G-MOD : 2 Channel Relay

Overview

A 2-channel relay module provides control for two independent relay channels. This makes it ideal for controlling two separate high-power loads simultaneously using low-power control signals from microcontrollers like Arduino, GLYPH, or even Raspberry Pi. Here's how it works:

Components

• Two Relays: Each relay can independently control a high-power (Both AC / DC) device.
• Control Pins: There are two input pins (IN1 and IN2) for controlling each relay.
• Power Supply: A single power source is used for both relays 5V
• Protection : Has 2 Optocoupler to electrical isolation between the control and relay circuits for both channels.

Pin Configuration

• VCC: Power supply for the module (5V).
• GND: Ground connection.
• IN1: Control signal for Relay 1.
• IN2: Control signal for Relay 2.
• COM1, NO1: Relay 1 switching terminals.
• COM2, NO2: Relay 2 switching terminals.

Relay Contacts

• COM (Common): The input terminal.
• NO (Normally Open): Open by default, closes when the relay is activated.

Working

• Each relay channel works independently, following the same principles as a single-channel relay:

  • When Control Signal is LOW (0V):

    The associated transistor remains off. The corresponding relay coil is de-energized. The relay's Normally Open (NO) contact stays open.

  • When Control Signal is HIGH (3.3V/5V):

    The associated transistor turns on, allowing current to flow through the relay coil. The coil energizes, creating a magnetic field that pulls the armature. The relay's NO contact closes, completing the circuit for the connected load.

  • Operation Sequence for Two Relays

    • IN1 HIGH: Activates Relay 1 to control Load 1.
    • IN2 HIGH: Activates Relay 2 to control Load 2.
    • Both IN1 and IN2 HIGH: Activates both relays simultaneously to control both loads.
    • Both IN1 and IN2 LOW: Deactivates both relays, disconnecting both loads.

Applications

• Home Automation: Controlling lights and fans independently.
• Industrial Automation: Managing two separate devices or motors.
• DIY Projects: Operating appliances remotely with microcontroller-based projects.

This guide will help you interface a 2 Channel Relay assuming you are using GLYPH-C3(but any GLYPH development board from the ESP32 Series should work)

Step 1: Hardware Required

1. Glyph Board
2. GMOD 2 Channel Relay Module

Step 2: Circuit Diagram

Step 3: Code Setup

1. Open Arduino IDE.
2. Copy and paste the following code into the Arduino IDE:

// Pin definitions for 2-Channel Relay Module
const int RELAY_1 = 3;  // GPIO2 for first relay
const int RELAY_2 = 2;  // GPIO3 for second relay

void setup() 

{
  // Initialize serial communication
  Serial.begin(115200);
  
  // Configure relay pins as outputs
  pinMode(RELAY_1, OUTPUT);
  pinMode(RELAY_2, OUTPUT);
  
  // Initialize Both Relay Channels to OFF state (relays are typically Active LOW- Means they are OFF when a HIGH Signal is Applied and vice-versa)
  digitalWrite(RELAY_1, HIGH);
  digitalWrite(RELAY_2, HIGH);
  
  Serial.println("Relay Module Initialized"); //Print that Relay Module is Initialized
}

void loop() 
{
  // Example control sequence
  
  // Turn ON Relay 1
  digitalWrite(RELAY_1, LOW);
  Serial.println("Turning on Relay 1");
  delay(2000);
  
  // Turn OFF Relay 1
  digitalWrite(RELAY_1, HIGH);
  Serial.println("Turning off Relay 1");
  delay(1000);
  
  // Turn ON Relay 2
  digitalWrite(RELAY_2, LOW);
  Serial.println("Turning on Relay 2");
  delay(2000);
  
  // Turn OFF Relay 2
  digitalWrite(RELAY_2, HIGH);
  Serial.println("Turning off Relay 2");
  delay(1000);
}

// Helper functions for relay control
void turnOnRelay(int relayPin) 
{
  digitalWrite(relayPin, LOW);
}

void turnOffRelay(int relayPin) 
{
  digitalWrite(relayPin, HIGH);
}

void toggleRelay(int relayPin) 
{
  digitalWrite(relayPin, !digitalRead(relayPin));
}

Step 4: Upload the Code

1. Connect the Board

• Connect your GLYPH board to your computer

2. Select the Board and Port

   Do the following settings in your Arduino IDE, Do the following settings in your Arduino IDE,

   • Tools > Board > esp32 > Pcbcupid GLYPH C3

warning

For the Pcbcupid GLYPH C3 to appear under Tools > Board > esp32, the esp32 board version installed in the Arduino IDE should be greater than or equal to 3.1.0.

• Tools > Port and select the port connected to your GLYPH.
• Tools > USB CDC on Boot > Enabled

warning

If USB CDC on BOOT not enabled, you won't be seeing any serial data on Arduino IDE.

3. Upload the Code

• Click the upload button (➡️ icon) or use the shortcut CTRL + U in Arduino IDE to upload the code to the board.

Step 5: Observe the Output

On Serial Monitor, you should see the output like this:

Along with this you should see the relay ticking and corresponding LED blink.