ymodem-xmodem-integration

ymodem-xmodem-integration is a skill for Claude Code, Codex from easyzoom/aix-skills. It costs 43 tokens per session (694 once invoked), scanned A, original, MIT.

An integration guide for XMODEM and YMODEM, serial file-transfer protocols often used to send firmware through a bootloader or maintenance console.

In plain words
What is it for?
Use it to build or debug serial firmware downloads over UART or USB serial, including packet handling, CRC checks, timeouts, and safe flash writing.
Why use it?
It helps prevent transfer timeouts, checksum errors, incorrect image sizes, failed packet negotiation, and firmware updates that leave a device unable to boot.

Skill for Claude CodeCodex

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

Good fit Use it to build or debug serial firmware downloads over UART or USB serial, including packet handling, CRC checks, timeouts, and safe flash writing.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/easyzoom/aix-skills/ymodem-xmodem-integration
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 ymodem-xmodem-integration
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 ymodem-xmodem-integration

README.md
[![agentmods](https://agentmods.dev/badge/skills/easyzoom/aix-skills/ymodem-xmodem-integration/github.svg)](https://agentmods.dev/skills/easyzoom/aix-skills/ymodem-xmodem-integration)
Your own site
<a href="https://agentmods.dev/skills/easyzoom/aix-skills/ymodem-xmodem-integration"><img src="https://agentmods.dev/badge/skills/easyzoom/aix-skills/ymodem-xmodem-integration/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for ymodem-xmodem-integration

Your own site · 80×15
<a href="https://agentmods.dev/skills/easyzoom/aix-skills/ymodem-xmodem-integration"><img src="https://agentmods.dev/badge/skills/easyzoom/aix-skills/ymodem-xmodem-integration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 694 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 $0.00043 $0.00694
Opus 5 $0.00022 $0.00347
Sonnet 5 $0.00009 $0.00139
Haiku 4.5 $0.00004 $0.00069

Measured 8d ago against content hash 9b65cebd3448, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

ymodem-xmodem-integration 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/ymodem-xmodem-integration/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

YMODEM XMODEM Integration

Overview

Use this skill for serial file-transfer protocols in bootloaders or maintenance consoles. Separate transport reliability, packet parsing, CRC/checksum, flash layout, and update safety before writing firmware to flash.

When To Use

Use this skill when:

  • The user wants to add or debug XMODEM/YMODEM firmware update over UART, USB CDC, or shell.
  • Transfers timeout, abort, fail CRC, write wrong file size, brick after update, or hang at C/NAK negotiation.
  • The task involves bootloader app download, serial protocol state machines, packet size, CRC16, SOH/STX/EOT/CAN, or flash programming.

Do not use this skill for general serial logging. Use embedded-serial-log-debug first if RX/TX is unreliable.

First Questions

Ask for:

  • Protocol: XMODEM, XMODEM-CRC, XMODEM-1K, YMODEM, or YMODEM batch.
  • Transport, baud, flow control, timeout, and terminal sender tool.
  • Bootloader/application flash layout and maximum image size.
  • CRC/checksum mode and packet size.
  • Whether current firmware/recovery image must be preserved.
  • Current transfer log or packet trace.

Integration Checklist

  1. Prove serial transport. Verify raw RX/TX at the target baud before protocol debugging.

  2. Implement protocol states explicitly. Negotiation, header, data packets, ACK/NAK, EOT, CAN abort, retry limit, and timeout should be visible in logs.

  3. Validate file metadata. For YMODEM, parse filename and size. Reject images larger than the allowed slot.

  4. Write flash safely. Erase only the intended slot, program aligned chunks, verify CRC/hash, and preserve bootloader/recovery areas.

  5. Commit update last. Mark the image bootable only after full transfer and verify succeed.

  6. Test abort and power loss. Ensure failed transfers do not leave the product without a bootable image.

Common Failures

  • Sender uses checksum mode while receiver expects CRC mode.
  • Packet sequence number or complement validation is skipped.
  • 1K packets overflow a small receive buffer.
  • Flash erase starts before image size and slot are validated.
  • EOT handling completes before final flash sync/verify.
  • Failed transfer marks a bad image as bootable.

Read the full file on GitHub · 85 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 · 85 lines · 43 tokens per session scan A 9b65cebd3448

Subscribe to this mod's changes

ymodem-xmodem-integration is a skill published in the GitHub repository easyzoom/aix-skills (31 stars, last pushed 1mo ago), licensed MIT. It adds 43 tokens to every session and 694 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 2026-09-03.