python - 如何通过 BeagleBone 上的 GPIO 引脚生成声音信号

Question

我正在寻找有关如何在 BeagleBone 上生成合成声音信号的指针/提示，类似于观察 Arduinos 上的tone() 函数。最终，我想在 GPIO 引脚上连接一个压电或扬声器，并从中听到声波。任何指针？

Answer 1

这就是我设法使用 Python 和PyBBIO在 Beaglebone 上解决这个问题的方法：

#!/usr/bin/python
# Circuit:
# * A Piezo is connected to pin 12 on header P8.        - GPIO1_12
# * A LED is connected to pin 14 on header P8.          - GPIO0_26
# * A button is connected to pin 45 on header P8.       - GPIO2_6
#   Use a pull-down resistor (around 10K ohms) between pin 45 and ground. 
#       3.3v for the other side of the button can be taken from pins 3 or 4 
#       on header P9. Warning: Do not allow 5V to go into the GPIO pins.
# * GND - pin 1 or 2, header P9.

def setup(): # this function will run once, on startup
    pinMode(PIEZO, OUTPUT) # set up pin 12 on header P8 as an output - Piezo
    pinMode(LED, OUTPUT) # set up pin 14 on header P8 as an output - LED
    pinMode(BUTTON, INPUT) # set up pin 45 on header P8 as an input - Button

def loop(): # this function will run repeatedly, until user hits CTRL+C
    if (digitalRead(BUTTON) == HIGH): 
        # was the button pressed? (is 3.3v making it HIGH?) then do:
            buzz()
    delay(10) # don't "peg" the processor checking pin

def delay(j):  #need to overwrite delay() otherwise, it's too slow
    for k in range(1,j):
            pass

def buzz():    #this is what makes the piezo buzz - a series of pulses
               # the shorter the delay between HIGH and LOW, the higher the pitch
    limit = 500     # change this value as needed; 
                    # consider using a potentiometer to set the value
    for j in range(1, limit):
            digitalWrite(PIEZO, HIGH)
            delay(j)
            digitalWrite(PIEZO, LOW)
            delay(j)
            if j==limit/2:
                    digitalWrite(LED, HIGH)
    digitalWrite(LED, LOW) # turn it off

run(setup, loop)

Answer 2

AM3359 的 GPIO 引脚电压低，驱动强度不足以直接驱动任何类型的传感器。为此，您需要构建一个带有运算放大器、晶体管或 FET 的小电路。

完成此操作后，您只需设置一个定时器循环，以所需频率更改 GPIO 线的状态。

到目前为止，从该板获取音频的最快和最简单的方法是使用 USB 音频接口。

Answer 3

看看这个页面。从用户态（例如python），您可以通过写入正确的sysfs文件来将引脚设置为高或低/sys/class/gpio。