This project reads an inexpensive TEMP_er1 USB temperature sensor on macOS, streams the readings over OSC, displays them in a Processing (Java) sketch, and can save daily tab-separated log files.
Such sensors are available on Amazon for about $20-30. Note that the sensor is a USB HID device (akin to a mouse or keyboard), not a serial device. It will not appear as an FTDI-style /dev/cu.* port, and it will not show up in serial terminal tools such as CoolTerm. macOS may describe it as a keyboard because one of its HID interfaces is keyboard-like; the temperature data comes from a separate HID interface.
Known supported USB IDs:
0c45:7401 TEMPer1V1.4 / TEMP_er1
1130:660c legacy TEMPer variant
This project includes a Terminal-based Python program which accesses, logs, and transmits (over OSC) the sensor data. The project also includes a Processing (Java) program which receives and displays the real-time OSC data from the Python program, shown at right in the screenshot below.
temp_er1_python/temper_cli.py
Python command-line reader for the USB HID sensor.
temp_er1_processing_osc_receiver/
Processing 4.3 sketch that receives OSC and displays live readings.
temp_er1_python/vendor/
Project-local Python dependencies, so a virtualenv is not required.
temp_er1_python/logs/
Daily TSV log output, generated only when logging is enabled.
From the repository root:
python3 temp_er1_python/temper_cli.py --listIf the device is connected, you should see something like:
TEMPer1V1.4 (0c45:7401, interface 1) path=...
Start OSC streaming:
python3 temp_er1_python/temper_cli.py --osc --quietThen open and run:
temp_er1_processing_osc_receiver/temp_er1_processing_osc_receiver.pde
The default OSC port is 8367, which spells TEMP on a US phone keypad. The
Processing sketch listens on the same port by default.
The repository is intended to run with project-local Python packages in
temp_er1_python/vendor/. If vendor/ is missing or you need to reinstall the
dependencies:
cd temp_er1_python
python3 -m pip install --target vendor -r requirements.txtIf hidapi fails to install or load on macOS, install the system library first:
brew install hidapi
python3 -m pip install --target vendor -r requirements.txtNo Python virtualenv is required.
Run commands from the repository root unless noted otherwise.
List supported HID devices:
python3 temp_er1_python/temper_cli.py --listPrint one reading:
python3 temp_er1_python/temper_cli.py --oncePrint Celsius once per second:
python3 temp_er1_python/temper_cli.pyChange the sensor read rate with --interval. This controls terminal output
and OSC transmission, but not the separate TSV logging interval:
python3 temp_er1_python/temper_cli.py --osc --interval 2Print Fahrenheit instead:
python3 temp_er1_python/temper_cli.py -FStream OSC to the default destination, 127.0.0.1:8367:
python3 temp_er1_python/temper_cli.py --oscStream OSC without printing readings in the terminal:
python3 temp_er1_python/temper_cli.py --osc --quietStream OSC to a custom destination:
python3 temp_er1_python/temper_cli.py --osc 127.0.0.1:9000Useful combined command for display plus logging:
python3 temp_er1_python/temper_cli.py --osc --quiet --logCommand options are case-sensitive. For example, -F is valid for Fahrenheit;
-f is not.
CLI option reference:
--help show help and exit
--list list supported HID devices and exit
--once print one reading and exit
--count N print/send N readings, then exit
--interval SECONDS seconds between sensor reads, terminal output, and OSC
--plain print only the numeric temperature
--json print one JSON object per reading
-F, --fahrenheit use Fahrenheit for terminal output and TSV logs
--scale N calibration scale applied to Celsius before output/logging
--offset N calibration offset applied to Celsius before output/logging
--osc [HOST:PORT] send OSC; default with no value is 127.0.0.1:8367
--osc-host HOST OSC host to use with --osc-port
--osc-port PORT OSC port to use with --osc-host
--osc-prefix PREFIX OSC address prefix, default /temp_er1
-log, --log [SECONDS] enable TSV logging; default interval is 10 seconds
--quiet do not print readings to stdout
The Python program sends these OSC messages once per sensor reading:
/temp_er1/temperature celsius fahrenheit
/temp_er1/temperature/celsius celsius
/temp_er1/temperature/fahrenheit fahrenheit
/temp_er1/device device label
/temp_er1/device/path HID path
Defaults:
host: 127.0.0.1
port: 8367
prefix: /temp_er1
The Processing receiver is already configured for those defaults.
The Processing sketch receives OSC. It does not launch Python and it does not talk to the USB sensor directly.
Workflow:
-
Start the Python reader:
python3 temp_er1_python/temper_cli.py --osc --quiet
-
Run the Processing sketch:
temp_er1_processing_osc_receiver/temp_er1_processing_osc_receiver.pde
The display shows:
- current Celsius temperature
- current Fahrenheit temperature
- detected HID device metadata
- OSC port/prefix information
- a 90-second temperature history chart
The Processing sketch uses Java's built-in UDP socket classes and a small OSC parser in the sketch, so no Processing OSC library is required.
Daily log files can be saved to temp_er1_python/logs/.
Enable logging with:
python3 temp_er1_python/temper_cli.py --logBy default this records Celsius every 10 seconds. To choose a different interval:
python3 temp_er1_python/temper_cli.py --log 60-log is also accepted:
python3 temp_er1_python/temper_cli.py -log 10Add -F to log Fahrenheit instead:
python3 temp_er1_python/temper_cli.py --log -FLog files are written under temp_er1_python/logs/, one file per local
calendar day:
temp_er1_python/logs/temp_er1_2026-06-25.tsv
Each row contains local time, a tab, and the selected temperature unit:
04:38:51 25.12 C
The logger explicitly saves the open file to disk once per minute, or once per logging interval when the logging interval is longer than a minute. It also saves on normal shutdown and rolls to a new file after local midnight.
The sensor's USB report format exposes more resolution than the device likely has in real absolute accuracy. The UI currently displays two decimal places because that is useful for watching short-term drift, but a cheap sensor like this should not be assumed to be accurate to hundredths of a degree.
This project builds on work and protocol information from:
- https://github.com/bitplane/temper
- https://paulherron.com/blog/logging_temperature_over_usb
- https://github.com/elpeo/rbtemper
Example product listings for similar TEMPer/TEMP_er1 devices:
- TEMPer1F USB Computer Thermometer
- TEMPer1F USB Temperature Humidity Meter
- USB Temperature Data Logger Temperature Recorders
- TEMPer2 Dual Temperature Sensor
- PCsensor USB Temperature Sensor
Developed by @golanlevin at the Frank-Ratchye STUDIO for Creative Inquiry, June 2026.