PSA: Elegoo Centauri Carbon & GPL Compliance

📌 The Issue

The Elegoo Centauri Carbon 3D printer uses a heavily modified version of Klipper firmware, specifically based on a commit 616 commits past v0.9.1 (shorthash 28f60f7e). Klipper is licensed under GPL-3.0, which legally requires all modifications to be made publicly available.

          Why this matters: GPL compliance isn't optional—it's
          a legal requirement. When companies use open-source software, they
          must respect the licenses. This ensures transparency, security, and
          the right for users to modify and improve their own devices.
        

Current Status: Despite clear evidence and community pressure since August 7, 2025, Elegoo has only provided generic support responses stating the issue is "under review by R&D."

🔍 Technical Evidence

Community investigation by user Sims revealed multiple pieces of evidence:

DSP MCU Firmware: Binary analysis shows clear Klipper MCU code paths. The DSP (part of Allwinner SoC) uses Xtensa architecture, which mainline Klipper doesn't support—proving modifications.
Bed MCU: Contains commands not present in mainline Klipper, indicating custom modifications.
Host Software: The main application at /app/app is C++, but contains transpiled Python code from Klipper's Klippy host, with references still intact.
Version Detection: Mainline Klipper can connect to the bed board but shuts down due to version mismatch, revealing the exact commit being used.

Note: While open-sourcing may be challenging due to Allwinner and Chitu involvement, other manufacturers like Creality have solved this by releasing source code alongside binary blobs for proprietary components.

🏢 Industry Context

Unfortunately, Elegoo isn't alone in GPL violations. Several major 3D printer manufacturers have similar issues:

Anycubic: KobraOS on 2.x and 3.x series violates GPL on multiple libraries including Klipper
Multiple vendors: Using modified Linux kernel, Entware, and other GPL software without source release

          The Solution: The 3D printing community needs to
          hold manufacturers accountable. GPL violations harm innovation,
          security, and user rights across the entire ecosystem.
        

🤝 Community Support

The community has rallied behind this issue with overwhelming support:

38 👍
Discord reactions

25+
Community members actively supporting

Multiple
Email requests sent

100%
Community agreement

Notable Community Quotes:

"Everyone including elegoo is required to stick to licensing rules. It's clearly Klipper under the hood so it has to be made available"

"Taking opensource projects and calling them your own is super scummy"

"If you take opensource software that's licensed under GPL-3.0, modify it and then not allow people to see the code, you're violating the license and are very easy to sue."

🙏 Special Thanks to Our Contributors

This community effort wouldn't be possible without the dedication and expertise of numerous individuals. We extend our heartfelt gratitude to everyone who has contributed to this important cause:

This is what open-source community looks like: Technical experts, concerned users, and advocates working together to protect everyone's rights. Every contribution, from detailed technical analysis to simple support messages, has been valuable in building this case.

🔬 Technical Analysis & Investigation

Sims (HACC) - Original researcher who identified the GPL violation, performed binary analysis, and provided detailed technical evidence
Rabir (HACC) - Verified that mainline Klipper can connect to the bed board, confirming version details
Kvviingu - Performed network traffic analysis showing excessive data usage
LA3QMA-KGB - Conducted tcpdump analysis to understand network behavior
erica - Provided technical insights on network traffic and security implications

✉️ Active Advocacy & Communication

Mikufan39s - Emailed Elegoo multiple times, shared responses, persistent follow-up
Anna | DevMiner (HACC) - Daily pings to Elegoo staff, strong GPL advocacy, community coordination
EXEN - Emailed Elegoo, tagged support staff, actively supported the cause
Marcel | CC (HACC) - Emailed Elegoo and shared identical response patterns
beiyr (HACC) - Daily pings to Elegoo staff, consistent support

💪 Community Support & Awareness

Lamarc | N4 | CC (HACC) - Full support, noted industry compliance issues
leiden6665 - Early recognition of GPL requirements, mentioned the issue before
Fabrizio | N4 - Clear support for source code release
coffeecup - Supported open source compliance
Delulu Delilah - 100% support for the request
zuturiddu - Full support for license adherence
nate™ (DVNO) - Co-signed the request

📚 Industry Context & Legal Insights

Corey Stup - Provided context about Anycubic's similar GPL violations
Motorhead1991 - Noted this has been mentioned before, highlighted other GPL violations (Linux kernel, Entware)
baconmilkshake (AHI) - Provided reasonable explanations and security concerns about outdated firmware
legionasaurus (HACC) - Commented on legal expert aspects
crazyantihacker - Raised awareness about related network traffic issues

Special Recognition: Owen (Technical Support) from Elegoo deserves credit for being the only Elegoo employee to acknowledge the issue directly and provide a timeline, showing that constructive dialogue is possible.

Community Moderators & Platform Providers:

YogurtDrink | Resin / CC - Clarified community roles and helped direct requests to appropriate Elegoo employees
Chirimorin | CC, N4Pro, S4U - Provided context on network traffic analysis

To everyone listed above and the many others who have supported this effort: Your collective voice has turned a single technical observation into a powerful community movement. This is exactly how open-source communities should work—together, transparently, and with respect for the legal frameworks that protect everyone's rights.

📧 Elegoo's Response

Community members have received mostly identical canned responses from Elegoo support:

Typical Response:

"We have submitted the relevant information to our Research and Development (R&D) team... We will get back to you as soon as we have relevant results. Thank you for your patience."

— Multiple Elegoo Support Representatives

However, one community member received a different response suggesting Elegoo believes they are "not supposed to comply with legal requirements"—a concerning stance for a company using GPL software.

Owen (Elegoo Technical Support) mentioned there "should be a response in a day or two" as of August 12, 2025, but no concrete action has been taken yet.

📢 What You Can Do

If you own a Centauri Carbon, care about open-source rights, or want to support legal compliance in the 3D printing industry, you can help by politely but firmly requesting Elegoo release the source code.

Email Elegoo Support:

Use this template to contact Elegoo directly. The more people who reach out, the more likely they are to take action:

Subject: Request for GPL Compliance – Centauri Carbon Firmware Dear Elegoo Support Team, I am writing regarding the Elegoo Centauri Carbon 3D printer and its firmware's GPL compliance obligations. BACKGROUND: It has been conclusively determined that the Centauri Carbon firmware is based on Klipper (commit 616 past v0.9.1, shorthash 28f60f7e), which is licensed under GPL-3.0. Community analysis has revealed: • Modified DSP MCU firmware with Klipper code paths • Custom bed MCU firmware with non-standard commands • Transpiled Klippy host code (Python to C++) with original references intact • Version strings that confirm the exact Klipper commit used LEGAL REQUIREMENT: Under GPL-3.0, all modifications to licensed code must be made available to users. This is not a request—it is a legal obligation that applies regardless of business preferences or technical challenges. REQUEST: I respectfully but firmly request that Elegoo immediately release the complete modified source code for: 1. DSP MCU firmware (Xtensa architecture modifications) 2. Bed MCU firmware with custom commands 3. Host-side Klippy code (C++ transpiled version) 4. Any other GPL-licensed components used in the system PRECEDENT: Other manufacturers like Creality have successfully handled similar situations by releasing source code alongside binary blobs for proprietary components where necessary. I expect a concrete timeline for source code release, not generic "under review" responses. The 3D printing community is watching how Elegoo handles this legitimate compliance request. Thank you for your prompt attention to this legal matter. Sincerely, [Your Name] [Your Contact Information]

Other Ways to Help:

Share this page with other Centauri Carbon owners
Join the discussion on Reddit, Discord, and 3D printing forums
Support open-source alternatives like mainline Klipper
Consider manufacturers who properly respect open-source licenses when making future purchases

🎯 Expected Outcomes

If Elegoo complies with the GPL license (as they legally must), users will gain:

Security updates: Community can patch vulnerabilities
Feature improvements: Open development enables innovation
Hardware longevity: Continued support even after EOL
Transparency: Users know exactly what's running on their devices
Learning opportunities: Study and understand the firmware

Consequences of Non-Compliance: GPL violations are legally enforceable. The community has both the right and standing to pursue legal action if necessary, though everyone hopes Elegoo will simply do the right thing voluntarily.