Home Automation PCB, for 8 Ch Relay of 5 V 

In this IoT project, I have shown how to make Alexa home automation project with manual switches using NodeMCU or ESP8266 and relay module. With this internet of things project, you can control 4 home appliances from Alexa and manual switches with and without internet. So this is a very useful homemade IoT based home automation system that you can easily make with NodeMCU, Relay Module, Push Buttons, and Alexa Echo Dot devices.

get coding idea from here

#ifdef ARDUINO_ARCH_ESP32
#include <WiFi.h>
#else
#include <ESP8266WiFi.h>
#endif
#include <Espalexa.h>
// define the GPIO connected with Relays and switches
#define RelayPin1 5  //D1
#define RelayPin2 4  //D2
#define RelayPin3 14 //D5
#define RelayPin4 12 //D6

#define SwitchPin1 10  //SD3
#define SwitchPin2 0   //D3 
#define SwitchPin3 13  //D7
#define SwitchPin4 3   //RX

#define wifiLed   16   //D0

int toggleState_1 = 0; //Define integer to remember the toggle state for relay 1
int toggleState_2 = 0; //Define integer to remember the toggle state for relay 2
int toggleState_3 = 0; //Define integer to remember the toggle state for relay 3
int toggleState_4 = 0; //Define integer to remember the toggle state for relay 4

// prototypes
boolean connectWifi();
//callback functions
void firstLightChanged(uint8_t brightness);
void secondLightChanged(uint8_t brightness);
void thirdLightChanged(uint8_t brightness);
void fourthLightChanged(uint8_t brightness);

// WiFi Credentials
const char* ssid = "WiFi Name";
const char* password = "WiFi Password";

// device names
String Device_1_Name = "Study Lamp";
String Device_2_Name = "CFL";
String Device_3_Name = "Yellow light";
String Device_4_Name = "Red light";

boolean wifiConnected = false;

Espalexa espalexa;

//our callback functions
void firstLightChanged(uint8_t brightness)
{
  //Control the device
  if (brightness == 255)
    {
      digitalWrite(RelayPin1, LOW);
      Serial.println("Device1 ON");
      toggleState_1 = 1;
    }
  else
  {
    digitalWrite(RelayPin1, HIGH);
    Serial.println("Device1 OFF");
    toggleState_1 = 0;
  }
}

void secondLightChanged(uint8_t brightness)
{
  //Control the device 
  if (brightness == 255)
    {
      digitalWrite(RelayPin2, LOW);
      Serial.println("Device2 ON");
      toggleState_2 = 1;
    }
  else
  {
    digitalWrite(RelayPin2, HIGH);
    Serial.println("Device2 OFF");
    toggleState_2 = 0;
  }
}

void thirdLightChanged(uint8_t brightness)
{
  //Control the device  
  if (brightness == 255)
    {
      digitalWrite(RelayPin3, LOW);
      Serial.println("Device3 ON");
      toggleState_3 = 1;
    }
  else
  {
    digitalWrite(RelayPin3, HIGH);
    Serial.println("Device3 OFF");
    toggleState_3 = 0;
  }
}

void fourthLightChanged(uint8_t brightness)
{
  //Control the device 
  if (brightness == 255)
    {
      digitalWrite(RelayPin4, LOW);
      Serial.println("Device4 ON");
      toggleState_4 = 1;
    }
  else
  {
    digitalWrite(RelayPin4, HIGH);
    Serial.println("Device4 OFF");
    toggleState_4 = 0;
  }
}

void relayOnOff(int relay){

    switch(relay){
      case 1: 
             if(toggleState_1 == 0){
              digitalWrite(RelayPin1, LOW); // turn on relay 1
              toggleState_1 = 1;
              Serial.println("Device1 ON");
              }
             else{
              digitalWrite(RelayPin1, HIGH); // turn off relay 1
              toggleState_1 = 0;
              Serial.println("Device1 OFF");
              }
             delay(100);
      break;
      case 2: 
             if(toggleState_2 == 0){
              digitalWrite(RelayPin2, LOW); // turn on relay 2
              toggleState_2 = 1;
              Serial.println("Device2 ON");
              }
             else{
              digitalWrite(RelayPin2, HIGH); // turn off relay 2
              toggleState_2 = 0;
              Serial.println("Device2 OFF");
              }
             delay(100);
      break;
      case 3: 
             if(toggleState_3 == 0){
              digitalWrite(RelayPin3, LOW); // turn on relay 3
              toggleState_3 = 1;
              Serial.println("Device3 ON");
              }else{
              digitalWrite(RelayPin3, HIGH); // turn off relay 3
              toggleState_3 = 0;
              Serial.println("Device3 OFF");
              }
             delay(100);
      break;
      case 4: 
             if(toggleState_4 == 0){
              digitalWrite(RelayPin4, LOW); // turn on relay 4
              toggleState_4 = 1;
              Serial.println("Device4 ON");
              }
             else{
              digitalWrite(RelayPin4, HIGH); // turn off relay 4
              toggleState_4 = 0;
              Serial.println("Device4 OFF");
              }
             delay(100);
      break;
      default : break;      
      }
}
// connect to wifi – returns true if successful or false if not
boolean connectWifi()
{
  boolean state = true;
  int i = 0;

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.println("");
  Serial.println("Connecting to WiFi");

  // Wait for connection
  Serial.print("Connecting...");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    if (i > 20) {
      state = false; break;
    }
    i++;
  }
  Serial.println("");
  if (state) {
    Serial.print("Connected to ");
    Serial.println(ssid);
    Serial.print("IP address: ");
    Serial.println(WiFi.localIP());
  }
  else {
    Serial.println("Connection failed.");
  }
  return state;
}

void addDevices(){
  // Define your devices here.
  espalexa.addDevice(Device_1_Name, firstLightChanged); //simplest definition, default state off
  espalexa.addDevice(Device_2_Name, secondLightChanged);
  espalexa.addDevice(Device_3_Name, thirdLightChanged);
  espalexa.addDevice(Device_4_Name, fourthLightChanged);
  espalexa.begin();
}
void setup()
{
  Serial.begin(115200);

  pinMode(RelayPin1, OUTPUT);
  pinMode(RelayPin2, OUTPUT);
  pinMode(RelayPin3, OUTPUT);
  pinMode(RelayPin4, OUTPUT);
  pinMode(wifiLed, OUTPUT);

  pinMode(SwitchPin1, INPUT_PULLUP);
  pinMode(SwitchPin2, INPUT_PULLUP);
  pinMode(SwitchPin3, INPUT_PULLUP);
  pinMode(SwitchPin4, INPUT_PULLUP);

  //During Starting all Relays should TURN OFF
  digitalWrite(RelayPin1, HIGH);
  digitalWrite(RelayPin2, HIGH);
  digitalWrite(RelayPin3, HIGH);
  digitalWrite(RelayPin4, HIGH);

  // Initialise wifi connection
  wifiConnected = connectWifi();

  if (wifiConnected)
  {
    addDevices();
  }
  else
  {
    Serial.println("Cannot connect to WiFi. So in Manual Mode");
    delay(1000);
  }
}

void loop()
{
   if (WiFi.status() != WL_CONNECTED)
  {
    //Serial.print("WiFi Not Connected ");
    //Serial.println(wifiConnected);
    digitalWrite(wifiLed, HIGH); //Turn off WiFi LED
    //Manual Switch Control
    if (digitalRead(SwitchPin1) == LOW){
      delay(200);
      relayOnOff(1);      
    }
    else if (digitalRead(SwitchPin2) == LOW){
      delay(200);
      relayOnOff(2);
    }
    else if (digitalRead(SwitchPin3) == LOW){
      delay(200);
      relayOnOff(3);
    }
    else if (digitalRead(SwitchPin4) == LOW){
      delay(200);
      relayOnOff(4);
    }
    
  }
  else
  {
    //Serial.print("WiFi Connected  ");
    //Serial.println(wifiConnected);
    digitalWrite(wifiLed, LOW);
    //Manual Switch Control
    if (digitalRead(SwitchPin1) == LOW){
      delay(200);
      relayOnOff(1);      
    }
    else if (digitalRead(SwitchPin2) == LOW){
      delay(200);
      relayOnOff(2);
    }
    else if (digitalRead(SwitchPin3) == LOW){
      delay(200);
      relayOnOff(3);
    }
    else if (digitalRead(SwitchPin4) == LOW){
      delay(200);
      relayOnOff(4);
    }
    //WiFi Control
    if (wifiConnected){
      espalexa.loop();
      delay(1);
    }
    else {
      wifiConnected = connectWifi(); // Initialise wifi connection
      if(wifiConnected){
      addDevices();
      }
    }
  }
}