Inside Bluetooth Low Energy 100%

This is the hardware layer responsible for actually sending and receiving signals over the 2.4 GHz band.

This is the most important part for developers. It defines how data is exchanged using a hierarchy of Services and Characteristics (e.g., a "Battery Service" with a "Level" characteristic). Inside bluetooth low energy

Handles the "raw bits" and frequency hopping across 40 channels to avoid interference. This is the hardware layer responsible for actually