Connor Rigby joins the Elixir Wizards to talk about Blue Heron BLE (Bluetooth Low Energy) support for Elixir apps. Blue Heron implements the BLE specs in pure Elixir, leveraging binary pattern matching and concurrent message processing to handle Bluetooth protocols. Unlike most solutions that require C ports or NIFs, Blue Heron runs entirely in user space, so it works seamlessly in both Nerves-based embedded projects and (eventually) desktop Elixir applications.

We discuss how Nerves development differs from building Phoenix apps. Connor shares challenges he's experienced with hardware compatibility, where some chips only partially implement the spec, and he discusses the surprisingly deep (but sometimes incomplete) world of BLE device profiles. His tip for anyone entering the BLE space: read the official spec instead of trusting secondhand blog posts. Tools like Nerves LiveBook give you hands-on examples, so you can get a BLE prototype running on a Raspberry Pi and your phone in no time.

Key topics discussed in this episode:

Blue Heron origins and “bird” naming convention
BLE vs. Bluetooth Classic: core differences
Pure Elixir implementation—no C dependencies
Binary pattern matching for packet parsing
Hardware transport options: UART, SPI, USB, SDIO
GenServer patterns in Nerves vs. Phoenix
Linux requirement and power-consumption trade-offs
GATT (Generic Attribute Table) implementation patterns
SQLite integration for Nerves apps
Hardware chip quirks and spec compliance
Manufacturer-specific commands and workarounds
BLE device profiles and spec gaps
Security Management Profile (SMP) for encryption
Device connection and pairing workflows
Web vs. embedded development differences
Where to get started: hardware recommendations and docs

Links mentioned:

https://github.com/ConnorRigby/
https://github.com/blue-heron/
https://nerves-project.org/
BLE (Bluetooth Low Energy) https://en.wikipedia.org/wiki/Bluetooth_Low_Energy
https://developer.apple.com/ibeacon/

https://learnyousomeerlang.com/building-otp-applications
Linux https://www.linux.org/
HCI (Host Controller Interface) https://en.wikipedia.org/wiki/Host_controller_interface
Circuits UART Library https://hexdocs.pm/circuits_uart/readme.html
SPI (Serial Peripheral Interface) https://github.com/elixir-circuits/circuits_spi
SDIO (Secure Digital Input Output https://en.wikipedia.org/wiki/SDIO
Raspberry Pi https://www.raspberrypi.com/
Coral SoM Dev Board https://coral.ai/products/dev-board/
BeagleBone Single-Board Linux Computer https://www.beagleboard.org/boards/beaglebone-black
https://www.bluetooth.com/bluetooth-resources/intro-to-bluetooth-gap-gatt/
Genservers https://hexdocs.pm/elixir/1.12/GenServer.html
https://hexdocs.pm/ecto/Ecto.html
https://github.com/elixir-sqlite/ecto_sqlite3
https://github.com/nerves-livebook/nerves_livebook

Special Guest: Connor Rigby.

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