#815 DHT11 Sensor Library Test
Logging temperature and humidity with DHT11 sensor. Uses the Adafruit Arduino DHT Sensor Library directly.
Notes
This is a test of the DHT11 with the Adafruit DHT Sensor Library directly (without the unified sensor framework).
See LEAP#816 DHT11 Unified Sensor Library Test for a variation that uses the Adafruit unified sensor framework.
See LEAP#301 DHT11 Basics for an introduction to the DHT11 sensor.
Circuit Design
I am using a DHT11 that is mounted on an adapter board that includes pull-up resistor for the data line, and a decoupling capacitor, similar to “New Temperature and Relative Humidity Sensor DHT11 Module with Cable for arduino Diy Kit” (aliexpress seller listing).
The schematic below shows the relevant components if a mounting module is not used. Designed with Fritzing: see Tester.fzz.
Demonstration Script
The DHT11 uses a single-wire two-way communications protocol.
The Tester.ino sketch simply outputs current readings to the console.
Requires the following Arduino libraries:
It is based on the DHTtester.ino example.
#include "DHT.h"
const int DHT_PIN = 2;
const int DHT_TYPE = DHT11;
const int DELAY = 2000;
DHT dht(DHT_PIN, DHT_TYPE);
void setup() {
Serial.begin(115200);
Serial.println("DHT11 test!");
dht.begin();
}
void loop() {
delay(DELAY);
float humidity = dht.readHumidity();
float temp_c = dht.readTemperature();
float temp_f = dht.readTemperature(true);
if (isnan(humidity) || isnan(temp_c) || isnan(temp_f)) {
Serial.println("Failed to read from DHT sensor!");
return;
}
float heat_index_c = dht.computeHeatIndex(temp_c, humidity, false);
float heat_index_f = dht.computeHeatIndex(temp_f, humidity);
Serial.print("Humidity: ");
Serial.print(humidity);
Serial.print("%\t");
Serial.print("Temperature: ");
Serial.print(temp_c);
Serial.print("˚C ");
Serial.print(temp_f);
Serial.print("˚F\t");
Serial.print("Heat index: ");
Serial.print(heat_index_c);
Serial.print("˚C ");
Serial.print(heat_index_f);
Serial.println("˚F");
}
Sample console output:
