DCP: a complementary protocol for LLM-driven hardware control at MCU scale

[WaylandYang]

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Hi folks —
Made this and figured this crowd might want to see it:

https://github.com/device-context-protocol/dcp

Short version. I had a local LLM running on a workstation and a drawer of ESP32s. Every path I tried for "let the model dim the lamp" turned into custom Python middleware with no schema and no safety. Compiling MCP itself onto a WROOM-32 wasn't going to fit. So I wrote DCP: keep MCP's mental model (manifest, tool calls, capability scopes) but the wire format is a 6-byte header + a CBOR map, and the intent table is closed at compile time. A typical call is 19 bytes. The firmware is about 14 KB of code on the MCU.

Not a fork. The reference Bridge speaks MCP to the LLM and DCP to the device, so Claude Desktop sees normal tools and the device sees a tiny binary frame. The two protocols stack — the Bridge translates and enforces the safety side (range / unit / capability / dry-run) before the wire.

Where it actually is right now:

• Validated on ESP32-WROOM-32 over UART, 13/13 round-trip tests pass
• Cross-compiles unchanged for ESP32-C3 / C6 / H2 / P4 — same firmware library, no #ifdef for any of them
• pip install pydcp, 12-page paper draft included in the repo

Three things I'd value feedback on if anyone has the time:

1. Does the "downstream consumer of MCP, not a competitor" framing read cleanly to you? I'd rather hear what wording you'd prefer for the README now than have it land wrong on the MCP project later.

2. Has there been any internal talk about a downstream / embedded profile of MCP itself? If so this might be useful as input, or as a precursor that gets absorbed.

3. Confirming my read of the 2026 roadmap: SaaS-tool scaling, not MCU-class hardware. If I've misread that and there's overlap I should know about, please tell me.

Other links if useful: SPEC.md, design rationale (covers why-not-WoT / Matter / Sparkplug-B / OpenAPI), 5-step add-a-feature walkthrough, paper PDF.

MIT.

Relevant Links

• Repo (MIT): https://github.com/device-context-protocol/dcp
• PyPI: https://pypi.org/project/pydcp/
• Paper draft (12 pages, PDF): https://github.com/device-context-protocol/dcp/releases/download/v0.3.0/main.pdf
• Spec: https://github.com/device-context-protocol/dcp/blob/main/SPEC.md
• Design rationale: https://github.com/device-context-protocol/dcp/blob/main/docs/RATIONALE.md