# Smart Parking System — separate TRIGs & ECHOs (pins match your Wokwi JSON)
# Displays only "Free" / "Full" on I2C 16x2 LCD. Threshold = 100 cm for all sensors.

from machine import Pin, I2C, time_pulse_us
import utime

# -------- LCD driver (self-contained) --------
class I2cLcd:
    def __init__(self, i2c, addr, rows=2, cols=16):
        self.i2c = i2c
        self.addr = addr
        self.rows = rows
        self.cols = cols
        self._init_lcd()

    def _write_byte(self, b):
        self.i2c.writeto(self.addr, bytes([b]))

    def _pulse(self, data):
        # EN high then low, keep backlight bit on (0x08 or 0x04 combos vary)
        self._write_byte(data | 0x0C)
        utime.sleep_us(150)
        self._write_byte(data & ~0x04)
        utime.sleep_us(150)

    def _send(self, value, mode=0):
        hi = value & 0xF0
        lo = (value << 4) & 0xF0
        self._pulse(hi | mode)
        self._pulse(lo | mode)

    def _init_lcd(self):
        utime.sleep_ms(50)
        self._pulse(0x30)
        utime.sleep_ms(5)
        self._pulse(0x30)
        utime.sleep_us(200)
        self._pulse(0x30)
        self._pulse(0x20)     # 4-bit mode
        self._send(0x28)      # function set
        self._send(0x08)      # display off
        self._send(0x01)      # clear
        utime.sleep_ms(2)
        self._send(0x06)      # entry mode
        self._send(0x0C)      # display on (no cursor)

    def clear(self):
        self._send(0x01)
        utime.sleep_ms(2)

    def move_to(self, col, row):
        offsets = (0x00, 0x40, 0x14, 0x54)
        if row >= self.rows:
            row = self.rows - 1
        self._send(0x80 | (col + offsets[row]))

    def putstr(self, text):
        for ch in text:
            self._send(ord(ch), 0x01)

# -------- Hardware (match your Wokwi JSON) --------
# I2C LCD pins: SDA -> GP0, SCL -> GP1
i2c = I2C(0, sda=Pin(0), scl=Pin(1), freq=400000)
lcd = I2cLcd(i2c, 0x27, 2, 16)   # if your I2C address is 0x3F, change 0x27 -> 0x3F

# Separate TRIG pins (one per sensor)
TRIG_PINS = [13, 17, 15]   # ultrasonic1.TRIG -> GP13, ultrasonic2.TRIG -> GP17, ultrasonic3.TRIG -> GP15
ECHO_PINS = [12, 16, 14]   # ultrasonic1.ECHO -> GP12, ultrasonic2.ECHO -> GP16, ultrasonic3.ECHO -> GP14

TRIGS = [Pin(p, Pin.OUT) for p in TRIG_PINS]
ECHOS = [Pin(p, Pin.IN) for p in ECHO_PINS]

# Threshold for "Full" (cm) for all sensors
THRESH_CM = 100.0

# small pause between sensor reads to reduce cross-talk
SENSOR_DELAY_MS = 80

# -------- Measurement helper (separate TRIG) --------
def measure_single(trig_pin, echo_pin, timeout_us=35000):
    # ensure trig low then send a 10us pulse on that trig pin
    trig_pin.low()
    utime.sleep_us(2)
    trig_pin.high()
    utime.sleep_us(10)
    trig_pin.low()
    # measure echo pulse width (returns <=0 on timeout or error)
    try:
        dur = time_pulse_us(echo_pin, 1, timeout_us)
    except Exception:
        return None
    if dur <= 0:
        return None
    return (dur * 0.0343) / 2  # cm

# -------- Display helper (only "Free"/"Full") --------
def update_lcd(statuses):
    # statuses: list of 3 entries ("Free" or "Full")
    line0 = f"1:{statuses[0]} 2:{statuses[1]}"
    if len(line0) > 16:
        line0 = line0[:16]
    line1 = f"3:{statuses[2]}"
    if len(line1) > 16:
        line1 = line1[:16]
    lcd.clear()
    lcd.move_to(0,0)
    lcd.putstr(line0)
    lcd.move_to(0,1)
    lcd.putstr(line1)

# -------- Main loop --------
try:
    while True:
        statuses = []
        # measure each sensor using its own TRIG/ECHO
        for trig_pin, echo_pin in zip(TRIGS, ECHOS):
            d = measure_single(trig_pin, echo_pin)
            if d is None:
                state = "Free"   # safe default if no echo
            else:
                state = "Full" if d < THRESH_CM else "Free"
            statuses.append(state)
            utime.sleep_ms(SENSOR_DELAY_MS)
        # update LCD (only Free/Full)
        update_lcd(statuses)
        utime.sleep(1.0)

except KeyboardInterrupt:
    lcd.clear()
    lcd.putstr("Stopped")