9. Input devices¶

Group assignment:¶

• Probe an input device(s)'s analog and digital signals

• Document your work on the group work page and reflect on your individual page what you learned

To see our group assignment click here

Individual assignment:¶

• measure something : add a sensor to a microcontroller board that you have designed and read it.

Introduction to the project¶

Pour cette semaine axée sur les dispositifs d'entrée, j'ai décidé de construire une station de surveillance compacte à l'aide de ma carte ESP32 personnalisée contruit à la semaine 5 cliquez ici pour plus de details. Le projet consiste à acquérir des données environnementales (température et humidité) via le capteur DHT11.

Presentation of the DHT11 Sensor¶

The DHT11 is a low-cost digital sensor used to measure temperature and humidity. It is widely used in electronics projects, especially with platforms such as Arduino, ESP32, and Raspberry Pi, due to its simplicity and ease of integration.

DHT11 Sensor Specifications

DHT11 Working Principle¶

The DHT11 is a composite digital sensor capable of measuring both temperature and ambient humidity. Unlike simple analog sensors, it integrates its own signal processing system.

Internal Components¶

The blue casing of the DHT11 contains three main elements:

• Resistive humidity sensor: It consists of two electrodes with a moisture-retaining substrate (usually a polymer) between them.

• NTC thermistor: A resistor whose value varies predictably with temperature.

• 8-bit microcontroller: It measures the variations from both sensors, performs analog-to-digital conversion, and transmits the data.

Wiring diagram¶

Project code¶

To use the DHT11 easily with Arduino, you need to install the "DHT sensor library".

To add a library in the Arduino IDE:

1. Go to the menu Tools → Manage Libraries
2. Search for "DHT sensor library"
3. Click Install

Program¶

#include <DHT.h>
#define DHTPIN 23
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  Serial.println("--- DHT11 Monitoring Ready ---");
  dht.begin();
}

void loop() {
  float hum = dht.readHumidity();
  float temp = dht.readTemperature(); // Celsius par défaut

  if (!isnan(hum) && !isnan(temp)) {
    Serial.print("Temperature: ");
    Serial.print(temp);
    Serial.print(" °C | Humidite: ");
    Serial.print(hum);
    Serial.println(" %");

    Serial.print("Temperature:");
    Serial.print(temp);
    Serial.print(",Humidite:");
    Serial.println(hum);
  } else {
    Serial.println("Erreur: lecture du capteur DHT11 impossible.");
  }
  delay(2000);
}

Result After Uploading the Code¶

The following result was obtained after uploading the program to the ESP32 board.

Files¶

Download Code files