

// Function to get average reading from a pin
float getAverageReading(int pin) {
  long sum = 0;
  for(int i = 0; i < SAMPLES; i++) {
    sum += analogRead(pin);
    delayMicroseconds(100);
  }
  return sum / (float)SAMPLES;
}

void setup() {
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  
  pinMode(VOLTAGE_SENSOR, INPUT);
  pinMode(CURRENT_SENSOR, INPUT);
  
  delay(120);
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Guc Olcer Hazir");
  delay(2500);
}

void loop() {
  // Get readings
  float rawVoltage = getAverageReading(VOLTAGE_SENSOR);
  float rawCurrent = getAverageReading(CURRENT_SENSOR);
  
  // Calculate voltage
  float voltage = (rawVoltage * VOLTAGE_FACTOR * VOLTAGE_DIVIDER_RATIO);
  
  // Calculate current
  float voltage_current = (rawCurrent * VOLTAGE_FACTOR);
  float current = ((voltage_current - VOLTAGE_OFFSET) / CURRENT_SENSITIVITY);
  
  // Apply current threshold
  current = abs(current);
  if(current < CURRENT_THRESHOLD) {
    current = 0;
  }
  
  // Calculate power
  float power = voltage * current;
  
  // Convert to mA and mW
  float current_mA = current * 1000;
  float power_mW = power * 1000;
  
  // Ensure power is zero if current is zero
  if(current == 0) {
    power_mW = 0;
  }
  
  // Display on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("V:");
  lcd.print(voltage, 1);
  lcd.print("V I:");
  lcd.print(current_mA, 1);
  lcd.print("mA");
  
  lcd.setCursor(0, 1);
  lcd.print("Guc:");
  lcd.print(power_mW, 1);
  lcd.print("mW");
  
  // Print to Serial Monitor
  Serial.println("Olcumler:");
  Serial.print("Voltaj: ");
  Serial.print(voltage, 3);
  Serial.println("V");
  
  Serial.print("Akim: ");
  Serial.print(current_mA, 3);
  Serial.println("mA");
  
  Serial.print("Guc: ");
  Serial.print(power_mW, 3);
  Serial.println("mW");
  Serial.println();
  
  delay(500);
}

This code initializes the I2C LCD and sets up the voltage and current sensors. It reads the sensor values, calculates the voltage, current, and power, and displays these values on the LCD and the serial monitor.