Arduino to IFTTT using Wemos D1 Mini - POST methods

post-to-ifttt.ino

#include <Arduino.h>
#include <ESP8266WiFi.h>

// WiFi parameters
const char* ssid = "your-ssid"; //replace with your ssid
const char* password = "your-pw";//replace with your pw

// IFTTT Maker parameters:
char MakerIFTTT_Key[] = "your-ifttt-key"; // Obtained when setting up/connecting the Maker channel in IFTTT
char MakerIFTTT_Event[] = "wemos-trigger"; // Arbitrary name for the event; used in the IFTTT recipe.

WiFiClient client;

#define pot      A0      // will be reported as "value1"
#define LOOP_DELAY_MSEC     (300*1000L)   // 5 minutes

void setupWiFi(){
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.print(ssid);
  Serial.println("...");

  WiFi.begin(ssid, password);
  int retries = 0;
  while ((WiFi.status() != WL_CONNECTED) && (retries < 15)){
    retries++;
    delay(500);
    Serial.print(".");
  }
  if(retries>14){
    Serial.println(F("WiFi conenction FAILED"));
  }
  if (WiFi.status() == WL_CONNECTED){
    Serial.println(F("WiFi connected!"));
    Serial.println("IP address: ");
    Serial.println(WiFi.localIP());
  }
  Serial.println(F("Setup ready"));
}

void setup() {
  Serial.begin(115200); //set the baud rate for Wemos D1 mini
  setupWiFi(); //call our WiFi method to connect to the internet
  // the input pin for this example
  pinMode(pot, INPUT);
}

// *** helper functions for constructing the POST data ***

// append a string or int to a buffer, return the resulting end of string
char *append_str(char *here, char *s) {
    while (*here++ = *s++)
	;
    return here-1;
}
char *append_ul(char *here, unsigned long u) {
    char buf[20];       // we "just know" this is big enough

    return append_str(here, ultoa(u, buf, 10));
}

// Send a POST to trigger the IFTTT/Maker event
void updateEvent() {
    // connect to the Maker event server
    client.connect("maker.ifttt.com", 80);

    // construct the POST request
    char post_rqst[256];    // hand-calculated to be big enough

    char *p = post_rqst;
    p = append_str(p, "POST /trigger/");
    p = append_str(p, MakerIFTTT_Event);
    p = append_str(p, "/with/key/");
    p = append_str(p, MakerIFTTT_Key);
    p = append_str(p, " HTTP/1.1\r\n");
    p = append_str(p, "Host: maker.ifttt.com\r\n");
    p = append_str(p, "Content-Type: application/json\r\n");
    p = append_str(p, "Content-Length: ");

    char *content_length_here = p; // we need to remember where the content length will go, which is:

    p = append_str(p, "NN\r\n"); // it's always two digits, so reserve space for them (the NN)
    p = append_str(p, "\r\n"); // end of headers
    char *json_start = p; // construct the JSON; remember where we started so we will know len

    // As described - this example reports a pin, uptime, and "hello world"
    Serial.println("Sending values to IFTTT");
    p = append_str(p, "{\"value1\":\"");
    p = append_ul(p, analogRead(pot));
    p = append_str(p, "\",\"value2\":\"");
    p = append_ul(p, millis());
    p = append_str(p, "\",\"value3\":\"");
    p = append_str(p, "hello, world!");
    p = append_str(p, "\"}");

    // go back and fill in the JSON length
    // we just know this is at most 2 digits (and need to fill in both)
    int i = strlen(json_start);
    content_length_here[0] = '0' + (i/10);
    content_length_here[1] = '0' + (i%10);

    // finally we are ready to send the POST to the server!
    client.print(post_rqst);
    client.stop();
}

void loop(){
}