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Setting up the 1-wire interface for the RPi

Last updated

Nov 12, 2020
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- BME680 sensor setup using I2C
- Digital and analog signals

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Setting up the 1-wire interface using the DS18B20 Temperature Sensor.

First enable the 1-wire interface on the RPi.

The following link demonstrates three methods for enabling 1-Wire Interface on the Raspberry Pi.

https://www.raspberrypi-spy.co.uk/2018/02/enable-1-wire-interface-raspberry-pi/

Methods, 1 and 2 use ‘sudo raspi-config’ or the GUI to enable 1-Wire.

Using ‘sudo raspi-config’ or the GUI will setup the default Pin 7 (GPIO4) port.

Method 3 shows how to enable 1-Wire Interface by editing the /boot/config.txt.

Understanding the manual editing of the /boot/config.txt file is essential for connecting two 1-Wire devices.

In the following example two gpiopins are initialized for 1-Wire interface, gpiopin=4 and gpiopin=5.

pi@aquaponics$ tail -6 /boot/config.txt

[all]
#dtoverlay=vc4-fkms-v3d
dtoverlay=w1-gpio,gpiopin=4
dtoverlay=w1-gpio,gpiopin=5

If only one 1-Wire Interface is needed the following methods can be used;

Activate the 1-wire interface as shown here;

Enabling the 1-wire interface can also be accomplished remotely using ssh on the terminal.

sudo raspi-config

Activate the 1-wire interface as shown here;

After enabling the 1-Wire Interface by any method a reboot is required.

Attached the DS18B20 to the breadboard as shown in the following link;

https://learn.adafruit.com/adafruits-raspberry-pi-lesson-11-ds18b20-temperature-sensing?view=all

A 4.7K resistor is required, see wiring in the link above.

Attached 1-Wire devices can be listed with the following command;

ls /sys/bus/w1/devices/

For this example two DS18B20 sensors are shown.

pi@aquaponics$ ls /sys/bus/w1/devices/
28-3c01b5569d9e  28-3c01b556bce8  w1_bus_master1  w1_bus_master2

The IDs for the two are 28-3c01b5569d9e and 28-3c01b556bce8.

These IDs are required for collecting data from the sensors.

The python script used in this example was found here;

https://www.raspberrypi-spy.co.uk/2013/03/raspberry-pi-1-wire-digital-thermometer-sensor/

The wget command can be used to download the python script.

wget https://bitbucket.org/MattHawkinsUK/rpispy-misc/raw/master/python/ds18b20.py

Note: in the python script ds18b20.py replace the device ID 28-00000482b243 with the ID for the device you are using.

The following link demonstrates how to setup one gpio port for several 1-wire devices.

https://raspberryautomation.com/connect-multiple-ds18b20-temperature-sensors-to-a-raspberry-pi/

The following fritzing diagram was found in the above link.

Note: when one of the two DS18B20 sensors failed the solution was to shut-down the RPi and reseat the pins into the breadboard. Both sensors were again showing up in the system.

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