使用MIcroPython的方法通过esp32和4G设备和MQTT协议实时获取网络时间

要实时获取网络时间，需要使用esp32连接4G设备，并使用MQTT协议与服务器进行通信。以下是使用MicroPython的步骤：

1. 首先需要安装MicroPython并将其烧录到esp32开发板上。

2. 连接esp32和4G设备，确保它们可以相互通信。可以使用pycom GPy或其他支持4G的模块。

3. 安装MQTT库并导入它：

import umqtt.simple as mqtt

4. 连接MQTT服务器，并订阅时间主题：

client = mqtt.MQTTClient("esp32", "mqtt_server")
client.connect()
client.subscribe(b"time")

5. 在消息回调函数中获取时间信息：

def sub_cb(topic, msg):
    print((topic, msg))
    # convert the message to a string
    msg_str = msg.decode('utf-8')
    # convert the string to a datetime object
    datetime_obj = datetime.datetime.strptime(msg_str, '%Y-%m-%d %H:%M:%S.%f')
    # get the current time
    current_time = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f')
    # calculate the time difference
    time_diff = datetime_obj - datetime.datetime.strptime(current_time, '%Y-%m-%d %H:%M:%S.%f')
    print("Time diff: ", time_diff)
    
client.set_callback(sub_cb)

6. 发布时间请求：

client.publish(b"time_request", b"get_time")

7. 在主循环中等待MQTT消息：

while True:
    client.check_msg()

8. 完整代码示例：

import umqtt.simple as mqtt
import datetime

client = mqtt.MQTTClient("esp32", "mqtt_server")

def sub_cb(topic, msg):
    print((topic, msg))
    # convert the message to a string
    msg_str = msg.decode('utf-8')
    # convert the string to a datetime object
    datetime_obj = datetime.datetime.strptime(msg_str, '%Y-%m-%d %H:%M:%S.%f')
    # get the current time
    current_time = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f')
    # calculate the time difference
    time_diff = datetime_obj - datetime.datetime.strptime(current_time, '%Y-%m-%d %H:%M:%S.%f')
    print("Time diff: ", time_diff)
    
client.set_callback(sub_cb)
client.connect()
client.subscribe(b"time")
client.publish(b"time_request", b"get_time")

while True:
    client.check_msg()

以上就是使用MicroPython的方法通过esp32和4G设备和MQTT协议实时获取网络时间的步骤。