ds18x20 — DS18x20 temperature sensor driver

The ds18x20 module provides a driver for the Maxim/Dallas DS18B20, DS18S20 and DS1822 1-Wire digital temperature sensors. It is built on top of the onewire module and supports multiple sensors sharing a single bus.

Example:

import time
from machine import Pin
from onewire import OneWire
from ds18x20 import DS18X20

ds = DS18X20(OneWire(Pin(15)))
roms = ds.scan()

ds.convert_temp()
time.sleep_ms(750)
for rom in roms:
    print(rom, ds.read_temp(rom))

Classes

class ds18x20.DS18X20(onewire: OneWire)

Construct a DS18x20 driver bound to the given onewire.OneWire bus. Multiple DS18x20 sensors may share the same bus.

scan() → list[bytearray]

Search the underlying 1-Wire bus and return a list of ROM codes that correspond to DS18x20-family devices. Only ROMs whose family code is 0x10 (DS18S20), 0x22 (DS1822) or 0x28 (DS18B20) are returned; other 1-Wire devices on the same bus are filtered out.

convert_temp() → None

Issue a temperature conversion command to all DS18x20 sensors on the bus simultaneously (using SKIP ROM). After calling this method you must wait for the conversion to complete (up to 750 ms at the default 12-bit resolution) before calling read_temp().

read_scratch(rom: bytes | bytearray) → bytearray

Read the 9-byte scratchpad from the device addressed by rom and return it as a bytearray. The scratchpad CRC is verified; raises Exception with the message "CRC error" on a CRC mismatch.

Note

The returned buffer is the driver’s internal buffer and is overwritten by subsequent calls.

write_scratch(rom: bytes | bytearray, buf: bytes | bytearray) → None

Write 3 bytes to the scratchpad of the device addressed by rom. buf must contain the high alarm trigger (TH), low alarm trigger (TL) and configuration register values.

read_temp(rom: bytes | bytearray) → float

Read the most recently converted temperature from the device addressed by rom and return it in degrees Celsius as a float. Handles both DS18S20 (family code 0x10) and DS18B20 / DS1822 (family codes 0x28 / 0x22) encodings, including negative temperatures.

Call convert_temp() and wait for the conversion to finish before calling this method.