How to use the DHT22 sensor with the Raspberry Pi Pico board in Python?

Getting started with the DHT22 sensor

The DHT22 is part of the DHTxx family. A comparison between the DHT11 and the DHT22 is available to see their differences better. The DTH22 has a white plastic housing, while the DHT11 has a blue one. If your sensor is blue, I recommend reading the DHT11 tutorial .

Wiring diagram for using the DHT22 module with an RPi Pi Pico

If your module does not include a pull-up resistor, adding one between the pins 3V3 and the signal (GP13 ) is necessary. The recommended range for this resistor is from 4.7kΩ to 10kΩ. Any output pin can be used, but in this example, we are using the GP13 . Make sure to adjust the circuit to your model if it differs slightly. 🙂

RPI Pi Pico

uPesy RP2040 DevKit

Here is an example with the uPesy RP2040 DevKit board, an upgraded Pico and a DHT22 module with the signal pin on the far right:

Measuring the temperature and humidity on the DHT22 module with MicroPython

Since DHT22 uses a proprietary protocol, it is necessary to use a library to communicate with the sensor. Fortunately, such a library is included in the latest versions of MicroPython, so you don’t need to download an additional one. You can directly import the module with import dht .

from machine import Pin
from time import sleep
import dht

sensor = dht.DHT22(Pin(13))

while True:
  try:
    sleep(1)     # the DHT22 returns at most one measurement every 2s
    sensor.measure()     # Recovers measurements from the sensor
    print(f"Temperature : {sensor.temperature():.1f}°C")
    print(f"Humidite    : {sensor.humidity():.1f}%")
  except OSError as e:
    print("Failed reception")

In the Thonny IDE terminal, you will see the temperature expressed in °C and the humidity in percentage.

In Python, you can use f-string to display variables with a text, for example, f"Humidite: {sensor.humidity():.1f}" . The string must start with an f , and the variable must be placed between square brackets. It is possible to specify the number of digits after the decimal point, which will be displayed with :.1f . Here, we put a figure after the decimal point because the sensor is accurate to 0.5°C.

Calculate the heat index | Real feel temperature

The heat index can calculate the temperature felt. It is a value in °C based on the temperature and the relative humidity in the air. The higher the humidity level in the air at a given temperature, the higher the temperature felt

The formula is a bit long 😨 :

Fortunately, I have made a ready-made function that takes care of it: 😉

from machine import