Knowledge Base

This tutorial details how to set up the 1 Wire File System with the 1 Wire Pi Plus and 1 Wire Pi Zero on an ODroid computer running Ubuntu 20.04 from https://www.hardkernel.com.

Step 1: Download the latest Ubuntu image and burn it to your SD Card following the instructions on https://wiki.odroid.com/getting_started/os_installation_guide.

Step 2: Follow our ODroid C1 Ubuntu I2C Setup or ODroid C2 Ubuntu I2C Setup tutorial to set up I2C on the ODroid platform.

Step 3:  Install OWFS

sudo apt-get update

sudo apt-get install owfs ow-shell

Step 4: Edit owfs.conf to enable the I2C 1 Wire interface

sudo nano /etc/owfs.conf

Comment out the following line

# server: FAKE = DS18S20,DS2405

Find the following section

# USB device: DS9490
#server: usb = all

Insert the line below to enable i2c support. 

server: device = /dev/i2c-1

Note: If your Odroid computer uses a different I2C bus for pins 3 and 5 on the GPIO header, change i2c-1 to the correct bus number for your setup. 

Find the section titled

######################### OWFS ##########################

Remove the hashes from the lines

mountpoint = /mnt/1wire
allow_other

Save your changes and exit the nano editor.

Step 5: Create a folder where the 1 Wire devices will be mounted.

sudo mkdir /mnt/1wire

Step 6: Reboot your ODroid

sudo reboot

Step 7: Enable the owserver service

sudo systemctl enable owserver.service

Step 8: Your ODroid should now work with OWFS.  

Your 1 Wire devices can be found in the directory /mnt/1wire

Each 1 Wire device directory will contain several files representing the values available from that device. For example, with the DS18B20 temperature sensors, there will be a directory in /mnt/1wire with the serial number for the sensor, normally starting with "28.". Inside the directory for the sensor, you may find the following files.

address errata id power r_locator temperature10 temperature9 tempres

alias family latesttemp r_address scratchpad temperature11 temphigh type

crc8 fasttemp locator r_id temperature temperature12 templow

The temperature for the sensor is stored in the "temperature" file, so we can use the "cat" command to display the file's contents. For example, with a sensor called "28.0844C4030000", you would use the following command.

cat /mnt/1wire/28.0844C4030000/temperature

Note:

On specific versions of owfs available on the ODroid and running Ubuntu 20.04, a bug causes devices in the /mnt/1wire directory to be duplicated, showing two folders for each device.

If you encounter this problem, it can be resolved by editing the configuration file for the owfs service.

Step 1: Open /lib/systemd/system/owfs.service in an editor.

sudo nano /lib/systemd/system/owfs.service

Step 2: Find the following line.

ExecStart=/usr/bin/owfs -c /etc/owfs.conf --allow_other %t/owfs

Remove "-c /etc/owfs.conf", so the line looks like this.

ExecStart=/usr/bin/owfs --allow_other %t/owfs

Step 3: Save the file and reboot your ODroid.

You should only see one device instance in the /mnt/1wire directory.

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