How to Use relay esp01s: Examples, Pinouts, and Specs

The Relay ESP01S is a compact and versatile relay module designed to work seamlessly with the ESP-01S Wi-Fi module. Manufactured by ESP, this component allows users to control high-voltage devices remotely via Wi-Fi. It is widely used in IoT applications, home automation systems, and smart appliances due to its ease of integration and reliable performance.

• Home automation (e.g., controlling lights, fans, or appliances)
• IoT projects requiring remote control of devices
• Smart switches and timers
• Industrial automation systems

• Operating Voltage: 5V DC
• Relay Type: Single-channel relay
• Relay Control Voltage: 3.3V (compatible with ESP-01S logic levels)
• Maximum Load: 10A at 250V AC or 10A at 30V DC
• Communication Interface: GPIO pins of the ESP-01S module
• Dimensions: 37mm x 25mm x 19mm (L x W x H)

The Relay ESP01S module has two main interfaces: the relay terminal block and the ESP-01S header pins.

1. Power the Module: Connect the VCC pin to a 5V DC power source and the GND pin to ground.
2. Connect the ESP-01S Module: Insert the ESP-01S Wi-Fi module into the header pins on the relay board.
3. Relay Connections:
   • Connect the device you want to control to the relay terminal block.
   • Use the COM and NO terminals for devices that should be off by default.
   • Use the COM and NC terminals for devices that should be on by default.
4. Control the Relay:
   • Use GPIO0 of the ESP-01S to control the relay. Setting GPIO0 LOW will activate the relay, while setting it HIGH will deactivate it.

• Ensure the relay's load does not exceed its maximum rating (10A at 250V AC or 30V DC).
• Use proper insulation and safety precautions when working with high-voltage devices.
• Avoid powering the ESP-01S module directly from the relay's VCC pin if the current draw exceeds the module's capacity.
• Use a flyback diode across the relay coil to protect the circuit from voltage spikes.

The following code demonstrates how to control the Relay ESP01S using an ESP-01S module connected to an Arduino UNO.

#include <SoftwareSerial.h>

// Define RX and TX pins for ESP-01S communication
SoftwareSerial espSerial(2, 3); // RX = Pin 2, TX = Pin 3

// Define GPIO0 pin for relay control
const int relayPin = 4;

void setup() {
  // Initialize serial communication with ESP-01S
  espSerial.begin(9600);
  
  // Initialize relay control pin
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, HIGH); // Ensure relay is off initially
  
  // Debugging via Serial Monitor
  Serial.begin(9600);
  Serial.println("Relay ESP01S Control Initialized");
}

void loop() {
  // Example: Turn relay ON for 5 seconds, then OFF for 5 seconds
  Serial.println("Turning relay ON");
  digitalWrite(relayPin, LOW); // Activate relay (active LOW)
  delay(5000); // Wait for 5 seconds
  
  Serial.println("Turning relay OFF");
  digitalWrite(relayPin, HIGH); // Deactivate relay
  delay(5000); // Wait for 5 seconds
}

1. Relay Not Activating:

   • Ensure the ESP-01S module is properly seated in the header pins.
   • Verify that GPIO0 is being set to LOW to activate the relay.
   • Check the power supply voltage (should be 5V DC).

2. ESP-01S Not Responding:

   • Confirm that the RX and TX pins are correctly connected to the Arduino or other microcontroller.
   • Ensure the ESP-01S firmware is correctly configured for communication.

3. High-Voltage Device Not Working:

   • Verify the wiring of the relay terminal block (COM, NO, NC).
   • Check that the load does not exceed the relay's maximum rating.

• Can I use a 3.3V power supply for the relay module? No, the relay module requires a 5V power supply to operate correctly.

• Is the Relay ESP01S compatible with other ESP modules? The module is specifically designed for the ESP-01S. Other ESP modules may not fit the header pins.

• How do I reset the ESP-01S module? Pull the RESET pin of the ESP-01S module LOW momentarily to reset it.

By following this documentation, you can effectively integrate the Relay ESP01S into your projects and troubleshoot common issues.