🌡️ Temperature Sensors Complete Guide

Monitor air temperature in greenhouses, crop storage, and soil temperature for planting decisions.

📊 Sensor Comparison:

🌡️ DHT22: Air Temperature and Humidity

#include "DHT.h"
#define DHTPIN 16
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

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

void loop() {
    float temp = dht.readTemperature();
    float hum = dht.readHumidity();
    
    if (!isnan(temp) && !isnan(hum)) {
        Serial.print("Temperature: ");
        Serial.print(temp);
        Serial.println("°C");
        Serial.print("Humidity: ");
        Serial.print(hum);
        Serial.println("%");
        
        if (temp > 35) {
            Serial.println("⚠️ HIGH TEMPERATURE - Open vents!");
        }
        if (hum > 80) {
            Serial.println("⚠️ HIGH HUMIDITY - Risk of fungus!");
        }
    }
    delay(2000);
}
    

🌍 DS18B20: Waterproof Soil Temperature

#include 
#include 

#define ONE_WIRE_BUS 17
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

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

void loop() {
    sensors.requestTemperatures();
    float soilTemp = sensors.getTempCByIndex(0);
    
    Serial.print("Soil Temperature: ");
    Serial.print(soilTemp);
    Serial.println("°C");
    
    if (soilTemp < 10) {
        Serial.println("⚠️ SOIL TOO COLD - Delay planting!");
    }
    delay(60000);
}
    

💰 NTC Thermistor: Budget Option ($1)

#define THERMISTOR_PIN 34
const float BETA = 3950;
const float SERIES_RES = 10000;

void loop() {
    int raw = analogRead(THERMISTOR_PIN);
    float voltage = raw * (3.3 / 4095.0);
    float resistance = (SERIES_RES * voltage) / (3.3 - voltage);
    float tempK = 1 / ((1 / 298.15) + (log(resistance / SERIES_RES) / BETA));
    float tempC = tempK - 273.15;
    
    Serial.print("Temperature: ");
    Serial.print(tempC);
    Serial.println("°C");
    delay(2000);
}