How to Use ESP32 Relay X2: Examples, Pinouts, and Specs

The ESP32 Relay X2 is a dual-channel relay module designed to interface seamlessly with the ESP32 microcontroller. It allows users to control high-voltage devices such as lights, fans, or appliances using low-voltage digital signals. Each relay channel can be independently controlled, making it ideal for home automation, IoT projects, and industrial control systems.

• Home automation (e.g., controlling lights, fans, or appliances)
• IoT projects requiring high-voltage device control
• Industrial automation and control systems
• Smart energy management systems
• Prototyping and educational projects

The following table outlines the key technical details of the ESP32 Relay X2 module:

The ESP32 Relay X2 module has the following pinout:

Each relay channel has three output terminals:

1. Power the Module: Connect the VCC pin to a 5V power source and the GND pin to ground.
2. Connect the ESP32:
   • Connect the IN1 pin to a GPIO pin on the ESP32 to control Relay 1.
   • Connect the IN2 pin to another GPIO pin on the ESP32 to control Relay 2.
3. Connect the Load:
   • For each relay, connect the high-voltage device to the COM and NO terminals if you want the device to turn on when the relay is active.
   • Use the COM and NC terminals if you want the device to turn off when the relay is active.
4. Control the Relays: Use the ESP32 to send LOW signals to the IN1 or IN2 pins to activate the corresponding relay.

• Power Supply: Ensure the module is powered with a stable 5V DC supply. Do not exceed the voltage rating.
• Isolation: The relay module provides electrical isolation between the control and load sides. However, always exercise caution when working with high-voltage circuits.
• Load Ratings: Do not exceed the maximum load voltage (250V AC / 30V DC) or current (10A) for each relay channel.
• GPIO Pin Configuration: Configure the ESP32 GPIO pins as outputs in your code to control the relays.

Below is an example Arduino sketch to control the ESP32 Relay X2 module:

// Define GPIO pins for the relay control signals
#define RELAY1_PIN  26  // GPIO pin connected to IN1
#define RELAY2_PIN  27  // GPIO pin connected to IN2

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(115200);

  // Set relay pins as outputs
  pinMode(RELAY1_PIN, OUTPUT);
  pinMode(RELAY2_PIN, OUTPUT);

  // Ensure relays are off at startup
  digitalWrite(RELAY1_PIN, HIGH); // Relay is active low
  digitalWrite(RELAY2_PIN, HIGH); // Relay is active low
}

void loop() {
  // Turn on Relay 1
  Serial.println("Turning on Relay 1");
  digitalWrite(RELAY1_PIN, LOW); // Activate relay
  delay(2000); // Wait for 2 seconds

  // Turn off Relay 1
  Serial.println("Turning off Relay 1");
  digitalWrite(RELAY1_PIN, HIGH); // Deactivate relay
  delay(2000); // Wait for 2 seconds

  // Turn on Relay 2
  Serial.println("Turning on Relay 2");
  digitalWrite(RELAY2_PIN, LOW); // Activate relay
  delay(2000); // Wait for 2 seconds

  // Turn off Relay 2
  Serial.println("Turning off Relay 2");
  digitalWrite(RELAY2_PIN, HIGH); // Deactivate relay
  delay(2000); // Wait for 2 seconds
}

1. Relays Not Activating:

   • Ensure the VCC and GND pins are properly connected to a 5V power source.
   • Verify that the control signals (IN1 and IN2) are being driven LOW by the ESP32.

2. ESP32 GPIO Pins Not Working:

   • Check that the GPIO pins used for IN1 and IN2 are configured as outputs in your code.
   • Avoid using GPIO pins that are reserved for special functions on the ESP32 (e.g., GPIO0, GPIO2).

3. Load Not Switching:

   • Confirm that the load is properly connected to the relay terminals (COM, NO, or NC).
   • Ensure the load does not exceed the relay's voltage or current ratings.

4. Relay Module Overheating:

   • Check that the load current does not exceed 10A per channel.
   • Use proper heat dissipation techniques if the module is used for extended periods.

Q1: Can I use the ESP32 Relay X2 with a 3.3V power supply?
A1: No, the module requires a 5V power supply for proper operation. However, the control signals are compatible with the ESP32's 3.3V logic levels.

Q2: Is the relay module opto-isolated?
A2: No, the ESP32 Relay X2 does not include opto-isolation. For additional safety, consider using an opto-isolated relay module.

Q3: Can I control both relays simultaneously?
A3: Yes, you can control both relays independently or simultaneously by sending appropriate signals to the IN1 and IN2 pins.

Q4: What happens if I send a HIGH signal to the IN1 or IN2 pins?
A4: The corresponding relay will deactivate, and the load connected to the NO terminal will turn off.