# https://wokwi.com/projects/474155768301636609
from machine import Pin, PWM, ADC
import dht
import time
import math

# -----------------------------
# Pins
# -----------------------------

DHT_PIN = 40
SERVO_PIN = 45
THERMISTOR_PIN = 4
BUTTON_PIN = 5

# -----------------------------
# Humidity range
# -----------------------------

MIN_HUMIDITY = 0
MAX_HUMIDITY = 100

# -----------------------------
# Thermistor beta coefficient
# -----------------------------

BETA = 3950

# -----------------------------
# Program running flag
# -----------------------------

running = True

# -----------------------------
# Component setup
# -----------------------------

# DHT22 sensor
sensor = dht.DHT22(
    Pin(DHT_PIN)
)

# Servo
servo = PWM(
    Pin(SERVO_PIN),
    freq=50
)

# Thermistor analog input
thermistor = ADC(
    Pin(THERMISTOR_PIN)
)

thermistor.atten(ADC.ATTN_11DB)

# Stop button
# GPIO5 is normally HIGH because of the internal pull-up.
# Pressing the button connects GPIO5 to GND.
button = Pin(
    BUTTON_PIN,
    Pin.IN,
    Pin.PULL_UP
)


# -----------------------------
# Interrupt function
# -----------------------------

def stop_program(pin):
    global running

    # Interrupt changes the running flag
    running = False


# Trigger interrupt when button is pressed
button.irq(
    trigger=Pin.IRQ_FALLING,
    handler=stop_program
)


# -----------------------------
# Servo function
# -----------------------------

def servo_angle(angle):

    # Servo pulse range:
    # 500–2500 microseconds
    min_us = 500
    max_us = 2500

    pulse_us = (
        min_us
        + (angle / 180)
        * (max_us - min_us)
    )

    # Convert pulse width into
    # a 16-bit PWM duty value
    duty = int(
        (pulse_us / 20000)
        * 65535
    )

    servo.duty_u16(duty)


# -----------------------------
# Humidity to servo angle
# -----------------------------

def humidity_to_angle(humidity):

    # Keep humidity between
    # 0% and 100%
    if humidity < MIN_HUMIDITY:
        humidity = MIN_HUMIDITY

    if humidity > MAX_HUMIDITY:
        humidity = MAX_HUMIDITY

    # Convert 0–100% humidity
    # into 0–180 degrees
    angle = (
        (humidity - MIN_HUMIDITY)
        * 180
        / (MAX_HUMIDITY - MIN_HUMIDITY)
    )

    return angle


# -----------------------------
# Thermistor function
# -----------------------------

def read_thermistor():

    # Read analog thermistor value
    analog_value = thermistor.read_u16()

    # Prevent division by zero
    if (
        analog_value <= 0
        or analog_value >= 65535
    ):
        return None

    # Convert analog reading
    # into degrees Celsius
    temperature = (
        1
        / (
            math.log(
                1 / (
                    65535 / analog_value - 1
                )
            ) / BETA
            + 1 / 298.15
        )
        - 273.15
    )

    return temperature


# -----------------------------
# Main program
# -----------------------------

while running:

    # Read the DHT22
    sensor.measure()

    dht_temperature = sensor.temperature()
    humidity = sensor.humidity()

    # Read the thermistor
    thermistor_temperature = read_thermistor()

    # Calculate servo position
    # from humidity
    angle = humidity_to_angle(humidity)

    # Move the servo
    servo_angle(angle)

    # Display DHT readings
    print(
        "DHT Temperature:",
        dht_temperature,
        "C"
    )

    print(
        "Humidity:",
        humidity,
        "%"
    )

    # Display thermistor reading
    if thermistor_temperature is not None:

        print(
            "Thermistor Temperature:",
            round(
                thermistor_temperature,
                1
            ),
            "C"
        )

    else:

        print(
            "Thermistor reading error"
        )

    # Display servo position
    print(
        "Servo Angle:",
        round(angle),
        "degrees"
    )

    print()

    time.sleep(2)


# -----------------------------
# Program stopped
# -----------------------------

servo.deinit()

print(
    "Program stopped by button interrupt."
)