w1thermsensor

by timofurrer

timofurrer / w1thermsensor

A Python package and CLI tool to work with w1 temperature sensors like DS1822, DS18S20 & DS18B20 on ...

436 Stars 105 Forks Last release: about 3 years ago (v1.0.5) MIT License 289 Commits 26 Releases

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W1ThermSensor

Gitter

Get the temperature from your w1 therm sensor in a single line of code!
It's designed to be used with the Rasperry Pi hardware but also works on a Beagle Bone and others.


CI PyPI version codecov.io Code style: black

Raspberry Pi: this package is available in Raspbian as

python-w1thermsensor
and
python3-w1thermsensor
.

Python 2 drop: all w1thermsensor releases from 2.0 are Python 3.5+

Supported devices

The following w1 therm sensor devices are supported:

  • DS18S20
  • DS1822
  • DS18B20
  • DS28EA00
  • DS1825/MAX31850K

Setup

The following hardware is needed:

  • w1 therm compatible sensor (some of them can be bought here: Adafruit: DS18B20)
  • wires to connect the sensor to your board (you might need a breadboard, too)
  • a board like the Raspberry Pi or the Beagle Bone)

On the Raspberry Pi, you will need to add

dtoverlay=w1-gpio"
(for regular connection) or
dtoverlay=w1-gpio,pullup="y"
(for parasitic connection) to your /boot/config.txt. The default data pin is GPIO4 (RaspPi connector pin 7), but that can be changed from 4 to
x
with
dtoverlay=w1-gpio,gpiopin=x
.

After that, don't forget to reboot.

Hardware-connection

Raspi VCC (3V3) Pin 1 -----------------------------   VCC    DS18B20
                                               |
                                               |
                                               R1 = 4k7 ...10k
                                               |
                                               |
Raspi GPIO 4    Pin 7 -----------------------------   Data   DS18B20


Raspi GND Pin 6 ----------------------------- GND DS18B20

Installation

From PIP

This possibility is supported on all distributions:

pip install w1thermsensor

Note: maybe root privileges are required

Use the

async
extra to add support for asyncio and
AsyncW1ThermSensor
:
pip install w1thermsensor[async]

On Raspbian using
apt-get

If you are using the

w1thermsensor
module on a Rasperry Pi running Raspbian you can install it from the official repository:
sudo apt-get install python3-w1thermsensor

Note: For older versions of this package you might get the following error:

ImportError: No module named 'pkg_resources'
which indicates that you need to install
python-setuptools
or
python3-setuptools
respectively.

Manually build and install the debian package

debuild -us -uc
dpkg -i ../python3-w1thermsensor_*.deb

Usage as python package

The usage is very simple and the interface clean.. All examples are with the

DS18B20
sensor - It works the same way for the other supported devices.

Basic usage with one sensor (implicit)

from w1thermsensor import W1ThermSensor, Unit

sensor = W1ThermSensor() temperature_in_celsius = sensor.get_temperature() temperature_in_fahrenheit = sensor.get_temperature(Unit.DEGREES_F) temperature_in_all_units = sensor.get_temperatures([ Unit.DEGREES_C, Unit.DEGREES_F, Unit.KELVIN])

The need kernel modules will be automatically loaded in the constructor of the

W1ThermSensor
class.
If something went wrong an exception is raised.

The first found sensor will be taken

Basic usage with one sensor (explicit)

The DS18B20 sensor with the ID

00000588806a
will be taken.
from w1thermsensor import W1ThermSensor, Sensor

sensor = W1ThermSensor(Sensor.DS18B20, "00000588806a") temperature_in_celsius = sensor.get_temperature()

Multiple sensors

With the

get_available_sensors
class-method you can get the ids of all available sensors.
from w1thermsensor import W1ThermSensor

for sensor in W1ThermSensor.get_available_sensors(): print("Sensor %s has temperature %.2f" % (sensor.id, sensor.get_temperature()))

Only sensors of a specific therm sensor type:

from w1thermsensor import W1ThermSensor, Sensor

for sensor in W1ThermSensor.get_available_sensors([Sensor.DS18B20]): print("Sensor %s has temperature %.2f" % (sensor.id, sensor.get_temperature()))

Set sensor resolution

Some w1 therm sensors support changing the resolution for the temperature reads.

w1thermsensor
enables to do so with the
W1ThermSensor.set_resolution()
method:
sensor = W1ThermSensor(Sensor.DS18B20, "00000588806a")
sensor.set_resolution(9)

If the

persist
argument is set to
False
this value is "only" stored in the volatile SRAM, so it is reset when the sensor gets power-cycled.

If the

persist
argument is set to
True
the current set resolution is stored into the EEPROM. Since the EEPROM has a limited amount of writes (>50k), this command should be used wisely.
sensor = W1ThermSensor(Sensor.DS18B20, "00000588806a")
sensor.set_resolution(9, persist=True)

Note: this is supported since Linux Kernel 4.7
Note: this requires

root
privileges

Disable kernel module auto loading

Upon import of the

w1thermsensor
package the
w1-therm
and
w1-gpio
kernel modules get loaded automatically. This requires the python process to run as root. Sometimes that's not what you want, thus you can disable the auto loading and load the kernel module yourself prior to talk to your sensors with
w1thermsensor
.

You can disable the auto loading feature by setting the

W1THERMSENSOR_NO_KERNEL_MODULE
environment variable to
1
:
# set it globally for your shell so that sub-processes will inherit it.
export W1THERMSENSOR_NO_KERNEL_MODULE=1

set it just for your Python process

W1THERMSENSOR_NO_KERNEL_MODULE=1 python my_awesome_thermsensor_script.py

Every other values assigned to

W1THERMSENSOR_NO_KERNEL_MODULE
will case
w1thermsensor
to load the kernel modules.

Note: the examples above also apply for the CLI tool usage. See below.

Async Interface

The

w1thermsensor
package implements an async interface
AsyncW1ThermSensor
for asyncio.

The following methods are supported:

  • get_temperature()
  • get_temperatures()
  • get_resolution()

For example:

from w1thermsensor import AsyncW1ThermSensor, Unit

sensor = AsyncW1ThermSensor() temperature_in_celsius = await sensor.get_temperature() temperature_in_fahrenheit = await sensor.get_temperature(Unit.DEGREES_F) temperature_in_all_units = await sensor.get_temperatures([ Unit.DEGREES_C, Unit.DEGREES_F, Unit.KELVIN])

Usage as CLI tool

The w1thermsensor module can be used as CLI tool since version

0.3.0
.
Please note that the CLI tool will only get installed with the Raspbian Python 3 package (
sudo apt-get install python3-w1thermsensor
)

List sensors

List all available sensors:

$ w1thermsensor ls
$ w1thermsensor ls --json  # show results in JSON format

List only sensors of a specific type:

$ w1thermsensor ls --type DS1822
$ w1thermsensor ls --type DS1822 --type MAX31850K  # specify multiple sensor types
$ w1thermsensor ls --type DS1822 --json  # show results in JSON format

Show temperatures

Show temperature of all available sensors: (Same synopsis as

ls
)
$ w1thermsensor all --type DS1822
$ w1thermsensor all --type DS1822 --type MAX31850K  # specify multiple sensor types
$ w1thermsensor all --type DS1822 --json  # show results in JSON format

Show temperature of a single sensor:

$ w1thermsensor get 1  # 1 is the id obtained by the ls command
$ w1thermsensor get --hwid 00000588806a --type DS18B20
$ w1thermsensor get 1  # show results in JSON format

Show temperature of a single sensor in the given resolution

$ w1thermsensor get 1 --resolution 10
$ w1thermsensor get --hwid 00000588806a --type DS18B20 --resolution 11

Change temperature read resolution and write to EEPROM

# w1thermsensor resolution 10 1
# w1thermsensor resolution --hwid 00000588806a --type DS18B20 11

Note: this requires

root
privileges

Contribution

I'm happy about all types of contributions to this project! :beers:


This project is published under MIT.
A Timo Furrer project.
- :tada: -

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