Code for ESP8266 to turn on relay for 5 second

Projects Programming
1

Guys I need help regarding coding my ESP8266 D1 mini. I want to keep the relay in ON state for 5 seconds. Then turn off.

Doing mqtt example project.

I am using IFTTT app to control via google assistant and adafruit io services.

Currently it turns on When I say to turn on. And turns off when I say again.

Codes................................................................................................

#include <ESP8266WiFi.h>
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"
#define relay D2

#define WLAN_SSID "MediaPad m5"
#define WLAN_PASS "knp213..."

#define AIO_SERVER "io.adafruit.com"
#define AIO_SERVERPORT 1883 // use 8883 for SSL
#define AIO_USERNAME "username"
#define AIO_KEY "adafruit aio key"

// Create an ESP8266 WiFiClient class to connect to the MQTT server.
WiFiClient client;
// or... use WiFiFlientSecure for SSL
//WiFiClientSecure client;

// Setup the MQTT client class by passing in the WiFi client and MQTT server and login details.
Adafruit_MQTT_Client mqtt(&client, AIO_SERVER, AIO_SERVERPORT, AIO_USERNAME, AIO_KEY);

// Setup a feed called 'onoff' for subscribing to changes.
Adafruit_MQTT_Subscribe onoffbutton = Adafruit_MQTT_Subscribe(&mqtt, AIO_USERNAME "/feeds/Wireless_2");

// Bug workaround for Arduino 1.6.6, it seems to need a function declaration
// for some reason (only affects ESP8266, likely an arduino-builder bug).
void MQTT_connect();

void setup() {
Serial.begin(115200);
delay(10);
pinMode(relay,OUTPUT);
Serial.println(F("Adafruit MQTT demo"));

// Connect to WiFi access point.
Serial.println(); Serial.println();
Serial.print("Connecting to ");
Serial.println(WLAN_SSID);

WiFi.begin(WLAN_SSID, WLAN_PASS);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println();

Serial.println("WiFi connected");
Serial.println("IP address: "); Serial.println(WiFi.localIP());

// Setup MQTT subscription for onoff feed.
mqtt.subscribe(&onoffbutton);
}

uint32_t x=0;

void loop() {
// Ensure the connection to the MQTT server is alive (this will make the first
// connection and automatically reconnect when disconnected). See the MQTT_connect
// function definition further below.
MQTT_connect();

// this is our 'wait for incoming subscription packets' busy subloop
// try to spend your time here

Adafruit_MQTT_Subscribe *subscription;
while ((subscription = mqtt.readSubscription(5000))) {
if (subscription == &onoffbutton) {
Serial.print(F("Got: "));
Serial.println((char *)onoffbutton.lastread);
uint16_t state = atoi((char *)onoffbutton.lastread);
digitalWrite(relay,state);
}
}

// ping the server to keep the mqtt connection alive
// NOT required if you are publishing once every KEEPALIVE seconds
/*
if(! mqtt.ping()) {
mqtt.disconnect();
}
*/
}

// Function to connect and reconnect as necessary to the MQTT server.
// Should be called in the loop function and it will take care if connecting.
void MQTT_connect() {
int8_t ret;

// Stop if already connected.
if (mqtt.connected()) {
return;
}

Serial.print("Connecting to MQTT... ");

uint8_t retries = 3;
while ((ret = mqtt.connect()) != 0) { // connect will return 0 for connected
Serial.println(mqtt.connectErrorString(ret));
Serial.println("Retrying MQTT connection in 5 seconds...");
mqtt.disconnect();
delay(5000); // wait 5 seconds
retries--;
if (retries == 0) {
// basically die and wait for WDT to reset me
while (1);
}
}
Serial.println("MQTT Connected!");
}

2

You have to focus here:

Adafruit_MQTT_Subscribe *subscription;
  while ((subscription = mqtt.readSubscription(5000))) {
    if (subscription == &onoffbutton) {
      Serial.print(F("Got: "));
      Serial.println((char *)onoffbutton.lastread);
      uint16_t state = atoi((char *)onoffbutton.lastread);
      digitalWrite(relay,state);
    }
  }

You have to set a timer when you write a '1' to pin relay.
Something like:

uint32_t onTimer =  0 ;  // global definition
. . .
. . .
if (state == 1 ) {
   digitalWrite(relay,state);
   onTimer = millis() ;
}

somewhere in the loop(), check if millis() - onTimer > 5000 ; and, if so, write a 0 to pin relay to expire the relay on state.

If the code which executes digitalWrite(relay,state) runs multiple consecutive times with state ==1,
then it is a bit more complicated because you will have to retain the last value of state (say oldState) and look for the condition if (state == 1 && oldState == 0) before setting the timer.