If you're looking to build a versatile IoT device capable of controlling up to 16 appliances or devices via your smartphone, then you're in the right place. In this tutorial, we’ll create a 16-channel relay module controlled using an ESP32 WROOM module and the RemoteXY platform. This setup is perfect for home automation projects. Let’s dive in!

What You’ll Need

Here is the list of components required for this project:

Hardware Components

1. ESP32 WROOM Module (NodeMCU ESP32 development board)
2. 5V 16-Channel Relay Module (16 relays)
3. 16 x 1N4007 Diodes (for flyback protection)
4. 16 x 330Ω Resistors (current-limiting resistors)
5. 16 x BC547 Transistors (to drive the relays)
6. 16 x AC Terminal Blocks (for load connections)
7. Power Socket (5V DC power supply for the relays and ESP32)
8. Jumper wires and connecting cables
9. Breadboard or PCB (optional for prototyping)

Software Tools

1. RemoteXY (for GUI design and app integration)
2. Arduino IDE (for ESP32 programming)
3. USB Cable (for uploading the code to the ESP32)

Step 1: Understanding the Circuit Design

In this setup:

1. The ESP32 WROOM will control the relays through the BC547 transistors.
2. Each relay will have its own protection circuit comprising a 1N4007 diode and 330Ω resistor.
3. The ESP32 will connect to your smartphone via RemoteXY, allowing you to toggle the relays on or off.
4. A 5V power supply will power both the relay board and ESP32.

Step 2: Design the Control Interface with RemoteXY

1. Create an Account: Go to RemoteXY and sign up for free.
2. Design the Interface:

• Choose the number of buttons (16, for each relay).
• Label each button (e.g., "Relay 1", "Relay 2").
• Arrange the buttons in a grid or list format for easy access.
• Save and download the generated code file for Arduino IDE.

Step 3: Build the Circuit

Circuit Connections

Relay Module:

• Connect the VCC of the relay module to the 5V power supply.
• Connect the GND of the relay module to the GND of the ESP32.

Transistor Circuit:

• Connect the collector of each BC547 transistor to the input pin of the corresponding relay.
• Connect the emitter to GND.
• Use a 330Ω resistor between the base of the BC547 and the GPIO pin of the ESP32.

Diodes:

• Place a 1N4007 diode parallel to each relay coil with the cathode connected to VCC and the anode to the collector of the transistor.

ESP32 Pins:

• Assign each GPIO pin of the ESP32 to control one relay (e.g., GPIO16, GPIO17, etc.).

Power Supply

Ensure the ESP32 and the relay board share a common GND for smooth operation.

Use a 5V DC power supply with enough current capacity to drive all relays simultaneously (around 2A is sufficient).

Step 4: Upload the Code

Install ESP32 Board Support:

Open the Arduino IDE.

Go to File > Preferences and add the following URL to the Additional Board Manager:

arduino

Copy code

https://dl.espressif.com/dl/package_esp32_index.json

Install the ESP32 board package from the Board Manager.

Include RemoteXY Library:

Add the library generated by the RemoteXY platform to the Arduino IDE.

Code Upload:

• Open the code file downloaded from RemoteXY.
• Modify it to match your GPIO pin assignments for the relays.
• Connect the ESP32 to your computer via USB and upload the code.

Step 5: Test and Control Your IoT Device

Install the RemoteXY App:

Download the RemoteXY app from the Google Play Store or Apple App Store.

Pair the app with your ESP32 (via WiFi or Bluetooth, depending on your setup).

Control Your Relays:

Open the app, and you should see the 16 buttons you designed.

Tapping a button will toggle the corresponding relay on or off, controlling the connected appliance.

Step 6: Integrate with Home Appliances

• Connect your home appliances to the AC terminal blocks of the relay module.
• Ensure proper insulation and safety precautions when dealing with AC mains.

Video Reference:

Conclusion

By following this tutorial, you’ve built a robust 16-channel IoT device using the ESP32 WROOM module and RemoteXY. This setup offers a flexible and scalable solution for home automation or industrial control systems. Feel free to customize the design to add more functionality, such as timers or sensors.