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Thermometer (DS18B20)

Wiring​

You'll need:

  • A Pi Pico W-H
  • A DS18B20 thermometer probe
  • A 4.7kΩ resistor
note

You can substitute the 4.7kΩ resistor for most resistors of higher values, but they might not work.

tip

Source files for this diagram are available here

Wiring diagram

Code​

You don't need any external libraries - everything is preinstalled in MicroPython.

import machine, onewire, ds18x20

ds_sensor = ds18x20.DS18X20(
    onewire.OneWire(
        machine.Pin(22)
    )
)
roms = ds_sensor.scan()
if len(roms) == 0:
    print("No thermometer found!")

def get_temp(unit: str="F") -> float:
    """
    Gets the temperature from the thermometer.

    Parameters:
    - unit: The unit of temperature to get the temperature in. Can be "F", "C", or "tuple". "tuple" causes a return value of (tempC, tempF).
    """
    global roms, ds_sensor
    ds_sensor.convert_temp()
    if unit not in ["F", "C", "tuple"]:
        raise ValueError(f"Invalid unit: {unit}")
    tempC = ds_sensor.read_temp(rom)
    tempF = temp * (9/5) + 32
    if unit == "tuple":
        return tempC, tempF
    elif unit == "C":
        return tempC
    elif unit == "F":
        return tempF

# ----- Example usage -----
# print(get_temp())
# > 75.0

# print(get_temp("C"))
# > 23.88889

# print(get_temp(unit="C"))
# > 23.88889

# print(get_temp("tuple"))
# > (23.88889, 75.0)
# print(get_temp("tuple")[1])
# > 75.0

Further Reading​