Individual skill

atmega32u4-beetle

Firmware development for the Beetle — the CJMCU / DFRobot "Mini Arduino Leonardo" USB board (ATmega32U4 @ 16 MHz, 5 V, 21×28 mm, castellated pads) — its native USB (CDC serial + HID keyboard/mouse/joystick), Caterina bootloader and 1200 bps touch upload, ten exposed I/O pads, four PWM pins across Timer0/Timer1, five ADC channels, I2C on D2/D3, SPI on the back-side ICSP pads, 28 KB usable flash and 2.5 KB SRAM, and the PlatformIO + Arduino AVR core (`board = leonardo`) setup around them. Use when working on this board or any ATmega32U4 Leonardo/Micro/Pro-Micro-class clone: project setup, platformio.ini, why the board shows up as two different serial ports, uploads that fail or hang, recovering a bricked or HID-spamming board by shorting the ICSP reset pads, pin mapping and which pads are missing, PWM/timer conflicts, Servo and tone, USB HID keyboard projects, the SRAM budget, powering from the + pad, or debugging why something on the board does not work.

skills/avr/atmega32u4-beetle/SKILL.md

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Last checked: Nov 11, 2026

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Repository stars (not skill ratings): 27
Repository last updated: Oct 30, 2026
License: MIT

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agentic-ai Repository topic
arduino Repository topic
claude-code Repository topic
esp32 Repository topic
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SKILL.mdcore · 19,718 bytes
SKILL.mdcore · 19,718 bytes
assets/IMAGE.mddoc · 448 bytes
reference/board-hardware.mddoc · 33,332 bytes
reference/recipes.mddoc · 18,735 bytes
template/.gitignoreasset · 13 bytes
template/README.mddoc · 4,609 bytes
template/include/board.hasset · 6,366 bytes
template/platformio.iniasset · 1,565 bytes
template/src/main.cppasset · 4,091 bytes
template/variants/hid/main.cppasset · 3,123 bytes
template/variants/minimal/main.cppasset · 1,019 bytes
template/variants/new-project.shruns · 1,703 bytes

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# Beetle — Mini Arduino Leonardo (ATmega32U4)

Board-specific firmware knowledge. The Beetle is an ATmega32U4 with **native
USB** and **ten pads**, and almost every trap on it comes from one of those
two facts: USB means the programming interface is the sketch you are about
to replace, and ten pads means most of the Leonardo pin numbering the
compiler accepts goes nowhere on this board.

- `reference/board-hardware.md` — the complete board reference: pad
  inventory and full pin map, the sixteen I/O lines that are not brought
  out, power tree, clock and PLL, memory map, fuses and the Caterina
  bootloader **plus** a development guide (Part II: §8 toolchain, §9 USB and
  the two serial ports, §10 peripheral cookbook, §11 gotchas, §12 flashing
  and recovery, §13 symptom → cause → fix table).