Pin Assignment

Produce a board-aware pin plan without losing the repository's declaration convention. A logical declaration ID is not automatically a physical GPIO number; keep those layers distinct.

Intake

Record the exact board/revision, MCU/module, framework/core version, toolchain, signal names, direction, voltage, current, pull requirements, bus ownership, boot/debug/USB/radio constraints, and whether the user wants declarations, physical wiring, or both. Resolve the target through ../board-support/SKILL.md first; its resolution_status must be resolved for the requested pin-advice purpose. Load the matching file under ../../references/boards/ before selecting a physical pin. If the board is a bounded family with missing identity fields, stop and request them instead of using a similar profile.

Process

1. Classify every signal as input, output, analog, PWM, bus, interrupt, boot, debug, USB, flash, PSRAM, or radio related.
2. Reserve board-specific flash, PSRAM, USB, boot-strapping, debug, and default bus pins unless the exact board documentation approves reuse.
3. Reject a candidate whose direction, pull capability, voltage, current, ADC, PWM, or protocol behavior does not match the signal.
4. Keep logical IDs stable and allocate them in the requested fixed order.
5. If the user requests only declarations, emit only the declarations as plain text. Do not add a code fence, heading, explanation, or trailing comment.
6. If a physical map is requested, provide it separately and label assumptions and source-backed constraints.

Required declaration convention

For the user's custom output mode, use raw C++ declarations in numeric order:

constexpr int btn_esc = 101;
constexpr int btn_enter = 102;
constexpr int led_status = 103;

Use the next sequential logical value for each requested signal. These values are stable logical identifiers unless the user explicitly defines them as physical GPIO numbers. Never replace this format with an enum, macro, array, namespace, explanatory wrapper, or reordered declaration list.

Anti-rationalization

Verification

• Declaration names and values are constexpr int and strictly increasing from the required starting ID.
• Every physical output avoids input-only, flash/PSRAM, USB, and unapproved strapping pins for the exact board.
• Voltage/current and pull-up requirements have a source or explicit unknown.
• Build proof, upload proof, hardware proof, and system proof are reported separately.

Shared output contract

Use the shared Arduino skill contract: state assumptions, required tools and versions, implementation steps, tests/evidence by proof stage, known limitations, and recovery/security notes.