2 Channel Relay interfacing with ESP 01 & NodeMCU | ESP 8266 | Control two high voltage devices.

In this tutorial, we will explore two channel relay. If you missed 1-channel relay interfacing read this tutorial. This is an extension and will introduce ESP 01 and ESP 8266 together. 

You can think of 2 channel relay as two 1-channel relays placed side by side. Relay needs 2 input triggers to operate each relay. 

Hardware Requirements

1. NodeMCU

2. ESP 01

3. Jumper wires

4. 2 Channel Relay (Active LOW trigger)

5. Multi output voltage power module

We will use the same code for both ESP 01 and ESP 8266. We will use GPIO pins 0 and 2. GPIO0 is D3  and GPIO2 is D4 on NodeMCU.

void setup() {
  pinMode(0, OUTPUT);
  pinMode(2, OUTPUT);
  digitalWrite(0, HIGH);
  digitalWrite(2, HIGH);
}

void loop() {
  digitalWrite(0,LOW);
  digitalWrite(2,HIGH);
  delay(3000);
  digitalWrite(0,HIGH);
  digitalWrite(2, LOW);
  delay(3000);
}

Above code will activate one relay for 3 seconds and then turns it off and activates the other for 3 seconds in a loop and works on NodeMCU and ESP 01. Now lets connect 2 channel relay to ESP 01 and ESP 8266.

NodeMCU	2 Channel Relay
3v	Vcc
GND	GND
D3	IN1
D4	IN2

 

    Nodemcu and 2 channel relay

ESP 01 3v -> Power module 3V

Relay Vcc -> Power module 3v 

Relay  GND -> Power module GND

ESP 01 GND -> Power module GND

ESP IO0 -> Relay IN1

ESP IO2 -> Relay IN2

ESP 01 and 2 channel relay

In the next tutorial we will explore 4 channel relay with NodeMCU.

Note

If you want to isolate power for relay and micro controller. You can use RY-Vcc and GND to power relay. In the above experiment i have shorted Vcc and RY-Vcc to use power from NodeMCU or power module.