Project Hub/Basic Analog & Power Electronics/Discrete & Component Electronics/ESP32 Bluetooth Low Energy (BLE) – Connecting to Fitness Band to Trigger a Bulb

Intermediate

ESP32

₹500 – ₹1,500

3 – 6 Hours

ESP32 Bluetooth Low Energy (BLE) – Connecting to Fitness Band to Trigger a Bulb

Learn how to configure an ESP32 as a Bluetooth Low Energy (BLE) client to detect a nearby fitness band by its unique MAC address and automatically trigger a connected lamp via a relay module.

Originally published by Aswinth Raj on CircuitDigest

View original tutorial

How It Works

This project establishes an automated control system using an ESP32 microcontroller acting as a Bluetooth Low Energy (BLE) client. Programmed via the Arduino IDE, the ESP32 periodically scans its surroundings for specific BLE broadcast signals, looking for the unique MAC address of a target fitness band. When the fitness band comes within range, the ESP32 recognizes the designated hardware identifier and changes the state of one of its digital output pins. Because the ESP32 operates at 3.3V logic and cannot directly drive high-voltage alternating current appliances, this control signal is routed to a relay module. The relay uses an electromagnetic coil—potentially isolated or driven via a transistor circuit like a BC548 if needed—to physically actuate a heavy-duty switch. This mechanical switching action safely bridges or breaks the connection to the AC load, such as a lamp plugged into mains power, causing the light to turn on or off based on the proximity of your wearable device.

Why Build This

Design and implement a practical IoT context-aware home automation prototype using wireless proximity detection.

Gain hands-on experience bridging low-voltage microcontroller logic with high-voltage AC electrical loads safely.

Explore advanced microcontroller communication protocols by configuring the ESP32 as an active BLE client.

Real-World Application

Automated home lighting that turns on when you enter a room wearing a wearable device like a fitness band or smartwatch, and turns off when you leave.

Skills You'll Learn

BLE client scanning

MAC address filtering

GPIO digital output control

relay module interfacing

AC load switching

microcontroller firmware development

Safety Precautions

Warning: The circuit deals with direct 220V AC mains voltage. Exercise extreme caution with live wires and ensure no short circuits occur.

Technology Tags

ESP32

BLUETOOTH LOW ENERGY

BLE CLIENT

RELAY MODULE

SMART HOME AUTOMATION

ARDUINO IDE

C++

WIRELESS PROXIMITY

Frequently Asked Questions

How do I find the unique MAC address of my fitness band?

You can use the nRF Connect mobile application on your smartphone to scan for nearby Bluetooth Low Energy devices and read their hardware MAC addresses.

Can I connect the AC lamp directly to the ESP32 output pin?

No, absolutely not. The ESP32 outputs 3.3V DC signals which cannot handle AC mains voltage, and direct connection will destroy the board and pose a severe shock hazard. You must use a properly rated relay module to isolate the low-voltage control circuit from the high-voltage load.

Does this project require an active internet connection or router?

No, this system relies entirely on local Bluetooth Low Energy (BLE) communication between your fitness band and the ESP32, so an external Wi-Fi network or internet connection is not necessary.