import machine
import utime

# GPIO pins for 7-segment display segments (a-g)
segments = [
    machine.Pin(0, machine.Pin.OUT),  # Segment a
    machine.Pin(1, machine.Pin.OUT),  # Segment b
    machine.Pin(2, machine.Pin.OUT),  # Segment c
    machine.Pin(3, machine.Pin.OUT),  # Segment d
    machine.Pin(4, machine.Pin.OUT),  # Segment e
    machine.Pin(5, machine.Pin.OUT),  # Segment f
    machine.Pin(6, machine.Pin.OUT)   # Segment g
]

# Pin states for each digit to display numbers 0-9 (corrected for typical 7-segment display)
number_map = [
    [1, 1, 1, 1, 0, 1, 1],  # 9
    [1, 1, 1, 1, 1, 1, 1],  # 8
    [1, 1, 1, 0, 0, 0, 0],  # 7
     [1, 0, 1, 1, 1, 1, 1],  # 6
     [1, 0, 1, 1, 0, 1, 1],  # 5
     [0, 1, 1, 1, 0, 1, 1],  # 4
     [1, 1, 1, 1, 0, 0, 1],  # 3
      [1, 1, 0, 1, 1, 0, 1],  # 2
       [0, 1, 1, 0, 0, 0, 0],  # 1
    [1, 1, 1, 1, 1, 1, 0],  # 0
]

# Function to display a specific number on the 7-segment display
def display_number(number):
    if 0 <= number <= 9:  # Ensure the number is between 0 and 9
        segments_values = number_map[number]
        for i in range(len(segments)):
            segments[i].value(segments_values[i])

# HC-SR04 Sensor setup
SOUND_SPEED = 340  # Speed of sound in air (cm/s)
TRIG_PULSE_DURATION_US = 10  # Duration of the trigger pulse (10 µs)

trig_pin = machine.Pin(15, machine.Pin.OUT)  # GPIO 15 for Trig
echo_pin = machine.Pin(14, machine.Pin.IN)  # GPIO 14 for Echo

# Function to measure distance using HC-SR04
def measure_distance():
    # Prepare the signal
    trig_pin.value(0)
    utime.sleep_us(5)
    
    # Create a 10 µs pulse
    trig_pin.value(1)
    utime.sleep_us(TRIG_PULSE_DURATION_US)
    trig_pin.value(0)
    
    # Measure the duration of the echo pulse
    ultrasonic_duration = machine.time_pulse_us(echo_pin, 1, 30000)  # Timeout 30ms
    
    # Calculate the distance (in cm)
    distance_cm = SOUND_SPEED * ultrasonic_duration / 20000
    return distance_cm

# Main loop
current_display_value = 0  # Start with 0

while True:
    distance = measure_distance()
    print(f"Distance: {distance:.2f} cm")  # Print the distance to console

    # Calculate the number of steps based on the distance divided by 40
    steps = int(distance // 40)  # Every 40 cm increase or decrease the number by 1

    # Adjust the display value based on the distance
    display_value = max(0, min(9, steps))  # Ensure the value stays between 0 and 9

    # Display the current number on the 7-segment display
    display_number(display_value)

    # Wait a short time before the next measurement
    utime.sleep(0.2)  # Adjusted sleep time for gradual transitions