Micropython如何让蜂鸣器声音播放的更久？

Question

我几乎完成了一个项目，但是当我给出一个很高的值时。我几乎听不到蜂鸣器的声音，因为它只播放了一秒钟。有谁知道怎么把蜂鸣器的声音放长一点？

import pycom
import machine
import time
from machine import Pin
import socket
from network import LoRa
import binascii
import array
from machine import PWM

############### Weightsensor ###############
def main():
    while True:
        adc = machine.ADC()             # create an ADC object
        apin = adc.channel(pin='P16')   # create an analog pin on P16
        val = apin()                    # read an analog value

        if val < 20:
            print(val)
            print("Weight is good")
            binaryString = bin(val)
            print(binaryString)
            time.sleep(5)
        if val > 20:
            print(val)
            print("Weight is to high")
            binaryString = bin(val)
            print(binaryString)
            # 50% duty cycle at 38kHz.
            pwm = PWM(3, frequency=78000)  # use PWM timer 0, with a frequency of 5KHz
            # create pwm channel on pin P12 with a duty cycle of 50%
            pwm_c = pwm.channel(0, pin='P20', duty_cycle=1.0)
            pwm_c.duty_cycle(0.3) # change the duty cycle to 30%
            time.sleep(5)


if __name__ == "__main__":
    main()

蜂鸣器在第二个“if”语句中播放。

有人可以帮帮我吗？

亲切的问候

Answer 1

我在您的代码中发现了多个问题：为什么您在 while 循环中一次又一次地重新定义 adc 和 apin？将它移到 while True

之前

Duty 在你的 PWN 中不应该影响你的蜂鸣器的音高，所以我的建议是省略所有的职责设置，或者至少让它像 250（试验一下）

蜂鸣器的音调是您 PWM 声明中的 frequency 值。您可以稍后在某处使用 pwm.frequency(hertz) 更改它。或者通过手动输入命令在控制台中找到最佳工作设置。

会响多久根据time.sleep()

在我看来代码应该是这样的（没有在船上测试过）：

import pycom
import machine
import time
from machine import Pin
import socket
from network import LoRa
import binascii
import array
from machine import PWM

############### Weightsensor ###############
def main():
    adc = machine.ADC()             # create an ADC object
    apin = adc.channel(pin='P16')   # create an analog pin on P16
    # 50% duty cycle at 38kHz.
    pwm = PWM(3, frequency=78000)  # use PWM timer 0, with a frequency of 5KHz
    # create pwm channel on pin P12 with a duty cycle of 50%
    pwm_c = pwm.channel(0, pin='P20')
    
    while True:

        val = apin()                    # read an analog value

        if val < 20:
            print(val)
            print("Weight is good")
            binaryString = bin(val)
            print(binaryString)
            time.sleep(5)
        if val > 20:
            print(val)
            print("Weight is to high")
            binaryString = bin(val)
            print(binaryString)
            
            pwm_c.freq(500)
            time.sleep(5)
            pwm_c.freq(0)


if __name__ == "__main__":
    main()

Micropython如何让蜂鸣器声音播放的更久？

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