import machine
import ssd1306  # For the OLED display
import time

# Pin definitions
TRIG_PIN = machine.Pin(13, machine.Pin.OUT)
ECHO_PIN = machine.Pin(12, machine.Pin.IN)
RELAY_PIN = machine.Pin(27, machine.Pin.OUT)

# OLED display setup
i2c = machine.I2C(scl=machine.Pin(22), sda=machine.Pin(21))  # Adjust pins as needed
oled = ssd1306.SSD1306_I2C(128, 64, i2c)

# Function to measure distance
def measure_distance():
    TRIG_PIN.off()
    time.sleep_us(2)  # Short delay
    TRIG_PIN.on()
    time.sleep_us(10)  # Trigger pulse
    TRIG_PIN.off()

    # Wait for echo pin to go high (start of the pulse)
    while ECHO_PIN.value() == 0:
        pass
    pulse_start = time.ticks_us()  # Capture the start time

    # Wait for echo pin to go low (end of the pulse)
    while ECHO_PIN.value() == 1:
        pass
    pulse_end = time.ticks_us()  # Capture the end time

    # Calculate duration of the pulse
    duration = time.ticks_diff(pulse_end, pulse_start)  # Time in microseconds

    # Calculate distance (speed of sound in air is approximately 34300 cm/s)
    distance = (duration * 0.0343) / 2  # Convert duration to cm
    return distance

# Main loop
THRESHOLD_DISTANCE = 5  # Threshold in cm, the pump should stop when the water level reaches this distance
distance = 50  # Start with an initial distance (in cm)

while True:
    # Simulate the decreasing water level by reducing distance by 10 cm
    if distance > THRESHOLD_DISTANCE:
        distance -= 5
    
          # Decrease the distance by 10 cm every cycle
    else:
        distance = THRESHOLD_DISTANCE  # Stop the decrease once it reaches the threshold

    # Debug print to check measured distance
    print("Measured Distance:", distance)

    # Display distance on OLED
    oled.fill(0)  # Clear the display
    oled.text("Water Level:", 0, 0)
    oled.text(f"{distance:.2f} cm", 0, 10)

    # Control the relay based on distance
    if distance > THRESHOLD_DISTANCE:
        RELAY_PIN.on()  # Turn on the pump if the distance is greater than the threshold (water level is low)
        oled.text("Pump: ON", 0, 30)
    else:
        RELAY_PIN.off()  # Turn off the pump if the distance is less than or equal to the threshold (water level is high)
        oled.text("Pump: OFF", 0, 30)
        distance += 50

    # Show changes on OLED
    oled.show()
  
    time.sleep(1)  # Wait before the next reading