"""HC-SR04:

VCC → 3.3V (Pin 39)
GND → GND (Pin 38)
Trigger → GP10 (Pin 14)
Echo → GP11 (Pin 15)


Lautsprecher/Piezo:

Ein Pin an GP12 (Pin 16), der andere Pin an GND (über einen Widerstand, falls nötig).


"""

from machine import Pin, PWM
import time
import math

# Pins für den HC-SR04
trigger = Pin(10, Pin.OUT)
echo = Pin(11, Pin.IN)

# Pin für den Lautsprecher (PWM)
buzzer = PWM(Pin(12))

# Frequenzen der Oktave (C bis C)
frequencies = [
    261.63,  # C4
    277.18,  # C#4
    293.66,  # D4
    311.13,  # D#4
    329.63,  # E4
    349.23,  # F4
    369.99,  # F#4
    392.00,  # G4
    415.30,  # G#4
    440.00,  # A4
    466.16,  # A#4
    493.88,  # B4
    523.25   # C5 (hohes C)
]

def get_distance():
    # Trigger-Impuls für 10 Mikrosekunden
    trigger.low()
    time.usleep(2)
    trigger.high()
    time.usleep(10)
    trigger.low()

    # Echo-Impuls messen
    while echo.value() == 0:
        pulse_start = time.ticks_us()
    while echo.value() == 1:
        pulse_end = time.ticks_us()

    # Entfernung in cm berechnen
    pulse_duration = time.ticks_diff(pulse_end, pulse_start)
    distance = (pulse_duration * 0.0343) / 2
    return min(max(distance, 0), 100)  # Begrenze auf 0-100 cm

def play_tone(frequency, duration=100):
    if frequency > 0:
        buzzer.freq(int(frequency))
        buzzer.duty_u16(32767)  # 50% Duty Cycle
        time.sleep_ms(duration)
        buzzer.duty_u16(0)  # Ton stoppen

# Hauptprogramm
try:
    while True:
        distance = get_distance()
        print(f"Entfernung: {distance:.1f} cm")

        # Berechne den Index für die Frequenz (0-12)
        index = int((1 - (distance / 100)) * 12)
        index = max(0, min(index, 12))  # Begrenze auf 0-12
        frequency = frequencies[index]

        # Spiele den Ton
        play_tone(frequency, 200)
        time.sleep(0.1)

except KeyboardInterrupt:
    buzzer.duty_u16(0)  # Ton stoppen