adafruit-circuitpython-dht

Introduction

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CircuitPython support for the DHT11 and DHT22 temperature and humidity devices.

Dependencies

This driver depends on:

• Adafruit CircuitPython <https://github.com/adafruit/circuitpython>_

Please ensure all dependencies are available on the CircuitPython filesystem. This is easily achieved by downloading the Adafruit library and driver bundle <https://github.com/adafruit/Adafruit_CircuitPython_Bundle>_.

.. note:: This library uses the pulseio module in CircuitPython. As of CircuitPython 7.0.0, pulseio is no longer available on the smallest CircuitPython builds, such as the Trinket M0, Gemma M0, and Feather M0 Basic boards. You can substitute a more modern sensor, which will work better as well. See the guide Modern Replacements for DHT11 and DHT22 Sensors <https://learn.adafruit.com/modern-replacements-for-dht11-dht22-sensors>_ for suggestions.

Installing from PyPI

On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI <https://pypi.org/project/adafruit-circuitpython-dht/>_. To install for current user:

.. code-block:: shell

pip3 install adafruit-circuitpython-dht

To install system-wide (this may be required in some cases):

.. code-block:: shell

sudo pip3 install adafruit-circuitpython-dht

To install in a virtual environment in your current project:

.. code-block:: shell

mkdir project-name && cd project-name
python3 -m venv .venv
source .venv/bin/activate
pip3 install adafruit-circuitpython-dht

Usage Example

Hardware Set-up

Designed specifically to work with the Adafruit DHT series sensors:

• Adafruit DHT22 temperature-humidity sensor + extras <https://www.adafruit.com/products/385>_
• Adafruit DHT11 temperature-humidity sensor + extras <https://www.adafruit.com/products/386>_

.. note:: DHT11 and DHT22 devices both need a pull-resistor on the data signal wire. This resistor is in the range of 1k to 5k

• Please check the device datasheet for the appropriate value.
• Be sure that you are running the Buster Operating System.
• Make sure that your user is part of the gpio group.

Known Issues

• The library may or may not work in Linux 64-bit platforms.
• The Raspberry PI Zero does not provide reliable readings.
• Readings in FeatherS2 does not work as expected.

.. note:: Using a more modern sensor will avoid these issues. See the guide Modern Replacements for DHT11 and DHT22 Sensors <https://learn.adafruit.com/modern-replacements-for-dht11-dht22-sensors>_.

Basics

Of course, you must import the library to use it:

.. code:: python

import adafruit_dht

The DHT type devices use single data wire, so import the board pin

.. code:: python

from board import <pin>

Now, to initialize the DHT11 device:

.. code:: python

dht_device = adafruit_dht.DHT11(<pin>)

OR initialize the DHT22 device:

.. code:: python

dht_device = adafruit_dht.DHT22(<pin>)

Read temperature and humidity

Now get the temperature and humidity values

.. code:: python

temperature = dht_device.temperature
humidity = dht_device.humidity

These properties may raise an exception if a problem occurs. You should use try/raise logic and catch RuntimeError and then retry getting the values after at least 2 seconds. If you try again to get a result within 2 seconds, cached values are returned.

Documentation

API documentation for this library can be found on Read the Docs <https://docs.circuitpython.org/projects/dht/en/latest/>_.

For information on building library documentation, please check out this guide <https://learn.adafruit.com/creating-and-sharing-a-circuitpython-library/sharing-our-docs-on-readthedocs#sphinx-5-1>_.

Contributing

Contributions are welcome! Please read our Code of Conduct <https://github.com/adafruit/Adafruit_CircuitPython_DHT/blob/main/CODE_OF_CONDUCT.md>_ before contributing to help this project stay welcoming.