A quick FYI for Apache Mynewt's 0.9 release...
Noteworthy is the world's first open source (controller level) Bluetooth Lo w Energy stack for MCUs. The first ports were to Nordic's nRF52 and nRF51. Specific to the OS with BLE (4.2), the open source approach has obvious ben efits to developers: access to source code; better debugging through settin g breakpoints, avoiding stack smashes, no stolen interrupts, etc.; direct a ccess to peripherals for granular power control; better, precise configurab ility of concurrent connections and flexibility across central and peripher al roles. The project aims to also have timely Bluetooth 5 support.
The OS is composable via a modern, Go-like build and package management too l. Components include secure boot loader, flash file system and TLV storage mechanisms, rich logging infrastructure, circular buffering schemes, and B LE! Scripting languages such as Javascript and Python is currently being wo rked.
The community welcomes your participation and feedback!