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127 lines
3.7 KiB
Markdown
127 lines
3.7 KiB
Markdown
# DHT22 Sensor Implementation for ESP32
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This document provides information about the DHT22 sensor implementation for ESP32 microcontrollers in this project.
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## Overview
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The DHT22 (also known as AM2302) is a digital temperature and humidity sensor that provides high-precision temperature and humidity readings. This implementation allows you to easily integrate DHT22 sensors with your ESP32 projects using MicroPython.
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## Features
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- Temperature readings in Celsius or Fahrenheit
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- Humidity readings as percentage
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- Automatic detection of simulation vs. hardware mode
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- Error handling for sensor reading failures
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- Temperature unit conversion methods
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- Comprehensive metadata including sensor type and last readings
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## Hardware Requirements
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- ESP32 microcontroller
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- DHT22/AM2302 temperature and humidity sensor
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- MicroPython firmware installed on the ESP32
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- Appropriate wiring:
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- Connect VCC to 3.3V or 5V power supply
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- Connect GND to ground
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- Connect DATA to a GPIO pin (default is GPIO4)
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- A 10K pull-up resistor between VCC and DATA is recommended
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## Software Dependencies
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- MicroPython with `dht` and `machine` modules
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- For simulation mode, only the standard Python libraries are required
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## Usage
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### Basic Usage
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```python
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from src.esp_sensors.dht22 import DHT22Sensor
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# Initialize the sensor
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sensor = DHT22Sensor("living_room", 4) # name, GPIO pin
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# Read temperature
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temperature = sensor.read()
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print(f"Temperature: {temperature}°C")
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# Read humidity
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humidity = sensor.read_humidity()
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print(f"Humidity: {humidity}%")
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# Get temperature in Fahrenheit
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fahrenheit = sensor.to_fahrenheit()
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print(f"Temperature: {fahrenheit}°F")
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```
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### Advanced Usage
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```python
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from src.esp_sensors.dht22 import DHT22Sensor
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import time
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# Initialize with custom parameters
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sensor = DHT22Sensor(
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name="outdoor",
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pin=5,
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interval=30, # Read every 30 seconds
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unit="F" # Use Fahrenheit
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)
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# Continuous reading
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try:
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while True:
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temp = sensor.read()
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humidity = sensor.read_humidity()
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# Get metadata
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metadata = sensor.get_metadata()
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print(f"Sensor: {metadata['name']}")
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print(f"Temperature: {temp}°F ({sensor.to_celsius()}°C)")
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print(f"Humidity: {humidity}%")
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time.sleep(metadata['interval'])
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except KeyboardInterrupt:
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print("Monitoring stopped")
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```
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## API Reference
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### Class: DHT22Sensor
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Extends the base `Sensor` class to provide DHT22-specific functionality.
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#### Constructor
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```python
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DHT22Sensor(name: str, pin: int, interval: int = 60, unit: str = "C")
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```
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- **name**: A string identifier for the sensor
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- **pin**: The GPIO pin number the sensor is connected to
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- **interval**: Reading interval in seconds (default: 60)
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- **unit**: Temperature unit, either "C" for Celsius or "F" for Fahrenheit (default: "C")
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#### Methods
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- **read()**: Reads the current temperature and updates humidity
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- **read_humidity()**: Returns the current humidity reading
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- **to_fahrenheit()**: Converts the last reading to Fahrenheit if it was in Celsius
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- **to_celsius()**: Converts the last reading to Celsius if it was in Fahrenheit
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- **get_metadata()**: Returns a dictionary with sensor information including temperature unit and humidity
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## Example
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See the `examples/dht22_example.py` file for a complete example of how to use the DHT22 sensor with an ESP32.
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## Troubleshooting
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- **No readings or errors**: Check your wiring and ensure the DHT22 is properly connected
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- **Inconsistent readings**: Make sure you have a pull-up resistor between VCC and DATA
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- **ImportError**: Ensure you're running on MicroPython with the required modules
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- **ValueError**: Check that you're using a valid temperature unit ("C" or "F")
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## License
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This implementation is provided under the same license as the main project. |