🌡️ Lesson 6: Sensors & Real-World Input

⏱️ Estimated time: 30 minutes | Difficulty: Intermediate

Temperature Sensor (TMP36)

int tempPin = A0;

void setup() {
    Serial.begin(9600);
}

void loop() {
    int reading = analogRead(tempPin);
    float voltage = reading * (5.0 / 1024.0);
    float tempC = (voltage - 0.5) * 100.0;
    float tempF = tempC * 9.0 / 5.0 + 32.0;

    Serial.print("Temperature: ");
    Serial.print(tempC);
    Serial.println(" °C");
    delay(1000);
}

Light Sensor (LDR / Photoresistor)

int ldrPin = A1;
int ledPin = 9;

void setup() {
    pinMode(ledPin, OUTPUT);
}

void loop() {
    int lightLevel = analogRead(ldrPin);
    // Dark = high value → LED brighter
    int brightness = map(lightLevel, 0, 1023, 255, 0);
    analogWrite(ledPin, brightness);
    delay(100);
}

Ultrasonic Distance Sensor (HC-SR04)

int trigPin = 9;
int echoPin = 10;

void setup() {
    Serial.begin(9600);
    pinMode(trigPin, OUTPUT);
    pinMode(echoPin, INPUT);
}

void loop() {
    // Send pulse
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);

    // Measure echo
    long duration = pulseIn(echoPin, HIGH);
    float distance = duration * 0.034 / 2;  // cm

    Serial.print("Distance: ");
    Serial.print(distance);
    Serial.println(" cm");
    delay(500);
}