#https://klipit.in/dpj79004

from machine import ADC, Pin
import time
import math

MAX_U16 = 2**16-1
VREF = 3.3

R0 = 9.64 # kOhm

adc = ADC(Pin(26))

t0 = time.ticks_ms()

def voltage_to_resistance(V, VREF, R0):
    R = R0/(VREF/V-1)
    return R

def ntc_resistance_to_temperature(R):
    R25 = 10.000
    
    T0 = 273.15
        
    A1 = 0.003354016434680530000
    B1 = 0.000256985018020000000
    C1 = 0.000002620130670900000
    D1 = 0.00000006383090799800
    
    lnR = math.log(R/R25)
    
    invT = A1 + B1*lnR + C1*lnR**2 + D1*lnR**3
    
    return 1/invT-T0

BUFFER_SIZE = 20
buffer = [0 for x in range(BUFFER_SIZE)]

ix = 0
ix_ = 0

while True:
    val = adc.read_u16()/MAX_U16*100
    val_V = VREF*adc.read_u16()/MAX_U16
    val_R = voltage_to_resistance(val_V, VREF, R0)
    val_T = ntc_resistance_to_temperature(val_R)
    
    buffer[ix] = val_T
    
    ix = ix+1
    ix_ = ix_+1
    
    ix = divmod(ix, BUFFER_SIZE)[1]
    
    if ix_<BUFFER_SIZE:
        T_avg = sum(buffer)/ix_
    else:
        T_avg = sum(buffer)/BUFFER_SIZE
    
    #print(f'{T_avg:5.1f}',end='')
    #print('\b'*5,end='')
   
    print(T_avg)
    time.sleep(0.1)