TI HDC Sensor Monitor

Watch temperature and relative humidity together, explore synchronized history, and save paired measurements to CSV. The dashboard runs locally in your browser, with Python handling the TI HDC3020EVM through USB / USB2ANY HID.

TI HDC3020EVM temperature and humidity evaluation board.

Modeled on ti-tmp-sensor-monitor using the same Dash interface conventions and single-session architecture.

Status: physical acquisition, CSV, live dashboard, volatile controls and one bounded test of the sensor's optional integrated heater passed on HDC3020EVMs. Automatic CSV start and daily rotation passed software/simulator checks and await review before a new physical check. Independent temperature/RH accuracy was not calibrated. See the validation report and current checkpoint.

Install uv, then open Bash (Git Bash on Windows) in this repository. With one HDC3020EVM connected and TI's GUI closed, run:

uv run --extra usb python app.py

Open the dashboard and follow the five-step guide to monitor, record and disconnect. For simulation without hardware, run uv run python app.py --simulate.

The USB backend supports 64-bit Python through hidapi; it does not require USB2ANY.dll, TI Cloud Agent, or TI's GUI. Installation downloads dependencies; monitoring serves assets locally and binds only to loopback. Run one app process per board. All browser tabs share that process's device session and recorder.

• Connect opens and identifies the device without sampling. It establishes on-demand LPM0 with the heater off; these are volatile changes.
• Start monitoring connects automatically or resumes. The default is a fresh paired conversion each second and automatic CSV capture. Uncheck Save CSV automatically while monitoring before starting for a quick view without a file. Stop pauses host acquisition; Disconnect drains the CSV, attempts heater-off and exit-auto, then releases the board.
• Live values show the last sample timestamp. Disconnected/paused readings are explicitly marked as retained. Statistics cover the entire 7,200-sample buffer.
• The two plots share their time range. Drag or zoom either plot; Follow live returns to the last five minutes. Clear data clears only the in-memory buffer.

See the history walkthrough for how to hold a time range and return to live following.

1. Leave Save CSV automatically while monitoring checked. After a successful Start monitoring, new samples go to recordings/. The writer opens a new file on the first sample of each UTC day; older files remain in that folder.
2. Watch the current filename, total written rows, file count and dropped rows in CSV recording. Stop pauses sampling while leaving the file open.
3. Click Stop recording to close the file while monitoring continues, or Disconnect to drain it and release the board. Download last CSV is available after the writer closes and downloads the most recent file.
4. For a quick view without automatic saving, uncheck the option before starting. Record starts a manual, non-rotating CSV when needed. Export buffer saves only the samples currently held in memory.

Recording starts with new samples; it does not include earlier history. Stop pauses acquisition but leaves recording armed for a later resume. Clear data does not erase files. Disk errors and dropped rows remain visible.

CSV pairs both channels with UTC timestamps, raw values, source and measurement settings. Plots use the computer's local time. Heater-on readings are marked in plots and CSV. See CSV columns and behavior for details.

Both pages remain mounted: changing tabs preserves plots, data, recording and draft controls. Choose a measurement mode and low-power mode, then click Apply measurement settings. The Applied line describes the active configuration; dropdowns are editable drafts.

Simulator example after applying auto 1 Hz and LPM1. The NIST serial is a simulator fixture, not a physical board's identity. The heater remains off.

• Measurement mode: on-demand, auto 1 Hz, or auto 0.5 Hz.
• LPM0 through LPM3 select the noise/power tradeoff.
• Take one sample works while paused in on-demand mode.
• Status read/clear, TI manufacturer ID, 48-bit NIST serial, and soft reset.
• A confirmed 5 s low-level heater pulse and an explicit Heater off control. Heat changes both measurements, including during cooldown. The host timer is best-effort, not a firmware watchdog. If communication fails, unplug the EVM.
• Soft reset restores this app's on-demand LPM0 configuration with heater off. EEPROM, offsets, thresholds, firmware and general-call reset are not exposed.

In auto mode, Stop pauses reads while the device continues autonomous conversions. Choose on-demand mode or Disconnect to stop autonomous conversion. See the settings walkthrough for draft/application behavior and the relationship between mode and sample interval.

The troubleshooting table covers missing/busy boards, failed reads, recording problems and held plots. Bad pairs are discarded; three consecutive failures close the session. Failed control operations disconnect immediately because a timed-out write may have taken effect. Resolve the error and reconnect explicitly. Cleanup failures remain visible; never assume a failed heater-off command succeeded.

uv run --locked --extra usb --extra dev python -m unittest discover -s tests -v
uv run --locked --extra usb --extra dev ruff check .
uv run --locked python -m hdcsensor.validate --samples 30

The last command checks acquisition/CSV/reconnect in simulation. For the approved physical test procedure and its results, see hardware validation and the validation report. One attended heater pulse was validated under H015; no further pulse is authorized by that result. The automatic-CSV candidate still awaits its separate non-heater physical check.

• Quick start: five steps from connection to CSV download.
• Usage guide: history, CSV, settings and recovery.
• Architecture: device ownership and background workers.
• Protocol: HID framing, raw I²C, commands, CRC and conversion.
• HDC3020EVM, EVM user guide, and HDC3020 datasheet.

Read PROJECT.md for intent, STATE.md for current evidence and next action, and AGENTS.md for the engineering loop/review gate. Licensed under MIT. Adaptation credits are in NOTICE.md.