# -----------------------------------------------------------
# Smart Vehicle Security Demo (Wokwi / Raspberry Pi Pico)
# Components & Pins
#   LED           GP15  (active-high)
#   Buzzer (+)    GP13  (PWM audio)
#   Push-button   GP28  (active-low, internal pull-up)
#   HC-SR04 Trig  GP3
#   HC-SR04 Echo  GP2


# led anode pico gp15
# led cathode 330ohm resistor then pico gnd.1

# Button	

# One leg on the left to pico GP28

# One leg on the right to pico GND.6

# HC-SR04 Trigger	pico GP3	
# HC-SR04 Echo	pico GP2	
# HC-SR04 VCC	pico VBUS
# HC-SR04 GND	pico GND.2

# Buzzer (+)	pico GP13	
# Buzzer (-)	pico GND.3

# -----------------------------------------------------------

from machine import Pin, PWM, time_pulse_us
import utime

# ---------- I/O SETUP ----------
LED_PIN       = 15
BUZZER_PIN    = 13
BUTTON_PIN    = 28
TRIG_PIN      = 3
ECHO_PIN      = 2

DIST_THRESHOLD_CM = 30        # Alarm when object is closer than this

led     = Pin(LED_PIN,  Pin.OUT)
button  = Pin(BUTTON_PIN, Pin.IN, Pin.PULL_UP)
trigger = Pin(TRIG_PIN,  Pin.OUT)
echo    = Pin(ECHO_PIN,  Pin.IN)
buzzer  = PWM(Pin(BUZZER_PIN))     # PWM for sound

armed = True                      # System starts armed

# ---------- BUZZER HELPERS ----------
def sound_buzzer(duration=0.25, freq=1000, duty=20000):
    """Play a single tone."""
    buzzer.freq(freq)
    buzzer.duty_u16(duty)         # 0–65535 (volume)
    utime.sleep(duration)
    buzzer.duty_u16(0)            # Off

# ---------- DISTANCE MEASUREMENT ----------
def measure_distance():
    """Return distance in cm using HC-SR04."""
    trigger.low()
    utime.sleep_us(2)
    trigger.high()
    utime.sleep_us(10)
    trigger.low()

    # Wait for echo and measure pulse
    duration = time_pulse_us(echo, 1, 30000)   # timeout 30 ms
    if duration < 0:                           # -1/-2 = timeout
        return 999
    return duration * 0.0343 / 2               # Speed of sound

# ---------- ALARM ----------
def alarm(reason):
    print("🚨  ALARM:", reason)
    for i in range(5):
        led.toggle()
        sound_buzzer(freq=1500 if i % 2 else 900)
    led.value(0)

# ---------- MAIN LOOP ----------
print("✅  System armed.")

last_button_state = 1
debounce_ms = 200
last_toggle_time = utime.ticks_ms()

while True:
    # --- Button: arm / disarm ---
    curr_state = button.value()
    now = utime.ticks_ms()
    if curr_state == 0 and last_button_state == 1 and utime.ticks_diff(now, last_toggle_time) > debounce_ms:
        armed = not armed
        state_txt = "🟢 Armed" if armed else "🔴 Disarmed"
        print(state_txt)
        sound_buzzer(duration=0.15, freq=600 if armed else 400)
        last_toggle_time = now
    last_button_state = curr_state

    # --- Distance check (only if armed) ---
    if armed:
        dist = measure_distance()
        if dist < DIST_THRESHOLD_CM:
            alarm(f"Object at {dist:.1f} cm")

    utime.sleep(0.4)