NB-IOT接入阿里云平台MQTT协议实现数据传输代码

以下是基于Arduino平台，使用Arduino IDE编写的NB-IoT接入阿里云平台MQTT协议实现数据传输的示例代码。在使用前需要先在阿里云平台创建设备和Topic，并且获取对应的设备信息和证书。

#include <SoftwareSerial.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <DFRobot_SIM808.h>

//定义NB-IoT模块相关参数
#define PIN_TX 7
#define PIN_RX 8
#define BAUDRATE 9600

//定义DS18B20温度传感器相关参数
#define ONE_WIRE_BUS 2
#define TEMPERATURE_PRECISION 9

//定义阿里云MQTT平台相关参数
#define MQTT_SERVER "xxx.mqtt.aliyuncs.com" //MQTT服务器地址
#define MQTT_PORT 1883 //MQTT服务器端口
#define MQTT_CLIENT_ID "GID_xxxxxxxxxxxxxx" //客户端ID
#define MQTT_USERNAME "xxxxxxxxxxxxx" //MQTT用户名
#define MQTT_PASSWORD "xxxxxxxxxxxxx" //MQTT密码
#define MQTT_TOPIC "/xxxxxxxxxxxxx/xxxxxxxxxxxxx" //MQTT Topic

SoftwareSerial mySerial(PIN_RX, PIN_TX);
DFRobot_SIM808 sim808(&mySerial);//创建NB-IoT模块对象
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

WiFiClient wifiClient;
PubSubClient mqttClient(MQTT_SERVER, MQTT_PORT, wifiClient);

void setup() {
  Serial.begin(9600);
  mySerial.begin(BAUDRATE);
  while(!sim808.init());//等待模块初始化完成
  delay(2000);
  Serial.println("SIM808 init success!");
  sensors.begin();
}

void loop() {
  sim808.checkPowerUp();//检查模块是否开机
  if (sim808.isNetworkRegistered()) {
    Serial.println("Network is registered.");
    if (sim808.isGprsActived()) {
      Serial.println("GPRS is actived.");
      if (!mqttClient.connected()) {
        Serial.println("MQTT client is not connected.");
        connectMqttServer();
      }
      mqttClient.loop();
      float temperature = readTemperature();
      publishMqttMessage(temperature);
    } else {
      Serial.println("GPRS is not actived, trying to activate...");
      sim808.activeGprs("CMNET");//激活GPRS
    }
  } else {
    Serial.println("Network is not registered, trying to register...");
    sim808.waitForNetworkRegistered();//等待网络注册
  }
}

float readTemperature() {
  sensors.requestTemperatures();
  float temperature = sensors.getTempCByIndex(0);
  return temperature;
}

void connectMqttServer() {
  Serial.println("Connecting to MQTT server...");
  if (mqttClient.connect(MQTT_CLIENT_ID, MQTT_USERNAME, MQTT_PASSWORD)) {
    Serial.println("MQTT server connected.");
    mqttClient.subscribe(MQTT_TOPIC);//订阅MQTT Topic
  } else {
    Serial.print("Failed to connect MQTT server, rc=");
    Serial.println(mqttClient.state());
  }
}

void publishMqttMessage(float temperature) {
  StaticJsonDocument<200> jsonDoc;
  jsonDoc["temperature"] = temperature;
  char message[200];
  serializeJson(jsonDoc, message, sizeof(message));
  mqttClient.publish(MQTT_TOPIC, message);//发布MQTT消息
}

此代码实现了以下功能：

1. 连接NB-IoT模块和DS18B20温度传感器；
2. 检查NB-IoT网络状态；
3. 激活GPRS连接；
4. 连接阿里云MQTT平台；
5. 订阅指定的MQTT Topic；
6. 读取DS18B20传感器数据；
7. 将温度数据以JSON格式发布到MQTT Topic。

注意：由于NB-IoT网络和阿里云MQTT平台的连接较为复杂，上述代码仅供参考，具体实现需要根据实际情况进行调整。