WEMOS D1 Mini + Shielded DHT22 not able to read from sensor

Hi all

Recently i bought a few Wemos D1 mini’s and some shielded DHT22. I wanted to play with these to log the temperature and humidity in some rooms. But it’s giving me a very hard time.

Maybe starting from the beginning, this is how it looks right now:

This is the code i’m currently using:

/* DHT Pro Shield - Simple
 * Example testing sketch for various DHT humidity/temperature sensors
 * Written by ladyada, public domain
 * Depends on Adafruit DHT Arduino library
 * https://github.com/adafruit/DHT-sensor-library

#include "DHT.h"

#define DHTPIN D4     // what pin we're connected to

// Uncomment whatever type you're using!
//#define DHTTYPE DHT11   // DHT 11
#define DHTTYPE DHT22   // DHT 22  (AM2302)
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor.
// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors.  This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster procs.

void setup() {
  Serial.println("DHTxx test!");


void loop() {
  // Wait a few seconds between measurements.

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");

  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);

  Serial.print("Humidity: ");
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(" *C ");
  Serial.print(" *F\t");
  Serial.print("Heat index: ");
  Serial.print(" *C ");
  Serial.println(" *F");

The library i’m using:
DHT sensor library by Adafruit Version 1.2.3

The output i receive:
Failed to read from DHT sensor!

As this is my very first small project, it could be something very stupid and small so don’t hesitate to be mister obvious…

If someone could help me out, would be great.


did you plug it in in the right way?

if you are holding it in the picture with the USB cable in your hands, then it’s the wrong side - isn’t it?