embedded-fault-debug

embedded-fault-debug is a skill for Claude Code, Codex from easyzoom/aix-skills. It costs 31 tokens per session (970 once invoked), scanned A, original, MIT.

A troubleshooting guide for crashes and unexpected resets in embedded firmware, the software running on devices such as microcontrollers. It focuses on preserving crash details and finding the first failing instruction.

In plain words
What is it for?
Use it for HardFaults, traps, illegal instructions, watchdog resets, default handlers, hangs, and crashes with logs, register dumps, backtraces, or ELF/MAP files.
Why use it?
It helps separate the original fault from later symptoms by examining registers, stack data, addresses, and matching program symbols before resetting the device.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it for HardFaults, traps, illegal instructions, watchdog resets, default handlers, hangs, and crashes with logs, register dumps, backtraces, or ELF/MAP files.

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Install with agentmods
npx agentmods add skills/easyzoom/aix-skills/embedded-fault-debug
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add easyzoom/aix-skills --skill embedded-fault-debug
Clone the repo
git clone --depth 1 https://github.com/easyzoom/aix-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for embedded-fault-debug

README.md
[![agentmods](https://agentmods.dev/badge/skills/easyzoom/aix-skills/embedded-fault-debug.svg)](https://agentmods.dev/skills/easyzoom/aix-skills/embedded-fault-debug)
Your own site
<a href="https://agentmods.dev/skills/easyzoom/aix-skills/embedded-fault-debug"><img src="https://agentmods.dev/badge/skills/easyzoom/aix-skills/embedded-fault-debug.svg" alt="Measured on agentmods" height="20"></a>
Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 970 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00031 $0.00970
Opus 5 $0.00015 $0.00485
Sonnet 5 $0.00006 $0.00194
Haiku 4.5 $0.00003 $0.00097

Measured 8d ago against content hash 0d579511f272, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

embedded-fault-debug scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/embedded-fault-debug/SKILL.md · 131 lines

How it starts

The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Embedded Fault Debug

Overview

Use this skill to preserve crash evidence and find the first failing instruction. The agent should read architecture-specific fault state before reset, map addresses to symbols, and separate root cause from secondary symptoms.

When To Use

Use this skill when:

  • Firmware hits HardFault, BusFault, UsageFault, trap, illegal instruction, default handler, watchdog reset, assert, or panic.
  • The board resets unexpectedly or hangs after a repeatable action.
  • The user has a register dump, fault log, crash PC, stack dump, watchdog event, or GDB backtrace.

Do not use this skill when the target cannot yet connect or flash; use mcu-flashing-debug first.

First Questions

Ask for:

  • Architecture/chip family and toolchain.
  • Exact symptom and whether it is reproducible.
  • Register dump, backtrace, fault/trap registers, assert log, or reset reason.
  • ELF/MAP file that matches the running image.
  • Whether the target has been reset since the fault.

Workflow

  1. Preserve state. Do not reset or reflash until fault registers, PC, LR/RA, SP, and stack frame are captured.

  2. Confirm image-symbol match. Ensure the ELF/MAP file matches the firmware currently running on target.

  3. Identify the faulting address. Map PC, exception return address, mepc, stacked PC, or return address to a symbol and source line.

  4. Classify the cause. Separate invalid memory access, illegal instruction, stack overflow, alignment, bus/peripheral access, watchdog, assert, and default handler cases.

  5. Walk backward to the first bad state. Inspect caller, input pointers, stack bounds, interrupt context, DMA/cache interactions, and recent initialization.

  6. Add a focused verification. Use a watchpoint, assertion, guard pattern, stack watermark, or minimal repro to prove the suspected cause.

Architecture Notes

Cortex-M

Read SCB fault registers before reset:

CFSR  = 0xE000ED28
HFSR  = 0xE000ED2C
MMFAR = 0xE000ED34
BFAR  = 0xE000ED38

Read the full file on GitHub · 131 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 131 lines · 31 tokens per session scan A 0d579511f272

Subscribe to this mod's changes

embedded-fault-debug is a skill published in the GitHub repository easyzoom/aix-skills (31 stars, last pushed 1mo ago), licensed MIT. It adds 31 tokens to every session and 970 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.