Detect a Waves Balance Update with an ESP8266 to turn on an LED

Description: A Wemos Lolin D1 Mini Pro V2 connected to WiFi and a Waves Node Server sends a GET Request every 5 seconds to retrieve Waves Blockchain JSON data for a particulary Waves Address via the browser. If a change to the JSON “balance” data is detected, a green LED light will turn ON for 5 seconds.

Notes: Scan the Waves QR code with Waves wallet, such as the Exodus Wallet. Send any amount of Waves to the address and within a few seconds the green LED will turn ON if the Waves transaction is successful. Make sure to set the baud rate to 115200 in the Serial Monitor.

Helpful Resources:

https://docs.waves.tech/en/

https://arduinojson.org/v6/assistant/

Supplies:

1 – Breadboard 400 Points
1 – Wemos Lolin D1 Mini Pro V2
1 – LED
1 – 220 Ohm Resistor

Arduino Code:

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <ArduinoJson.h>

const char* ssid = "Network Name";
const char* password = "password";

long int oldbalance = 0;

#define led 5

void setup() {

  pinMode(led, OUTPUT);

  Serial.begin(115200);
  Serial.println();
  Serial.println();
  Serial.print("Connecting to WiFi  ");

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print("*");
  }

  Serial.print("  Connected!");
  Serial.println();
  Serial.println();

}

void loop() {

  if (WiFi.status() == WL_CONNECTED) {

    WiFiClient client;
    HTTPClient http;  // HTTPClient class object
    http.begin(client, "http://nodes.wavesnodes.com/addresses/balance/3P272McBt9uTUthmQS8dazkbdQbz9Hgi7HG");

    // get json data
    int httpCode = http.GET();

    if (httpCode > 0) {  //Check the returning code
      
      const char* json = http.getString().c_str();
      Serial.println(json);

      // Stream& input;

      StaticJsonDocument<128> doc;

      DeserializationError error = deserializeJson(doc, json);

      if (error) {
        Serial.print(F("deserializeJson() failed: "));
        Serial.println(error.f_str());
        return;
      }

      const char* address = doc["address"]; // "3P272McBt9uTUthmQS8dazkbdQbz9Hgi7HG"
      int confirmations = doc["confirmations"]; 
      long balance = doc["balance"];

      delay(5000);

      if(balance != oldbalance) {
       digitalWrite(led, HIGH);
       delay(5000);
       digitalWrite(led, LOW);
       Serial.println(balance);
       oldbalance = balance;
      
      }
    }
  }
}