WiFi IoT模块 · HTTPGet()方法调用失败问题

WiFi IoT模块使用MQTT协议连接EasyIoT平台，已在前篇描述过，现在利用HTTP连接一台Web服务器，遇到一点问题。

IoT、WiFi、HTTP配置看上去都完成了，但是调用HTTPGet()方法时，一直失败。我的思路是利用HTTPGet()方法，向一台Web服务器（上位机http://openkevin.net，Servlet为dfrobotWifi，唯一参数a01）提交室内温度数据（DS18B20温度传感连在数字端口2）。

代码如下：

#include <SoftwareSerial.h>
#include <OneWire.h>
#include "DFRobot_WiFi_IoT_Module.h"
DFRobot_WiFi_IoT_Module_I2C IoT;

const char *WIFI_SSID                       = "Linksys19544";
const char *WIFI_PASSWORD          = "********";

const char *EASY_IOT_SERVER        = "iot.dfrobot.com.cn";
const char *EASY_IOT_PORT           = "1883";
const char *EASY_IOT_ID                  = "********";
const char *EASY_IOT_PWD            = "********";
const char *SUBSCRIBE_TOPIC        = "RrRlB-yMR";
const char *PUBLISH_TOPIC            = "RrRlB-yMR";
const char *HTTP_ADDRESS            = "openkevin.net";
const char *EASY_IOT_SEND_MESSAGE  = "";

int DS18S20_Pin = 2;
OneWire ds(DS18S20_Pin);

void setup() 
{
  Serial.begin(115200);
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);

  while(IoT.begin() != 0)
  {  
    Serial.println("IoT init ERROR!!!!");
    delay(100);
  }
  Serial.println("IoT init Success");

  while(IoT.connectWifi(WIFI_SSID, WIFI_PASSWORD) != 0)
  {  
    Serial.print(".");
    delay(100);
  }
  Serial.println("Wifi Connect Success");

  while(IoT.HTTPBegin(HTTP_ADDRESS) != 0)
  {
    Serial.println("Parameter is empty!");
    delay(100);
  }
  Serial.println("HTTP Configuration Success");
  
  while(IoT.HTTPGet("http://openkevin.net/servlet/dfrobotWifi?a01=00") != 0)
  {
    Serial.println("Error...");
  }
  Serial.println("HTTPGet Success");
}

void loop()
{
  //float temperature = getTemp();
  //Serial.println(temperature);
  //String txtTemp2 = "http://openkevin.net/servlet/dfrobotWifi?a01=" + String(temperature);
  //while(IoT.HTTPGet(txtTemp2)!=0)
  //{
  //  Serial.println("Error...");
  //}
  //Serial.println("HTTPGet Success");
}

float getTemp()
{
  //returns the temperature from one DS18S20 in DEG Celsius
  byte data[12];
  byte addr[8];
  if ( !ds.search(addr))
  {
    //no more sensors on chain, reset search
    ds.reset_search();
    return -1000;
  }
  if ( OneWire::crc8( addr, 7) != addr[7])
  {
    Serial.println("CRC is not valid!");
    return -1000;
  }
  if ( addr[0] != 0x10 && addr[0] != 0x28)
  {
    Serial.print("Device is not recognized");
    return -1000;
  }
  ds.reset();
  ds.select(addr);
  ds.write(0x44,1); // start conversion, with parasite power on at the end
  byte present = ds.reset();
  ds.select(addr);
  ds.write(0xBE); // Read Scratchpad
  for (int i = 0; i < 9; i++)
  {
    // we need 9 bytes
    data[i] = ds.read();
  }
  ds.reset_search();
  byte MSB = data[1];
  byte LSB = data[0];
  float tempRead = ((MSB << 8) | LSB); //using two's compliment
  float TemperatureSum = tempRead / 16;
  return TemperatureSum;
}

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