from machine import Pin, ADC, PWM
import dht
import time
import math

# ==========================
# Pin Definitions
# ==========================
DHT_PIN = 4
THERM_PIN = 1
SERVO_PIN = 18
BUTTON_PIN = 15

# ==========================
# Devices
# ==========================
dht_sensor = dht.DHT22(Pin(DHT_PIN))

thermistor = ADC(Pin(THERM_PIN))
thermistor.atten(ADC.ATTN_11DB)

button = Pin(BUTTON_PIN, Pin.IN, Pin.PULL_UP)

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

# ==========================
# Servo Function
# ==========================
def set_servo_angle(angle):
    angle = max(0, min(180, angle))

    pulse_us = 500 + (angle / 180) * 2000
    duty = int((pulse_us / 20000) * 1023)

    servo.duty(duty)

# ==========================
# Thermistor Function
# 10k NTC, Beta = 3950
# ==========================
def thermistor_temp():

    adc = thermistor.read()

    if adc <= 0 or adc >= 4095:
        return 0

    # ADC to Voltage
    voltage = (adc / 4095) * 3.3

    # Voltage divider calculation
    R_FIXED = 10000
    resistance = R_FIXED * voltage / (3.3 - voltage)

    # Beta equation
    BETA = 3950
    R0 = 10000
    T0 = 298.15  # 25°C in Kelvin

    temp_k = 1 / (
        (1 / T0) +
        (math.log(resistance / R0) / BETA)
    )

    temp_c = temp_k - 273.15

    return temp_c

# ==========================
# Main Program
# ==========================
print("System Started")

while True:

    if button.value() == 0:
        print("Interrupt Triggered")
        print("Program Ended")
        set_servo_angle(0)
        break

    try:
        # Read DHT22
        dht_sensor.measure()
        dht_temp = dht_sensor.temperature()
        humidity = dht_sensor.humidity()

        # Read Thermistor
        therm_temp = thermistor_temp()

        # Calculate Average Temperature
        avg_temp = (dht_temp + therm_temp) / 2

        # Servo follows humidity
        servo_angle = int((humidity / 100) * 180)
        set_servo_angle(servo_angle)

        # Print values
        print("------------------------")
        print("DHT22 Temp      : {:.1f} C".format(dht_temp))
        print("Humidity        : {:.1f} %".format(humidity))
        print("Thermistor Temp : {:.1f} C".format(therm_temp))
        print("Average Temp    : {:.1f} C".format(avg_temp))
        print("Servo Angle     : {} deg".format(servo_angle))

    except Exception as e:
        print("Error:", e)

    time.sleep(2)

servo.deinit()