from machine import Pin,Timer
from time import sleep_us, sleep

def start(p):
    global cnt
    # se emite pulso en TRIGGER
    trig.on()
    trig.off()
  
def mide(p):
    global cnt
    if echo.value()==1:
        cnt = 0
    else:
        dist = cnt/58 # cm/us
        print(dist,' cm')
        cnt=0
        sleep(0.001)

echo = Pin(27,Pin.IN)
push = Pin(2,Pin.IN,Pin.PULL_UP)
echo.irq(trigger = Pin.IRQ_RISING|Pin.IRQ_FALLING,handler = mide)
push.irq(trigger = Pin.IRQ_FALLING,handler = start)
trig= Pin(14,Pin.OUT)

cnt = 0 
while(1):
    cnt += 1
    sleep_us(1)