import time
time.sleep(0.1) # Wait for USB to become ready
import machine
import utime

# Configure Trigger (Output) and Echo (Input)
trigger = machine.Pin(16, machine.Pin.OUT)
echo = machine.Pin(17, machine.Pin.IN)

# Configure Onboard LED
led = machine.Pin("LED", machine.Pin.OUT)

def get_distance():
    # Ensure trigger is low
    trigger.low()
    utime.sleep_us(2)
    # Send 10us pulse
    trigger.high()
    utime.sleep_us(10)
    trigger.low()
    
    # Measure echo time
    while echo.value() == 0:
        signaloff = utime.ticks_us()
    while echo.value() == 1:
        signalon = utime.ticks_us()
    
    timepassed = signalon - signaloff
    # Distance formula: (Time * Speed of Sound) / 2
    distance = (timepassed * 0.0343) / 2
    return distance

while True:
    dist = get_distance()
    print("Distance: ", dist, "cm")
    
    if dist < 100:
        # Blink if object is close
        led.high()
        utime.sleep(0.1)
        led.low()
        utime.sleep(0.1)
    else:
        led.low()
        
    utime.sleep(0.2)
print("Hello, Pi Pico!")