raspberry pi (6) 有源蜂鸣器，无源蜂鸣器

1. 有源蜂鸣器
   内置震荡源，通电时会发出声音。

#!/usr/bin/env python3
import RPi.GPIO as GPIO
import time

Buzzer = 11    # pin11

def setup(pin):
	global BuzzerPin
	BuzzerPin = pin
	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
	GPIO.setup(BuzzerPin, GPIO.OUT)
	GPIO.output(BuzzerPin, GPIO.HIGH)

def on():
	GPIO.output(BuzzerPin, GPIO.LOW)

def off():
	GPIO.output(BuzzerPin, GPIO.HIGH)

def beep(x):
	on()
	time.sleep(x)
	off()
	time.sleep(x)

def loop():
	while True:
		beep(1)

def destroy():
	GPIO.output(BuzzerPin, GPIO.HIGH)
	GPIO.cleanup()                     # Release resource

if __name__ == '__main__':     # Program start from here
	setup(Buzzer)
	try:
		loop()
	except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the child program destroy() will be  executed.
		destroy()

2. 无源蜂鸣器
内部没有振荡源，使用直流信号不会发出蜂鸣声，需要使用频率在2k到5k间的方波驱动它。

《九九艳阳天》简谱
https://www.zhaogepu.com/jianpu/3422.html

#!/usr/bin/env python3

import RPi.GPIO as GPIO
import time

Buzzer = 11

CL = [0, 131, 147, 165, 175, 196, 211, 248]		# Frequency of Low C notes
CM = [0, 262, 294, 330, 350, 393, 441, 495]		# Frequency of Middle C notes
CH = [0, 525, 589, 661, 700, 786, 882, 990]		# Frequency of High C notes

song_3 = [ CM[5], CM[5], CM[6], CH[1], CM[6], CM[5], CM[3], CM[2], CM[5], CM[6], CH[1], CH[1], CM[6], CH[1], CH[2], CH[3], CH[2],
           CH[1], CH[2], CH[3], CH[5], CH[3], CH[2], CH[3], CH[1], CH[3], CH[2], CH[2], CH[1], CM[6], CM[5], CM[6], CM[5], CM[3],
           CM[2], CM[3], CM[2], CM[3], CM[5], CM[5], CM[6], CM[5], CM[2], CH[3], CH[1], CH[2], CM[6], CM[5], CM[3], CM[5], CM[3], CM[2], CM[3],
           CH[3], CH[3], CH[2], CH[1], CH[2], CH[3], CH[5], CH[2], CH[2], CH[3], CM[7], CM[6], CM[7], CM[6], CM[7], CM[5], CM[6], CH[1],
]

beat_3 = [
            2, 4, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 4,
            1, 1, 4, 1, 1, 1, 1, 4, 2, 2, 1, 1, 1, 1, 2, 4, 2,
            1, 1, 4, 2, 2, 4, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4,
            2, 1, 1, 1, 1, 1, 1, 2, 4, 1, 1, 1, 1, 1, 1, 2, 1, 8,
]

def setup():
	GPIO.setmode(GPIO.BOARD)		# Numbers GPIOs by physical location
	GPIO.setup(Buzzer, GPIO.OUT)	# Set pins' mode is output
	global Buzz						# Assign a global variable to replace GPIO.PWM 
	Buzz = GPIO.PWM(Buzzer, 440)	# 440 is initial frequency.
	Buzz.start(50)					# Start Buzzer pin with 50% duty ration

def loop():
	while True:
		print('\n    Playing song 3...')
		for i in range(1, len(song_3)):		# Play song 1
			Buzz.ChangeFrequency(song_3[i])	# Change the frequency along the song note
			time.sleep(beat_3[i] * 0.2)		# delay a note for beat * 0.2s

def destory():
	Buzz.stop()					# Stop the buzzer
	GPIO.output(Buzzer, 1)		# Set Buzzer pin to High
	GPIO.cleanup()				# Release resource

if __name__ == '__main__':		# Program start from here
	setup()
	try:
		loop()
	except KeyboardInterrupt:  	# When 'Ctrl+C' is pressed, the child program destroy() will be  executed.
		destory()