.. note:: Hello, welcome to the SunFounder Raspberry Pi & Arduino & ESP32 Enthusiasts Community on Facebook! Dive deeper into Raspberry Pi, Arduino, and ESP32 with fellow enthusiasts. **Why Join?** - **Expert Support**: Solve post-sale issues and technical challenges with help from our community and team. - **Learn & Share**: Exchange tips and tutorials to enhance your skills. - **Exclusive Previews**: Get early access to new product announcements and sneak peeks. - **Special Discounts**: Enjoy exclusive discounts on our newest products. - **Festive Promotions and Giveaways**: Take part in giveaways and holiday promotions. 👉 Ready to explore and create with us? Click [|link_sf_facebook|] and join today! .. _py_dht11: 6.2 Measuring Temperature and Humidity with DHT11 ======================================================= In this lesson, we'll learn how to use a **DHT11 temperature and humidity sensor** with the Raspberry Pi Pico 2. The DHT11 is a basic, low-cost digital sensor that can measure ambient temperature and humidity, providing a calibrated digital output. **What You'll Need** In this project, we need the following components. It's definitely convenient to buy a whole kit, here's the link: .. list-table:: :widths: 20 20 20 :header-rows: 1 * - Name - ITEMS IN THIS KIT - LINK * - Newton Lab Kit - 450+ - |link_newton_lab_kit| You can also buy them separately from the links below. .. list-table:: :widths: 5 20 5 20 :header-rows: 1 * - SN - COMPONENT - QUANTITY - LINK * - 1 - :ref:`cpn_pico_2` - 1 - |link_pico2_buy| * - 2 - Micro USB Cable - 1 - * - 3 - :ref:`cpn_breadboard` - 1 - |link_breadboard_buy| * - 4 - :ref:`cpn_wire` - Several - |link_wires_buy| * - 5 - :ref:`cpn_dht11` - 1 - |link_dht22_buy| **Understanding the DHT11 Sensor** The **DHT11** sensor uses a capacitive humidity sensor and a thermistor to measure the surrounding air. It outputs a digital signal on the data pin, and it's fairly simple to use, but requires precise timing to read data. * Temperature Range: 0–50 °C with ±2 °C accuracy * Humidity Range: 20–80% RH with ±5% accuracy * Sampling Rate: 1 Hz (once every second) **Circuit Diagram** |sch_dht11| **Wiring Diagram** |wiring_dht11| **Writing the Code** Let's write a MicroPython program to read temperature and humidity values from the DHT11 sensor. .. note:: * Open the ``6.2_temperature_humidity.py`` from ``newton-lab-kit/micropython`` or copy the code into Thonny, then click "Run" or press F5. * Ensure the correct interpreter is selected: MicroPython (Raspberry Pi Pico).COMxx. * Here you need to use the library called ``dht.py``, please check if it has been uploaded to Pico, for a detailed tutorial refer to :ref:`add_libraries_py`. .. code-block:: python from machine import Pin import utime import dht # Initialize the DHT11 sensor sensor = dht.DHT11(Pin(16)) while True: try: # Trigger measurement sensor.measure() # Read values temperature = sensor.temperature # In Celsius humidity = sensor.humidity # In Percent # Print values print("Temperature: {}°C Humidity: {}%".format(temperature, humidity)) except OSError as e: print("Failed to read sensor.") # Wait before the next reading utime.sleep(2) Once the code is running, the temperature and humidity readings will display in the Thonny Shell. .. code-block:: Temperature: 29.3°C Humidity: 60.0% Temperature: 29.2°C Humidity: 60.0% Temperature: 29.2°C Humidity: 60.0% Temperature: 29.1°C Humidity: 60.0% Temperature: 29.2°C Humidity: 60.0% Temperature: 29.3°C Humidity: 60.0% **Understanding the Code** #. Import Modules: * ``machine.Pin``: For controlling the GPIO pins. * ``utime``: Contains time-related functions. * ``dht``: The library for DHT sensors. #. Initialize the Sensor: .. code-block:: python sensor = dht.DHT11(Pin(16)) Creates an instance of the DHT11 sensor connected to GP16. #. Main Loop: * ``sensor.measure()``: Triggers the sensor to take a measurement. * ``sensor.temperature``: Reads the temperature in Celsius. * ``sensor.humidity``: Reads the humidity percentage. * ``Exception Handling``: Catches any errors that occur during reading. * ``utime.sleep(2)``: Waits 2 seconds between readings. .. code-block:: python while True: try: sensor.measure() temperature = sensor.temperature humidity = sensor.humidity print("Temperature: {}°C Humidity: {}%".format(temperature, humidity)) except OSError as e: print("Failed to read sensor.") utime.sleep(2) **Experimenting Further** * Convert Temperature to Fahrenheit: .. code-block:: python temperature_f = temperature * 9 / 5 + 32 print("Temperature: {}°F Humidity: {}%".format(temperature_f, humidity)) * Display Readings on an LCD: Integrate an LCD display to show the readings without a computer. * Set Up Alerts: Use an LED or buzzer to alert when temperature or humidity exceeds certain thresholds. **Troubleshooting Tips** * Incorrect Readings: * Ensure the sensor is connected properly. * Check for loose wires or poor connections. * Failed to Read Sensor: This may happen occasionally due to timing issues. The code includes a try-except block to handle this. * Pull-Up Resistor: If the sensor doesn't work, ensure that a pull-up resistor is connected between VCC and Data pins if your sensor requires it. **Conclusion** In this lesson, you've learned how to use the DHT11 temperature and humidity sensor with the Raspberry Pi Pico 2. Monitoring environmental conditions is a fundamental aspect of many projects, from weather stations to home automation systems. * `Try Statement - Python Docs `_