SDT board

SDT — SCPI Display Thermometer

Benchtop USB thermometer with a SCPI interface and an 8-character LED display, built around an STM32C071CBT6 (ARM Cortex-M0+). Measures temperature (and optionally humidity), shows it on the display, and exposes a full instrument control interface over USB.

📖 Full documentation: https://bartkepl.github.io/SDT_board/ (PL)

Status — WIP

• First revision of schematic and PCB done
• PCB and parts ordered
• Prototypes assembled and tested
• Firmware (v3.1)

Features

• 4-layer PCB
• ARM Cortex-M0+ MCU, LQFP48 (STM32C071CBT6)
• USB 2.0 device — USB-TMC class, SCPI (IEEE 488.2) command set
• TMP117 and/or SHT45 for temperature (and humidity) measurement, auto-detected
• 8-character LED dot-matrix display (2× DLR2416)

Repository layout

Firmware

The firmware is an STM32CubeIDE project in firmware/USB-TMC_src/.

1. Open the project in STM32CubeIDE (File → Open Projects from File System…).
2. Build (Project → Build All).
3. Flash via ST-Link, or over USB DFU (the device exposes a SYSTem:DFU command and the host app has a one-click flash helper).

Vendored dependencies are included in-tree so the project builds without extra setup:

• TinyUSB — USB-TMC device stack
• scpi-parser by Jan Breuer — SCPI command parser

Host software

A desktop companion app lives in software/:

cd software
pip install -r requirements.txt
python main.py

It provides a live readout and plot, a SCPI console, sensor/display configuration, CSV logging, and a DFU flashing helper. See software/README.md for details.

You can also talk to the board from any VISA-capable environment:

import pyvisa
rm = pyvisa.ResourceManager('@py')          # VID=0xCAFE, PID=0x4000
inst = rm.open_resource('USB0::0xCAFE::0x4000::SDT_YOURHASH::INSTR')
print(inst.query('*IDN?'))
print(inst.query('SENSor:TEMPerature?'))

Documentation

The full hardware, firmware, and SCPI command reference is published at https://bartkepl.github.io/SDT_board/ and authored in doc/ (MkDocs Material). Build it locally with:

pip install -r doc/requirements-docs.txt
mkdocs serve -f doc/mkdocs.yml

License and credits

Idea based on SCPI Capable Thermometer.

Display part & footprint from kicad-intelligent-displays by 74hc595.

USB-TMC stack from TinyUSB. SCPI parser from scpi-parser by Jan Breuer.

Released under the MIT License. Open to contributions in both software and hardware!