Arduino

Arduino

This skill is for end-to-end Arduino work that must survive contact with real hardware: board selection, wiring, firmware structure, PlatformIO, testing, debugging, and troubleshooting.

If the task is mainly about choosing sensors or dealing with noisy detection in robotics/domotica, also load sensors.

Workflow

1. Lock the target board, toolchain, and capability profile.

   • Prefer exact names: Arduino Uno, Uno R4 WiFi, Nano ESP32, ESP32 Dev Module, etc.
   • Lock the toolchain: Arduino IDE 2, Arduino CLI, PlatformIO, or Arduino Cloud.
   • If the target is unknown, state assumptions and choose the narrowest safe target.
   • Immediately note: board family, voltage domain, resource limits, reserved pins, wireless stack.

2. Plan hardware and wiring before code structure.

   • Separate inputs, outputs, buses, interrupts, and high-current loads.
   • Document pull-up or pull-down assumptions, current draw, and shared grounds.
   • Call out when motors, relays, LEDs, displays, or radio modules need external power, drivers, transistors, or level shifting.

3. Choose the right project shape.

   • Use a single .ino only for small sketches or fast experiments.
   • For reusable or testable firmware, split pure logic from hardware access.
   • For professional or multi-file work, prefer PlatformIO with src/, lib/, include/, and test/.
   • When migrating from Arduino sketches to PlatformIO, remember that .ino preprocessing disappears: add #include <Arduino.h>, proper headers, and forward declarations.

4. Write firmware for bring-up, maintenance, and testability.

   • Keep pin constants, feature flags, calibration values, and timing constants centralized.
   • Prefer millis() scheduling, finite-state machines, or task-style loops over long blocking delay() chains.
   • Isolate pure logic so it can be unit-tested without hardware.
   • Add serial diagnostics that help first power-on, but avoid unbounded serial spam.
   • Use compile-time flags or config constants for optional hardware and verbose logging.

5. Define a verification ladder before finishing.

   • Smoke test: compile, upload, and confirm a minimal heartbeat or serial log.
   • Functional test: verify each sensor, bus, actuator, and failure path.
   • For PlatformIO projects, include build, upload, monitor, and test steps.
   • If the board supports debugging, include a debug plan and probe assumptions.
   • If the board does not support practical source-level debugging, fall back to serial tracing, staged bring-up, and smaller test sketches.

6. Deliver complete output.

   • firmware files
   • wiring table / pin map
   • library or dependency list
   • board/toolchain assumptions
   • first power-on checklist
   • test plan
   • troubleshooting notes for the most likely failure modes

Board-family rules

Load references/board-families.md for full details. Minimum awareness without loading the reference:

• Classic AVR: tight RAM/flash; avoid String abuse and large buffers; D0/D1 are serial-sensitive.
• Renesas R4: not a faster AVR; check USB behavior, timers, analog resolution, and extra peripherals.
• ESP32-based: 3.3V logic; be explicit about radio constraints and boot-sensitive pins.
• Native USB: while (!Serial) {} blocks autonomous boot; serial port can disappear on reset.

Review checklist

• board target is explicit
• toolchain is explicit (Arduino IDE 2, Arduino CLI, or PlatformIO)
• pin map in code matches pin map in docs
• analog/digital assumptions are documented
• power and voltage-domain notes are present
• blocking delay() use is justified or removed
• optional hardware is behind flags or clearly separated
• first bring-up and troubleshooting path exists
• PlatformIO config, if present, matches the board and monitor assumptions
• library and dependency versions are pinned when reproducibility matters

Output rules

• Do not claim portability across boards when using board-specific pins.
• Do not invent a PlatformIO board ID, upload protocol, or debugger choice.
• Do not scatter GPIO numbers through the code.
• Do not leave voltage-domain assumptions implicit.
• Do not recommend powering motors, servos, relays, or LED strips directly from a board pin.
• Call out when serial debugging may fail because of board/port selection, driver issues, baud mismatch, native USB resets, or while (!Serial) {}.
• For Uno R4 WiFi, mention board-specific caveats when they matter: Qwiic is 3.3V on Wire1, HID can change the USB port, and direct ESP32 programming can break the default bridge firmware.
• If a sensor needs protection or signal conditioning, say so clearly.
• Pin library versions in dependency lists and lib_deps when the project needs reproducibility.

When to load references

• Load references/project-patterns.md for project shape, architecture, OTA guidance, bring-up flow, and deliverables.
• Load references/pin-planning.md when assigning GPIOs, documenting wiring, or checking bus and voltage constraints.
• Load references/board-families.md when selecting a board, comparing families, or explaining board-specific caveats.
• Load references/platformio-testing-debugging.md when the request mentions PlatformIO, tests, upload issues, serial monitor issues, or debugging.

Resources

references/

• references/project-patterns.md — project intake, architecture, deliverable bundles, and first-power-on workflow.
• references/pin-planning.md — GPIO planning, voltage-domain checks, bus mapping, and wiring-output format.
• references/board-families.md — practical differences between AVR, R4, ESP32-based, and native-USB Arduino targets.
• references/platformio-testing-debugging.md — PlatformIO structure, migration guidance, unit testing, debugging, and troubleshooting.