DweetGet_LAN8720.ino

/****************************************************************************************************************************
  DweetGet_LAN8720.ino - Simple Arduino web server sample for Ethernet shield

  For STM32 with built-in Ethernet LAN8742A (Nucleo-144, DISCOVERY, etc) or W5x00/ENC28J60 shield/module

  EthernetWebServer_STM32 is a library for the STM32 running Ethernet WebServer

  Based on and modified from ESP8266 https://github.com/esp8266/Arduino/releases
  Built by Khoi Hoang https://github.com/khoih-prog/EthernetWebServer_STM32
  Licensed under MIT license

  Connects to dweet.io once every ten seconds, sends a GET request and a request body. Uses SSL

  Shows how to use Strings to assemble path and parse content from response. dweet.io expects:
  https://dweet.io/get/latest/dweet/for/thingName

  For more on dweet.io, see https://dweet.io/play/

  created 15 Feb 2016
  updated 22 Jan 2019
  by Tom Igoe
 *****************************************************************************************************************************/

#include "defines.h"

const char serverAddress[] = "dweet.io";  // server address
int port = 80;
String dweetName = "scandalous-cheese-hoarder"; // use your own thing name here

EthernetClient      client;
EthernetHttpClient  httpClient(client, serverAddress, port);

void setup()
{
  Serial.begin(115200);
  delay(2000);

  Serial.print("\nStarting DweetGet_LAN8720 on " + String(BOARD_NAME));
  Serial.println(" with " + String(SHIELD_TYPE));
  Serial.println(ETHERNET_WEBSERVER_STM32_VERSION);

  // start the ethernet connection and the server:
  // Use DHCP dynamic IP and random mac
  uint16_t index = millis() % NUMBER_OF_MAC;
  // Use Static IP
  //Ethernet.begin(mac[index], ip);
  Ethernet.begin(mac[index]);

  Serial.print(F("Using mac index = "));
  Serial.println(index);

  Serial.print(F("Connected! IP address: "));
  Serial.println(Ethernet.localIP());
}

void loop()
{
  // assemble the path for the GET message:
  String path = "/get/latest/dweet/for/" + dweetName;

  // send the GET request
  Serial.println("Making GET request");
  httpClient.get(path);

  // read the status code and body of the response
  int statusCode = httpClient.responseStatusCode();
  String response = httpClient.responseBody();
  Serial.print("Status code: ");
  Serial.println(statusCode);
  Serial.print("Response: ");
  Serial.println(response);

  /*
    Typical response is:
    {"this":"succeeded",
    "by":"getting",
    "the":"dweets",
    "with":[{"thing":"my-thing-name",
      "created":"2016-02-16T05:10:36.589Z",
      "content":{"sensorValue":456}}]}

    You want "content": numberValue
  */
  // now parse the response looking for "content":
  int labelStart = response.indexOf("content\":");
  // find the first { after "content":
  int contentStart = response.indexOf("{", labelStart);
  // find the following } and get what's between the braces:
  int contentEnd = response.indexOf("}", labelStart);
  String content = response.substring(contentStart + 1, contentEnd);
  Serial.println(content);

  // now get the value after the colon, and convert to an int:
  int valueStart = content.indexOf(":");
  String valueString = content.substring(valueStart + 1);
  int number = valueString.toInt();
  Serial.print("Value string: ");
  Serial.println(valueString);
  Serial.print("Actual value: ");
  Serial.println(number);

  Serial.println("Wait ten seconds\n");
  delay(10000);
}