5 samples at 100ms (500ms window) wasn't enough to smooth NAU7802 ADC
noise — the averaged value still varied by >2g between 1s report
intervals, and the stability state kept flipping, triggering a report
every cycle. Increased to 20 samples (2s window) so noise is smoothed
before reaching the reporting layer.
The daemon imports read_tag and scale_diag as bare modules, but they
live in spoolbuddy/scripts/ which isn't on sys.path when systemd runs
the daemon. Added scripts/ to sys.path at startup, resolved relative
to the module file. Also moved the read_tag import inside NFCReader's
try/except (was crashing the daemon instead of skipping gracefully)
and demoted hardware-not-available messages from ERROR to INFO.
constructor before the try/except, so the FileNotFoundError was unhandled and crashed the entire daemon via asyncio.gather().
Now when the scale hardware isn't available (no /dev/i2c-0), it logs "Scale init failed" and sets self._ok = False, so scale_poll_loop will skip polling with "Scale not
available, skipping scale polling" — same graceful degradation the NFC reader already has.
SpoolBuddy turns a Raspberry Pi 4B with a PN5180 NFC reader and
NAU7802 scale into a filament management station that integrates
with Bambuddy via REST API and WebSocket.
Backend: SpoolBuddyDevice model, 10 REST endpoints (/spoolbuddy/*),
6 WebSocket broadcast types, background offline-detection watchdog.
RPi daemon: asyncio service with concurrent NFC polling (300ms,
MIFARE Classic + Bambu HKDF key derivation), scale reading (10 SPS,
5-sample moving average, stability detection), and 10s heartbeat
with exponential backoff reconnect.
Frontend: kiosk-optimized 1024x600 UI at /spoolbuddy with Dashboard
(live weight + NFC spool detection), AMS Overview, Inventory,
Printers, and Settings pages. useSpoolBuddyState reducer hook
driven by WebSocket CustomEvents.
i18n: all 6 locales (en, de, fr, it, ja, pt-BR).
MartinNYHC