Configurable 940 nm through-beam spoke sensor for a Seeed Studio XIAO ESP32-S3. A discrete analog front end restores a 25-50 kHz optical carrier; ESP-IDF RMT detects its interruption and learns the wheel's spoke pattern.
This repository is the wheel-speed-sensor subsystem of BicycleOBU. The online Interactive BOM is generated directly from the authoritative KiCad PCB.
Hardware V0.1 (KiCad CAD revision R4) was ordered and is preserved as a
GitHub release.
main is now hardware V0.2-dev; physical validation is still open for V0.1.
| Area | Current evidence |
|---|---|
| Hardware | KiCad 10 ERC: 0 errors, 3 known library-sync warnings; DRC: 0 violations, 0 unconnected pads |
| Connectivity | 70 schematic endpoints, PCB pad nets and SPICE topology cross-checked |
| Simulation | Python transient, 10,000-case sweep and ngspice cross-check pass |
| Firmware | Portable core, RMT/CAN adapters and BLE CSC component implemented; ESP32-S3 target build passes, HIL pending |
| Manufacturing | Versioned JLC Gerber/BOM/CPL package generated; assembly-preview approval pending |
| Physical performance | Sunlight, alignment, contamination, vibration and power tests pending |
Do not treat simulation as production validation. The remaining gates are listed in TODO.md.
| Goal | Guide |
|---|---|
| Understand the signal chain | System overview |
| Open the design or run the simulator | Getting started |
| Change configuration, firmware or captured CAD | Development workflow |
| Order or review the PCB | Manufacturing |
| Inspect or place components | Interactive BOM |
| Bring up and correlate a prototype | Bring-up and test |
| Trace a requirement to evidence | Verification matrix |
| Find a technical reference | Documentation index |
| Property | V0.1 value |
|---|---|
| Optical path | 940 nm VSMB1940X01 emitter to VEMD10940FX01 photodiode |
| Carrier | 25-50 kHz runtime range; 38 kHz default; 50% duty |
| Receiver | TLV9062 TIA/band-pass, TLV7011 Schmitt comparator |
| MCU interface | GPIO1 RMT TX, GPIO2 RMT RX with carrier demodulation |
| Wheel design range | 16-48 spokes; 60 km/h requirement, 80 km/h stress calculation |
| Receiver outline | 17.8 x 21.4 mm XIAO outline |
| Emitter outline | 21 x 15 mm, two M2.5 holes |
| Panel | Two-layer PCB with one routed mouse-bite breakaway tab |
| Remote link | 600 mm two-conductor JST-GH harness after snap-off |
| Optional interface | Official XIAO MCP2515 CAN expansion; disabled by default |
| BLE interface | Wheel-only Bluetooth Cycling Speed and Cadence Sensor (0x1816) |
.\Open-IR-Spoke-Sensor.cmd
.\Open-Interactive-BOM.cmd
py -3.14 simulation\local_server.py
powershell -ExecutionPolicy Bypass -File tests\run_all.ps1
powershell -ExecutionPolicy Bypass -File hardware\export_jlc.ps1 -Revision V0.2The KiCad launcher also starts the InteractiveHtmlBom watcher at
http://127.0.0.1:8766/; every complete PCB save regenerates and reloads the
browser view. The simulator opens at http://127.0.0.1:8765/. Disposable
simulation evidence is written under ignored build/.
| Concern | Authoritative source |
|---|---|
| Tunable system values | config/system.json |
| Pins and electrical nets | hardware/connectivity.json |
| Parts, fields and procurement | hardware/component_catalog.json |
| Captured schematic and routing | hardware/ir_spoke_link/layout_manifest.json |
| Requirements | requirements/requirements.yaml |
| Project paths and revision | project_manifest.json |
| Hardware/software versions | docs/versioning.md |
| Changes between releases | CHANGELOG.md |
Generators restore the captured user layout and must not synthesize, remove or reroute tracks. See CONTRIBUTING.md before changing CAD or generated files.
No project license has been selected yet. Until one is added, the repository must not be presented as granting open-hardware, software or documentation reuse rights.