ESP8266 Community Forum

- Wed Feb 01, 2017 5:13 pm #61893 Hello everybody,

My initial goal was to call a web service which will send a JSON response which will open or close a solenoid.
However I have trouble to communicate with my serve and receive the JSON response because I have to use an arduino uno + esp8266.
Now the status is that I am calling the URL [url]jsonplaceholder.typicode.com/posts/1[/url] which is supposed to to return a good JSON.

I do not understand why I do not get the response from the server.

Code: Select all#include <SoftwareSerial.h>
#include <ArduinoJson.h>



SoftwareSerial ESP8266(10, 11);

String NomduReseauWifi = "wifiName";
String MotDePasse      = "password";
String cmd;
String server = "jsonplaceholder.typicode.com";
String uri = "/posts/1";

/****************************************************************/
/*                             INIT                             */
/****************************************************************/
void setup()
{
  Serial.begin(115200);
  ESP8266.begin(115200);
  Serial.println();  //Clear some garbage that may be printed to the serial console
  reset();
  connectWifi();
  httppost();
}
/****************************************************************/
/*                        LOOP                        */
/****************************************************************/
void loop()
{
  while (Serial.available())  // forward data from monitor to esp
  ESP8266.write(Serial.read());
  while (ESP8266.available())  // forward data from esp to monitor
  Serial.write(ESP8266.read());
  delay(1000);
}

/****************************************************************/
/*                ESP8266 INITIALIZATION            */
/****************************************************************/
void reset(){
  Serial.println("RESETING!");
  ESP8266.println("AT+RST");
  delay(1000);
  if(ESP8266.find("OK") ) Serial.println("Module Reset");
}

/****************************************************************/
/*                WIFI INITIALIZATION        */
/****************************************************************/
void connectWifi()
{ 
  Serial.println("************************Connection***************************");
  String cmd = "AT+CWJAP=\"" +NomduReseauWifi+"\",\"" + MotDePasse + "\"";
  ESP8266.println(cmd);
  delay(3000);
  if(ESP8266.find("OK")) {
     Serial.println("Connected!");
  }
  else {
    connectWifi();
    Serial.println("Cannot connect to wifi");
    }
}

/****************************************************************************************/
/*    CALLING THE URL AND GET THE ANSWER FROM THE SERVER    */
/***************************************************************************************/
void httppost(){
  ESP8266.println("AT+CIPSTART=\"TCP\",\"" + server + "\",80");//start a TCP connection.
  delay(500);
  if( ESP8266.find("OK")){
    Serial.println("TCP connection ready");
  }
  delay(3000);
  cmd="GET /posts/1\r\n";//"/coiner/feed/?action=call&udi=123456789 HTTP/1.1\r\n";
  cmd+="Host: jsonplaceholder.typicode.com\r\n\r\n";
  String sendCmd = "AT+CIPSEND=";//determine the number of caracters to be sent.
  ESP8266.print(sendCmd);
  Serial.println(cmd.length());
  ESP8266.println(52);
  delay(200);
  StaticJsonBuffer<200> jsonBuffer;
  if(ESP8266.find(">")) {
    Serial.println("Sending..");
    ESP8266.print(cmd);
    if(ESP8266.find("SEND OK")) {
      Serial.println("Packet sent");
      while (ESP8266.available() > 0) {
        //Serial.println(ESP8266.read());
        String line = ESP8266.readStringUntil('\r');
        JsonObject& root = jsonBuffer.parseObject(line);
        //Serial.println(line);
        if (!root.success()) {
          Serial.println("parseObject() failed");
          return;
        }
        else{
          Serial.println("result: ");
          Serial.println((const char*)root["title"]);
        }
       }
      }
      // close the connection
      ESP8266.println("AT+CIPCLOSE");
    }
  }

I've been struggling a long time and I am wondering if what I would like to do is actually possible.

Thanks in advance

- Mon Apr 27, 2020 9:55 am #86782 The Arduino (uno and others) does not have enough power on the 3.3Volt pin for the ESP. Either use a separate power supply for the ESP or use a 5 Volt version of the ESP.