import machine
from machine import Pin, time_pulse_us, PWM, I2C
import time
from i2c_lcd1602 import I2cLcd

# Khai báo chân
SDA_PIN = 21
SCL_PIN = 22

trig_pin = machine.Pin(18, machine.Pin.OUT)  
echo_pin = machine.Pin(19, machine.Pin.IN)    
buzzer_pin = machine.Pin(23, machine.Pin.OUT)

AddressOfLcd = 0x27
i2c = I2C(scl=Pin(SCL_PIN), sda=Pin(SDA_PIN), freq=400000)
lcd = I2cLcd(i2c, AddressOfLcd, 2, 16)

def measure_distance():
    trig_pin.value(0)
    time.sleep_us(2)
    trig_pin.value(1)
    time.sleep_us(10)
    trig_pin.value(0)

    start_time = time.ticks_us()
    duration = 0  # Khởi tạo biến duration

    while echo_pin.value() == 0:
        start_time = time.ticks_us()

    while echo_pin.value() == 1:
        duration = time.ticks_us() - start_time

    # Tính toán khoảng cách
    distance = (duration * 0.0343) / 2
    return distance

while True:
    distance = measure_distance()  
    print("Khoảng cách:", distance, "cm")
    lcd.clear()
    lcd.move_to(0, 0)
    lcd.putstr("{} cm".format(distance))
    
    # Bật cảnh báo nếu khoảng cách dưới 50 cm
    if distance < 50:
        buzzer_pin.value(1)  # Bật buzzer
        print("đang phát")
        lcd.move_to(0, 1)
        lcd.putstr("Warning!!")
    else:
        buzzer_pin.value(0)  # Tắt buzzer

    time.sleep(0.5)