按键3松开时，蜂鸣器响5声，以上均不支持连续触发，按键2按下时，一位静态数码管显示5，按键1按下时，实现自左向右流水灯；

以下是Python代码实现：

import RPi.GPIO as GPIO
import time

# 设置GPIO模式为BCM编码方式
GPIO.setmode(GPIO.BCM)

# 定义按键和蜂鸣器的GPIO口
key1 = 18
key2 = 23
key3 = 24
buzzer = 25

# 定义数码管的GPIO口
# 按照a,b,c,d,e,f,g,dp的顺序排列
digit_pins = [4, 17, 27, 22, 5, 6, 13, 19]

# 定义数码管显示的数字
# 按照0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f的顺序排列
digit_num = [
    [1, 1, 1, 1, 1, 1, 0, 0],  # 0
    [0, 1, 1, 0, 0, 0, 0, 0],  # 1
    [1, 1, 0, 1, 1, 0, 1, 0],  # 2
    [1, 1, 1, 1, 0, 0, 1, 0],  # 3
    [0, 1, 1, 0, 0, 1, 1, 0],  # 4
    [1, 0, 1, 1, 0, 1, 1, 0],  # 5
    [1, 0, 1, 1, 1, 1, 1, 0],  # 6
    [1, 1, 1, 0, 0, 0, 0, 0],  # 7
    [1, 1, 1, 1, 1, 1, 1, 0],  # 8
    [1, 1, 1, 1, 0, 1, 1, 0],  # 9
    [1, 1, 1, 0, 1, 1, 1, 0],  # a
    [0, 0, 1, 1, 1, 1, 1, 0],  # b
    [1, 0, 0, 1, 1, 1, 0, 0],  # c
    [0, 1, 1, 1, 1, 0, 1, 0],  # d
    [1, 0, 0, 1, 1, 1, 1, 0],  # e
    [1, 0, 0, 0, 1, 1, 1, 0],  # f
]

# 初始化GPIO口
GPIO.setup(key1, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(key2, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(key3, GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.setup(buzzer, GPIO.OUT)
for pin in digit_pins:
    GPIO.setup(pin, GPIO.OUT)

# 定义按键和蜂鸣器的状态变量
key1_pressed = False
key2_pressed = False
key3_pressed = False
buzzer_on = False

# 定义数码管显示的数字变量
digit_index = 0

# 定义流水灯的状态变量
led_index = 0

# 定义流水灯的方向变量
led_direction = 1

# 循环执行
while True:
    # 检测按键1的状态
    if GPIO.input(key1) == GPIO.LOW:
        key1_pressed = True
    else:
        if key1_pressed:
            key1_pressed = False
            # 按键1按下时，实现自左向右流水灯
            GPIO.output(digit_pins[led_index], GPIO.LOW)
            led_index += led_direction
            if led_index == len(digit_pins):
                led_index = len(digit_pins) - 2
                led_direction = -1
            elif led_index == -1:
                led_index = 1
                led_direction = 1
            GPIO.output(digit_pins[led_index], GPIO.HIGH)

    # 检测按键2的状态
    if GPIO.input(key2) == GPIO.LOW:
        key2_pressed = True
    else:
        if key2_pressed:
            key2_pressed = False
            # 按键2按下时，一位静态数码管显示5
            for i in range(len(digit_pins)):
                GPIO.output(digit_pins[i], digit_num[5][i])

    # 检测按键3的状态
    if GPIO.input(key3) == GPIO.LOW:
        key3_pressed = True
    else:
        if key3_pressed:
            key3_pressed = False
            # 按键3松开时，蜂鸣器响5声
            for i in range(5):
                GPIO.output(buzzer, GPIO.HIGH)
                time.sleep(0.1)
                GPIO.output(buzzer, GPIO.LOW)
                time.sleep(0.1)

    # 数码管显示的数字循环加1
    digit_index += 1
    if digit_index == 16:
        digit_index = 0

    # 数码管显示的数字变化
    for i in range(len(digit_pins)):
        GPIO.output(digit_pins[i], digit_num[digit_index][i])

    # 延时一段时间
    time.sleep(0.1)

# 清理GPIO口
GPIO.cleanup()