Reading 905 nm UART Laser Rangefinder Modules: Two Frame Families, Per-Model Units, and Manual Inconsistencies

Abstract

Technical note by the module manufacturer (ERDI Technology (Chengdu), https://erdilrf.com/). Summarises the two UART wire-protocol families of ERDI 905 nm laser rangefinder modules (8-byte 55 AA command/response; free-running 5C frames), the per-model unit differences (centimetres vs millimetres vs 0.1 m counts), the different transmit/reply checksum scopes, and places where the manufacturer manuals contradict themselves. All facts are transcribed from the manufacturer's module manuals and implemented in the MIT-licensed driver repository https://github.com/yu911517778-a11y/erdi-lrf-drivers. No measurement results or performance claims are made.