From Sensor to Screen: Build a Digital Thermometer in Minutes

A simple digital thermometer built with an Arduino, a DHT11 temperature & humidity sensor, and a 4-digit common-anode 7-segment display. Only three of the four digits are used, which is enough to display room and outside temperatures.

Apr 12, 2026

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MIT

Weather

Devices & Components

Arduino Uno Rev3

Hardware & Tools

Quad Digit 7-Segment

220 Ohm resistor

Humidity Sensor DHT11

Software & Tools

DHT11 Library

SevSeg Library

Project description

Code

thermometer

cpp

Setup pins, then read sensor and update display.

1#include <DHT11.h>
2#include "SevSeg.h"
3
4SevSeg sevseg;
5
6DHT11 dht11(2);
7
8void setup() {
9  byte numDigits = 3;  
10  byte digitPins[] = { 3, 4, 5};
11  byte segmentPins[] = {6, 7, 8, 9, 10, 11, 12, 13};
12  bool resistorsOnSegments = 0; 
13  sevseg.begin(COMMON_ANODE, numDigits, digitPins, segmentPins, resistorsOnSegments);
14  sevseg.setBrightness(90);
15}
16
17unsigned long lastRead = 0;
18bool firstRead = true;
19int temperature = 0;
20
21void loop() {
22  unsigned long interval = firstRead ? 1000 : 60000;
23  if (millis() - lastRead >= interval) {
24    lastRead = millis();
25    firstRead = false;
26    temperature = dht11.readTemperature();
27    sevseg.setNumber(temperature);
28  }
29  sevseg.refreshDisplay();
30}

#include <DHT11.h>
#include "SevSeg.h"

SevSeg sevseg;

DHT11 dht11(2);

void setup() {
  byte numDigits = 3;  
  byte digitPins[] = { 3, 4, 5};
  byte segmentPins[] = {6, 7, 8, 9, 10, 11, 12, 13};
  bool resistorsOnSegments = 0; 
  sevseg.begin(COMMON_ANODE, numDigits, digitPins, segmentPins, resistorsOnSegments);
  sevseg.setBrightness(90);
}

unsigned long lastRead = 0;
bool firstRead = true;
int temperature = 0;

void loop() {
  unsigned long interval = firstRead ? 1000 : 60000;
  if (millis() - lastRead >= interval) {
    lastRead = millis();
    firstRead = false;
    temperature = dht11.readTemperature();
    sevseg.setNumber(temperature);
  }
  sevseg.refreshDisplay();
}

Documentation

README

documentation

README.md

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