今日目標
在完成了前三天的智慧倒車雷達、智慧溫室與節能路燈後，今天我們要實作第四個極具實用性與趣味性的物聯網綜合應用——防盜密碼門禁系統。

今天我們將結合Push Button實體按鈕、SSD1306 OLED螢幕，以及蜂鳴器。透過3個實體按鈕輸入特定組合密碼在 OLED 上即時呈現星號(*)、輸入狀態、解鎖成功或密碼錯誤的動畫與聲光提示。

程式碼
import time
from machine import Pin, I2C, PWM
import ssd1306

i2c = I2C(0, scl=Pin(22), sda=Pin(21), freq=400000)
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

btn_a = Pin(4, Pin.IN, Pin.PULL_UP)
btn_b = Pin(5, Pin.IN, Pin.PULL_UP)
btn_c = Pin(18, Pin.IN, Pin.PULL_UP)

buzzer_pwm = PWM(Pin(19), freq=1000, duty=0)

PASSWORD = ['A', 'B', 'C']
input_buffer = []

def play_tone(freq, duration_ms):
buzzer_pwm.freq(freq)
buzzer_pwm.duty(512)
time.sleep_ms(duration_ms)
buzzer_pwm.duty(0)

def sound_key_click(): play_tone(1200, 40)
def sound_success():
play_tone(1047, 100)
time.sleep_ms(50)
play_tone(1318, 200)
def sound_denied():
play_tone(400, 300)

def draw_ui(status_text="ENTER CODE", stars=""):
oled.fill(0)
oled.text("=== DOOR LOCK ===", 0, 0)
oled.hline(0, 12, 128, 1)

oled.text(status_text, 10, 24)

oled.text(f"Key: {stars}", 20, 42)
oled.hline(0, 56, 128, 1)
oled.show()

print("=== 門禁防盜密碼鎖系統啟動 ===")
draw_ui()

last_press_time = 0

def check_button(pin, key_name):
global last_press_time
now = time.ticks_ms()
if pin.value() == 0 and time.ticks_diff(now, last_press_time) > 200:
last_press_time = now
sound_key_click()
return key_name
return None

while True:
key = check_button(btn_a, 'A') or check_button(btn_b, 'B') or check_button(btn_c, 'C')

if key:
    input_buffer.append(key)
    stars = "*" * len(input_buffer)
    draw_ui("INPUTTING...", stars)
    print(f"目前輸入: {input_buffer}")
    
    if len(input_buffer) == len(PASSWORD):
        time.sleep_ms(300)
        if input_buffer == PASSWORD:
            print("✅ 密碼正確，允許進入！")
            draw_ui("ACCESS GRANTED", "***")
            sound_success()
        else:
            print("❌ 密碼錯誤，拒絕進入！")
            draw_ui("ACCESS DENIED", "ERROR")
            sound_denied()
        
        time.sleep(2)
        input_buffer.clear()
        draw_ui()

time.sleep_ms(20)

心得
今天我們使用狀態機邏輯與組合按鍵，實作出了極具質感的密碼門禁卡鎖。透過聲光提示與視覺UI的整合，體驗到了完整的產品級互動設計。