Gesture-Controlled Lighting System Based on STM32 and MPU6050

In the applications of smart homes and the Internet of Things, gesture control is an interactive method that provides a great user experience—no need to press switches, just wave your hand to control the lights.The MPU6050 is a six-axis sensor that integrates a three-axis accelerometer and a three-axis gyroscope, which can obtain the motion posture of an object in real-time. By analyzing the changes in acceleration and angular velocity, actions such as waving can be recognized, achieving “contactless” control.

Application Scenarios

  • Smart lighting control

  • Contactless exhibit lighting in museums and exhibition halls

  • Touchless operation for the elderly or people with limited mobility

System Composition and Principles

Hardware Composition

  • Main Control: STM32F103C8T6 (or other STM32 series)

  • Sensor: MPU6050 six-axis sensor module

  • Lighting: LED (different colors indicate different states)

Hardware Connection (I²C Interface)

STM32 Pin MPU6050 Pin
PB6 (SCL) SCL
PB7 (SDA) SDA
3.3V VCC
GND GND

Working Principle

  1. Data Acquisition: Obtain acceleration and gyroscope data from the MPU6050 via I²C.

  2. Data Processing: Analyze acceleration changes to determine if a waving action has occurred.

  3. Control Output: If a waving action is recognized, switch the LED state (on/off).

Code Implementation (STM32 Standard Library)

MPU6050 Driver File

#ifndef __MPU6050_H
#define __MPU6050_H
#include "stm32f10x.h"
#define MPU6050_ADDR 0x68  // 7-bit address
typedef struct {
    int16_t ax, ay, az;
    int16_t gx, gy, gz;
} MPU6050_Data;
void MPU6050_Init(void);
void MPU6050_ReadData(MPU6050_Data *data);
#endif

Code Explanation

#define MPU6050_ADDR 0x68

This is the I²C address of the MPU6050, equivalent to a “house number” that the STM32 uses to locate this sensor.

typedef struct {
    int16_t ax, ay, az;
    int16_t gx, gy, gz;
} MPU6050_Data;

This defines a data structure to store the values measured by the sensor:

ax, ay, az → acceleration in three directions

gx, gy, gz → angular velocity in three directions (rate of rotation)

void MPU6050_Init(void);
void MPU6050_ReadData(MPU6050_Data *data);

Declares two functions: one to initialize the sensor and one to read data.

mpu6050.c

#include "mpu6050.h"
#include "i2c.h"
void MPU6050_Init(void) {
    I2C_WriteReg(MPU6050_ADDR, 0x6B, 0x00); // Wake up from sleep mode
}
void MPU6050_ReadData(MPU6050_Data *data) {
    uint8_t buf[14];
    I2C_ReadMulti(MPU6050_ADDR, 0x3B, buf, 14);
    data->ax = (buf[0] << 8) | buf[1];
    data->ay = (buf[2] << 8) | buf[3];
    data->az = (buf[4] << 8) | buf[5];
    data->gx = (buf[8] << 8) | buf[9];
    data->gy = (buf[10] << 8) | buf[11];
    data->gz = (buf[12] << 8) | buf[13];
}

Code Explanation

void MPU6050_Init(void) {
    I2C_WriteReg(MPU6050_ADDR, 0x6B, 0x00); // Wake up from sleep mode
}

The MPU6050 is in sleep mode by default (power-saving mode). Writing register 0x6B to 0x00 wakes it up to work.

void MPU6050_ReadData(MPU6050_Data *data) {
    uint8_t buf[14];
    I2C_ReadMulti(MPU6050_ADDR, 0x3B, buf, 14);

Starting from register 0x3B, read 14 bytes at once. The data includes:

6 bytes: acceleration (X, Y, Z)

2 bytes: temperature (not used here)

6 bytes: gyroscope (X, Y, Z)

data->ax = (buf[0] << 8) | buf[1];

Combines the high 8 bits and low 8 bits into a 16-bit integer (the sensor outputs 16-bit raw values).

The same method is used to combine ay, az, gx, gy, and gz.

Main Program

#include "stm32f10x.h"
#include "mpu6050.h"
#include "delay.h"
MPU6050_Data mpu_data;
uint8_t led_state = 0;
void LED_Init(void) {
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOC, &amp;GPIO_InitStructure);
}
void LED_Toggle(void) {
    if (led_state) {
        GPIO_SetBits(GPIOC, GPIO_Pin_13);
        led_state = 0;
    } else {
        GPIO_ResetBits(GPIOC, GPIO_Pin_13);
        led_state = 1;
    }}
int main(void) {
    delay_init();
    I2C_Init_Config();
    MPU6050_Init();
    LED_Init();
    while (1) {
        MPU6050_ReadData(&amp;mpu_data);
        // Simple gesture recognition: detect changes in X-axis acceleration
        if (mpu_data.ax &gt; 15000 || mpu_data.ax &lt; -15000) {
            LED_Toggle();
            delay_ms(500); // Debounce
        }
    }}

Leave a Comment