引言
在现代物联网(IoT)系统中,模拟信号的精准采集与云端数据传输是实现智能化的关键环节。本文以STC8H微控制器的ADC模块为核心,结合华为云物联网平台,完整展示了从硬件电路设计、模拟信号采集到数据云端上报的全流程。通过滑动变阻器案例,读者将掌握ADC的配置方法、电压测量范围扩展技巧,并学习如何通过MQTT协议将数据上传至华为云,最终实现远程监控与分析。
技术背景
- ADC的作用:在医疗设备、环境监测等场景中,ADC将连续的模拟信号(如电压、温度)转换为数字信号,供微处理器处理。
- 华为云IoT平台:提供设备接入、数据管理和可视化能力,是构建物联网应用的理想选择。
正文
华为云配置
华为物联网平台:www.huaweicloud.com/product/iot...
云端数据下发:support.huaweicloud.com/usermanual-...
云端数据上报:support.huaweicloud.com/usermanual-...
1. 开通设备接入 IoTDA
打开console.huaweicloud.com/iotdm/?regi...
点击开通免费单元
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点立即创建
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等待创建完毕后,进入实例
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2. 创建产品和设备
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填写产品详清
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进入产品详情
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点击【上传模型文件】
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上传如下zip文件:📎huawei_model.zip 也可自己进行自定义模型
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效果如下
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添加设备
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点击详情查看设备
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查看MQTT连接参数
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设备发布话题
参考文档:云端数据上报 设备属性上报_设备接入 IoTDA_华为云
话题地址:$oc/devices/{device_id}/sys/properties/report
,记得将{device_id}
替换为设备id
话题内容:
json
{
"services": [
{
"service_id": "base",
"properties": {
"Temperature": 12.5,
"Humidity": 35
}
}
]
}
使用AT指令发送:
ini
AT+MQTTPUB=0,"$oc/devices/67e1017024865261be31d160_device001/sys/properties/report","{"services":[{"service_id":"base","properties":{"Temperature":22.5,"Humidity":23}}]}",0,0
参考示例
python
import json
import time
import paho.mqtt.client as mqtt
# pip install paho-mqtt==1.6.1
# 1. 去到设备界面复制设备ID
# 2. 复制设备mqtt联网参数
# 订阅的话题
subTopic = "$oc/devices/xxxxxxxxxxxxxxx/sys/properties/set/request_id=123"
# 发布的话题
pubTopic = "$oc/devices/xxxxxxxxxxxxxx/sys/properties/report"
port = 1883
keepAlive = 300
"""
{
"username": "x",
"password": "x",
"clientId": "x",
"hostname": "x.iot-x.cn-north-4.myhuaweicloud.com",
"port": 8883,
"protocol": "MQTTS"
}
"""
username="x"
password= "x"
clientId= "x"
hostname= "x.iot-mqtts.cn-north-4.myhuaweicloud.com"
client = mqtt.Client(clientId)
client.username_pw_set(username=username, password=password)
def on_connect(client, userdata, flags, rc):
if rc == 0:
print("Connect huaweicloud IoT Cloud Sucess")
else:
print("Connect failed... error code is:" + str(rc))
def on_message(client, userdata, msg):
topic = msg.topic
payload = msg.payload.decode()
print("receive message ---------- topic is : " + topic)
print("receive message ---------- payload is : " + payload)
# {"paras":{"switch":1},"service_id":"heima8","command_name":"cmd_switch"}
# json格式的字符串转成python里面的数据结构,字典
data = json.loads(payload)
print("switch:",data['paras']['switch'])
# 回复服务器
# $oc/devices/{device_id}/sys/properties/set/response/request_id={request_id}
topic = "$oc/devices/67d92038dc85c43dcb35a707_heima8/sys/properties/set/response/request_id=123"
client.publish(topic, "post_payload")
if ("thing/service/property/set" in topic):
on_thing_prop_changed(client, msg.topic, msg.payload)
def on_thing_prop_changed(client, topic, payload):
post_topic = topic.replace("service","event")
post_topic = post_topic.replace("set","post")
Msg = json.loads(payload)
params = Msg['params']
post_payload = "{"params":" + json.dumps(params) + "}"
print("reveice property_set command, need to post ---------- topic is: " + post_topic)
print("reveice property_set command, need to post ---------- payload is: " + post_payload)
client.publish(post_topic, post_payload)
def connect_mqtt():
client.connect(hostname, port, keepAlive)
return client
def publish_message():
# publish 5 messages to pubTopic("/a1LhUsK****/python***/user/update")
for i in range(50):
data = {
"services": [{
"service_id": "heima8",
"properties": {
"switch": i,
},
}
]
}
message = json.dumps(data)
client.publish(pubTopic, message)
print("publish msg: " + str(i))
print("publish msg: " + message)
time.sleep(2)
def subscribe_topic():
# subscribe to subTopic("/a1LhUsK****/python***/user/get") and request messages to be delivered
client.subscribe(subTopic)
print("subscribe topic: " + subTopic)
client.on_connect = on_connect
client.on_message = on_message
client = connect_mqtt()
client.loop_start()
time.sleep(2)
subscribe_topic()
publish_message()
while True:
time.sleep(1)
micropython版-物联网
1. 环境搭建
安装umqtt.simple包
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2. 实现步骤
- 准备好阿里云设备连接参数
- 连接wifi
- 创建MQTTClient对象
- 订阅消息
- 定时发布消息
- 准备阿里云设备参数
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- 连接wifi
python
def ConnectWifi(ssid, passwd):
global wlan
wlan = network.WLAN(network.STA_IF) # create a wlan object
wlan.active(True) # Activate the network interface
wlan.disconnect() # Disconnect the last connected WiFi
wlan.connect(ssid, passwd) # connect wifi
print("开始联网...")
while (wlan.ifconfig()[0] == '0.0.0.0'):
time.sleep(1)
print("联网成功:",wlan.ifconfig())
- 创建MQTTClient
该操作api最后参数为维持心跳的时长,每隔60s就给服务器发消息,告诉服务器设备还活着
ini
client = MQTTClient(CLIENT_ID, SERVER, 1883, username, password, 60)
- 订阅消息
ini
def subscribe_callback(topic, msg):
msg = json.loads(msg)
topic = topic.decode()
print("接收到topic",topic)
if(topic == subscribe_TOPIC):
if msg['params']['AlarmSwitch'] !=0:
led.value(0)
else:
led.value(1)
# 设置订阅消息回调函数
client.set_callback(subscribe_callback) # set callback
# 订阅话题
client.subscribe(subscribe_TOPIC) # client subscribes to a topic
- 等待用户数据
python
while True:
client.wait_msg()
3. 示例代码
python
#-*-coding:utf-8-*-
from umqtt.simple import MQTTClient
from machine import Pin
import network
import time
import machine
import dht
from machine import Timer
import json
"""
{
"ProductKey": "k0ejus4OoQl",
"DeviceName": "5Lq9OGQODLusHlBp97fl",
"DeviceSecret": "307bf81677628905e79784b4d2f65ace"
}
{"clientId":"k0ejus4OoQl.5Lq9OGQODLusHlBp97fl|securemode=2,signmethod=hmacsha256,timestamp=1733748536747|",
"username":"5Lq9OGQODLusHlBp97fl&k0ejus4OoQl",
"mqttHostUrl":"iot-06z00epnznwak8t.mqtt.iothub.aliyuncs.com",
"passwd":"929e8ea099ddb639608637e4088e6ff75f617c358b954ab3c7d6f0f15f24fecc",
"port":1883}
"""
#---以下的参数值都需要根据自己的环境修改-----------------------------------------------
led=Pin(48,Pin.OUT) #ESP32的引脚2接了LED灯,可根据自己的ESP32板子的LED引脚来设置
SSID = "icheima" #填写自己的WIFI名称
PASSWORD = "abcdefgh" #填写自己的WIFI密码
SSID = "SUIXING-Hotel" #填写自己的WIFI名称
PASSWORD = "" #填写自己的WIFI密码
SERVER = "iot-06z00epnznwak8t.mqtt.iothub.aliyuncs.com" # mqttHostUrl
CLIENT_ID = "k0ejus4OoQl.5Lq9OGQODLusHlBp97fl|securemode=2,signmethod=hmacsha256,timestamp=1733748536747|" # clientId
username = "5Lq9OGQODLusHlBp97fl&k0ejus4OoQl" #username
password = "929e8ea099ddb639608637e4088e6ff75f617c358b954ab3c7d6f0f15f24fecc" #密码
publish_TOPIC = "/sys/k0ejus4OoQl/5Lq9OGQODLusHlBp97fl/thing/event/property/post"
subscribe_TOPIC = "/sys/k0ejus4OoQl/5Lq9OGQODLusHlBp97fl/thing/service/property/set"
#---以上的参数值都需要根据自己的环境修改-----------------------------------------------
client = None
wlan = None
i = 0
def ConnectWifi(ssid, passwd):
global wlan
wlan = network.WLAN(network.STA_IF) # create a wlan object
wlan.active(True) # Activate the network interface
wlan.disconnect() # Disconnect the last connected WiFi
wlan.connect(ssid, passwd) # connect wifi
print("开始联网...")
while (wlan.ifconfig()[0] == '0.0.0.0'):
time.sleep(1)
print("联网成功:",wlan.ifconfig())
def subscribe_callback(topic, msg):
msg = json.loads(msg)
topic = topic.decode()
print("接收到topic",topic)
if(topic == subscribe_TOPIC):
if msg['params']['AlarmSwitch'] !=0:
led.value(0)
else:
led.value(1)
def publish_message(mytimer):
global client
global i
i+=1
try:
request_params = {
"CurrentTemperature": 11+i,
"CurrentHumidity": 120+i,
"CurrentVoltage": 120+i,
"AlarmSwitch":1+i
}
request = {
"id": 1,
"version": "1.0",
"params": request_params,
"method": "thing.event.property.post"
}
message = json.dumps(request)
print('发布消息============================')
print(message)
client.publish(topic=publish_TOPIC, msg=message, retain=False, qos=0)
print("发布消息成功")
except Exception as e:
print('exception:', e)
mytimer.deinit()
def wifi_deng_run():
global client
global led
global wlan
print('物联网点灯大师启动...')
try:
ConnectWifi(SSID, PASSWORD)
client = MQTTClient(CLIENT_ID, SERVER, 0, username, password, 60) # create a mqtt client
print('client:%s' % str(client))
led.value(1)
client.set_callback(subscribe_callback) # set callback
client.connect() # connect mqtt
client.subscribe(subscribe_TOPIC) # client subscribes to a topic
mytimer = Timer(0)
mytimer.init(mode=Timer.PERIODIC, period=2000, callback=publish_message)
while True:
client.wait_msg() # wait message
except Exception as ex_results:
print('exception1', ex_results)
return "FAILED"
finally:
if (client is not None):
led.value(0)
client.disconnect()
wlan.disconnect()
wlan.active(False)
print("重新连接")
return 'FAILED'
while (True):
if wifi_deng_run() == 'FAILED':
print('FAILED,retry to connect')
time.sleep(5)
总结与展望
通过本文实践,我们完成了以下目标:
- 硬件层 :配置STC8H的ADC模块,实现0
2.5V电压测量,并通过分压电路扩展量程(如05V)。 - 软件层:编写ADC数据采集代码,解析电压值并处理数据溢出问题。
- 云端对接:利用华为云IoT平台,通过MQTT协议上报数据,实现设备与云端的双向通信。
未来优化方向
- 精度提升:采用更高精度的基准电压芯片(如REF5025)或软件滤波算法(如滑动平均)。
- 低功耗设计:在电池供电场景下,优化ADC采样频率和云端通信间隔。
- 多传感器融合:结合温湿度传感器(如DHT11),丰富数据采集维度。
结语
物联网技术的核心在于"连接"与"数据"。掌握ADC与云平台的结合,不仅为智能硬件开发奠定了基础,更为后续的大数据分析、AI决策提供了可能。希望本文能为读者的IoT项目开发带来启发,助力更多创新应用落地。
附录
- 常见问题解答:如ADC读数不稳定、华为云连接超时等问题的排查方法。