ACiQ ACIQ-K18W-W-32-HP2300 mini split (TCL WBR1 module): Decoding a mini split's cloud-dongle UART protocol and replacing the dongle with ESPHome

An author writing as codypendant reports decoding the UART bus between a TCL WBR1 WiFi module and the mainboard of an ACiQ K18W-W-32-HP2300 wall-mount mini split, then replacing the vendor cloud dongle with an ESP32 running ESPHome that drives a Home Assistant climate entity with no CRC failures. The unit's bus runs at 115200 baud 8N1 with 0xA5 frame starts, a length byte for frames of 12 to 93 bytes, and a CRC-16/XMODEM check over a region with a hole, differing from the 0xBB framing at 9600 baud 8E1 used in published TCL guides; the module itself is Tuya silicon (an RTL8720CF) running TCL firmware. The author reports proving takeover on hardware on 13 August 2026, when a setpoint sent from Home Assistant changed the unit's display, and adding a frame-fed climate entity two days later, with 21 of 46 commits carrying a Claude Opus 5 trailer and no independent confirmation reported.

Evidence at a glance Based on the linked sources. The author's reported result and independent confirmation are separate checks. - AI involvement - Reported models: Claude Opus 5. Tools: ESPHome, ESP32, Home Assistant. The writeup below describes the work attributed to AI. - Reported result - Works. This is the directory's source-based outcome classification. - Independent confirmation - Not reported. - Human work and limitations - The author codypendant did the hardware work: removing the dongle and wiring the ESP32 to the unit. Remote presses arrive by infrared and only show up as state changes, and a mapping queue in the ESPHome node lists fields that are not yet identified. Original sources What was done The author reports decoding the UART bus between a TCL WBR1 WiFi module and the mainboard of an ACiQ K18W mini split. An ESP32 now replaces the cloud dongle and drives a Home Assistant climate entity with no CRC failures. The ACiQ K18W-W-32-HP2300 wall-mount mini split ships with a TCL WBR1 WiFi module that talks only to the vendor cloud. The bus between that module and the indoor board carries power, mode, setpoint, temperatures, fan and louver positions, compressor speed and input power, so the repository documents that bus. The README is blunt that the protocol is not the one every published TCL guide describes. Those use 0xBB framing at 9600 baud 8E1. This unit runs at 115200 baud 8N1, starts frames with 0xA5, uses a length byte for frames of 12 to 93 bytes, and checks them with a CRC-16/XMODEM computed over a region with a hole in it, plus a counter and explicit acknowledgement. The module turned out to be Tuya silicon an RTL8720CF running TCL firmware. Two modes are documented: listen-only, which keeps the dongle and transmits nothing, and a takeover where an ESP32 sits on the CN-16 header and gives local control. The author reports proving takeover on hardware on 13 August 2026, when a setpoint sent from Home Assistant changed the unit's display, and adding a climate entity two days later that is fed from decoded frames rather than from sent commands. Twenty-one of 46 commits carry a Claude Opus 5 trailer, and the repository has a CLAUDE.md and a METHOD.md. Reproduce it Read PROTOCOL.md and METHOD.md, then use the esphome directory for a listen-only node or a dongle replacement. You need the same unit and your own ESP32; the repository contains captures and no vendor firmware. Community Ask a question, share what worked, or follow the next milestone. Your library https://reversedwithai.com/library