Automatic chessboard copy

Working prototype PCB and legacy design reference

The existing fabricated long PCB is functional and runs the photographed prototype after external wire and resistor modifications. Do not manufacture the archived PCB design unchanged and do not generate production Gerbers from it.

These KiCad files are preserved because their long component layout matches the physical working board and can help explain how the modules were arranged. They predate current firmware 4.6.0 wiring and are not the electrical source of truth or a verified fabrication release.

Required rework for the current prototype

When reusing an already fabricated board, implement the complete ../../connections.csv contract. In particular:

• leave the legacy D10 switch connector unused;
• connect HC-08 TXD through 1 kohm to Nano D10;
• wire the second normally-open switch between Nano A6 and GND;
• add a 10 kohm pull-up from A6 to 5 V;
• connect Nano D1/TX through 1 kohm to HC-08 RXD, and add 2 kohm from that divider node to GND; and
• complete the sensor, motor, power, and load connections that are not routed by the board using insulated, strain-relieved external wiring.

Do not plug the second switch into the old D10 position: D10 is now the firmware's receive input for Bluetooth. Verify every modification by net name and meter continuity rather than copying wire colors from a photograph. The working-prototype page shows the physical board and its external rework.

Known limitations include:

• sensor-channel and several motor/load connections were completed with external wiring rather than PCB traces;
• the historical schematic contains 89 explicit no-connect markers, including the multiplexer channel area;
• the driver RESET/SLEEP pair is not explicitly routed to 5 V;
• it predates the HC-08 on D10, the A6 switch/pull-up change, and the current 5 V power recommendation;
• the historical power labels include a 12 V/VIN arrangement that is not used by the current 24 V plus regulated-5 V design;
• no current-limit, fuse, emergency cutoff, reverse-polarity, enclosure, or production verification is encoded in the PCB source;
• no DRC/ERC or manufacturing review has been certified for these files.

Use ../../WIRING.md, ../../connections.csv, and ../../sensor-map.csv for the current build. The archive intentionally contains no Gerbers, drill files, pick-and-place files, or fabrication ZIP. An existing board being operational does not remove the need for the current public-build fuses, cutoff, polarity protection, verified 5 V supply, and commissioning checks.

Files:

• automatic_chessboard_copy.kicad_pcb: long board layout matching the photographed controller form.
• automatic_chessboard_copy.kicad_pro: historical KiCad project settings.
• reference-schematic.kicad_sch: related historical circuit drawing; layout and present-day wiring do not fully match it.