LCD thermometer

Temperature and humidity on a 16×2 display.

Open in Circuit Lab Simulator

Interactive Simulation

LCD thermometerarduino-uno

Open in Lab

Required Components Checklist

Assembly Steps

Wire the sensor

DHT VCC to 5V, GND to GND, DATA to pin 4.

Wire the display

LCD VCC to 5V, GND to GND, SDA to A4, SCL to A5.

Show the values

Read every 2 seconds, handle NaN, and pad numbers with spaces.

Arduino Sketch

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

DHT dht(4, DHT11);
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  Serial.begin(9600);
  dht.begin();
  lcd.init();
  lcd.backlight();
}

void loop() {
  float t = dht.readTemperature();
  float h = dht.readHumidity();
  if (isnan(t) || isnan(h)) {
    lcd.setCursor(0, 0);
    lcd.print("Sensor error    ");
    Serial.println("Check the DHT wiring");
  } else {
    lcd.setCursor(0, 0);
    lcd.print("Temp: ");
    lcd.print(t);
    lcd.print(" C  ");
    lcd.setCursor(0, 1);
    lcd.print("Hum:  ");
    lcd.print(h);
    lcd.print(" %  ");
    Serial.print(t);
    Serial.print(" C, ");
    Serial.print(h);
    Serial.println(" %");
  }
  delay(2000); // the DHT11 can only be read about once per second
}

Challenges & Extensions

Ready to take this project further? Try these challenges:

•Show °F on the second line.
•Track the minimum and maximum temperature.
•Blink the backlight above 35 °C.