Connect multiple DS18B20 temperature sensors to a Raspberry Pi

Supplies needed:

  • DS18B20 temperature sensors
  • 4.7K resistor
  • A raspberry Pi offcourse
  • Installed with Raspbian and domoticz

Step 1: Connect the DS18B20 sensors to the Raspberry Pi

DS18B20Raspberry
REDPIN1 – 3.3V
YELLOW (WHITE)PIN7 (GPIO4)
BLACKPIN6 GRND

In the connection diagram below you see a circuit to connect three DS18B20 temperature sensors to a raspberry Pi, with the help of a breadboard.

If you want to connect a single DS18B20 temperature sensor, just remove 2 sensors from this circuit.

Step 2: Active a One Wire GPIO

By default the W1 protocol is disabled on a raspberry Pi. We can active this protocol by adding this line in the boot/config.

sudo vim /boot/config.txt

Add this line at the bottom of the file

dtoverlay=w1-gpio

#If you wanted to active the protocol an a custom pin (default is BCM4) use the code bellow. (for this example i use GPIO4
dtoverlay=w1-gpio,gpiopin=4

Reboot the raspberry Pi

sudo reboot

Step 3: Validate the DS18B20

Goto the folder where the w1 devices are located.

cd /sys/bus/w1/devices

#show the content of the folder
ls

Here you can see all the W1 devices. You can recognize a temperature sensor if it starts with 28. If you see a folder, goto the folder and read the sensor.

cd 28-xxxxxx
cat w1_slave

Now you should see something like this

Here the temperature is t=17687 (17.687 Celcius)

Step 4: Add the sensors to Domoticz

Now we can add the sensors to Domoticz. My higher goal is to automate a swimmingpool, so i need to add 3 sensors to domoticz.

In Domoticz goto

  1. Setup -> Hardware
  2. Add new hardware of type ‘1-Wire (System)
  3. For the DS18B20 we don’t use OWFS, so remote the ‘/mnt/wire/’ for the OWFS path field.
  4. Set the Sensor Poll Period to the value you want. I think once every 30sec is enough, so my value is 30000.
  5. Click on Add

If you goto Setup -> Devices you see now the connected temperature sensors. Give each sensor a name and active it in Domoticz.
If you goto the Temperature page you see all the sensors.

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