PHP and MQTT: realize data transmission and control of smart home systems

PHP and MQTT: Realizing data transmission and control of smart home systems

The rapid development of smart home systems has caused more and more people to start using smart devices to control home devices. In order to realize data transmission and control of smart home systems, we can use the MQTT protocol to implement communication between devices. This article will introduce how to use PHP and MQTT to create a simple smart home system.

First, we need to install the MQTT extension library. We can install the Mosquitto PHP extension with the following command:

pecl install Mosquitto-alpha

After the installation is complete, enable the extension in the php.ini file:

extension=mosquitto.so

Next, we need to install an MQTT broker, such as Mosquitto , used for communication between devices. We can install the Mosquitto agent using the following command in the command line:

sudo apt-get install mosquitto

After the installation is complete, we can start the Mosquitto agent through the following command:

mosquitto -v

Now, let us write a piece of PHP code To realize data transmission and control of smart home systems. Suppose we have a temperature sensor and an LED light as a home device. The temperature sensor will send the temperature value to the MQTT broker, and the LED light will control the switch according to the instructions received.

<?php
 
require("phpMQTT.php");
 
$mqtt = new phpMQTT("localhost", 1883, "ClientID".rand());
 
if(!$mqtt->connect()){
    exit(1);
}
 
$topics['temperature'] = array("qos" => 0, "function" => "procTemperature");
$mqtt->subscribe($topics, 0);
 
while($mqtt->proc()){
}
 
$mqtt->close();
 
function procTemperature($topic, $msg){
    echo "Received temperature: " . $msg . "C" . "
";
 
    // 控制LED灯的代码
 
    // 如果温度大于30°C，开启LED灯
    if($msg > 30){
        echo "Turn on LED" . "
";
    }else{
        echo "Turn off LED" . "
";
    }
}
 
?>

The above code uses the phpMQTT class to connect and perform MQTT operations. We first create an instance of phpMQTT and pass in the address and port number of the MQTT broker. We then establish a connection to the MQTT broker by calling the connect() method.

In the subscription part, we define a topic named "temperature" and specify the callback function procTemperature. When the temperature sensor releases new temperature data, the callback function procTemperature will be called.

In the callback function, we first print out the received temperature value. Then, we control the on/off status of the LED light based on the temperature value.

In the main loop, we use the proc() method to process MQTT messages until the connection is closed.

If we want to send instructions to control the switch of the LED light, we can write the following code:

<?php
 
require("phpMQTT.php");
 
$mqtt = new phpMQTT("localhost", 1883, "ClientID".rand());
 
if(!$mqtt->connect()){
    exit(1);
}
 
$topic = "led";
$message = "on";
$mqtt->publish($topic, $message, 0);
 
$mqtt->close();
 
?>

In the above code, we first create an instance of phpMQTT and establish a connection with the MQTT broker . We then specified a topic "led" and message "on" and used the publish() method to send the message to the MQTT broker. Finally, we close the connection to the MQTT broker.

The above code examples demonstrate how to use PHP and MQTT to implement data transmission and control of smart home systems. By using the MQTT protocol, we can simply implement communication between devices to create a smart home system. Through further expansion and optimization, we can achieve more complex and intelligent home control systems.

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