Hand Gesture Media Controller

A real-time Bluetooth-enabled gesture-controlled media system built using the STM32 Nucleo-L476RG, HC-SR04 ultrasonic sensor, and HC-05 Bluetooth module.

The project uses hand movements to control media playback on a PC, including:

• Play/Pause
• Next Track
• Previous Track
• Volume Control

The firmware is written using bare-metal register-level programming without relying on STM32 HAL libraries, while a lightweight Python script handles media control on the host PC.

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🚀 Features

• Real-time gesture recognition
• Bluetooth wireless communication
• Finite State Machine (FSM)-based gesture handling
• Bare-metal STM32 programming
• Volume and swipe gesture support
• Python-based media automation
• Modular driver-based firmware structure

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🗺️ System Architecture

Hand Gesture
     ↓
HC-SR04 Ultrasonic Sensor
     ↓
STM32L476RG
     ↓
Gesture State Machine
     ↓
USART1 UART Communication
     ↓
HC-05 Bluetooth Module
     ↓
Windows Bluetooth COM Port
     ↓
Python Script
     ↓
OS Media Control

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🛠️ Hardware Used

Component	Purpose
STM32 Nucleo-L476RG	Main Controller
HC-SR04 Ultrasonic Sensor	Distance Measurement
HC-05 Bluetooth Module	Wireless Communication
Jumper Wires	Connections
USB Cable / 5V Charger	Power Supply

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📌 Pin Configuration

Pin	Connected To	Function
PA5	HC-SR04 Echo	TIM2 Input Capture
PA6	HC-SR04 Trigger	Trigger Output
PA9	HC-05 RX	USART1_TX
PA10	HC-05 TX	USART1_RX

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🧠 Key Firmware Concepts

1. Bare-Metal Peripheral Programming

The project directly configures:

• RCC clocks
• GPIO modes
• Alternate functions
• USART communication
• Timer input capture
• SysTick timing

without using STM32 HAL libraries.

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2. Ultrasonic Distance Measurement

The HC-SR04 sensor is used to calculate hand distance using:

• trigger pulse generation
• timer input capture
• echo pulse width measurement

Distance calculation:

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Implemented as:

distance_cm = (del_t * 0.0343f)/2.0f;

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3. Gesture Recognition using FSM

A finite state machine is used to manage:

• gesture detection
• gesture locking
• mode transitions
• swipe interpretation
• volume control

States

IDLE
MODE_SELECTION
SWIPE_MODE
VOLUME_MODE
PLAYPAUSE_LOCK

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🎛️ Gesture Controls

Gesture	Action
Hold hand very close	Play/Pause
Fast inward swipe	Next Track
Fast outward swipe	Previous Track
Move hand away in Volume Mode	Volume Up
Move hand closer in Volume Mode	Volume Down

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📂 Project Structure

├── Core/
│   ├── main.c
│   ├── gpio_driver.c
│   ├── rcc_driver.c
│   ├── usart_driver.c
│   ├── timer_driver.c
│   ├── ultrasonic.c
│   └── systick_driver.c
│
└── Python/
    └── gesture_control.py

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💻 Python Host Application

The Python application:

• reads Bluetooth serial data
• parses gesture commands
• triggers media key events using PyAutoGUI

Required Libraries

pip install pyserial pyautogui

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▶️ Running the Project

1. Flash the Firmware

Build and flash the STM32 firmware using STM32CubeIDE.

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2. Pair the HC-05

Pair the Bluetooth module with the PC.

Default password:

1234

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3. Find the Bluetooth COM Port

Open:

Device Manager → Ports (COM & LPT)

Identify the HC-05 COM port.

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4. Update Python Script

ser.port = 'COMX'

Replace COMX with your Bluetooth COM port.

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5. Run the Python Script

python gesture_control.py

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🔮 Future Improvements

• Native HID Support: Configure the STM32 to behave like a plug-and-play HID media keyboard over USB/Bluetooth, removing the need for the Python script running on the PC.
• DSP-Based Gesture Smoothing: Implement filtering techniques to reduce ultrasonic noise and improve gesture stability.
• Audio-Reactive LED Effects: Use FFT processing through the CMSIS-DSP library to detect bass frequencies from music and drive LEDs that pulse in sync with the audio.
• Hardware Status Display: Add a small I2C LCD display to show active modes, gesture states, connection status, and distance readings.
• Computer Vision + TinyML Expansion: Explore camera or ToF-based gesture tracking combined with lightweight machine learning models for more advanced gesture recognition.

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📚 Key Learnings

This project helped develop practical experience in:

• Bare-metal embedded systems programming
• UART communication
• Timer input capture
• Bluetooth serial communication
• GPIO alternate functions
• Real-time state machine design
• Hardware-level debugging
• Embedded-to-PC system integration

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✅ Final Outcome

Successfully developed a:

Real-time Bluetooth-enabled gesture-controlled media controller using STM32 bare-metal programming and Python automation.

The project combines:

• embedded systems
• wireless communication
• sensor interfacing
• state-machine-based control
• PC automation

into a complete end-to-end interactive system.