### lab3-1 ###

>>> import os		# 匯入 os 模組 (os 模組提供了數十個與作業系統溝通的函式)
>>> os.listdir()	# listdir() 可查看裝置內的檔案



### lab3-2

from hcsr04 import HCSR04			# 匯入函式庫 HCSR04

sonar = HCSR04(trigger_pin = 14, echo_pin = 12)	# 建立超音波模組物件 
distance = sonar.distance_cm()			# 呼叫 sonar.distance_cm() 方法，讀取偵測到的障礙物距離
print(distance)					# 電腦螢幕上顯示


### lab3-3

from machine import Pin, I2C
from ssd1306 import SSD1306_I2C
from hcsr04 import HCSR04
import utime

oled = SSD1306_I2C(128, 64, I2C(scl=Pin(5), sda=Pin(4)))	# 建立 OLED 模組物件 
sonar = HCSR04(trigger_pin = 14, echo_pin = 12)

while True:
    
    distance = sonar.distance_cm()
    
    oled.fill(0)					# 清空 OLED 畫面
    oled.text("Distance:", 0, 0)
    oled.text(str(distance) + " cm", 0, 16)		# 和 OLED 上一行字，相隔一行
    oled.show()						# 顯示 OLED 畫面
    print("偵測距離: " + str(distance) + " 公分")	# 同步在電腦螢幕上顯示
    
    utime.sleep_ms(25)					# 暫停 25ms (毫秒)



### lab3-4

from machine import Pin, PWM
import utime

buzzer = PWM(Pin(15, Pin.OUT), freq = 0, duty = 512)	# 建立 PWM 模組物件
buzzer.freq(261)					# 頻率設為 261Hz --> 中音 C (Do)
utime.sleep_ms(1000)					# 讓聲音持續 1000ms
buzzer.deinit()						# 結束，關閉 PWM (完全關閉蜂鳴器)



### lab3-5

from machine import Pin, I2C, PWM
from ssd1306 import SSD1306_I2C
from hcsr04 import HCSR04
import utime

alarm_distance = 10			# 觸發警報距離

oled = SSD1306_I2C(128, 64, I2C(scl = Pin(5), sda = Pin(4)))	# 建立 OLED 模組物件 
sonar = HCSR04(trigger_pin = 14, echo_pin = 12)			# 建立超音波模組物件

buzzer = PWM(Pin(15, Pin.OUT), freq = 880, duty = 0)		# 建立 PWM 模組物件

while True:
    
    distance = sonar.distance_cm()
    
    oled.fill(0)
    oled.text("Distance:", 0, 0)
    oled.text(str(distance) + " cm", 0, 16)
    
    if 2 <= distance <= alarm_distance:
        buzzer.duty(512)
        oled.text("!!! ALARM !!!", 0, 40)	# 在 OLED 顯示警報訊息
        print("!!! 觸發警報 !!!")
    else:
        buzzer.duty(0)
        print("無警報")
    
    oled.show()
    
    utime.sleep_ms(25)



### lab3-6

from machine import Pin, I2C, PWM
from ssd1306 import SSD1306_I2C
from hcsr04 import HCSR04
import utime

oled = SSD1306_I2C(128, 64, I2C(scl=Pin(5), sda=Pin(4)))
sonar = HCSR04(trigger_pin = 14, echo_pin = 12)

buzzer = PWM(Pin(15, Pin.OUT), freq = 784, duty = 0)

sound_delay = 500
buzzer_time = utime.ticks_ms()

while True:
    
    distance = sonar.distance_cm()
    oled.fill(0)
    oled.text("Distance:", 0, 0)
    oled.text(str(distance) + " cm", 0, 16)
    oled.show()
    print("偵測距離: " + str(distance) + " 公分")
    
    if 2 <= distance <= 50:
        buzzer.duty(512)
        utime.sleep_ms(10)
        buzzer.duty(0)
        sound_delay = int(distance) * 10 - 10
    else:
        sound_delay = 500
    
    utime.sleep_ms(sound_delay)



### lab3-7

from machine import Pin, I2C, PWM
from ssd1306 import SSD1306_I2C
from hcsr04 import HCSR04
import utime

note_min = 220	# 最小頻率 (Hz)
note_max = 880	# 最大頻率 (Hz)
dist_min = 40	# 測距最小距離 (公厘)
dist_max = dist_min + (note_max - note_min)	# 測距最大距離 (公厘)

oled = SSD1306_I2C(128, 64, I2C(scl = Pin(5), sda = Pin(4)))
sonar = HCSR04(trigger_pin = 14, echo_pin = 12)
buzzer = PWM(Pin(15, Pin.OUT), freq = 0, duty = 0)

while True:
    
    distance = sonar.distance_mm()
    
    if dist_min <= distance <= dist_max:
        key = note_min + (distance - dist_min)
        buzzer.freq(key)
        buzzer.duty(512)
    else:
        key = 0
        buzzer.duty(0)
        
    oled.fill(0)
    oled.text("Dist: " + str(distance) + " mm", 0, 0)
    oled.text("Note: " + str(key) + " Hz", 0, 16)
    oled.show()
    print("偵測距離: " + str(distance) + " 公厘, 播放頻率: " + str(key) + " 赫茲")

    utime.sleep_ms(10)