# Raspberry Pi + DHT22/DHT11 使用方法

最後更新時間
* 2024/12/23: 新建立

## 硬體環境
本教學相容樹莓派所有型號，包括
* [Raspberry Pi 5 Model B](https://piepie.com.tw/product/raspberry-pi-5)
* [Raspberry Pi 4 Model B](https://www.piepie.com.tw/28040/raspberry-pi-4-model-b)
* [Raspberry Pi 3B+](https://www.piepie.com.tw/19429/57)
* [Raspberry Pi 3A+](https://piepie.com.tw/product/raspberry-pi-3-model-a-plus)
* [Raspberry Pi 3B](https://www.piepie.com.tw/10684/55)
* [Raspberry Pi 2B](https://www.piepie.com.tw/4063/54)
* [Raspberry Pi Zero W](https://www.piepie.com.tw/15425/raspberry-pi-zero-w-joins-family)
* [Raspberry Pi Zero](https://www.piepie.com.tw/9975/raspberry-pi-zero)
* [Raspberry Pi Zero 2 W](https://piepie.com.tw/product/raspberry-pi-zero-2-w)。

## 系統環境
本教學測試的環境為
* [raspios_arm64-2024-11-19/bookworm](https://downloads.raspberrypi.org/raspios_arm64/images/raspios_arm64-2024-11-19/)

## 感測器
* DHT11 溫濕度感測器
* [DHT22 溫濕度感測器](https://piepie.com.tw/product/dht22-temperature-and-humidity-sensor) - [英文規格書(DHT22)](http://go.aws/2TpVTQQ)

## 接線(實際接線需要配合感測器上的標示！)


## 安裝步驟

cd ~
sudo apt-get update
sudo apt-get install -y pigpiod libgpiod2
python3 -m venv venv --system-site-packages
source ~/venv/bin/activate
pip3 install adafruit-circuitpython-dht

## 範例程式
### test_dht22.py

# test_dht22.py

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import board
import adafruit_dht

# Initial the dht device, with data pin connected to:
dhtDevice = adafruit_dht.DHT22(board.D18)

# you can pass DHT22 use_pulseio=False if you wouldn't like to use pulseio.
# This may be necessary on a Linux single board computer like the Raspberry Pi,
# but it will not work in CircuitPython.
# dhtDevice = adafruit_dht.DHT22(board.D18, use_pulseio=False)

try:
    while True:
        # Print the values to the serial port
        temperature_c = dhtDevice.temperature
        temperature_f = temperature_c * (9 / 5) + 32
        humidity = dhtDevice.humidity
        print(
            "Temp: {:.1f} F / {:.1f} C    Humidity: {}% ".format(
                temperature_f, temperature_c, humidity
            )
        )
        
        time.sleep(2.0)
            
except RuntimeError as error:
    # Errors happen fairly often, DHT's are hard to read, just keep going
    print(error.args[0])
except KeyboardInterrupt as error:
    print(error)
except Exception as error:
    print(error)
finally:
    dhtDevice.exit()

### test_dht11.py

# test_dht11.py

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT

import time
import board
import adafruit_dht

# Initial the dht device, with data pin connected to:
dhtDevice = adafruit_dht.DHT11(board.D18)

# you can pass DHT22 use_pulseio=False if you wouldn't like to use pulseio.
# This may be necessary on a Linux single board computer like the Raspberry Pi,
# but it will not work in CircuitPython.
# dhtDevice = adafruit_dht.DHT22(board.D18, use_pulseio=False)

try:
    while True:
        # Print the values to the serial port
        temperature_c = dhtDevice.temperature
        temperature_f = temperature_c * (9 / 5) + 32
        humidity = dhtDevice.humidity
        print(
            "Temp: {:.1f} F / {:.1f} C    Humidity: {}% ".format(
                temperature_f, temperature_c, humidity
            )
        )
        
        time.sleep(2.0)
            
except RuntimeError as error:
    # Errors happen fairly often, DHT's are hard to read, just keep going
    print(error.args[0])
except KeyboardInterrupt as error:
    print(error)
except Exception as error:
    print(error)
finally:
    dhtDevice.exit()

## 執行程式

### 在終端機上執行

python test_dht22.py


### 在 Thonny 上執行(需要先切換到虛擬環境)

執行 Thonny。

如果在 Thonny 執行 test_dht22.py 出現錯誤訊息，是因為在 Thonny 沒有指到虛擬環境！

在 Thonny 指到正確虛擬環境的作法是，按右上角的 "switch to regular mode"

在 "Run" 選擇 "Configure interpreter"

點選 "Python excutable"

選擇之前建立的 "/home/pi/venv/bin/python3"

完成後可以看到右下角的 Local Python3 指到 /home/pi/venv/bin/python3

再次執行 test_dht22.py 就可以了～

如果要中斷程式，請使用 `Run` > `Interrupt execution`

再次執行 test_dht22.py～

## 參考資料
* [DHT Humidity Sensing on Raspberry Pi or Beaglebone Black with GDocs Logging](https://learn.adafruit.com/dht-humidity-sensing-on-raspberry-pi-with-gdocs-logging/python-setup)
* [Using Virtual Environments in Thonny on a Raspberry Pi](https://core-electronics.com.au/guides/using-virtual-environments-in-thonny-on-a-raspberry-pi/)

###### tags: `教學`, `DHT22`, `DHT11`, `感測器`, `sensor`