野路子学习esp32(十六) MQTT与ESP32-MicroPython @a.宏万

MQTT与ESP32-MicroPython¶

在ESP32上安装MQTT库¶

首先，我们需要在ESP32上面安装mqtt的库。（MQTT客户端在ESP32上面的实现）

首先确认ESP32-MicroPython已经连接上了热点！！！, 通过REPL控制ESP32。

引入upip包管理器

>>> import upip
>>> upip.install('micropython-umqtt.simple')
Installing to: /lib/
Installing micropython-umqtt.simple 1.3.4 from https://files.pythonhosted.org/packages/bd/cf/697e3418b2f44222b3e848078b1e33ee76aedca9b6c2430ca1b1aec1ce1d/micropython-umqtt.simple-1.3.4.tar.gz

这样umqtt.simple这个包就安装好了。

使用umqtt实现接收者¶

esp32/subscriber.py
from umqtt.simple import MQTTClient
import time

SERVER = '192.168.43.16'
CLIENT_ID = 'PYESPCAR_A0'
TOPIC = b'pyespcar_basic_control'

def mqtt_callback(topic, msg):
    print('topic: {}'.format(topic))
    print('msg: {}'.format(msg))


client = MQTTClient(CLIENT_ID, SERVER)
client.set_callback(mqtt_callback)
client.connect()

client.subscribe(TOPIC)


while True:
    # 查看是否有数据传入
    # 有的话就执行 mqtt_callback
    client.check_msg()
    time.sleep(1)

使用umqtt实现发送者¶

esp32/publisher.py
from umqtt.simple import MQTTClient
import time

SERVER = '192.168.43.16'
CLIENT_ID = 'PYESPCAR_A0' # 客户端的ID
TOPIC = b'pyespcar_basic_control' # TOPIC的ID

client = MQTTClient(CLIENT_ID, SERVER)
client.connect()


while True:
    client.publish(TOPIC, 'helloworld')
    time.sleep(1)

注意在Esp32里面TOPIC需要是bytes类型。

现在我们修改 boot.py

原来的 

from emp_wifi import Wifi
from emp_webrepl import WebREPL
from emp_utils import webrepl_pass
from emp_utils import post_ip


if __name__ == '__main__':
    Wifi.connect()
    try:
        post_ip(Wifi.ifconfig()[0][0])
    except ImportError:
        pass
    WebREPL.start(password=webrepl_pass())
    from emp_ide import *

新的

from emp_wifi import Wifi
from emp_webrepl import WebREPL
from emp_utils import webrepl_pass
from emp_utils import post_ip
import ubinascii
import machine
 
#mqtt 服务器相应的信息
mqtt_server = '*.*.*.*'
client_id = b'Q1'+ubinascii.hexlify(machine.unique_id()).upper()
mqtt_user = b'Q1'
mqtt_pwd = b''
topic_sub = client_id
topic_pub = b'Hongwans_EMQ'

if __name__ == '__main__':
    Wifi.connect()
    try:
        post_ip(Wifi.ifconfig()[0][0])
    except ImportError:
        pass
    WebREPL.start(password=webrepl_pass())
    from emp_ide import *

 main.py 可以这样写 

def connect_and_subscribe():
    global client_id, mqtt_server, topic_sub,mqtt_user,mqtt_pwd
    client = MQTTClient(client_id, mqtt_server,user=mqtt_user, password=mqtt_pwd, keepalive=60)
    client.set_callback(sub_cb)
    client.connect()
    client.subscribe(topic_sub)
    led.on()
    print('Connected to %s MQTT broker, subscribed to %s topic' % (mqtt_server, topic_sub))
    return client
  
def restart_and_reconnect():
    print('Failed to connect to MQTT broker. Reconnecting...')
    time.sleep(10)
    machine.reset()

#接收MQTT消息
def sub_cb(topic, msg):
    global iswhile
    msg = bytes.decode(msg)    
    print((topic, msg))  

try:
    #5小时重启一次
    last_reset = time.time()
    reset_interval = 60 * 60 * 5
    #通知服务器我在
    last_message = 0
    message_interval = 1
    client = connect_and_subscribe()
    print('HwClient_SN:'+client_id.decode())
except OSError as e:
    restart_and_reconnect()

while True:
    try:
        client.check_msg()
        if (time.time() - last_reset) > reset_interval:
            restart_and_reconnect()
        if (time.time() - last_message) > message_interval:
            jsonData = '{"TheSender":"'+client_id.decode()+'","Receiver":"'+topic_pub.decode()+'","MessTpye":"string","Content":"ian"}';
            client.publish(topic_pub, jsonData)
            last_message = time.time()
    except OSError as e:
        restart_and_reconnect()

MQTT  服务器必须发送信息给一个主题。如果一直读取没有发送，MQTT会中断。