Filament progress sensor

Research-stage optical-motion sensor that measures filament surface movement without a mechanical encoder ball.

Development status

Baseline documentation snapshot: 2026-10-11, before the requested connector/protection/usability revision program. New revision features require their own reviewed source and qualification evidence.

This page documents an unqualified engineering study, not a released or tested product. Saved CAD, renders and automated checks do not establish a safe assembly, compatible cable, firmware support or a usable current rating.

Board-specific qualification limits: 13 purchased MPNs/121 selected/2695 historical members match; retained native0; holder/optical/firmware/host/physical gates open.

Interfaces and wiring

The selected optical-motion study uses PAT9125EL-TKMT with a tri-state interface buffer and TPD4E1U06DCKR protection. Optical geometry and sensor initialization are part of the interface contract; do not assume a generic mouse-sensor module pinout.

Power off before changing connections. Use the selected schematic and a continuity check to verify connector orientation and pin numbering before first power.

Electrical design requirements

Host-current allowance, undocumented initialization, optical surface response and physical alignment remain unresolved. Holder-height/no-metal constraints conflict and prevent a qualified filament-motion detector.

Selected component architecture

Selected v25 retains PAT9125EL-TKMT, the tri-state buffer and already fitted exact V2 Id27 protection array. Complete component review covers all27 records/13 purchased identities and conditional V1 bypass reuse; no successor. Native retained ERC/DRC/opens/parity0 does not close the holder-height/no-metal conflicts, host-current assumptions, undocumented initialization or optical/physical qualification. Current sensor/hole axis is y17.8mm; older coordinates are historical.

Configuration and commissioning

Use the configuration and firmware contract for the exact selected revision. Do not copy another module’s socket assignments or assume that an unused pin is available. First-article work must verify source selection, reset/unplug behavior, cable orientation and the actual load or sensor interface before normal operation.

Requested connector and usability upgrades

The following are requirements for the next design iterations; this page does not claim they are already fitted:

• On electrically suitable three/four-pin low-voltage ports, provide compact alternative 2.54 mm header/Molex-style and keyed STEMMA-family footprints. Populate one connector option per shared position and document its pin order. Use STEMMA QT only for compatible four-wire I²C; connector appearance does not make another signal protocol I²C-compatible.
• Render each supported connector population separately. Document clearances, cable access and the exact fitted option.
• Use uppercase titles in a consistent Montserrat-style face, labels on both sides, visible domain boundaries, a revision-specific wiring guide and this page’s URL on the silk where readable.
• Keep mounting-hole centers on a documented 10 mm lattice; add cable-tie holes where space and electrical clearances permit. Place status LEDs near accessible edges and give every indicator its own disable solder jumper. Provide labeled test pads and a ground observation point.
• Review applicable DC power entries for reverse-polarity cutoff with a blinking warning, overvoltage cutoff/indication, controlled startup and electronic overcurrent protection. Indicator and protection circuits must work in the fault state without defeating isolation or safe output defaults. Thermal protection belongs only where the power/thermal analysis justifies it.
• Electronic protection does not automatically replace a required mains/branch safety fuse. Backfeed blocking and inductive-load flyback clamps are separate design functions. Do not add identity EEPROMs, fault memory, calibration storage or paid self-test hardware under this upgrade program.

Design sources

• Board specification
• Architecture and component decisions
• Selected-revision review and qualification record
• All extension boards

Documentation route: smoothieware.org/extensions/filament-progress-sensor.

Additive design studies

The 2026-10-11 upgrade program has saved additional candidates v26, v27, v28. These studies preserve the historical design described above. Their connector, LED, mechanical and protection changes are revision-specific and remain unqualified.

See the per-board changes, failures and remaining work and mandatory family specification. Use the source hash and native check for the exact candidate being reviewed; do not infer hardware ratings from a rendered population.

Upgrade candidate readback

The three additional revisions are v26, v27, v28. They are engineering studies; saved CAD and renders do not release the hardware. The latest candidate is described below. Older baseline notes above remain historical.

filament-sensor

• Latest PCB source, SHA-256 fd6fb96c18bca3d6a827ced0e76be774a518008593f1e4bff9b83077ddc73977.
• Last native check: 0 errors, including 0 open connections. This is a CAD result, not electrical, assembly or firmware qualification.
• No alternative connector population is recorded for this physical role. Any applicable connector conversion remains an explicit design-review item.
• normal population/render record: 6 images; source current; image hashes match; 0 unresolved models.
• Changes, failed trials and remaining work.

Applicable protection, current-path, thermal, pinout, cable access and physical tests remain open wherever the linked board record has not verified them. A zero native-error count does not close those gates.

Second-round usability candidate — V29

The additive v29 native candidate adds a readable complete documentation URL and current revision labels while preserving the protected preceding circuit, placements, outline and electrical rules. Parent rechecks found zero enabled electrical errors, open connections or schematic-parity findings and clean schematic checks; 2 text-thickness warnings remain. All 6 declared populated/bare views and current manufacturing exports are source-bound. Earlier revision/component selections on this page are historical context. No current rating, sensor/host compatibility, optical or mechanical fit, purchasing savings or fabrication release is established.

PCB source SHA-256: dc82cef7f73d845ca608c948f834133c5ecd41f96bd463f7cbab9f89c5cfbd77.

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