The NAU7802 ADC returns a stale max-scale value (0x7FFFFF) on its
first conversion after power-up, polluting the moving average and
making the initial weight report wildly inaccurate. Flush the first
reading during init().
Also extract both hardware drivers out of diagnostic scripts into
proper daemon modules:
- NAU7802 scale driver: scripts/scale_diag.py -> daemon/nau7802.py
- PN5180 NFC driver: scripts/read_tag.py -> daemon/pn5180.py
The production daemon was importing driver classes from test scripts
since the original SpoolBuddy commit. Diagnostic scripts now import
from the driver modules. Removed the sys.path hack from main.py.
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).
maziggy