Blynk_LED_status_of_button.ino

 /*************************************************************

  Blynk using a LED widget on your phone!

  App project setup:
    LED widget on V3
 *************************************************************/

/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial


#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266_SSL.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "";
char pass[] = "";

// Select your pin with physical button
const int btnPin = 1; // TX na D1 mini

WidgetLED led3(V3);

BlynkTimer timer;

// V3 LED Widget represents the physical button state
boolean btnState = false;
void buttonLedWidget()
{
  // Read button
  boolean isPressed = (digitalRead(btnPin) == LOW);

  // If state has changed...
  if (isPressed != btnState) {
    if (isPressed) {
      led3.on();      
    } else {
      led3.off();
    }
    btnState = isPressed;
    
  }
}

void setup()
{
  // Debug console
  Serial.begin(9600);

  Blynk.begin(auth, ssid, pass);
  // You can also specify server:
  //Blynk.begin(auth, ssid, pass, "blynk-cloud.com", 80);
  //Blynk.begin(auth, ssid, pass, IPAddress(192,168,1,100), 8080);

  // Setup physical button pin (active low)
  pinMode(btnPin, INPUT_PULLUP);

  timer.setInterval(500L, buttonLedWidget);
}

void loop()
{
  Blynk.run();
  timer.run();
}