ESP32 连接 HC-SR04 超声波测距模块与蜂鸣器报警实验

from machine import Pin
import time

TRIG_PIN = 5
ECHO_PIN = 4
MAX_ECHO_US = 30000
SOUND_SPEED_CM_PER_US = 0.0343


def measure_single(trig_pin=TRIG_PIN, echo_pin=ECHO_PIN):
    trig = Pin(trig_pin, Pin.OUT)
    echo = Pin(echo_pin, Pin.IN)

    trig.value(0)
    time.sleep_us(2)
    trig.value(1)
    time.sleep_us(10)
    trig.value(0)

    start_wait = time.ticks_us()
    while echo.value() == 0:
        if time.ticks_diff(time.ticks_us(), start_wait) > MAX_ECHO_US:
            return -1

    start = time.ticks_us()
    while echo.value() == 1:
        if time.ticks_diff(time.ticks_us(), start) > MAX_ECHO_US:
            return -1

    duration = time.ticks_diff(time.ticks_us(), start)
    distance = duration * SOUND_SPEED_CM_PER_US / 2
    return distance


def measure(samples=5, trig_pin=TRIG_PIN, echo_pin=ECHO_PIN):
    values = []
    for _ in range(samples):
        d = measure_single(trig_pin, echo_pin)
        if d >= 0:
            values.append(d)
        time.sleep_ms(10)

    if not values:
        return -1

    values.sort()
    n = len(values)
    if n % 2 == 1:
        return values[n // 2]
    return (values[n // 2 - 1] + values[n // 2]) / 2

import time
from machine import Pin
from hcsr04 import measure

TRIG_PIN = 18
ECHO_PIN = 19
BUZZER_PIN = 23

# 低电平触发设为 False；高电平触发设为 True
active_high = False

buzzer = Pin(BUZZER_PIN, Pin.OUT)
buzzer.value(0 if active_high else 1)

THRESHOLD_CM = 10
INTERVAL_MS = 3000
BEEP_MS = 200

while True:
    distance = measure(samples=5, trig_pin=TRIG_PIN, echo_pin=ECHO_PIN)
    print('distance: %.1f cm' % distance)

    if 0 <= distance < THRESHOLD_CM:
        print('ALARM: distance < %d cm' % THRESHOLD_CM)
        buzzer.value(1 if active_high else 0)
        time.sleep_ms(BEEP_MS)
        buzzer.value(0 if active_high else 1)

    time.sleep_ms(INTERVAL_MS)