from machine import ADC, Pin
import time
import math

# Define the pin connected to the NTC thermistor
ntc_pin = Pin(26)

# Create ADC object
adc = ADC(0)  # Use ADC 0 (0-65535)

# Function to read temperature from NTC sensor
def read_temperature():
    # Read raw analog value from ADC
    adc_value = adc.read_u16()

    # Convert ADC value to voltage
    voltage = adc_value * 3.3 / 65535  # 3.3V reference voltage

    # Calculate resistance of NTC based on voltage divider
    resistor = 10000  # 10kOhm resistor
    ntc_resistance = resistor * (3.3 / voltage - 1)

    # Calculate temperature using Steinhart-Hart equation
    # NTC parameters: resistance at 25°C (R25), B coefficient, reference temperature (Tref)
    R25 = 10000  # Resistance of NTC at 25°C
    B_coefficient = 3950  # B coefficient of NTC
    Tref = 298.15  # Reference temperature in Kelvin (25°C)

    # Calculate temperature in Kelvin
    temperature_kelvin = 1 / (1 / Tref + 1 / B_coefficient * math.log(ntc_resistance / R25))

    # Convert temperature from Kelvin to Celsius
    temperature_celsius = temperature_kelvin - 273.15

    return temperature_celsius

# Main loop
while True:
    # Read temperature from NTC sensor
    temperature = read_temperature()

    # Print temperature
    print("Temperature: {:.2f} °C".format(temperature))

    # Wait for a short period
    time.sleep(1)