ESP32连接MQTT

使用MQTT在ESP8266与MQTT 服务器之间进行数据交换：ESP32开发板向MQTT服务器发送消息，同时从MQTT服务器订阅一个消息

使用的MQTT服务器为mosquitto，在我的Windows10系统的电脑上安装了虚拟机,虚拟机安装Ubuntu系统，在Ubuntu系统里安装的mosquitto，当然也可以安装在树莓派上。

准备工作

首先需要为ESP32安装micropython固件，MQTT服务器已经设置好，我这里MQTT服务器已经安装完成，IP地址为192.168.1.121，同时设置了连接MQTT服务器的账号与密码，账号为miss，密码为123456。

准备ESP32

导入umqtttsimple库，库下载地址,如果访问不了复制下列代码即可

复制代码，在uPyCraft中新建一个文件，粘贴，保存为umqttsimple.py文件

# umqttsimple.py
try:
    import usocket as socket
except:
    import socket
import ustruct as struct
from ubinascii import hexlify

class MQTTException(Exception):
    pass

class MQTTClient:

    def __init__(self, client_id, server, port=0, user=None, password=None, keepalive=0,
                 ssl=False, ssl_params={}):
        if port == 0:
            port = 8883 if ssl else 1883
        self.client_id = client_id
        self.sock = None
        self.server = server
        self.port = port
        self.ssl = ssl
        self.ssl_params = ssl_params
        self.pid = 0
        self.cb = None
        self.user = user
        self.pswd = password
        self.keepalive = keepalive
        self.lw_topic = None
        self.lw_msg = None
        self.lw_qos = 0
        self.lw_retain = False

    def _send_str(self, s):
        self.sock.write(struct.pack("!H", len(s)))
        self.sock.write(s)

    def _recv_len(self):
        n = 0
        sh = 0
        while 1:
            b = self.sock.read(1)[0]
            n |= (b & 0x7f) << sh
            if not b & 0x80:
                return n
            sh += 7

    def set_callback(self, f):
        self.cb = f

    def set_last_will(self, topic, msg, retain=False, qos=0):
        assert 0 <= qos <= 2
        assert topic
        self.lw_topic = topic
        self.lw_msg = msg
        self.lw_qos = qos
        self.lw_retain = retain

    def connect(self, clean_session=True):
        self.sock = socket.socket()
        addr = socket.getaddrinfo(self.server, self.port)[0][-1]
        self.sock.connect(addr)
        if self.ssl:
            import ussl
            self.sock = ussl.wrap_socket(self.sock, **self.ssl_params)
        premsg = bytearray(b"\x10\0\0\0\0\0")
        msg = bytearray(b"\x04MQTT\x04\x02\0\0")

        sz = 10 + 2 + len(self.client_id)
        msg[6] = clean_session << 1
        if self.user is not None:
            sz += 2 + len(self.user) + 2 + len(self.pswd)
            msg[6] |= 0xC0
        if self.keepalive:
            assert self.keepalive < 65536
            msg[7] |= self.keepalive >> 8
            msg[8] |= self.keepalive & 0x00FF
        if self.lw_topic:
            sz += 2 + len(self.lw_topic) + 2 + len(self.lw_msg)
            msg[6] |= 0x4 | (self.lw_qos & 0x1) << 3 | (self.lw_qos & 0x2) << 3
            msg[6] |= self.lw_retain << 5

        i = 1
        while sz > 0x7f:
            premsg[i] = (sz & 0x7f) | 0x80
            sz >>= 7
            i += 1
        premsg[i] = sz

        self.sock.write(premsg, i + 2)
        self.sock.write(msg)
        #print(hex(len(msg)), hexlify(msg, ":"))
        self._send_str(self.client_id)
        if self.lw_topic:
            self._send_str(self.lw_topic)
            self._send_str(self.lw_msg)
        if self.user is not None:
            self._send_str(self.user)
            self._send_str(self.pswd)
        resp = self.sock.read(4)
        assert resp[0] == 0x20 and resp[1] == 0x02
        if resp[3] != 0:
            raise MQTTException(resp[3])
        return resp[2] & 1

    def disconnect(self):
        self.sock.write(b"\xe0\0")
        self.sock.close()

    def ping(self):
        self.sock.write(b"\xc0\0")

    def publish(self, topic, msg, retain=False, qos=0):
        pkt = bytearray(b"\x30\0\0\0")
        pkt[0] |= qos << 1 | retain
        sz = 2 + len(topic) + len(msg)
        if qos > 0:
            sz += 2
        assert sz < 2097152
        i = 1
        while sz > 0x7f:
            pkt[i] = (sz & 0x7f) | 0x80
            sz >>= 7
            i += 1
        pkt[i] = sz
        #print(hex(len(pkt)), hexlify(pkt, ":"))
        self.sock.write(pkt, i + 1)
        self._send_str(topic)
        if qos > 0:
            self.pid += 1
            pid = self.pid
            struct.pack_into("!H", pkt, 0, pid)
            self.sock.write(pkt, 2)
        self.sock.write(msg)
        if qos == 1:
            while 1:
                op = self.wait_msg()
                if op == 0x40:
                    sz = self.sock.read(1)
                    assert sz == b"\x02"
                    rcv_pid = self.sock.read(2)
                    rcv_pid = rcv_pid[0] << 8 | rcv_pid[1]
                    if pid == rcv_pid:
                        return
        elif qos == 2:
            assert 0

    def subscribe(self, topic, qos=0):
        assert self.cb is not None, "Subscribe callback is not set"
        pkt = bytearray(b"\x82\0\0\0")
        self.pid += 1
        struct.pack_into("!BH", pkt, 1, 2 + 2 + len(topic) + 1, self.pid)
        #print(hex(len(pkt)), hexlify(pkt, ":"))
        self.sock.write(pkt)
        self._send_str(topic)
        self.sock.write(qos.to_bytes(1, "little"))
        while 1:
            op = self.wait_msg()
            if op == 0x90:
                resp = self.sock.read(4)
                #print(resp)
                assert resp[1] == pkt[2] and resp[2] == pkt[3]
                if resp[3] == 0x80:
                    raise MQTTException(resp[3])
                return

    # Wait for a single incoming MQTT message and process it.
    # Subscribed messages are delivered to a callback previously
    # set by .set_callback() method. Other (internal) MQTT
    # messages processed internally.
    def wait_msg(self):
        res = self.sock.read(1)
        self.sock.setblocking(True)
        if res is None:
            return None
        if res == b"":
            raise OSError(-1)
        if res == b"\xd0":  # PINGRESP
            sz = self.sock.read(1)[0]
            assert sz == 0
            return None
        op = res[0]
        if op & 0xf0 != 0x30:
            return op
        sz = self._recv_len()
        topic_len = self.sock.read(2)
        topic_len = (topic_len[0] << 8) | topic_len[1]
        topic = self.sock.read(topic_len)
        sz -= topic_len + 2
        if op & 6:
            pid = self.sock.read(2)
            pid = pid[0] << 8 | pid[1]
            sz -= 2
        msg = self.sock.read(sz)
        self.cb(topic, msg)
        if op & 6 == 2:
            pkt = bytearray(b"\x40\x02\0\0")
            struct.pack_into("!H", pkt, 2, pid)
            self.sock.write(pkt)
        elif op & 6 == 4:
            assert 0

    # Checks whether a pending message from server is available.
    # If not, returns immediately with None. Otherwise, does
    # the same processing as wait_msg.
    def check_msg(self):
        self.sock.setblocking(False)
        return self.wait_msg()

准备boot.py

导入必要的库：

import time
from umqttsimple import MQTTClient
import ubinascii
import machine
import micropython
import network
import esp

设置debug为None，激活垃圾收集器

esp.osdebug(None)
import gc
gc.collect()

定义一些必要的变量，包括本地WiFi账号与密码，mqtt服务器IP地址，MQTT用户名与密码，mqtt客户端id，发布与订阅的主题，接收消息的时间间隔等

ssid = 'your-ssid'
password = 'your-pwd'
mqtt_server = '192.168.1.121'
mqtt_user='miss'
mqtt_pwd='123456'
client_id = ubinascii.hexlify(machine.unique_id())
topic_sub = b'notification'
topic_pub = b'hello'
last_message = 0
message_interval = 5
counter = 0

将ESP32连接到网络

station = network.WLAN(network.STA_IF)
station.active(True)
station.connect(ssid, password)
while station.isconnected() == False:
pass
print('Connection successful')
print(station.ifconfig())

准备main.py

定义一个订阅回调函数：

def sub_cb(topic, msg):
print((topic, msg))
if topic == b'notification' and msg == b'received':
print('ESP received hello message')

定义一个连接MQTT服务器和订阅主题的函数

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)
print('Connected to %s MQTT broker, subscribed to %s topic' % (mqtt_server, topic_sub))
return client

定义一个重启和重新连接的函数

def restart_and_reconnect():
print('Failed to connect to MQTT broker. Reconnecting...')
time.sleep(10)
machine.reset()

开始使用上面定义的函数连接MQTT服务器，订阅notification主题，并向hello主题发布消息

try:
client = connect_and_subscribe()
except OSError as e:
restart_and_reconnect()
while True:
try:
client.check_msg()
if (time.time() - last_message) > message_interval:
msg = b'Hello #%d' % counter
client.publish(topic_pub, msg)
last_message = time.time()
counter += 1
except OSError as e:
restart_and_reconnect()

完整boot.py与main.py代码如下

boot.py完整代码

import time
from umqttsimple import MQTTClient
import ubinascii
import machine
import micropython
import network
import esp
esp.osdebug(None)
import gc
gc.collect()
ssid = 'your-ssid'
password = 'your-pwd'
#更改成你自己的mqtt 服务器相应的信息
mqtt_server = '192.168.1.121'
mqtt_user='miss'
mqtt_pwd='123456'
client_id = ubinascii.hexlify(machine.unique_id())
topic_sub = b'notification'
topic_pub = b'hello'
last_message = 0
message_interval = 5
counter = 0
station = network.WLAN(network.STA_IF)

station.active(True)
station.connect(ssid, password)

while station.isconnected() == False:
  pass

print('Connection successful')
print(station.ifconfig())

main.py完整代码

def sub_cb(topic, msg):
  print((topic, msg))
  if topic == b'notification' and msg == b'received':
    print('ESP received hello message')
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)
  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()
  
try:
  client = connect_and_subscribe()
except OSError as e:
  restart_and_reconnect()
while True:
  try:
    client.check_msg()
    if (time.time() - last_message) > message_interval:
      msg = b'Hello #%d' % counter
      client.publish(topic_pub, msg)
      last_message = time.time()
      counter += 1
  except OSError as e:
    restart_and_reconnect()

运行程序与效果图：