Circuit Documentation

Summary

This circuit is designed to control the brightness of an LED based on ambient light intensity using a PID controller. The system includes an Arduino UNO microcontroller, multiple potentiometers for tuning PID parameters, an ambient light sensor, an LCD display for real-time feedback, and additional passive components like resistors, capacitors, and inductors.

Component List

1. Arduino UNO

   • Description: Microcontroller board based on the ATmega328P.
   • 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

2. Potentiometer

   • Description: Variable resistor used for adjusting PID parameters.
   • Pins: GND, Output, VCC

3. Ambient Light Sensor

   • Description: Sensor to measure ambient light intensity.
   • Pins: GND, OUT, VCC

4. LCD 20x4 I2C

   • Description: 20x4 character LCD display with I2C interface.
   • Pins: GND, 5V, SCA, SCL

5. Electrolytic Capacitor

   • Description: Capacitor used for filtering.
   • Pins: -, +
   • Properties: Capacitance: 0.000001 Farads

6. Inductor

   • Description: Inductor used in the circuit.
   • Pins: pin 0, pin 1
   • Properties: Inductance: 0.1 Henrys

7. Resistor

   • Description: Resistor used in the circuit.
   • Pins: pin1, pin2
   • Properties: Resistance: 200 Ohms

8. Bulb

   • Description: Bulb used as an indicator.
   • Pins: GND, power

Wiring Details

Arduino UNO

• 5V connected to:

  • Potentiometer (VCC)
  • Potentiometer (VCC)
  • Ambient Light Sensor (VCC)
  • LCD 20x4 I2C (5V)
  • Potentiometer (VCC)
  • Potentiometer (VCC)

• GND connected to:

  • Potentiometer (GND)
  • Potentiometer (GND)
  • Ambient Light Sensor (GND)
  • LCD 20x4 I2C (GND)
  • Potentiometer (GND)
  • Potentiometer (GND)
  • Bulb (GND)

• A0 connected to:

  • Ambient Light Sensor (OUT)

• A1 connected to:

  • Potentiometer (Output)

• A2 connected to:

  • Potentiometer (Output)

• A3 connected to:

  • Potentiometer (Output)

• A4 connected to:

  • Potentiometer (Output)

• SCL connected to:

  • LCD 20x4 I2C (SCL)

• SDA connected to:

  • LCD 20x4 I2C (SCA)

• D3 connected to:

  • Electrolytic Capacitor (+)
  • Inductor (pin 1)

Potentiometer

• VCC connected to:

  • Arduino UNO (5V)

• GND connected to:

  • Arduino UNO (GND)

• Output connected to:

  • Arduino UNO (A1)
  • Arduino UNO (A2)
  • Arduino UNO (A3)
  • Arduino UNO (A4)

Ambient Light Sensor

• VCC connected to:

  • Arduino UNO (5V)

• GND connected to:

  • Arduino UNO (GND)

• OUT connected to:

  • Arduino UNO (A0)

LCD 20x4 I2C

• 5V connected to:

  • Arduino UNO (5V)

• GND connected to:

  • Arduino UNO (GND)

• SCA connected to:

  • Arduino UNO (SDA)

• SCL connected to:

  • Arduino UNO (SCL)

Electrolytic Capacitor

• + connected to:

  • Arduino UNO (D3)
  • Inductor (pin 1)

• - connected to:

  • Bulb (power)
  • Resistor (pin1)

Inductor

• pin 0 connected to:

  • Resistor (pin2)

• pin 1 connected to:

  • Electrolytic Capacitor (+)
  • Arduino UNO (D3)

Resistor

• pin1 connected to:

  • Electrolytic Capacitor (-)

• pin2 connected to:

  • Inductor (pin 0)

Bulb

• GND connected to:

  • Arduino UNO (GND)

• power connected to:

  • Electrolytic Capacitor (-)

Code Documentation

#include <PID_v1.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Initialize the LCD with I2C address 0x27 and size 20x4
LiquidCrystal_I2C lcd(0x27, 20, 4);

const int MAX_DUTY_CYCLE = 255; // Max duty cycle for 8-bit resolution

// PID parameters and variables
double Setpoint, Input, Output;
double kp, ki, kd;
PID myPID(&Input, &Output, &Setpoint, kp, ki, kd, DIRECT);

// Pin definitions
const int temt6000Pin = A0; // Analog pin for TEMT6000 sensor
const int ledPin = 3;       // PWM pin for LED control via MOSFET
const int kpPin = A1;       // Analog pin for potentiometer to adjust Kp
const int kiPin = A2;       // Analog pin for potentiometer to adjust Ki
const int kdPin = A3;       // Analog pin for potentiometer to adjust Kd

// Fading parameters
int targetBrightness = 0;
int currentBrightness = 0;
const int fadeAmount = 1; // Fade amount for each step
const int fadeDelay = 30; // Delay in milliseconds for each fade step

//lux tuning parameter
const int LUX_TUNING = 200;

void setup() {
  Serial.begin(115200);

  // Initialize the LCD
  lcd.init();
  lcd.backlight();

  // Set initial PID parameters
  Setpoint = 0; // Desired light intensity in lux

  myPID.SetMode(AUTOMATIC);
  myPID.SetSampleTime(100); // Sample time in milliseconds

  pinMode(ledPin, OUTPUT); // Set LED pin as output
}

void loop() {
  // Read the light intensity from the TEMT6000 sensor
  int light_value = analogRead(temt6000Pin);
  float volts = light_value * 3.3 / 1023.0; // Arduino has 10-bit ADC resolution and 3.3V reference voltage
  float amps = volts / 10000.0; // across 10,000 Ohms
  float microamps = amps * 1000000;
  float lux = microamps * 2.0;
  Input = lux;

  // Read and scale potentiometer values to 0-10 range for PID parameters
  kp = analogRead(kpPin) * (10.0 / 1023.0);
  ki = analogRead(kiPin) * (10.0 / 1023.0);
  kd = analogRead(kdPin) * (10.0 / 1023.0);
  myPID.SetTunings(kp, ki, kd);

  // Compute the PID output
  myPID.Compute();
  
  // Set the LED brightness based on the lux value directly (scale 0-255)
  targetBrightness = map(lux, 0, LUX_TUNING, MAX_DUTY_CYCLE, 0);
  targetBrightness = constrain(targetBrightness, 0, MAX_DUTY_CYCLE);

  // Smoothly adjust currentBrightness towards targetBrightness
  if (currentBrightness < targetBrightness) {
    currentBrightness = min(currentBrightness + fadeAmount, targetBrightness);
  } else if (currentBrightness > targetBrightness) {
    currentBrightness = max(currentBrightness - fadeAmount, targetBrightness);
  }

  // Set the LED brightness
  analogWrite(ledPin, currentBrightness);

  // Display PID parameters and light intensity on the LCD
  lcd.setCursor(0, 0);
  lcd.print("P=");
  lcd.print(kp, 2);
  lcd.print(" I=");
  lcd.print(ki, 2);

  lcd.setCursor(0, 1);
  lcd.print("D=");
  lcd.print(kd, 2);

  lcd.setCursor(0, 2);
  lcd.print("Light Intensity:");
  lcd.setCursor(0