trouble

TrouBLE is a Bluetooth Low Energy (BLE) Host implementation for embedded devices written in Rust, with a future goal of qualification. The initial implementation was based on bleps but has been adapted to work with types and traits from bt-hci and adding support for more of the BLE specification such as L2CAP connection oriented channels. The current implementation also takes strong inspiration from the nrf-softdevice project.

What is a Host?

A BLE Host is one side of the Host Controller Interface (HCI). The BLE specification defines the software of a BLE implementation in terms of a controller (lower layer) and a host (upper layer).

These communicate via a standardized protocol, that may run over different transports such as as UART, USB or a custom in-memory IPC implementation.

The advantage of this split is that the Host can generally be reused for different controller implementations.

Hardware support

TrouBLE can use any controller that implements the traits from bt-hci. At present, that includes:

• nRF Softdevice Controller.
• UART HCI.
• Raspberry Pi Pico W.
• Apache NimBLE Controller.
• ESP32.
• Linux HCI Sockets.

Current status

The implementation has the following functionality working:

• Peripheral role - advertise as a peripheral and accept connections.
• Central role - scan for devices and establish connections.
• Basic GATT server supporting write, read, notifications
• Basic GATT client supporting service and characteristic lookup and read + write
• L2CAP CoC (Connection oriented Channels) with credit management (for both central and peripheral)

See the issues for a list of TODOs.

Documentation

See the documentation and the rustdoc.

Minimum supported Rust version (MSRV)

Trouble is guaranteed to compile on stable Rust 1.80 and up. It might compile with older versions but that may change in any new patch release.

Examples

See examples for example applications for different BLE controllers.

• nrf52 for the nRF52 based using the nrf-sdc crate.
• nrf54 for the nRF54 based using the nrf-sdc crate.
• serial-hci which runs on std using a controller attached via a serial port (Such as this Zephyr sample).
• apache-nimble which uses the controller from the NimBLE stack through high-level bindings from the apache-nimble crate.
• esp32 which uses the BLE controller in the esp-hal.
• rp-pico-w which uses the BLE controller in the Raspberry Pi Pico W.
• rp-pico-2-w which uses the BLE controller in the Raspberry Pi Pico 2 W.
• linux which uses the HCI socket interface.

Since a lot of the examples demo the same BLE functionality, they only contain basic wiring specific to the BLE controller, and share the 'business logic' within the examples/apps folder.

More information on these examples can be found is the examples/README.md.

License

Trouble is licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.