from machine import Pin
import utime, time
from time import sleep
import rp2 
from rp2 import PIO

trigger = Pin(3, Pin.OUT)
echo1 = Pin(2, Pin.IN)
speaker = Pin(0, Pin.OUT)

@rp2.asm_pio(out_init=[PIO.OUT_LOW])
def echo():
    wrap_target()
    mov(pins, isr)     
    mov(isr, invert(isr))
    pull(noblock)      
    mov(x, osr)
    mov(y, x)
    label("loop")
    jmp(y_dec, "loop")  
    wrap()


sm = rp2.StateMachine(0, echo, freq=1_000_000, out_base=Pin(7))
sm.active(1)

def play(freq):
  if freq:
    sm.put(1_000_000//freq)
  else:
    sm.put(0)


def ultra(frec):
   trigger.low()
   utime.sleep_us(2)
   trigger.high()
   utime.sleep_us(5)
   trigger.low()
   while echo1.value() == 0:
       signaloff = utime.ticks_us()
   while echo1.value() == 1:
       signalon = utime.ticks_us()
   timepassed = signalon - signaloff
   distance = (timepassed * 0.0343) / 2
   
   if distance < 170:
        print("The distance from object is ",distance,"cm")
        play(frec)
        sleep(1)
        play(frec-1000)
        sleep(0.1)

   else:
        print("The distance from object is ",distance,"cm")
        play(frec-frec)

    
        
   
while True:
   ultra(2000)
   utime.sleep(0.3)