# MicroPython Program for Raspberry Pi Pico
# Project: Water Quality Monitoring & Auto Filtration System

from machine import Pin, ADC, I2C
from time import sleep
from ssd1306 import SSD1306_I2C
import hcsr04

# --- OLED Setup (SSD1306) ---
i2c = I2C(0, scl=Pin(5), sda=Pin(4))  # GP5 = SCL, GP4 = SDA
oled = SSD1306_I2C(128, 64, i2c)

# --- Potentiometers as Analog Inputs ---
ph_sensor = ADC(Pin(26))  # ADC0
tds_sensor = ADC(Pin(27))  # ADC1

# --- Ultrasonic Sensor Setup ---
trig = Pin(2, Pin.OUT)
echo = Pin(3, Pin.IN)

# --- LED Output ---
led = Pin(15, Pin.OUT)

# --- Function: Read Ultrasonic ---
def read_distance():
    trig.low()
    sleep(0.002)
    trig.high()
    sleep(0.01)
    trig.low()

    while echo.value() == 0:
        start = time.ticks_us()
    while echo.value() == 1:
        end = time.ticks_us()

    duration = time.ticks_diff(end, start)
    distance_cm = (duration / 2) / 29.1
    return distance_cm

# --- Main Loop ---
while True:
    # Read analog values (0 - 65535, scaled to 0 - 100 for simplicity)
    ph_val = ph_sensor.read_u16() * 100 / 65535
    tds_val = tds_sensor.read_u16() * 100 / 65535

    # Read ultrasonic sensor
    try:
        level_cm = read_distance()
    except:
        level_cm = 0  # fallback if sensor reading fails

    # Display on OLED
    oled.fill(0)
    oled.text("pH : {:.1f}".format(ph_val), 0, 0)
    oled.text("TDS: {:.1f}".format(tds_val), 0, 10)
    oled.text("Level: {:.1f}cm".format(level_cm), 0, 20)
    oled.show()

    # Actuator logic: turn on LED if pH or TDS out of bounds
    if ph_val < 20 or ph_val > 80 or tds_val > 70:
        led.value(1)
    else:
        led.value(0)

    sleep(1)