W1ThermSensor
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.
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
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R1 = 4k7 ...10k
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Raspi GPIO 4 Pin 7 ----------------------------- Data DS18B20
(BCM) (BOARD)
Raspi GND Pin 6 ----------------------------- GND DS18B20
Soft-pull-up
Alternatively to the hardware pull-up made by a physical resistor, or to the above mentioned software configuration dtoverlay=w1-gpio,pullup="y" in /boot/config.txt, the following soft pull-up can be used:
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setup(4, GPIO.IN, pull_up_down=GPIO.PUD_UP)When using this software pull-up, 1-Wire devices will be visible to the kernel only while the program pulls the GPIO pin up.
Hw device connection verification
Run the following command:
ls -l /sys/bus/w1/devicesYou should check the availability of one or more filenames starting with "28-".
Filenames starting with "00-" possibly mean that the pull-up resistor is missing.
1-Wire devices can be plugged in dynamically and are visible to the kernel driver just after their hw connection.
To test reading the temperature, issue the following command:
for i in /sys/bus/w1/devices/28-*; do cat $i/w1_slave; doneInstallation
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-w1thermsensorNote: 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_type=Sensor.DS18B20, sensor_id="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_type=Sensor.DS18B20, sensor_id="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_type=Sensor.DS18B20, sensor_id="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.pyEvery 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!
This project is published under MIT.
A Timo Furrer project.
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