from machine import Pin, I2C
from time import sleep, sleep_us, ticks_us, ticks_diff
import ssd1306

# OLED Display settings
i2c = I2C(0, scl=Pin(22), sda=Pin(21))  # Connect OLED to SDA and SCL pins
oled_width = 128
oled_height = 64
oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)

# Ultrasonic sensor pins
trig = Pin(27, Pin.OUT)
echo = Pin(26, Pin.IN)

def measure_distance():
    # Send a 10us pulse to trigger the sensor
    trig.off()
    sleep_us(2)
    trig.on()
    sleep_us(10)
    trig.off()
    
    # Initialize start time
    start_time = ticks_us()
    
    # Measure the duration of the echo pulse
    while echo.value() == 0:
        signal_off = ticks_us()
        # Timeout if echo signal takes too long
        if ticks_diff(signal_off, start_time) > 100000:  # 100ms timeout
            return -1  # Return -1 to indicate timeout
    
    while echo.value() == 1:
        signal_on = ticks_us()
        if ticks_diff(signal_on, start_time) > 100000:  # 100ms timeout
            return -1  # Return -1 to indicate timeout
        
    # Calculate distance in cm (speed of sound is ~34300 cm/s)
    time_passed = signal_on - signal_off
    distance = (time_passed * 0.0343) / 2  # Divide by 2 for round-trip
    return distance

def display_distance(distance):
    oled.fill(0)  # Clear display
    oled.text("Water Level Monitor", 0, 0)
    oled.text("Distance:", 0, 20)
    
    if distance == -1:
        oled.text("Out of range", 0, 40)  # Display if there's a timeout
    else:
        oled.text(f"{distance:.2f} cm", 0, 40)
    
    oled.show()

def main():
    while True:
        # Measure distance
        distance = measure_distance()
        
        # Display distance on OLED
        display_distance(distance)
        
        # Print to console (for debugging)
        if distance == -1:
            print("Distance: Out of range")
        else:
            print(f"Distance: {distance:.2f} cm")
        
        # Delay before next measurement
        sleep(1)

# Run the main function
main()