Agent skill

Embedded Debug

Firmware crash analysis, stack trace decoder, and register dump interpreter for ESP32/ARM/AVR platforms.

MITAuto-check passedDevelopment

Install Embedded Debug

skills CLI

$ npx skills add FastLED/FastLED --skill embedded-debug -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install FastLED/FastLED embedded-debug --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/FastLED/FastLED.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/embedded-debug .claude/skills/embedded-debug && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "embedded-debug" agent skill from https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug into .claude/skills/embedded-debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "embedded-debug", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add FastLED/FastLED --skill embedded-debug -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install FastLED/FastLED embedded-debug --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/FastLED/FastLED.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/embedded-debug .agents/skills/embedded-debug && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "embedded-debug" agent skill from https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug into .agents/skills/embedded-debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "embedded-debug", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add FastLED/FastLED --skill embedded-debug -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install FastLED/FastLED embedded-debug --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/FastLED/FastLED.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/embedded-debug .cursor/skills/embedded-debug && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "embedded-debug" agent skill from https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug into .cursor/skills/embedded-debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "embedded-debug", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/FastLED/FastLED.git --path .claude/skills/embedded-debug

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add FastLED/FastLED --skill embedded-debug -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install FastLED/FastLED embedded-debug --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/FastLED/FastLED.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/embedded-debug .gemini/skills/embedded-debug && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "embedded-debug" agent skill from https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug into .gemini/skills/embedded-debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "embedded-debug", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install FastLED/FastLED embedded-debug

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add FastLED/FastLED --skill embedded-debug -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/FastLED/FastLED.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/embedded-debug .github/skills/embedded-debug && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "embedded-debug" agent skill from https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug into .github/skills/embedded-debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "embedded-debug", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add FastLED/FastLED --skill embedded-debug -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install FastLED/FastLED embedded-debug --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/FastLED/FastLED.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/embedded-debug .opencode/skills/embedded-debug && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "embedded-debug" agent skill from https://github.com/FastLED/FastLED/tree/master/.claude/skills/embedded-debug into .opencode/skills/embedded-debug/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "embedded-debug", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: embedded-debug
GitHub stars: 7.5k
Token cost: ~1.4k tokens
SKILL.md length: 539 words
Files: 1
Skills in repo: 23
Repo updated: Oct 7, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Firmware crash analysis, stack trace decoder, and register dump interpreter for ESP32/ARM/AVR platforms.

Works in 5 steps: Crash Analysis: Parse panic handlers,… → Stack Trace Decoding: Decode raw… → Register Dump Interpretation: Analyze… → …
Debugging device crashes
SKILL.md covers What This Skill Does, Supported Platforms, How To Use and What You'll Get, plus 1 more section
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Embedded Debug is an agent skill from FastLED/FastLED. Firmware crash analysis, stack trace decoder, and register dump interpreter for ESP32/ARM/AVR platforms. Use when debugging device crashes, panics, guru meditation errors, hard faults, or analyzing core dumps.

Its SKILL.md is about 1.4k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Embedded systems, Debugging and Health and fitness tracking. It works with ESP32. The repository describes itself as: The FastLED library for colored LED animation on Arduino. Please direct questions/requests for help to the FastLED Reddit community: http://fastled.io/r We'd like to use github… The licence is MIT.

When your agent uses it

Debugging device crashes
Guru meditation errors
Analyzing core dumps

Example prompts

“/embedded-debug”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

Crash Analysis: Parse panic handlers, guru meditation errors, hard faults, watchdog resets
Stack Trace Decoding: Decode raw addresses to function names using ELF binaries
Register Dump Interpretation: Analyze CPU register state at crash time
Root Cause Identification: Correlate crash data with source code to find the bug
Fix Recommendations: Suggest specific code changes to prevent the crash

What it can do on your machine

Read from SKILL.md and the folder at commit 8d6ed12. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are c and bash).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Embedded Debug loads about 1.4k tokens when it runs. Until then it costs about 56 tokens; SKILL.md has 539 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~56
When it runs · the whole SKILL.md, loaded when a task matches: ~1.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from FastLED/FastLED at commit 8d6ed12, republished under its MIT licence (© FastLED). 539 words, ~1,381 tokens.

Download SKILL.mdSave it as .claude/skills/embedded-debug/SKILL.md (or your agent's skills folder).

name: embedded-debug
description: Firmware crash analysis, stack trace decoder, and register dump interpreter for ESP32/ARM/AVR platforms. Use when debugging device crashes, panics, guru meditation errors, hard faults, or analyzing core dumps.
argument-hint: <crash output or description of the issue>
context: fork
agent: embedded-debug-agent

Analyze firmware crash output, decode stack traces, and diagnose embedded system failures.

$ARGUMENTS

What This Skill Does

Crash Analysis: Parse panic handlers, guru meditation errors, hard faults, watchdog resets
Stack Trace Decoding: Decode raw addresses to function names using ELF binaries
Register Dump Interpretation: Analyze CPU register state at crash time
Root Cause Identification: Correlate crash data with source code to find the bug
Fix Recommendations: Suggest specific code changes to prevent the crash

Supported Platforms

Platform	Crash Types
ESP32 (all variants)	Guru Meditation, LoadProhibited, StoreProhibited, InstrFetchProhibited, watchdog reset, brownout, cache errors
ARM Cortex-M (STM32, Teensy, nRF)	HardFault, MemManage, BusFault, UsageFault, watchdog reset
AVR (Arduino Uno/Mega)	Stack overflow (silent corruption), watchdog reset, undefined opcode
RISC-V (ESP32-C3/C6/H2)	Illegal instruction, load/store fault, breakpoint

How To Use

With crash output

/embedded-debug
Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.
Core 0 register dump:
PC      : 0x400d1234  PS      : 0x00060030  A0      : 0x800d5678
...

With a description

/embedded-debug Device reboots every 30 seconds, serial shows "rst:0x3 (SW_RESET)"

With a core dump

/embedded-debug Analyze the core dump from the last crash

What You'll Get

Decoded stack trace with source file and line numbers
Explanation of the crash type and what triggered it
Identification of the faulty code path
Specific fix recommendations with code examples
Prevention strategies (stack size tuning, watchdog config, null checks)

ESP32 Crash Quick Reference

Exception Type → Root Cause

Exception	EXCVADDR hint	Likely Root Cause
`LoadProhibited`	~0x00000000	NULL pointer dereference (uninitialized LED strip?)
`LoadProhibited`	Other	Read from freed or out-of-bounds memory
`StoreProhibited`	Any	Write to read-only or invalid memory address
`InstrFetchProhibited`	Any	Jump to invalid/NULL function pointer or corrupt vtable
`IllegalInstruction`	Any	Stack overflow corrupting code, or corrupt heap
`IntegerDivideByZero`	N/A	Division by zero in LED index math
`Unaligned`	Any	Misaligned memory access (DMA buffer not 4-byte aligned)
`Cache disabled but cache memory range accessed`	Any	ISR accessing flash — add `IRAM_ATTR` to ISR function

Key Register Meanings (ESP32 Xtensa)

Register	Meaning
`PC`	Program Counter — where the crash happened
`EXCVADDR`	Address that caused the fault (NULL pointer, invalid write target)
`A1`	Stack pointer — compare to task stack base to detect overflow
`A0`	Return address — calling function

Show full SKILL.md (224 more words)Show less

ISR Violation Pattern

Symptoms: Cache disabled but cache memory range accessed or crash inside FreeRTOS API

Cause: FastLED ISR handler calling blocking or flash-accessing code.

Diagnosis: Look for crash inside xSemaphoreTake, vTaskDelay, printf, or any non-ISR-safe function.

Fix:

Add IRAM_ATTR to all ISR-related functions
Replace blocking calls with ISR-safe variants (xSemaphoreGiveFromISR, xQueueSendFromISR)
Move logging out of ISR to a deferred task

Watchdog Reset Pattern

Symptoms: rst:0x7 (TG0WDT_SYS_RESET) or rst:0x8 (TG1WDT_SYS_RESET)

Cause: Task or interrupt handler not yielding — common with:

FastLED show() blocking on DMA in a task with watchdog enabled
High LED counts causing long encoding loops without yield
Spinning in a loop without vTaskDelay(0) or taskYIELD()

Fix:

Call esp_task_wdt_reset() in long loops, or
Move FastLED show() to a dedicated task exempt from watchdog, or
Reduce LED count to bring encoding time under watchdog timeout

Stack Overflow Pattern

Symptoms: StackOverflow + task name, or IllegalInstruction with A1 near stack limit

Diagnosis: Check task stack size in xTaskCreate or xTaskCreatePinnedToCore. FastLED show() with large LED arrays can use significant stack.

Fix: Increase task stack size (minimum 4096 bytes for tasks calling FastLED show with encoding)

Memory Corruption Pattern

Symptoms: IllegalInstruction at random address, corrupted register values, intermittent crashes

Diagnosis: Enable diagnostics:

// In sdkconfig or menuconfig:
CONFIG_HEAP_POISONING_COMPREHENSIVE=y
CONFIG_HEAP_TASK_TRACKING=y
CONFIG_FREERTOS_WATCHPOINT_END_OF_STACK=y

Common FastLED Cause: Writing past end of CRGB array (index out of bounds in user sketch)

Backtrace Decoding Commands

bash

# ESP32 (Xtensa)
xtensa-esp32-elf-addr2line -pfiaC -e build/firmware.elf 0xADDR1 0xADDR2

# ESP32-S3
xtensa-esp32s3-elf-addr2line -pfiaC -e build/firmware.elf 0xADDR1

# ESP32-C3/C6 (RISC-V)
riscv32-esp-elf-addr2line -pfiaC -e build/firmware.elf 0xADDR1

# Live decode via idf.py
idf.py -p /dev/ttyUSB0 monitor

Files

Just SKILL.md in .claude/skills/embedded-debug of FastLED/FastLED.

Open the folder on GitHubat commit 8d6ed12

Compare with similar skills

Embedded Debug next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Embedded Debug compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Embedded Debug this skillFastLED/FastLED	7.5k	—	~1.4k	Automated safety check: Pass	MIT	today
Commodore64 Vice Debuggingidolpx/meatloaf	128	—	~4.8k	Automated safety check: Pass	GPL-3.0	yesterday
C64 Meatloaf Debugidolpx/meatloaf	128	—	~12k	Automated safety check: Pass	GPL-3.0	yesterday
Meatloaf Networkingidolpx/meatloaf	128	—	~7.1k	Automated safety check: Pass	GPL-3.0	yesterday
Embedded DebuggerAdancurusul/embedded-debugger-mcp	199	—	~1.4k	Automated safety check: Pass	MIT	2 mo ago
Dongle Crash Analysishaumacher/phoneblock	366	—	~1.9k	Automated safety check: Notes	GPL-3.0	4 days ago

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Questions about Embedded Debug

What does Embedded Debug do?

Firmware crash analysis, stack trace decoder, and register dump interpreter for ESP32/ARM/AVR platforms. Embedded Debug is an agent skill from FastLED/FastLED. Firmware crash analysis, stack trace decoder, and register dump interpreter for ESP32/ARM/AVR platforms.

When should I use Embedded Debug?

Embedded Debug fits situations like: debugging device crashes; guru meditation errors; analyzing core dumps.

How do I install Embedded Debug in Claude Code?

Run `npx skills add FastLED/FastLED --skill embedded-debug -a claude-code`. Or copy the skill folder (.claude/skills/embedded-debug in FastLED/FastLED) into .claude/skills/embedded-debug in your project. Claude Code loads it when a task matches its description.

How do I install Embedded Debug in Codex?

Run `npx skills add FastLED/FastLED --skill embedded-debug -a codex`. Or copy the skill folder (.claude/skills/embedded-debug in FastLED/FastLED) into .agents/skills/embedded-debug in your project. Codex loads it when a task matches its description.

Can I use Embedded Debug in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add FastLED/FastLED --skill embedded-debug -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/embedded-debug, .gemini/skills/embedded-debug, .github/skills/embedded-debug and .opencode/skills/embedded-debug in your project.

What does Embedded Debug need to run?

SKILL.md names no scripts, command-line tools or credentials: Embedded Debug is instructions for the agent only.

Does Embedded Debug access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Embedded Debug safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Embedded Debug use?

Embedded Debug is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Embedded Debug use?

About 1.4k tokens (SKILL.md is roughly 5.5k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Embedded Debug?

Skills that share tags, products or a category with Embedded Debug: Commodore64 Vice Debugging (idolpx/meatloaf, 128 stars), C64 Meatloaf Debug (idolpx/meatloaf, 128 stars), Meatloaf Networking (idolpx/meatloaf, 128 stars) and Embedded Debugger (Adancurusul/embedded-debugger-mcp, 199 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Embedded Debug?

FastLED (a GitHub organization) maintains it in FastLED/FastLED, which has 7,506 GitHub stars. The repository holds 23 skills in this directory. The repository was last updated on October 7, 2026.

Source: FastLED/FastLED on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Embedded Debug

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

What This Skill Does

Supported Platforms

How To Use

With crash output

With a description

With a core dump

What You'll Get

ESP32 Crash Quick Reference

Exception Type → Root Cause

Key Register Meanings (ESP32 Xtensa)

ISR Violation Pattern

Watchdog Reset Pattern

Stack Overflow Pattern

Memory Corruption Pattern

Backtrace Decoding Commands

Files

Compare with similar skills

Similar skills

More from FastLED/FastLED

Related

Questions about Embedded Debug