Ecoport bridge v1

EcoPort Bridge

EcoPort Bridge is a hobby reverse-engineering and hardware project to build a communication bridge for appliances using the CTA-2045 "EcoPort" interface (AC-form-factor UCM connector, RS-485 @ 19,200 baud) — starting with a Rinnai REHP65 heat pump water heater (CTA-2045-B / SGD, connector CN50, physical connector part 420B2V12FL0).

The goal is to expose the appliance's CTA-2045 data (tank temperature, setpoint, operating state, energy, demand-response/shed status, faults, etc.) to home automation systems (MQTT, Matter, Home Assistant) via a small ESP32-class bridge device, built on top of a Python implementation of the CTA-2045 protocol.

Rev A: ESP32-C6 board with an on-board mains supply, plugged straight into the heater's CTA-2045 connector. See hardware/rev-a for the board and hardware/enclosure for the 3D-printed case.

Design principles

• Generic CTA-2045 core, separate from appliance-specific logic. The cta2045 layer implements the protocol (framing, messages, CRC, link, Basic DR / Intermediate messages). Appliance-specific behavior (e.g. Rinnai REHP65 quirks and capability mappings) lives under appliances/rinnai (or a Rinnai crate in firmware) so other CTA-2045/EcoPort appliances can be supported later without untangling Rinnai assumptions from the protocol implementation.
• Protocol reverse engineering is kept separate from electrical reverse engineering. Most of the protocol can be worked out via the EPRI UCM simulator without ever touching the heater.
• Facts vs. hypotheses are recorded separately in docs/protocol.md and per-capture notes, so reverse-engineering guesses don't quietly turn into "the spec" later.
• Captures are first-class project artifacts. Raw captures + notes live under captures/ as a reproducible dataset, not a pile of Wireshark screenshots.

Architecture

                   ┌───────────────────────────────┐
                   │       Your application        │
                   │ Home Assistant / MQTT / etc.  │
                   └───────────────┬───────────────┘
                                   │
                         Python CTA-2045 API
                                   │
                   ┌───────────────▼───────────────┐
                   │       CTA-2045 protocol       │
                   │ link + Basic DR + Intermediate│
                   └───────────────┬───────────────┘
                                   │
                              RS-485 UART
                                   │
                   ┌───────────────▼───────────────┐
                   │       Isolated RS-485         │
                   │       transceiver             │
                   └───────────────┬───────────────┘
                                   │
                         CTA-2045 AC connector
                                   │
                   ┌───────────────▼───────────────┐
                   │       Rinnai REHP65           │
                   │          SGD / CN50           │
                   └───────────────────────────────┘

Hardware notes (confirmed)

• Physical connector: 420B2V12FL0 (EPRI's "UCM Connector")
• Only pins 1 (D-), 7 (D+), 8 (GND) are used; all other pins are left unconnected.
• EPRI documents 19,200 baud, 8 data bits, 1 stop bit, no parity.
• This is a mains-adjacent AC-form-factor interface — treat it with a deliberate electrical isolation strategy (isolated USB/RS-485 adapter).

See docs/hardware.md and docs/protocol.md for details, and captures/ for recorded traffic.

Repository layout

ecoport-bridge/
│
├── README.md
├── LICENSE             # AGPL-3.0 (software); hardware/LICENSE is CERN-OHL-S-2.0
├── CONTRIBUTING.md
│
├── docs/                 # architecture, hardware, protocol, HOWTOs
├── hardware/             # PCB revisions + 3D-printed enclosure
├── firmware/             # ESP32-C6 bridge firmware (Rust on ESP-IDF)
├── python/               # ecoport Python package (protocol + tooling)
├── tools/                # CLI tools: sniff, decode, query, interactive
├── captures/             # recorded protocol traffic + notes (EPRI + Rinnai)
├── test/                 # cross-cutting test fixtures/integration tests
└── scripts/              # dev setup / flashing helpers

Status

Early planning / hardware on order. See docs/reverse-engineering.md and captures/ as the project progresses.

Documentation

• docs/architecture.md — software layering and the device ↔ Azure cloud architecture (telemetry, commands, storage, dashboard, security)
• docs/hardware.md — connector, pinout, safety, bring-up hardware
• docs/protocol.md — CTA-2045 protocol facts, capability matrix
• docs/capabilities.md — what we can see, infer, log and control on the Rinnai REHP65
• docs/reverse-engineering.md — staged plan (EPRI oracle → passive capture → queries → writes)
• docs/references.md — source material, tools, and libraries (EPRI, python-cta2045, ANSI, EcoPort DB, OpenADR, connector part numbers)
• docs/troubleshooting.md — common issues

License

Both licenses are copyleft: you can use, modify and share this project, and anything you distribute that's based on it has to stay under the same terms.

• Software (firmware/, python/, tools/, scripts/, test/) — GNU Affero General Public License v3.0 (AGPL-3.0-only), see LICENSE.
• Hardware (hardware/: KiCad board, footprints, fab outputs, enclosure CAD) — CERN Open Hardware Licence v2, Strongly Reciprocal (CERN-OHL-S-2.0), see hardware/LICENSE.
• Docs and captures — AGPL-3.0, same as the software.

Source location for the hardware (CERN-OHL-S §1.9): https://github.com/jrowe88/ecoport-bridge. It is also printed on the board.