How to use DigiTemp to set up USB Thermometer

DigiTemp is a lightweight solution for monitoring 1-Wire temperature sensors on Linux. It is one of many apps that let you read USB Thermometer sensor. By following these steps, you can set up DigiTemp on Debian, Ubuntu, or Raspberry Pi OS and automate data collection for long-term monitoring.

1. Installation
   • Ubuntu / Raspberry Pi OS / Debian
2. DigiTemp configuration
   • Identify Your USB Thermometer
   • Initialize DigiTemp
     • More about configuration file
   • Read Temperature Data
   • Automate Data Logging
     • Using DigiTemp’s Built-in Logging Feature (Recommended)
     • Using Cron for Scheduled Logging

Installation

Ubuntu / Raspberry Pi OS / Debian

sudo apt install digitemp

Execution of this command will install three programs:

• digitemp_DS2490
• digitemp_DS9097
• digitemp_DS9097U

into the /usr/bin/ directory. For usage with the USB Thermometer we will need only digitemp_DS9097.

DigiTemp configuration

Step 1: Identify Your USB Thermometer

You can identify your USB Thermometer serial port using:

ls /dev/ttyUSB*

This will list available USB-to-serial devices (e.g., /dev/ttyUSB0) one of them is your connected USB Thermometer.

Step 2: Initialize DigiTemp

Once you’ve identified the correct device, initialize DigiTemp:

digitemp_DS9097 -i -s /dev/ttyUSB0

Remember to replace /dev/ttyUSB0 with your actual device.

After running this command, you should see output similar to:

DigiTemp v3.7.2 Copyright 1996-2018 by Brian C. Lane
GNU General Public License v2.0 - http://www.digitemp.com
Turning off all DS2409 Couplers
.
Searching the 1-Wire LAN
286C530570230702 : DS18B20 Temperature Sensor
ROM #0 : 286C530570230702
Wrote .digitemprc

More about configuration file

When you first initialize DigiTemp it creates a hidden configuration file named .digitemprc by default inside the current directory. This file stores essential settings for future readings like serial device, sensor ROM IDs, and logging format.

You can also specify a custom location for this file when running DigiTemp:

digitemp_DS9097 -c /path/to/custom_config -a -s /dev/ttyUSB0

The .digitemprc file contains the following:

TTY /dev/ttyUSB0
READ_TIME 1000
LOG_TYPE 1
LOG_FORMAT "%b %d %H:%M:%S Sensor %s C: %.2C F: %.2F"
SENSORS 1
ROM 0 0x28 0x6C 0x53 0x05 0x70 0x23 0x07 0x02

• TTY /dev/ttyUSB0 → The serial/USB device’s port.
• READ_TIME 1000 → Delay in milliseconds between sensor reads.
• LOG_TYPE 1 → Defines the output format (0 = plain text).
• LOG_FORMAT → Specifies how the temperature data is displayed (date, time, sensor ID, temperature in °C and °F).
• SENSORS 1 → The number of detected sensors.
• ROM 0 0x28 0x6C 0x53 0x05 0x70 0x23 0x07 0x02 → The unique ROM address of Sensor 0.

Each 1-Wire sensor has a globally unique ROM ID, which helps DigiTemp identify individual sensors even if they are rearranged.

Now that DigiTemp is initialized and .digitemprc is created, you can read sensor data without specifying the serial device each time

sudo digitemp_DS9097 -a

This will automatically use the settings stored in .digitemprc.

Step 3: Read Temperature Data

Once initialized, you can read temperature values with:

cd /path/to/directory/with/config
digitemp_DS9097 -a

if you are using default .digitemprc or use:

digitemp_DS9097 -c /path/to/custom_config -a

if you would like to use custom config file.

Example output:

Mar 10 14:42:39 Sensor 0 C: 25.75 F: 78.35

Step 5: Automate Data Logging (Optional)

DigiTemp can log data automatically using a log file and predefined format stored in the .digitemprc file.

To continuously monitor temperature readings, you can either use cron for scheduled logging or run DigiTemp as a background process without cron.

Option 1: Using DigiTemp’s Built-in Logging Feature (Recommended)

DigiTemp provides built-in logging capabilities that allow temperature readings to be stored in a structured format, making it easier to automate and analyze data.

For example, to log readings every 60 seconds indefinitely:

digitemp_DS9097 -a -r 0 -d 60 -l /var/log/digitemp.log

Explanation:

• -a → Reads all sensors.
• -n 0 → Repeats indefinitely (0 means infinite loop).
• -d 60 → Waits 60 seconds between readings.
• -l /var/log/digitemp.log → Stores logs in the specified file.

Run it in the background:

nohup digitemp_DS9097 -a -n 0 -d 60 -l /var/log/digitemp.log &

This allows DigiTemp to log temperature readings every minute in the background, even if you log out.

To stop logging:

pkill -f digitemp_DS9097

Option 2: Using Cron for Scheduled Logging

If you prefer cron, DigiTemp can still be scheduled to run periodically.

Open the Crontab editor:

crontab -e

To log every minute (* * * * *), add the logging command:

* * * * * /usr/bin/digitemp_DS9097 -a -l /var/log/digitemp.log

This runs DigiTemp every minute and appends the data to /var/log/digitemp.log.

After a few minutes, check the log file:

tail -f /var/log/digitemp.log