Tiny Motion Detection Alarm

Hi, in this project, we are going to make a motion detection alarm with IMU 6050, it is a 3-axis Accelerometer and Gyro Sensor module. By using this, if a small movement is detected by the IMU, it will trigger a sound in the buzzer. It will alert you if an object moves even if it is supposed to be stationary, like a door, home appliance, or drawer. You can attach this device to any surface with double tape. It is also useful for monitoring children and elderly people.

How to use it

Activation sequence 

After powering on the alarm will not be activated. To activate this alarm you need to press down the push button then you will hear one beep sound which indicates the activation sequence is successful.

Stand by sequence 

After pressing the button we will have 4 seconds to place this alarm, any movement happening during this 4 seconds will be ignored. 

Detection sequence

After the stand-by sequence, you will hear two beep sounds which indicate the Detection sequence is started. From here the alarm is fully armed. Any small movements happening in the 3 axis of the device will be detected and trigger this alarm continually for 10 seconds. After this alarm is offline we need to reboot the alarm with the power switch and again go through the activation sequences.

We can customize the stand-by time, alarm duration, and movement threshold (sensitivity) from the code. so let's get into it 

Parts

• Seeed studio xiao esp32c3 
• MPU-6050 3-Axis Accelerometer and Gyro Sensor
• 500mah 3.7v battery (identical battery with 600mah)
• Slide switch 
• Push switch 
• Buzzer 

Tools

• Glue gun
• Soldering iron
• 3d printer 
• wire shrink
• soldering kit
• small gauge wire
• wire cutter

Used Fusion 360 to plan and design my project. The main body is designed to hold the battery and electronics without needing screws—it just snaps into place. To make sure everything stays secure, I used some hot glue. I found some accurate models of the modules online. that made the design process much easier, all design files are given below

I always like to upload the code to the microcontroller before assembly. Here we are using a tiny Xiao ESP32C3 from the Seeedstudio. I chose this because I have to make this device as small as possible, xiao is a very small version of ESP32C3, also it has a battery protection chip built-in so we don't need external BMS on it, and we can save space in it 

I am using Arduino IDE for flashing the code. Make sure to install the Adafruit_MPU6050.h library before compiling.

Code

#include <Wire.h>
#include <Adafruit_MPU6050.h>
Adafruit_MPU6050 mpu;  // Create the sensor object
const int buttonPin = 2;
const int ledPin = 11;

const int activationTime = 3000;
const int standbyDelay = 4000;
const int alarmDuration = 10000;
const int movementThreshold = 12;

unsigned long buttonPressTime = 0;
unsigned long activationStartTime = 0;
bool alarmActive = false;
bool inStandby = false;

void setup() {
  Serial.begin(9600);
  while (!Serial) {
    delay(10);
  }


  Serial.println("Motion detection alarm system starting...");
  pinMode(buttonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
}


void loop() {
  // Button press handling and activation sequence
  if (!digitalRead(buttonPin)) {
    buttonPressTime = millis();
    Serial.println("Button pressed");
  } else if (buttonPressTime > 0 && millis() - buttonPressTime >= activationTime) {
    activationStartTime = millis();
    alarmActive = true;
    inStandby = true;  // Enter standby mode
    digitalWrite(ledPin, HIGH);
    delay(500);
    digitalWrite(ledPin, LOW);
    Serial.println("Alarm activation sequence initiated");
    buttonPressTime = 0;
  }
  // Standby sequence (no sensor readings)
  if (inStandby && millis() - activationStartTime >= standbyDelay) {
    for (int i = 0; i < 2; i++) {
      digitalWrite(ledPin, HIGH);
      delay(250);
      digitalWrite(ledPin, LOW);
      delay(250);
    }
    Serial.println("Detection sequence started");
    inStandby = false;  // Exit standby mode


    // Activate MPU6050 only after standby
    if (!mpu.begin()) {
      Serial.println("Failed to find MPU6050 chip");
      while (1) {
        delay(10);
      }
    }
  }
  // Motion detection and alarm (now using sensor readings)
  if (!inStandby && alarmActive) {
    sensors_event_t a, g, temp;
    mpu.getEvent(&a, &g, &temp);  // Read sensor data
    int totalAccel = sqrt(a.acceleration.x * a.acceleration.x +
                           a.acceleration.y * a.acceleration.y +
                           a.acceleration.z * a.acceleration.z);
    Serial.print("Total acceleration: ");
    Serial.println(totalAccel);

    if (totalAccel >= movementThreshold) {
      Serial.println("Motion detected!");
      unsigned long alarmStart = millis();
      while (millis() - alarmStart <= alarmDuration) {
        digitalWrite(ledPin, HIGH);
        delay(500);
        digitalWrite(ledPin, LOW);
        delay(500);
      }
      Serial.println("Alarm stopped");
      alarmActive = false;  // Reset for next activation
    } else {
      Serial.println("No motion");
    }
  }
}

The brain of this project is xiao ESP32C3 which is paired with an IMU 6050 sensor, a small push button on D1. and a buzzer connected on the D0. We also have a slide switch for power control. Everything is powered by this 3.7v 500mah battery. Now let's look at the detailed build instructions in the next step.

Step 1

Solder 4 small wires into the imu6050 sda scl vcc gnd also not the wire colors

Step 2

Glue the IMU in the battery 

Step 3

Put some glue on the main body and place the battery and IMU into it 

Step 4

Glur the xiao in top of the battery also along the usb c port through gap in the 3d print

Step 5

Cut and solder all 4 wires form the IMU 6050

Step 6

Solder wired to the push button and buzzer, i connected button and buzzard ground into a common ground

Step 7

Glue the push button and buzzer into the 3d print

Step 8

Solder the wires into the buzzer and button and ground them to the xiao

Step 9

Cut the battery +ve wire and solder it to the power switch and another end of the power switch into the +ve of battery input of xiao Connect the battery -ve wire directly into the battery -ve input to the xiao and glue the switch 

Step 10

Close the back body with a cap

Follow the steps given in the intro to learn the operations. you can use double-tap stick it into any surface. I used a Xiao esp32c3 for future-proof-design because without any hardwire change we can convert it to a lot of devices like notifying alarm triggers with phone notifications or performing other tasks like if you open the door it will switch on the room lights etc. I can implement this function on upcoming firmware updates for now this is all we have. thanks for checking out this project