nRF52832 — __attribute__((section(x))) Use the detailed Nordic observer mode

1. Attribute ((section(x))) detailed explanation

Both GNU and ARM compilers support the compilation attributes specified by __attribute__. Here we will focus on how to use the section in __attribute__ in the KEIL environment.

2. BLE event observer mode

Starting from version 14, the nRF5 SDK has updated the event callback mechanism and introduced an observer mode to decouple the callback functions of different BLE Layers for BLE events.
The Flash section is used to implement this mechanism. The idea of ​​combining function calls in RAM with section operations in Flash is very novel.
This article attempts to understand and track the entire callback process, and write a piece of code to verify our thinking.