What is stm32wb-hci?

This project provides a way for embedded devices built with STM32WB microcontrollers to communicate over Bluetooth. Specifically, it handles the "Host-Controller Interface", the protocol that lets a microcontroller's software talk to its Bluetooth radio hardware. It's written in Rust and is designed for developers building small, low-power devices that need wireless connectivity, like smart sensors, wearables, or IoT gadgets. At its core, the library defines a set of standard Bluetooth commands and events based on the official Bluetooth specification. It supports Bluetooth versions 4.1, 4.2, and 5.0, with 4.1 being the default. The way it works is that a developer implements two basic functions for their specific hardware: one to write data to the Bluetooth chip and one to read data from it. Once those low-level input and output functions are in place, this library handles the rest of the Bluetooth communication logic on top of them. The target audience is embedded hardware engineers and hobbyists programming STM32WB chips in Rust. For example, if you're building a custom BLE-enabled thermometer or a small smart-home device and you want to write the firmware in Rust, this library gives you the building blocks to send and receive Bluetooth commands without having to implement the entire Bluetooth protocol from scratch. One notable aspect is that the implementation is currently partial. The README notes that it only covers the commands and events used by the BlueNRG Bluetooth chip as of September 2018, and it's unclear whether certain data packet types are fully supported yet. This means it may not cover every Bluetooth use case, but it provides a foundation that aligns with the official specification and can be extended over time. The project is also a fork of an earlier Rust Bluetooth library, adapted specifically for the STM32WB family.