How to use Codex to repair projector firmware
A hobbyist used Codex to diagnose incompatible HDMI-CEC controller firmware, rewrite and test it, and upload it over the air through an ESPHome-connected setup.
news.ycombinator.com
Prompt to try
Editorial adaptation, not the source author’s exact prompt. Replace bracketed inputs and review tool permissions first.
Investigate why [HDMI-CEC controller] firmware connected to [ESPHome setup] fails with [projector model]. Diagnose the incompatibility, propose and implement a firmware fix, test it against [device behavior], and prepare an over-the-air upload for my review.
Reach people exploring AI agents
See placements →What happened
The author reports that Codex diagnosed the controller issue, rewrote and tested the firmware, and uploaded it over the air while they waited in a store.
Reported by nickthegreek on Hacker NewsHow the agent did it
- Diagnosed the controller firmware incompatibility with the PX3-pro.
- Rewrote the firmware to address the diagnosed issue.
- Tested the rewritten firmware before deployment.
Where a person stepped in
The author directed the work from a phone; the post does not describe a separate human firmware review.
A person set the goal and reviewed the result.
A homelab hobbyist described using Codex to repair firmware for an HDMI-CEC controller connected to ESPHome. They had bought the controller for their projector, but its firmware did not work with the PX3-pro. Codex diagnosed the issue, rewrote the firmware, tested it, and uploaded it over the air. The author directed this work from their phone while waiting in line at a store.
The repair was one example of a broader pattern of giving coding agents access to homelab systems. The author also reported using Codex to find duplicate photos across multiple Immich user libraries and quarantine them, a task their Immich setup only supported within a single user library. In another photo task, Codex located old grid-based images, wrote software to convert them into animated WebP images, and handled the conversion.
Codex also reviewed the Immich setup and recommended changes to the CLIP model and backup strategy. The post reports firmware testing but does not describe the test procedure or a separate human review before upload. Who it's for: homelab hobbyists who can provide device access and supervise changes to their own equipment.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Hacker News · nickthegreek
Frequently asked questions
What controller problem did Codex address?
The author said their HDMI-CEC controller firmware did not work with the PX3-pro projector. Codex diagnosed the issue and rewrote, tested, and uploaded the firmware over the air.
Did the author work from a desktop computer?
The author reported completing the firmware work from their phone while waiting in line at a store.
More details
Remaining steps
- Uploaded the firmware to the controller over the air.
About this account
Codex performed diagnosis, rewriting, testing and the over-the-air firmware upload.
Platform: Hacker News. Attribution: https://news.ycombinator.com/item?id=49541723. Prompt: Suggested (written by Agents In Use, not the author's). Sourced by the Agents In Use pipeline.
Credit: nickthegreek on Hacker News
Source published 2 Sept 2026
Source checked 14 Oct 2026
Tools and topics
Codex · ESPHome · HDMI-CEC controller
Firmware · Homelab · ESPHome
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.