import machine
from machine import Pin
from time import sleep
from hcsr04 import HCSR04
from servo import Servo

sensor = HCSR04(trigger_pin=12, echo_pin=13, echo_timeout_us=1000000)
my_servo = Servo(machine.Pin(15))

while True:
    for i in range(0,180,10):
        
        my_servo.write_angle(i)
        distance = sensor.distance_cm()
        
        if(distance<=30):
            print("Object at: "+str(i)+" distance: "+ str(distance))
        sleep(0.03)
        
    for i in range(180,0,-10):
        my_servo.write_angle(i)
        distance = sensor.distance_cm()
        
        if(distance<=30):
            print("Object at: "+str(i)+" distance: "+ str(distance))
        sleep(0.03)


main.py

diagram.json

from machine import PWM
import math

# originally by Radomir Dopieralski http://sheep.art.pl
# from https://bitbucket.org/thesheep/micropython-servo

class Servo:
    """
    A simple class for controlling hobby servos.
    Args:
        pin (machine.Pin): The pin where servo is connected. Must support PWM.
        freq (int): The frequency of the signal, in hertz.
        min_us (int): The minimum signal length supported by the servo.
        max_us (int): The maximum signal length supported by the servo.
        angle (int): The angle between the minimum and maximum positions.
    """
    def __init__(self, pin, freq=50, min_us=600, max_us=2400, angle=180):
        self.min_us = min_us
        self.max_us = max_us
        self.us = 0
        self.freq = freq
        self.angle = angle
        self.pwm = PWM(pin, freq=freq, duty=0)

    def write_us(self, us):
        """Set the signal to be ``us`` microseconds long. Zero disables it."""
        if us == 0:
            self.pwm.duty(0)
            return
        us = min(self.max_us, max(self.min_us, us))
        duty = us * 1024 * self.freq // 1000000
        self.pwm.duty(duty)

    def write_angle(self, degrees=None, radians=None):
        """Move to the specified angle in ``degrees`` or ``radians``."""
        if degrees is None:
            degrees = math.degrees(radians)
        degrees = degrees % 360
        total_range = self.max_us - self.min_us
        us = self.min_us + total_range * degrees // self.angle
        self.write_us(us)


servo.py

import machine, time
from machine import Pin

__version__ = '0.2.0'
__author__ = 'Roberto S茅聬 氓卢露莽庐炉chez'
__license__ = "Apache License 2.0. https://www.apache.org/licenses/LICENSE-2.0"

class HCSR04:
    """
    Driver to use the untrasonic sensor HC-SR04.
    The sensor range is between 2cm and 4m.

    The timeouts received listening to echo pin are converted to OSError('Out of range')

    """
    # echo_timeout_us is based in chip range limit (400cm)
    def __init__(self, trigger_pin, echo_pin, echo_timeout_us=500*2*30):
        """
        trigger_pin: Output pin to send pulses
        echo_pin: Readonly pin to measure the distance. The pin should be protected with 1k resistor
        echo_timeout_us: Timeout in microseconds to listen to echo pin. 
        By default is based in sensor limit range (4m)
        """
        self.echo_timeout_us = echo_timeout_us
        # Init trigger pin (out)
        self.trigger = Pin(trigger_pin, mode=Pin.OUT, pull=None)
        self.trigger.value(0)

        # Init echo pin (in)
        self.echo = Pin(echo_pin, mode=Pin.IN, pull=None)

    def _send_pulse_and_wait(self):
        """
        Send the pulse to trigger and listen on echo pin.
        We use the method `machine.time_pulse_us()` to get the microseconds until the echo is received.
        """
        self.trigger.value(0) # Stabilize the sensor
        time.sleep_us(5)
        self.trigger.value(1)
        # Send a 10us pulse.
        time.sleep_us(10)
        self.trigger.value(0)
        try:
            pulse_time = machine.time_pulse_us(self.echo, 1, self.echo_timeout_us)
            return pulse_time
        except OSError as ex:
            if ex.args[0] == 110: # 110 = ETIMEDOUT
                raise OSError('Out of range')
            raise ex

    def distance_mm(self):
        """
        Get the distance in milimeters without floating point operations.
        """
        pulse_time = self._send_pulse_and_wait()

        # To calculate the distance we get the pulse_time and divide it by 2 
        # (the pulse walk the distance twice) and by 29.1 becasue
        # the sound speed on air (343.2 m/s), that It's equivalent to
        # 0.34320 mm/us that is 1mm each 2.91us
        # pulse_time // 2 // 2.91 -> pulse_time // 5.82 -> pulse_time * 100 // 582 
        mm = pulse_time * 100 // 582
        return mm

    def distance_cm(self):
        """
        Get the distance in centimeters with floating point operations.
        It returns a float
        """
        pulse_time = self._send_pulse_and_wait()

        # To calculate the distance we get the pulse_time and divide it by 2 
        # (the pulse walk the distance twice) and by 29.1 becasue
        # the sound speed on air (343.2 m/s), that It's equivalent to
        # 0.034320 cm/us that is 1cm each 29.1us
        cms = (pulse_time / 2) / 29.1
        return cms
