带flask的RPI dht22 :无法将行4设置为input -等待PulseIn消息超时

import RPi.GPIO as GPIO
import time

# 设置GPIO模式
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

# 设置GPIO引脚
DHT_PIN = 4
GPIO.setup(DHT_PIN, GPIO.OUT)

# 初始化DHT22传感器
def init_dht22():
    GPIO.output(DHT_PIN, GPIO.LOW)
    time.sleep(0.018)
    GPIO.output(DHT_PIN, GPIO.HIGH)
    time.sleep(0.02)

# 读取DHT22传感器数据
def read_dht22():
    init_dht22()
    while GPIO.input(DHT_PIN) == GPIO.LOW:
        pulse_start = time.time()
    while GPIO.input(DHT_PIN) == GPIO.HIGH:
        pulse_end = time.time()
    pulse_duration = pulse_end - pulse_start
    return pulse_duration

# 主循环
try:
    while True:
        pulse_duration = read_dht22()
        print("Pulse duration:", pulse_duration)
        time.sleep(2)
except KeyboardInterrupt:
    GPIO.cleanup()

from flask import Flask, jsonify
import RPi.GPIO as GPIO
import time

app = Flask(__name__)

# 设置GPIO模式
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

# 设置GPIO引脚
DHT_PIN = 4
GPIO.setup(DHT_PIN, GPIO.OUT)

# 初始化DHT22传感器
def init_dht22():
    GPIO.output(DHT_PIN, GPIO.LOW)
    time.sleep(0.018)
    GPIO.output(DHT_PIN, GPIO.HIGH)
    time.sleep(0.02)

# 读取DHT22传感器数据
def read_dht22():
    init_dht22()
    while GPIO.input(DHT_PIN) == GPIO.LOW:
        pulse_start = time.time()
    while GPIO.input(DHT_PIN) == GPIO.HIGH:
        pulse_end = time.time()
    pulse_duration = pulse_end - pulse_start
    return pulse_duration

@app.route('/sensor_data', methods=['GET'])
def sensor_data():
    pulse_duration = read_dht22()
    return jsonify({"pulse_duration": pulse_duration})

if __name__ == '__main__':
    try:
        app.run(host='0.0.0.0', port=5000)
    except KeyboardInterrupt:
        GPIO.cleanup()