原创【昉·星光 2 高性能RISC-V单板计算机体验】五、物联网应用————使用MQTT协议远程驱动舵机

 2023-12-29 15:25  352 4 3 分类: MCU/ 嵌入式

一、按照发布的第一篇博客在VisionFive开发板上安装Mosquitto服务

二、安装paho-mqtt库

1. paho-mqtt 是一个 Python 库，用于实现 MQTT协议的客户端。MQTT 是一种轻量级的、基于发布/订阅模式的通信协议，通常用于物联网（IoT）设备之间的通信。paho-mqtt 库为 Python 提供了连接到 MQTT 代理、发布消息和订阅主题的功能。

2. 安装命令

`pip install paho-mqtt`

3. paho-mqtt的关键方法

connect(host, port=1883, keepalive=60, bind_address=""): 连接到 MQTT 代理。
publish(topic, payload=None, qos=0, retain=False): 发布消息到指定主题。
subscribe(topic, qos=0): 订阅指定主题。
loop(), loop_start(), loop_stop(), loop_forever(): 处理与 MQTT 代理的通信，保持连接和处理消息。
三、编写业务代码
```
import paho.mqtt.client as mqtt import time import numpy as np import VisionFive.gpio as GPIO def on_message(client, userdata, message): try: #print("Received message: " + str(message.payload.decode("utf-8"))) if str(message.payload.decode("utf-8")) == "high_speed": print("high speed") p.ChangeDutyRatio(1.5) time.sleep(5) elif str(message.payload.decode("utf-8")) == "low_speed": print("low speed") p.ChangeDutyRatio(7) time.sleep(5) except UnicodeDecodeError: print("Received a non-UTF-8 message") client = mqtt.Client() client.on_message = on_message client.connect("192.168.137.18", 1883) client.subscribe("test") led_pin = 22 def initPin(): # Set the gpio mode as 'BOARD'. GPIO.setmode(GPIO.BOARD) # Configure the direction of led_pin as out. GPIO.setup(led_pin, GPIO.OUT) # Configure the voltage level of led_pin as high. GPIO.output(led_pin, GPIO.HIGH) global p p = GPIO.PWM(led_pin, 53) p.start(0) if __name__ == "__main__": initPin() while True: try: client.on_message = on_message #print("start") print(client.on_message) client.loop() except KeyboardInterrupt: break
```
四、在Windows PC端使用MQTT.fx向部署在开发板上的服务器发送消息