Introduction: 🐞 Bug in Circuit: Learn Debugging With This IoT Relay Board

📘 Introduction

Build, break, debug, and learn — all in one kit!

The Bug in Circuit is an IoT-based ESP32 relay board for students, makers, and educators. But there's a twist — the board comes with a built-in fault. You must find and fix it using real-world debugging techniques like continuity testing and logic tracing before making it work.

It's not just plug-and-play. It's plug, probe, patch, program — and then play.

Perfect for engineering students, IoT learners, and anyone who loves solving real problems.

Supplies

Bug in Circuit IoT Relay Board (2 / 4 / 6 Channel Variant)

ESP32 (pre-soldered)

USB Cable for programming

Multimeter

Jumper wires

5V DC power supply (or USB)

Arduino IDE (Installed)

Arduino IoT Cloud account (optional)

Breadboard (optional but helpful)

Step 1: Understanding the Bugged Relay Board

This is no ordinary relay board. The Bug in Circuit board includes a subtle issue — maybe an open trace, a missing jumper, or misrouted signal.

Your first challenge:

  1. Power the board via USB or 5V terminal.
  2. Use a multimeter in continuity mode.
  3. Trace logic and power paths.
  4. Spot the fault and fix it!
The goal is to simulate real-life engineering debug situations in a safe, educational way.


Step 2: Fixing the Circuit

Once you've found the bug, it's time to patch it!

Common fixes might include:

  1. Adding a jumper wire
  2. Soldering a small patch
  3. Bypassing a track

After fixing:

  1. Use a simple multimeter check to confirm relay switching path is now closed.
  2. Proceed to test your relay circuit manually with GPIOs.


Step 3: Programming the ESP32

Now that the circuit is fixed, it's time to upload your first sketch:

cpp
CopyEdit
int relayPin = 5;

void setup() {
pinMode(relayPin, OUTPUT);
}

void loop() {
digitalWrite(relayPin, HIGH);
delay(1000);
digitalWrite(relayPin, LOW);
delay(1000);
}
  1. Use Arduino IDE.
  2. Select “ESP32 Dev Module” as the board.
  3. Flash the code and observe relay click.

🧠 Update the GPIO pin numbers based on your actual relay input pins.

Step 4: IoT Cloud Control (Optional)

Want to make it smarter? Use Arduino IoT Cloud to control relays from your phone or Alexa.

  1. Sign in at Arduino IoT Cloud
  2. Add your ESP32 board.
  3. Create variables like Relay1, Relay2.
  4. Upload the cloud sketch.
  5. Test switching from the dashboard or link Alexa/Google.

Step 5: Kit Variants Available

Choose the difficulty level:

  1. 2-Channel Relay Board – Beginner-friendly
  2. 4-Channel Relay Board – Intermediate
  3. 6-Channel Relay Board – Includes onboard SMPS for 230V input

Each variant features a different “bug” to fix!

Step 6: Learning Outcomes

With this kit, you’ll learn:

  1. Circuit tracing with multimeter
  2. Relay working principles
  3. ESP32 programming with GPIOs
  4. Debugging faulty circuits
  5. IoT cloud integration

This is not just another project—it’s a real experience.

Step 7: Why It Matters

Debugging is a vital skill in electronics. Unlike kits that work out-of-the-box, Bug in Circuit makes you think, test, fail, and succeed — just like real engineers do every day.

It’s more than a project. It’s preparation for the real world.