ESP8266 Community Forum

Posted: **Mon Mar 19, 2018 9:38 am**

beeing able to send data with one browser but not the other might indeed point towards proxy being involved. Some browsers come with "auto proxy discovery" but not esp, so you need information about proxy, especially name/ip and port.

Most recent proxies can be used like this:
direct your client to the proxy

Code: Select allif (myClient.connect(proxy_name,proxy_port)){ ...

so you contact proxy instead of thingspeak and proxy reads real server credentials from

Code: Select allmyClient.print("Host: api.thingspeak.com:80\n");

to connect you to wanted server on internet.

Posted: **Wed Mar 21, 2018 1:29 am**

Finally I was able to make it work. I do not yet know what was the error, but when I broke the problem down to just the essential lines of code, it worked fine. Here's the code, including the ping and the reception of the response to the POST:

Code: Select all

#include <ESP8266WiFi.h>
#include <ESP8266Ping.h>                    // https://github.com/dancol90/ESP8266Ping
#include "DHT.h"                            // https://github.com/adafruit/DHT-sensor-library

#define DHTPIN 12                           // Pin 12 for DHT22
#define DHTTYPE DHT22                      

DHT dht(DHTPIN, DHTTYPE);                       

const char* ssid      = "myNetworkName";    // Name of the WLAN network
const char* password  = "myPassword";       // Password of the WLAN network
const char* server    = "api.thingspeak.com";
String apiKey         = "xxxxyyyyyyyyxxxx"; // Write key from thingspeak channel

const IPAddress remote_ip(208, 67, 222, 222);// Address of OpenDNS

float humidity;
float temperature;
boolean error;
    
WiFiClient myClient;

void setup() {
  Serial.begin(115200);
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid,password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  Serial.println();
  Serial.print("Pinging ip: ");
  Serial.println(remote_ip);

  if(Ping.ping(remote_ip)){Serial.println("Ping PASS");}
  else                    {Serial.println("Ping FAIL");} 
}

void loop() {
  if (0 == (millis()%20000)){
    humidity    = dht.readHumidity();
    temperature = dht.readTemperature();  

    if ((isnan(humidity) || isnan(temperature))){
      Serial.println("Error reading DHT22");
    }
    else {
      if (myClient.connect(server,80)){
        String postStr = apiKey;
        
        postStr += "&field1=";  
        postStr += String(temperature);          
        postStr += "&field2="; 
        postStr += String(humidity);         
        postStr += "\r\n\r\n";
        myClient.print("POST /update HTTP/1.1\n");
        myClient.print("Host: api.thingspeak.com\n");
        myClient.print("Connection: close\n");
        myClient.print("X-THINGSPEAKAPIKEY:" + apiKey +"\n");
        myClient.print("Content-Type: application/x-www-form-urlencoded\n");
        myClient.print("Content-Length: ");
        myClient.print(postStr.length());
        myClient.print("\n\n");
        myClient.print(postStr);
    
        Serial.print("Temperature: ");
        Serial.print(temperature);
        Serial.println(" *C");
        Serial.print("Humidity: ");
        Serial.print(humidity);
        Serial.println(" %");
      }

      /* The following lines were copied from the answer to the thread
       * https://arduino.stackexchange.com/questions/39705/how-to-get-the-server-response-when-i-post-to-a-web-api
       */
      Serial.println("Server Response:");
      uint32_t lastRead = millis();
      while (millis() - lastRead < 2000){
        while (myClient.available()){
          Serial.write(myClient.read());
          lastRead = millis();
        }
      }  
      
      myClient.stop();    
      Serial.println(); 
    }
  }
}

Thanks to those who tried to help!

Posted: **Wed Mar 21, 2018 2:49 am**

Addendum:

I just realised that it's the reading of the response that makes it work. If I comment the reading out, it stops working. Maybe some body can explain why I don't have to do that when conneted to my home network.

Posted: **Wed Mar 21, 2018 1:26 pm**

I do recall similar problems but no details anymore. For some time now I use the thingspeak library which works well and makes the code compact and readable. I can really recommend it.
https://github.com/mathworks/thingspeak-arduino

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