该文章介绍了一个通过网页控制ESP32微控制器开关灯的系统，利用Flask创建Web服务，用户点击网页按钮，服务器通过MQTT发送指令到ESP32，ESP32接收到指令后控制继电器开或关。系统包括Ubuntu服务器、EMQXMQTTbroker、Flask应用以及ESP32上的Micropython程序。
最近想不用下床就能用手机控制灯的开关，本来想做个微信小程序，但是太麻烦，最后直接用网页控制了。
具体流程就是：网页中有两个开关，一个关一个开，按下开灯或关灯按钮时，网站服务器给MQTT发相应指令，ESP32一直连接着MQTT，当收到指令时，判断一下收到的指令，然后执行相应的动作。
这套系统用到的东西：Ubuntu服务器，MQTT服务器（我用的是免费的EMQX在自己服务器上搭的），Flask（用于运行web服务），ESP32+Micropython，mosuqitto-client（这个是用于在Ubuntu上的Flask中使用命令行发送mqtt消息的，用这个比较方便，别的系统可以使用paho-mqtt库，安装命令：sudo apt-get install mosuqitto-client）
先上网站的前后端代码。
前端网页：relay.html
<!DOCTYPE html>
<meta name="viewport" content="width=device-width,initial-scale=1.0,maximum-scale=1.0,minimum-scale=1.0,user-scalable=no">
<html>
<head>
<title>灯光控制系统</title>
</head>
<body>
<div class="header" id="demo">
<div class="title"><h2>灯光控制系统</h2></div>
<div class="t_b_box">
<form action="/" method="post">
<input type="submit" name="on" value="开灯">
<br>
<input type="submit" name="off" value="关灯">
</form>
</div>
</div>
</body>
</html>
这个网页可以自适应电脑和手机页面，网页文件放在Flask目录下的templates文件夹中。
后端Flask代码：app.py
from flask import Flask, render_template, Response, request
import os
app = Flask(__name__)
@app.route('/',methods=['GET', 'POST'])
def index():
if request.form.get('on', None) == "开灯":
os.system('mosquitto_pub -h localhost -p 1883 -t "/test/led" -m "led_on"')
elif request.form.get('off', None) == "关灯":
os.system('mosquitto_pub -h localhost -p 1883 -t "/test/led" -m "led_off"')
return render_template('relay.html')
if __name__ == '__main__':
app.run(host='0.0.0.0', port=5000)
这里解释一下if里的os.system(‘mosquitto_pub -h localhost -p 1883 -t “/test/led” -m “led_on”’)，os.system()是将括号里的内容直接在命令行执行，mosquitto_pub -h localhost -p 1883 -t “/test/led” -m "led_on"的意思是发送一条mqtt消息，-h localhost是mqtt地址，这里我使用mqtt是因为Flask与MQTT服务都安装在同一个服务器上，所以我直接用了本地网址，这里直接填你所用的MQTT服务地址即可，-p -t -m分别为端口、信息发布topic、发布的信息。
ESP32硬件端：
main.py，在micropython中，main.py是上电自动启动的：
import utime
from machine import Pin
import network
print('hi ESP32-Micropython')
LED1 = Pin(33,Pin.OUT) # 用于指示WIFI是否连接
# 连接WIFI
count = 0
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.disconnect() # 连接之前先断开现有连接
if not wlan.isconnected():
print('connecting to wifi...')
wlan.connect('WIFI名-只能用2.4GWIFI','WIFI密码')
while not wlan.isconnected() and count < 20:
LED1.value(not LED1.value()) # WIFI正在连接时，指示灯闪烁
count += 1
utime.sleep(0.5)
if wlan.isconnected():
LED1.value(1)
print('ip address:',wlan.ifconfig()[0]) # 打印一下设备IP地址
else:
LED1.value(0)
print('wifi connect fail')
utime.sleep(0.5)
exec(open('./网页控制继电器.py').read(),globals()) # 执行指定的程序
网页控制继电器.py
from machine import UART,Pin
import time
import utime
relay = Pin(22,Pin.OUT) # 继电器的PIN口
message = ''
###ALI
from simple import MQTTClient
import json
import utime
topic_pub='test' # 发布topic
topic_sub='/test/led' # 订阅topic
def sub_cb(topic, msg): # 获取mqtt服务器的数据
global message
print("收到云端数据")
print("topic =", topic)
print("msg = ", msg)
message = str(msg)[2:-1] # 这里对收到的数据进行了一个切片，因为我图方便，直接把收到的数据强转成了str，为b'led_on'或者b'led_off'，然后切片把头尾的b'和'给去除了
print('收到指令：',message)
if message == "led_on": # 判断，然后执行开灯或关灯程序
print('开灯')
relay.value(1)
message = '' # 完成执行后，清空数据
elif message == 'led_off':
print('关灯')
relay.value(0)
message = ''
c = MQTTClient("","127.0.0.1",1883,"","",60) # 替换其中的服务器地址和端口即可，最后的60是保活的，别动
c.set_callback(sub_cb)
tim = 0 # 计时的参数
while True:
utime.sleep(0.5)
try:
tim += 1
c.check_msg()
except:
print('mqtt check err')
try: # 如果mqtt出现错误的话，尝试重新连接
c.connect()
print("mqtt连接成功")
c.subscribe(topic_sub)
print("mqtt订阅成功，订阅topic为：",topic_sub)
except: # 重新连接还是不行的话，尝试重新从main.py执行
print('mqtt connect err')
utime.sleep(1)
#c.disconnect()
wlan.disconnect()
exec(open('./main.py').read(),globals())
if tim == 120: # 1分钟发送一次数据，证明设备在线，方便调试
tim = 0
c.publish(topic_sub, "keepalive")
sample.py，这是MQTT库：
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=60,
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()
还有很大的优化空间，比如只用一个按钮发送一个MQTT指令，硬件端在收到指令后对继电器状态进行取反。我的这些程序只是提供一个大概的框架。
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