#importation of libraries needed
from machine import Pin
import utime

#assigning or hardwares to a GPIO pin of the micro controller
trigger = Pin(16, Pin.OUT)
echo = Pin(17, Pin.IN)
relay = Pin(15, Pin.OUT)

#a fuction that calculates the time and distance from our ultrasonic sensor
def u_sensor():
            trigger.low()
            utime.sleep_us(2)
            trigger.high()
            utime.sleep_us(5)
            trigger.low()
            
            while echo.value() == 0:
                signaloff = utime.ticks_us()
            while echo.value() == 1:
                signalon = utime.ticks_us()
                
            total_time = signalon - signaloff
            distance = (total_time * 0.0343)/2
            max_d = 100
            min_d = 10
            mid_d = 70
            print(f"The distance from object is {distance}cm")
            
            if distance <= min_d:
                relay.off()
            elif mid_d <= distance <= max_d:
                relay.on()
                if min_d <= distance <= mid_d:
                    if relay.off():
                        print()
                elif distance < mid_d:
                    relay.on() 

#the loop that runs the whole code over and over    
while True:
    u_sensor()
    utime.sleep(1)