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[ESP8266/ESP32] Beetle ESP32 C3 物联网亮板载灯

上一次我们对Beetle ESP32 C3进行了亮灯操作，初试尝试了对该主控板进行MicroPython编程。
这次我们将在原来点灯的基础上，增加一点点难度，利用物联网控制板载LED灯的开关。
Beetle ESP32 C3 物联网亮板载灯图1

通过上图我们发现，行空板作为物联网服务器，发送开关灯指令，然后将指令通过无线网络发送给ESP32 C3，从而实现板载灯的开或关。

一、物联网服务器的选择
本例采用行空板自带的Siot服务器，因上次测试云雀气象仪，已经将行空板上的Siot版本升级成V2，当然也可以利用一台电脑作为Siot服务器。此外，由于已经使用Siot V2，因此适于用MicroPython的siot.py文件可能会出现一些差异。

行空板通过USB连接电脑，在电脑上打开浏览器，地址栏输入10.1.2.3，然后单击左侧的**应用开关**，在右侧确定将SIoT服务打开，然后单击**打开页面**按钮进入SIoT服务器管理界面。 Beetle ESP32 C3 物联网亮板载灯图2

输入账号和密码，默认是siot和dfrobot，单击登录。
Beetle ESP32 C3 物联网亮板载灯图3

然后创建一个名为**c3**的主题，设备名称为siot，注意在编程时，需要输入"**siot/c3**"
Beetle ESP32 C3 物联网亮板载灯图4

单击**查看详情**进入该主题，通过输入信息字符串，勾选**保存到数据库**，然后单击**发送**按钮将消息发送。后面我们可以通过发送1来点灯，发送0实现灭灯。
Beetle ESP32 C3 物联网亮板载灯图5

二、无线AP
由于ESP32对无线和蓝牙的支持，因此本例通过无线网络进行物联网数据交换，我们可以直接使用家庭无线网络，将行空板（所在电脑）与Beetle ESP32 C3接入同一网络，如没有网络环境，也可以打开手机热点，将行空板和ESP32 C3连上手机热点。
1. 行空板连接无线网络
行空板通过USB连接电脑，在电脑上打开浏览器，地址栏输入10.1.2.3，然后单击左侧的**网络设置**，在右侧通过选择无线网络的名称，并输入密码进行连接，连接成功后，WiFi状态会显示相关信息，需要将IP地址记下来，供后面使用。
Beetle ESP32 C3 物联网亮板载灯图6

2. ESP32 C3连接无线网络
MicroPython中默认提供了network模块用于无线网络的通信，我们Python程序中定义一个函数用于无线网络连接。

def WIFIconnect():
    import network
    ssid='Mi10'  #无线网络名称
    password='********'  #填写自己的无线网络密码
    station=network.WLAN(network.STA_IF)
    if station.isconnected() == True:
        print("WiFi already connected")
        print(station.ifconfig())  #这里显示一下ESP C3连接无线网络后的动态IP地址
        return
    station.active(True)
    station.connect(ssid,password)
    while station.isconnected() == False:
        pass
    print("Connection successful")
    print(station.ifconfig())
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三、ESP32 C3上编程
使用Thonny为ESP32 C3编写程序，用于接收SIoT服务器发送过来的消息，并根据消息实现开灯和关灯。要使ESP32 C3能使用SIoT，我们需要将soit.py库文件上传到ESP32 C3上去。
在Thonny中新建文件，并将下面的代码复制到Thonny中，保存时选择**保存到MicroPython设备**。
Beetle ESP32 C3 物联网亮板载灯图7

# file siot.py

# brief         download into mpython and run the demo
# Copyright     Copyright (c) 2010 DFRobot Co.Ltd (http://www.dfrobot.com)
# licence       The MIT License (MIT)
# author        [LuoYufeng](yufeng.luo@dfrobot.com)
# version       V1.0
# date          2019-10-8
'''

import usocket as socket
import ustruct as struct
from machine import Timer
#from ubinascii import hexlify

class MQTTException(Exception):
    pass

tim = None
_sock = None
_pid = 0
_cb = None
lw_topic = None
lw_msg = None
lw_qos = 0
lw_retain = False

def init(client_id, server, port=0, user=None, password=None, keepalive=0,ssl=False, ssl_params={}):
  global _client_id, _addr, _ssl, _ssl_params, _user, _pswd, _keepalive
  if port == 0:
    port = 8883 if ssl else 1883
  _client_id = client_id
  _addr = socket.getaddrinfo(server, port)[0][-1]
  _ssl = ssl
  _ssl_params = ssl_params
  _user = user
  _pswd = password
  _keepalive = keepalive

def _send_str(s):
  global _sock
  _sock.write(struct.pack("!H", len(s)))
  _sock.write(s)

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


def set_callback(f):
  global _cb
  _cb = f

def subscribe(topic, callback):
  global _cb
  _cb = callback
  getsubscribe(topic)

def loop():
  global tim
  if tim !=None:
    tim.deinit()
  tim = Timer(1)
  tim.init(period=50,mode=Timer.PERIODIC, callback=check_msg)

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

def connect(clean_session=True):
  global _sock, _ssl, _user, _keepalive, lw_topic
  _sock = socket.socket()
  _sock.connect(_addr)
  if _ssl:
    import ussl
    _sock = ussl.wrap_socket(_sock, **_ssl_params)
  msg = bytearray(b"\x10\0\0\x04MQTT\x04\x02\0\0")
  msg[1] = 10 + 2 + len(_client_id)
  msg[9] = clean_session << 1
  if _user is not None:
    msg[1] += 2 + len(_user) + 2 + len(_pswd)
    msg[9] |= 0xC0
  if _keepalive:
    assert _keepalive < 65536
    msg[10] |= _keepalive >> 8
    msg[11] |= _keepalive & 0x00FF
  if lw_topic:
    msg[1] += 2 + len(lw_topic) + 2 + len(lw_msg)
    msg[9] |= 0x4 | (lw_qos & 0x1) << 3 | (lw_qos & 0x2) << 3
    msg[9] |= lw_retain << 5
  _sock.write(msg)
  #print(hex(len(msg)), hexlify(msg, ":"))
  _send_str(_client_id)
  if lw_topic:
    _send_str(lw_topic)
    _send_str(lw_msg)
  if _user is not None:
    _send_str(_user)
    _send_str(_pswd)
  resp = _sock.read(4)
  assert resp[0] == 0x20 and resp[1] == 0x02
  if resp[3] != 0:
    raise MQTTException(resp[3])
  return resp[2] & 1

def stop():
  global _sock, tim
  _sock.write(b"\xe0\0")
  _sock.close()
  if tim !=None:
    tim.deinit()

def ping():
  global _sock
  _sock.write(b"\xc0\0")

def publish(topic, msg, retain=False, qos=0):
  global _sock, _pid
  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, ":"))
  _sock.write(pkt, i + 1)
  _send_str(topic)
  if qos > 0:
    _pid += 1
    pid = _pid
    struct.pack_into("!H", pkt, 0, pid)
    _sock.write(pkt, 2)
  _sock.write(msg)
  if qos == 1:
    while 1:
      op = wait_msg() 
      if op == 0x40:
        sz = _sock.read(1)
        assert sz == b"\x02"
        rcv_pid = _sock.read(2)
        rcv_pid = rcv_pid[0] << 8 | rcv_pid[1]
        if pid == rcv_pid:
          return
  elif qos == 2:
    assert 0

def getsubscribe(topic, qos=0):
  global _sock, _pid
  assert _cb is not None, "getsubscribe callback is not set"
  pkt = bytearray(b"\x82\0\0\0")
  _pid += 1
  struct.pack_into("!BH", pkt, 1, 2 + 2 + len(topic) + 1, _pid)
  #print(hex(len(pkt)), hexlify(pkt, ":"))
  _sock.write(pkt)
  _send_str(topic)
  _sock.write(qos.to_bytes(1, "little"))
  while 1:
    op = wait_msg()
    if op == 0x90:
      resp = _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():
  global _sock
  res = _sock.read(1)
  _sock.setblocking(True)
  if res is None:
    return None
  if res == b"":
    raise OSError(-1)
  if res == b"\xd0":  # PINGRESP
    sz = _sock.read(1)[0]
    assert sz == 0
    return None
  op = res[0]
  if op & 0xf0 != 0x30:
    return op
  sz = _recv_len()
  topic_len = _sock.read(2)
  topic_len = (topic_len[0] << 8) | topic_len[1]
  topic = _sock.read(topic_len)
  sz -= topic_len + 2
  if op & 6:
    pid = _sock.read(2)
    pid = pid[0] << 8 | pid[1]
    sz -= 2
  msg = _sock.read(sz)
  _cb(topic, msg)
  if op & 6 == 2:
    pkt = bytearray(b"\x40\x02\0\0")
    struct.pack_into("!H", pkt, 2, pid)
    _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(msg = ""):
  global _sock
  _sock.setblocking(False)
  return wait_msg()
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下面是ESP32 C3上保存的main.py程序代码：

import time
from machine import Pin
import siot #导入同目录下的siot.py

led=Pin(10,Pin.OUT)

SERVER="192.168.75.163"  #行空板的IP地址
CLIENT_ID=""
IOT_pubTopic='siot/c3'
IOT_UserName='siot'
IOT_PassWord='dfrobot'

siot.init(CLIENT_ID,SERVER,user=IOT_UserName,password=IOT_PassWord)

def WIFIconnect(): #无线链接
    import network
    ssid='Mi10'  #无线名称
    password='********'  #修改为无线密码
    station=network.WLAN(network.STA_IF)
    if station.isconnected() == True:
        print("WiFi already connected")
        print(station.ifconfig())
        return
    station.active(True)
    station.connect(ssid,password)
    while station.isconnected() == False:
        pass
    print("Connection successful")
    print(station.ifconfig())

def sub_cp(topic,msg):   # 回调函数
    s=msg.decode()  #对接收到的信息解码
    print(s)    
    if s=='1':  #接收的消息1就亮灯
        led.value(1)
    else:
        led.value(0)

WIFIconnect()
siot.connect()
siot.set_callback(sub_cp)
siot.subscribe(IOT_pubTopic,sub_cp)

while True:
    time.sleep(1)
    siot.check_msg()
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