Acquire the 18 visible/near-infrared channels of one generation-2 AS72651/52/53 cluster for controlled reflectance experiments. The PCBA reports sensor data and status over host I²C; normalization, material classification and the dataset are host/fixture work. The named prototype target is in attempt/scope.md.
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: v27 strictnative/ordinaryassembly0;100checklist unsigned and wavelength/opticalfixture/calibration/I2C/host/stock/physical open.
The exact prototype target is P12 Prime2590 J38 from a fresh exported host netlist in attempt/host-interface-evidence.md. The fitted board and harness must still be continuity-checked before power. The table is the actual design assignment, with no guessed alternate UART or LED wiring.
| Pin | I socket / P12 J38 | Board assignment |
|---|---|---|
| 1 | switched 3.3 V | V3V3 |
| 2 | switched 5 V | no connect |
| 3–7 | GPIO/reserved by socket type | no connect |
| 8 | I2C2 SDA | host SDA through ESD protection to U5 A side |
| 9 | I2C2 SCL | host SCL through ESD protection to U5 A side |
| 10 | GND | common ground |
Power off before connecting or changing jumpers. Verify pin 1, signal direction, supply voltage and ground at both ends of every cable. A mechanically fitting connector is not proof of electrical compatibility. If a host pin mapping or current allocation remains unresolved in the design record, do not connect the board until it is resolved.
The following are specification requirements or study assumptions; they are not measured operating ratings. A newer selected-revision note takes precedence over historical draft options.
The design describes the following protection intent. Check the selected schematic and remaining qualification gates before relying on it:
attempt/flash-programming.mdSee current review. Retain18-channel AS72651/52/53 and TCA9517A powered-off isolation;AS7343/AS7341 changes410–940nmresponse/fixturecontract. Conditional V1 0603 bypass/pull families only,no successor. Current selected v27; retained native/stock/physical qualification limits remain explicit.
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.
The following are requirements for the next design iterations; this page does not claim they are already fitted:
Documentation route: smoothieware.org/extensions/spectral-analysis-board.
The 2026-10-11 upgrade program has saved additional candidates v28, v29, v30. 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.
The three additional revisions are v28, v29, v30. 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.
7361b2bde4d11be5b3a52f4ed4e430744f4489e0124e808ffdcea4fea613591e.PinHeader_1x04_P2.54mm_Vertical. Fit only the selected population; check its pin map and voltage in the design record.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.
Protected source v30; current PCB SHA-256 146c0f332dc9fd34bba6561d71c96533401bce51db60e9ee663315521c9d2b48. Fresh checks: zero enabled PCB errors/opens/parity and ERC errors; 2 PCB warnings. Electrical geometry, project rules and 57 historical files unchanged. Verified 70 model entries, 17 exports and 12 current population views, all inspected. Full documentation URL readable. Exact authored local-libraries restored; initial library warning regression rejected before export Inherited native warnings and enabled-rule exclusions remain explicit Physical/thermal/current/connector-fit qualification open No priced or area savings established by annotation candidate.