from machine import Pin, I2C, PWM
import struct
import time

# =====================================================
# I2C Configuration
# =====================================================

# Initialize I2C communication using GPIO22 (SCL) and GPIO21 (SDA)
i2c = I2C(0, scl=Pin(22), sda=Pin(21))

# MPU6050 I2C address
MPU_ADDR = 0x68

# Wake up the MPU6050 by clearing the sleep mode bit
i2c.writeto_mem(MPU_ADDR, 0x6B, b'\x00')

# =====================================================
# Output Devices
# =====================================================

# Green LED indicates normal operation
green_led = Pin(2, Pin.OUT)

# Red LED indicates a security alert
red_led = Pin(12, Pin.OUT)

# Configure the buzzer
buzzer = PWM(Pin(14))
buzzer.freq(2000)      # Set buzzer frequency to 2 kHz
buzzer.duty(0)         # Keep the buzzer OFF initially

# =====================================================
# Detection Thresholds
# =====================================================

# Minimum vibration level required to trigger detection (in g)
VIBRATION_THRESHOLD = 0.15

# Minimum rotation speed required to trigger detection (degrees/second)
ROTATION_THRESHOLD = 40

# =====================================================
# Variables for Previous Accelerometer Readings
# =====================================================

# Store previous acceleration values to calculate vibration
prev_ax = 0
prev_ay = 0
prev_az = 0

# =====================================================
# Function: Read MPU6050 Sensor
# =====================================================

def read_mpu():
    """
    Reads accelerometer and gyroscope data from the MPU6050.

    Returns:
        ax, ay, az : Raw accelerometer values
        gx, gy, gz : Raw gyroscope values
    """

    # Read 14 bytes starting from the accelerometer register
    data = i2c.readfrom_mem(MPU_ADDR, 0x3B, 14)

    # Unpack the received bytes
    # ax, ay, az, temperature, gx, gy, gz
    ax, ay, az, temp, gx, gy, gz = struct.unpack(">hhhhhhh", data)

    return ax, ay, az, gx, gy, gz

# =====================================================
# Main Program Loop
# =====================================================

while True:

    # -----------------------------------------
    # Read sensor measurements
    # -----------------------------------------

    ax, ay, az, gx, gy, gz = read_mpu()

    # -----------------------------------------
    # Convert accelerometer readings to g
    # (Default sensitivity: ±2g)
    # 16384 LSB = 1g
    # -----------------------------------------

    ax = ax / 16384
    ay = ay / 16384
    az = az / 16384

    # Remove the Earth's gravity from the Z-axis
    az = az - 1.0

    # -----------------------------------------
    # Calculate vibration
    # -----------------------------------------
    # Compare the current reading with the
    # previous reading. A large difference
    # indicates sudden movement or vibration.
    # -----------------------------------------

    delta_x = abs(ax - prev_ax)
    delta_y = abs(ay - prev_ay)
    delta_z = abs(az - prev_az)

    # Use the largest vibration value
    vibration = max(delta_x, delta_y, delta_z)

    # Save the current readings for the next iteration
    prev_ax = ax
    prev_ay = ay
    prev_az = az

    # -----------------------------------------
    # Convert gyroscope readings to degrees/second
    # (Default sensitivity: ±250°/s)
    # 131 LSB = 1°/s
    # -----------------------------------------

    gx = gx / 131
    gy = gy / 131
    gz = gz / 131

    # Calculate the maximum rotation speed
    rotation = max(abs(gx), abs(gy), abs(gz))

    # -----------------------------------------
    # Display sensor information
    # -----------------------------------------

    print("--------------------------------")

    print("Acceleration (g)")
    print("AX = {:.2f}  AY = {:.2f}  AZ = {:.2f}".format(ax, ay, az))

    print("Gyroscope (deg/s)")
    print("GX = {:.2f}  GY = {:.2f}  GZ = {:.2f}".format(gx, gy, gz))

    print("Vibration = {:.2f} g".format(vibration))
    print("Rotation  = {:.2f} deg/s".format(rotation))

    # -----------------------------------------
    # Sensor Fusion Decision
    # -----------------------------------------
    # Trigger the alarm only if:
    # 1. Strong vibration is detected
    # AND
    # 2. Fast rotation is detected
    # -----------------------------------------

    if vibration > VIBRATION_THRESHOLD or rotation > ROTATION_THRESHOLD:

        # Turn ON the alarm indicators
        red_led.on()
        green_led.off()

        buzzer.duty(512)

        print("SAFE TAMPERING DETECTED")
        print("ALARM ON")

    else:

        # Keep the safe in normal operating mode
        green_led.on()
        red_led.off()

        buzzer.duty(0)

        print("SAFE SECURE")
        print("ALARM OFF")

    # Wait before taking the next measurement
    time.sleep(0.5)