### 物联网技能大赛 Python 控制设备 示例项目教程 #### 设备准备与环境搭建 为了参与物联网技能大赛并利用Python控制设备，首先需要准备好相应的硬件和软件环境。硬件方面可以选择Raspberry Pi作为主控板，并配备诸如DHT11这样的温度传感器来收集环境数据[^2]。 安装所需的Python库可以通过命令`pip install paho-mqtt`实现，这一步骤确保了能够通过MQTT协议发送接收消息。 ```bash pip install paho-mqtt ``` #### 编写Python脚本连接传感器 接下来编写一段简单的Python代码用于读取来自DHT11温湿度传感器的数据： ```python import Adafruit_DHT as dht import time sensor = dht.DHT11 pin = 4 # GPIO pin number where the sensor is connected. def read_sensor(): humidity, temperature = dht.read_retry(sensor, pin) if humidity is not None and temperature is not None: print(f'Temperature={temperature:.1f}°C Humidity={humidity}%') else: print('Failed to get reading from the sensor.') while True: read_sensor() time.sleep(2) # Delay between readings. ``` 这段程序会每隔两秒钟打印一次当前室内的温度和相对湿度值。 #### 数据上传至云端平台 为了让所采集的信息可以被远程访问，在本地获取到传感数值之后还需要将其推送到云平台上。这里采用的是轻量级的消息队列遥测传输协议(MQTT)，它非常适合于低带宽、高延迟或不可靠的网络环境中使用。 创建一个新的Python文件用来发布主题消息给指定broker地址的服务端口上: ```python import paho.mqtt.client as mqtt client_id = "iot_device" broker_address = "test.mosquitto.org" client = mqtt.Client(client_id) topic = "/environment/room1" def on_connect(client, userdata, flags, rc): if rc == 0: print("Connected successfully.") else: print(f"Connection failed with code {rc}") def publish_data(temp, humi): payload = f"Temperature:{temp},Humidity:{humi}" client.publish(topic, payload=payload) client.on_connect = on_connect client.connect(broker_address, port=1883, keepalive=60) # Start looping background thread which handles reconnecting etc. client.loop_start() try: while True: temp, humi = dht.read_retry(dht.DHT11, 4) if temp and humi: publish_data(temp, humi) time.sleep(5) except KeyboardInterrupt: pass finally: client.disconnect() # Disconnect gracefully when interrupted by user input like Ctrl+C. client.loop_stop() # Stop loop after disconnecting cleanly. ``` 此段代码实现了周期性的向公共测试Broker(Test.Mosquitto.Org)上的特定Topic推送室内环境参数的功能。