NodeMCU interfacing with 4 channel relay | ESP 8266

Interfacing 4 channel Relay with NodeMCU

Did you ever wonder, whats present inside a smart switch socket or a touch switch board. It has relays inside 😃. Imagine controlling a device from any where over internet. Now that can be achieved using two major components as described below.

In the last tutorial, we have learned about 2 channel relay and interfacing with ESP 01 and NodeMCU. In this tutorial, we will explore 4 channel relay with NodeMCU. 

A 4 channel relay is similar to four 1 channel or two 2 channel relays kept side by side. It can control 4 high voltage devices with 4 input triggers from low voltage device like NodeMCU.  

Hardware Requirements
1. NodeMCU
2. 4 Channel Relay

3. Jumper wires

Go to Aurdino IDE, Select Tools -> Board -> ESP 8266 Boards -> NodeMCU 1.0

This will allow you to have D1, D2 etc in the code and wont result in a compile error.

Connections

NodeMCU	Relay
3v	Vcc
GND	GND
D1	IN1
D2	IN2
D3	IN3
D4	IN4

void setup() {
  pinMode(D1, OUTPUT);
  pinMode(D2, OUTPUT);
  pinMode(D3, OUTPUT);
  pinMode(D4, OUTPUT);
  digitalWrite(D1, HIGH);
  digitalWrite(D2, HIGH);
  digitalWrite(D3, HIGH);
  digitalWrite(D4, HIGH);
  delay(2000);
}

void loop() {
  digitalWrite(D1, LOW);
  delay(1500);
  digitalWrite(D2, LOW);
  delay(1500);
  digitalWrite(D3, LOW);
  delay(1500);
  digitalWrite(D4, LOW);
  delay(1500);

  //reset relays
  digitalWrite(D1, HIGH);
  digitalWrite(D2, HIGH);
  digitalWrite(D3, HIGH);
  digitalWrite(D4, HIGH);
}

We will set each of the relays in 1.5 sec difference and reset all of them to start loop.

Now you can design smart socket for your home. If you need more devices to connect, upgrade to a higher channel relay. (8 channel or 16 channel). You can have a web server running on the NodeMCU and use it to control devices. In future tutorials, we will explore how to send MQTT messages and control ESP from any where.