feat(daq): add Arduino Firmata DAQ driver by dalvarez-204 · Pull Request #117 · nominal-io/instro

dalvarez-204 · 2026-06-17T20:52:00Z

Closes INSTRO-324. Fixes #49

Summary

Adds ArduinoFirmata driver implementing DAQDriverBase via pyfirmata2
Supports analog input/pwm output, digital input/output
Uses callback-based value streaming (pyfirmata2 does not support polling); daemon supported through callback-populated queue
Hardware-timed acquisition not supported;
Sampling rate capped at 1000Hz (Firmata wire format limit)
Adds 'arduino' optional extra to pyproject.toml

Test plan

Manually validated on Mac, Linux, and Windows with real Arduino hardware

mintlify · 2026-06-17T20:53:36Z

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dalvarez-204 · 2026-06-17T21:14:01Z

Here are screenshots of windows and linux PCs demonstrating analog read, digital write, and digital read (this was also verified on mac)

dalvarez-204 · 2026-06-17T21:16:15Z

PWM is not implemented in this PR, but should be added later because it's a popular use case for arduinos. This DAQ implementation also relies on users knowing which analog and digital pins are available to them.

dalvarez-204 · 2026-06-23T21:36:11Z

Here are some of the results from the hardware testing. The first two images are from manual tests but the final image is from the arduino's hardware test file in the code.

…d limitations.

…thod, updated docstrings

…mata

…ting sample rate adjusts HWTimingConfig

…e for Measurement

…ue race in ArduinoFirmata read_analog/read_digital_line now raise RuntimeError instead of silently returning 0 when no Firmata report has arrived yet for a channel, so a race read can't be confused with a genuine low/zero reading. The background daemon already isolates per-call exceptions, so this can't stall the data flow. _on_analog_callback now attempts the queue put first and only evicts on queue.Full, tolerating fetch_analog's drain loop concurrently emptying the queue between the full-check and the evict (which previously raised an uncaught queue.Empty on the pyfirmata2 reader thread, permanently killing sample production). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Rebase conflict resolution on uv.lock kept taking main's side at each step, which dropped pyfirmata2 from the lockfile. Regenerating from pyproject.toml restores it. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

_wait_for_digital's whole purpose is to poll through a transient not-ready condition, but had no exception handling. read_digital_line now raises RuntimeError instead of silently defaulting until the first Firmata report arrives, so the helper needs to retry through that too. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

…ose() close() previously never stopped the pyfirmata2 Iterator thread (it wasn't even stored on self) and never reset _latest_values/_sample_queue/ _pending_updates. Reusing a closed driver via open() again could see a stale callback from the old reader thread land in the new session, and read_analog()/read_digital_line() could silently return leftover data from before close() instead of raising for a channel that hasn't reported yet in the new session. close() now stops and joins the iterator before tearing down the board, then clears all stream state. Channel configuration (_ai_channels, etc.) is left intact, matching normal open/close/reopen DAQ lifecycle. Documented the AI/DI alias-collision limitation (shared _latest_values dict) as a known limitation rather than fixing it in this pass. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

mintlify Bot deployed to staging - docs/guides June 17, 2026 20:54 View deployment

mintlify Bot deployed to staging - docs/guides June 17, 2026 21:02 View deployment

mintlify Bot deployed to staging - docs/guides June 17, 2026 21:03 View deployment

dalvarez-204 marked this pull request as ready for review June 17, 2026 21:16

dalvarez-204 requested a review from nhschwab June 17, 2026 21:16

nhschwab reviewed Jun 18, 2026

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