Raspberry Pi 3B+通过GPIO在3.5mm插孔上获得静态噪声

Question

我对Raspberry Pi和Python没有什么经验，但我成功地为一个系统集成了一个解决方案，该系统在有人在场时会做出反应（使用PIR传感器），并且根据人数，它会命令更改由Arduino控制的蠕动泵的速度（使用HC-06通过蓝牙进行通信）。你知道吗

The job made by the RPi is getting event by PIR sensor, making the count of people using a camera, send BT command and playing or changing a sound track.

Problem I just got is static sound in the 3.5mm jack while playing the audio.

我已经检查过的东西： +扬声器和连接与其他设备配合良好 +GPIO连接良好且相互隔离 +音频在节目之外播放得很好 +增加了“pwm模式=2”和“禁用音频抖动=1”配置.txt你知道吗

在virtualenv上运行Raspberry pi3b+NOOBS、OpenCV和python3 代码：

from picamera import PiCamera
from time import sleep
from threading import Timer
from random import randint
import numpy as np
import imutils
import RPi.GPIO as GPIO
import serial
import cv2
import pygame


pygame.mixer.init(frequency=44100, size=-16, channels=2, buffer=4096)

pir = 4
crowd = 0
last = 0
lv = 1
waiting = True
state = False
active = False

GPIO.setmode(GPIO.BCM)
GPIO.setup(pir, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

camera = PiCamera()
camera.resolution = (640, 480)

intro = pygame.mixer.Sound('./audio/0.wav')
first = pygame.mixer.Sound('./audio/1.wav')
second = pygame.mixer.Sound('./audio/2.wav')
third = pygame.mixer.Sound('./audio/3.wav')
outro = pygame.mixer.Sound('./audio/m1.wav')

btSerial = serial.Serial( "/dev/rfcomm0", baudrate=9600 )
sleep(2)

hog = cv2.HOGDescriptor()
hog.setSVMDetector(cv2.HOGDescriptor_getDefaultPeopleDetector())

def shot(channel):
    global waiting
    print(channel)
    waiting = False
    t.cancel()
    k.cancel()
    camera.start_preview()
    sleep(2)
    camera.capture('/home/pi/Desktop/crowd.bmp')
    camera.stop_preview()
    print ('Photo captured')
    people_counter()
    if not active:
            start()
    else:
        update()

def deactiv():
    global active
    global last
    active = False
    intro.fadeout(8200)
    first.fadeout(8200)
    second.fadeout(8200)
    third.fadeout(8200)
    outro.play(0,10000,6500)
    last = 0
    send_bt('OFF')

def keep_on():
    send_bt('READY')

def people_counter():
    global crowd
    image = cv2.imread('crowd.bmp')
    image = imutils.resize(image, width=min(400, image.shape[1]))
    (rects, weights) = hog.detectMultiScale(image, winStride=(4, 4),
        padding=(16, 16), scale=1.003)
    crowd = len(rects)
    print(crowd)

def start():
    global active
    active = True
    intro.play(0,-1, 6500)
    send_bt('TRIG')

def update():
    global last
    global lv
    if 0 <= crowd <= 2 :
        lv = 1
    elif 2 < crowd <= 5 :
        lv = 2
    elif crowd >= 5 :
        lv = 3
    if lv == last and last != 3:
        pass
    else:
        if lv == 1:
            intro.fadeout(8200)
            first.fadeout(8200)
            second.fadeout(8200)
            third.fadeout(8200)
            first.play(-1,-1,6500)
            send_bt('SET:50')
        elif lv == 2:
            intro.fadeout(8200)
            first.fadeout(8200)
            second.fadeout(8200)
            third.fadeout(8200)
            second.play(-1,-1,6500)
            send_bt('SET:160')
        elif lv == 3:
            if last != 3:
                intro.fadeout(8200)
                first.fadeout(8200)
                second.fadeout(8200)
                third.fadeout(8200)
                third.play(-1,-1,6500)
            n_sp = randint(200, 350)
            send_bt('SET:'+str(n_sp))
        last = lv

def send_bt(pump_com):
    print('sending'+pump_com)
    btSerial.write(pump_com.encode())
    #Wait "Done!"

send_bt('READY')
t = Timer(180, deactiv)
k = Timer(30, keep_on)
GPIO.add_event_detect(pir, GPIO.RISING, shot)
while True:
        state = GPIO.input(pir)
        if active and not state:
                if not waiting:
                        t = Timer(180, deactiv)
                        t.start()
                        waiting = True
                elif flag:
                        k = Timer(30, keep_on)
                        k.start()
                        flag = False