Lesson 5: Light Sensor (BH1750)

/*
  Vumbua Synapse Kit - Lesson 5: Basic BH1750 Light Sensor
  Read ambient light intensity in lux units
  BH1750 I2C address: 0x5C
*/

#include <Wire.h>
#include <BH1750.h>

// Create BH1750 object with address 0x5C
BH1750 lightMeter(0x5C);

void setup() {
  Serial.begin(9600);
  
  // Initialize I2C bus (Wire)
  Wire.begin();
  
  // Initialize BH1750 sensor
  if (lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
    Serial.println("BH1750 Light Sensor Initialized Successfully!");
  } else {
    Serial.println("Error: BH1750 not detected. Check connections.");
    while (1); // Stop if sensor not found
  }
  
  Serial.println("Vumbua Synapse Kit - Light Intensity Monitor");
  Serial.println("============================================");
  Serial.println("Move sensor to different light conditions");
  Serial.println();
}

void loop() {
  // Read light level in lux
  float lux = lightMeter.readLightLevel();
  
  // Determine light condition
  String condition = getLightCondition(lux);
  
  // Display results
  Serial.print("Light Intensity: ");
  Serial.print(lux);
  Serial.print(" lux (");
  Serial.print(condition);
  Serial.println(")");
  
  // Wait 1 second before next reading
  delay(1000);
}

// Function to categorize light levels
String getLightCondition(float lux) {
  if (lux < 10) {
    return "Dark";
  } else if (lux < 50) {
    return "Dim";
  } else if (lux < 200) {
    return "Normal Indoor";
  } else if (lux < 1000) {
    return "Bright Indoor";
  } else if (lux < 10000) {
    return "Daylight";
  } else {
    return "Direct Sunlight";
  }
}

/*
  BH1750 Mode Selection Demo
  Show different measurement modes
*/

#include <Wire.h>
#include <BH1750.h>

BH1750 lightMeter(0x5C);

void setup() {
  Serial.begin(9600);
  Wire.begin();
  
  Serial.println("BH1750 Mode Comparison");
  Serial.println("======================");
}

void loop() {
  // Test CONTINUOUS_HIGH_RES mode
  lightMeter.configure(BH1750::CONTINUOUS_HIGH_RES_MODE);
  delay(120); // Wait for measurement
  float luxHighRes = lightMeter.readLightLevel();
  
  // Test CONTINUOUS_LOW_RES mode
  lightMeter.configure(BH1750::CONTINUOUS_LOW_RES_MODE);
  delay(16);
  float luxLowRes = lightMeter.readLightLevel();
  
  // Test ONE_TIME_HIGH_RES mode
  lightMeter.configure(BH1750::ONE_TIME_HIGH_RES_MODE);
  delay(120);
  float luxOneTime = lightMeter.readLightLevel();
  
  // Display comparison
  Serial.print("HIGH_RES (1 lux): ");
  Serial.print(luxHighRes);
  Serial.print(" lux | LOW_RES (4 lux): ");
  Serial.print(luxLowRes);
  Serial.print(" lux | ONE_TIME: ");
  Serial.print(luxOneTime);
  Serial.println(" lux");
  
  delay(2000);
}

/*
  BH1750 Calibration Example
  Apply calibration factor for improved accuracy
*/

#include <Wire.h>
#include <BH1750.h>

BH1750 lightMeter(0x5C);

// Calibration factor - adjust based on reference measurement
const float CALIBRATION_FACTOR = 1.2;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
  
  Serial.println("BH1750 Calibrated Measurement");
  Serial.println("Calibration Factor: " + String(CALIBRATION_FACTOR));
}

float getStableLux() {
  // Take 5 readings and average
  float sum = 0;
  for (int i = 0; i < 5; i++) {
    sum += lightMeter.readLightLevel();
    delay(50);
  }
  return sum / 5.0;
}

void loop() {
  // Get raw measurement
  float rawLux = getStableLux();
  
  // Apply calibration
  float calibratedLux = rawLux * CALIBRATION_FACTOR;
  
  // Display results
  Serial.print("Raw: ");
  Serial.print(rawLux);
  Serial.print(" lux | Calibrated: ");
  Serial.print(calibratedLux);
  Serial.println(" lux");
  
  delay(1000);
}

/*
  Vumbua Synapse Kit - Smart Lighting Automation
  Control LED brightness based on ambient light
  Automatic night light / daylight harvesting
*/

#include <Wire.h>
#include <BH1750.h>

BH1750 lightMeter(0x5C);

// LED connected to PWM pin 9
const int ledPin = 9;

// Light thresholds (in lux)
const int DARK_THRESHOLD = 50;    // Below this: LED ON full
const int BRIGHT_THRESHOLD = 200;  // Above this: LED OFF

void setup() {
  Serial.begin(9600);
  Wire.begin();
  
  // Initialize sensor
  lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
  
  // Initialize LED pin
  pinMode(ledPin, OUTPUT;
  
  Serial.println("Smart Lighting System Active");
  Serial.println("============================");
  Serial.println("DARK (<50 lux): LED ON");
  Serial.println("DIM (50-200 lux): LED proportional");
  Serial.println("BRIGHT (>200 lux): LED OFF");
  Serial.println();
}

void loop() {
  // Read ambient light level
  float lux = lightMeter.readLightLevel();
  
  int ledBrightness = 0;
  
  if (lux <= DARK_THRESHOLD) {
    // Dark: LED at full brightness
    ledBrightness = 255;
  } else if (lux >= BRIGHT_THRESHOLD) {
    // Bright: LED off
    ledBrightness = 0;
  } else {
    // Dim: Proportional brightness
    // Map lux value (50-200) to brightness (255-0)
    ledBrightness = map(lux, DARK_THRESHOLD, BRIGHT_THRESHOLD, 255, 0);
    ledBrightness = constrain(ledBrightness, 0, 255);
  }
  
  // Control LED
  analogWrite(ledPin, ledBrightness);
  
  // Calculate LED brightness percentage
  int ledPercent = map(ledBrightness, 0, 255, 0, 100);
  
  // Display status
  Serial.print("Light: ");
  Serial.print(lux);
  Serial.print(" lux | LED: ");
  Serial.print(ledBrightness);
  Serial.print(" (");
  Serial.print(ledPercent);
  Serial.println("%)");
  
  delay(500);
}

/*
  Plant Light Monitor
  Monitor if plants are receiving adequate light
*/

#include <Wire.h>
#include <BH1750.h>

BH1750 lightMeter(0x5C);

// Plant light requirements (lux)
const int PLANT_MIN_LIGHT = 1000;  // Minimum for healthy growth
const int PLANT_MAX_LIGHT = 10000; // Maximum before damage

// LED indicators
const int LED_TOO_DARK = 2;
const int LED_GOOD = 3;
const int LED_TOO_BRIGHT = 4;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE);
  
  // Setup LED pins
  pinMode(LED_TOO_DARK, OUTPUT);
  pinMode(LED_GOOD, OUTPUT);
  pinMode(LED_TOO_BRIGHT, OUTPUT);
  
  Serial.println("Plant Light Monitor Active");
  Serial.println("<1000 lux: Too dark (Red LED)");
  Serial.println("1000-10000 lux: Good (Green LED)");
  Serial.println(">10000 lux: Too bright (Yellow LED)");
}

void loop() {
  float lux = lightMeter.readLightLevel();
  
  // Reset all LEDs
  digitalWrite(LED_TOO_DARK, LOW);
  digitalWrite(LED_GOOD, LOW);
  digitalWrite(LED_TOO_BRIGHT, LOW);
  
  // Control LEDs based on light level
  if (lux < PLANT_MIN_LIGHT) {
    digitalWrite(LED_TOO_DARK, HIGH);
  } else if (lux > PLANT_MAX_LIGHT) {
    digitalWrite(LED_TOO_BRIGHT, HIGH);
  } else {
    digitalWrite(LED_GOOD, HIGH);
  }
  
  // Display recommendation
  Serial.print("Light: ");
  Serial.print(lux);
  Serial.print(" lux - ");
  
  if (lux < PLANT_MIN_LIGHT) {
    Serial.println("Move plant to brighter location");
  } else if (lux > PLANT_MAX_LIGHT) {
    Serial.println("Provide some shade for plant");
  } else {
    Serial.println("Perfect light conditions! ✓");
  }
  
  delay(2000);
}