micropython-simple-thermistor

read NTC thermistor temperature wired in a potential divider

WILL NOT WORK WITH

• ESP8266 (limited 1 V max ADC)
• W600 (no ADC!)

WILL NOT IMPLEMENT

• High-side thermistor
• °F conversion

TODO

• some docs would be nice
• implement:
  • Beta calculation from known second temperature and resistance (T₁, R₁): β(T₀/T₁) = ln(R₁/R₀) / (1/T₁ - 1/T₀)
  • Steinhart-Hart three-term calculation
• platform testing:
  • rp2
  • EPS32
  • STM32/pyboard
  • SAMD
  • external ADC?
• thermistor type testing
  • MF52
  • Adafruit 10K Precision Epoxy Thermistor - 3950 NTC
  • 100 kΩ glass bead thermistor (aka 3d printer thermistor)
  • Vishay NTCLE100E3

Sample Code

# MicroPython, Raspberry Pi Pico
# pylint: disable=E0401
# -*- coding: utf-8 -*-

import machine
import time
from simple_thermistor import Thermistor


# setup for KY-013-alike thermistor on GPIO 26
t = Thermistor(
    adc=machine.ADC(
        26
    ),  # ADC object with read_u16() method returning 0–65535
    beta=3950,
    r0=10000,  # thermistor nominal resistance of 10 kΩ at 25 °C
    t0=Thermistor.fromC(25),  # everything is Kelvin internally
    resistor=10000,  # high side resistor of 10 kΩ
)
while True:
    print(
        "%6.1f °C / %.1f Ω"
        % (Thermistor.toC(t.temperature()), t.resistance())
    )
    time.sleep(5)