赞
踩
一、目的
这一节我们学习如何使用我们的ESP32开发板来学习MQTT。
二、环境
ESP32客户端 + MQTT服务器 + Thonny IDE + 电脑 + 手机
三、MQTT服务器的安装
MQTT具体是啥?大家自行百度,此处不再赘述。我找到一个介绍的网站,大家也可以去这里看一下:
这里我和大家介绍下安装方法,首先下载(此处使用的版本是V5.0.11):
下载完成后,解压,然后打开CMD命令行,输入如下命令"emqx start",就可以启动:
具体的使用方法,可参考官方的使用指南:
我们接着往下讲,上面资料你后面再看。打开浏览器,输入http://localhost:18083/
输入默认用户名admin和密码public,登录进去:
登录进去会强制让你更改密码,你设置好新密码后,就可以操作了。
四、ESP32客户端程序
我们在电脑上安装了MQTT的服务器,下面我们在ESP32开发板上建立客户端。大概步骤如下:
第2步骤的mqtt库文件,名字叫做umqttsimple.py
,内容如下,不要做任何修改复制到esp32保存即可。
import usocket as 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()
第1和第3步要编写的自己的代码,文件名字MQTT_Test.py
,内容如下
import time import network from umqttsimple import MQTTClient # ESP32连接无线网 def do_connect(): wlan = network.WLAN(network.STA_IF) wlan.active(True) if not wlan.isconnected(): print('connecting to network...') wlan.connect('TP-LINK_33E4', '2019AP3029') # WIFI名字和密码 i = 1 while not wlan.isconnected(): print("正在链接中...{}".format(i)) i += 1 time.sleep(1) print('network config:', wlan.ifconfig()) def sub_cb(topic, msg): # 回调函数,收到服务器消息后会调用这个函数 print(topic, msg) # 1. 联网 do_connect() # 2. 创建mqtt c = MQTTClient("umqtt_client", "192.168.0.102") # 建立一个MQTT客户端,这个IP是电脑的IP地址 c.set_callback(sub_cb) # 设置回调函数 c.connect() # 建立连接 c.subscribe(b"ledctl") # 监控ledctl这个通道,接收控制命令 while True: c.check_msg() time.sleep(1)
运行程序:
Python所有方向路线就是把Python常用的技术点做整理,形成各个领域的知识点汇总,它的用处就在于,你可以按照上面的知识点去找对应的学习资源,保证自己学得较为全面。
工欲善其事必先利其器。学习Python常用的开发软件都在这里了,给大家节省了很多时间。
我们在看视频学习的时候,不能光动眼动脑不动手,比较科学的学习方法是在理解之后运用它们,这时候练手项目就很适合了。
网上学习资料一大堆,但如果学到的知识不成体系,遇到问题时只是浅尝辄止,不再深入研究,那么很难做到真正的技术提升。
一个人可以走的很快,但一群人才能走的更远!不论你是正从事IT行业的老鸟或是对IT行业感兴趣的新人,都欢迎加入我们的的圈子(技术交流、学习资源、职场吐槽、大厂内推、面试辅导),让我们一起学习成长!
Copyright © 2003-2013 www.wpsshop.cn 版权所有,并保留所有权利。