from machine import Pin, ADC, Timer
import math


BETA = 3950  
R1 = 10000
# This defines the top voltage expected (in the case of the pico 3.3v)  
V_REF = 3.3

# Configure a pin for LED control
LED = Pin(0, Pin.OUT)
adc = ADC(Pin(26))

# This function will be called by 'temp_timer' to check 
# The current voltage on the pin, then math magic will 
# convert this into the temp in celsius
# Note:
def get_temp():

    # Read the current voltage from the pin
    analog_value = adc.read_u16()
    voltage = (analog_value / 65535) * V_REF
    resistance = R1 / ((V_REF / voltage) - 1)
    kelvin = 1 / (1 / 298.15 + 1 / BETA * math.log(resistance / 10000))
    celsius = kelvin - 273.15

    return celsius


def check_temp(temp_timer):

    temperature = get_temp()
    print(f"Temperature: {temperature:.2f} ℃")

    # Test if temp is over 65 Degrees Celcius, if so turn on alert
    if temperature >= 65.0  or temperature <= -2:
        LED.on()
    # If the temp is lower than 65 all is good 
    else:
        LED.off()


# This time works just like the LED flasher buy it is being used to trigger
# the function that checks if the switch is currently on or off
temp_timer = Timer(mode=Timer.PERIODIC, period=1000, callback=check_temp)