LOW ENERGY CORE CONFIGURATION
在武漢疫情期間，難得有空餘時間，根據最近更新Bluetooth core spec v5.2，整理一下ble相關知識。
希望能夠在上班之前，系統的把ble 相關理論知識梳理一遍。如有偏差，也歡迎專家指證，感謝！
該系列文章以spec爲主要來源，會加入一些個人的理解，如有闡述不清的地方，也歡迎您留言交流.
Host part：
| Layer | Required Features |
|---|---|
| L2CAP ([Vol 3] Part A) | If the GAP Peripheral or Central role is supported, L2CAP LE Signaling channel (CID 0x0005) and all mandatory features associated with it |
| GAP ([Vol 3] Part C) | All mandatory features for at least one of the LE GAP roles (Broadcaster, Observer, Peripheral or Central) in sections 9-12 and section 15 |
| ATT ([Vol 3] Part F) | If the GAP Peripheral or Central role is supported, all mandatory features |
| GATT ([Vol 3] Part G) | GATT is mandatory when ATT is supported. When supported,all mandatory features |
| SM ([Vol 3] Part H) | If the GAP Peripheral or Central role is supported, all mandatory features |
Controller part：
| Layer | Required Features |
|---|---|
| PHY ([Vol 6] Part A) | All mandatory features |
| LL ([Vol 6] Part B) | All mandatory features |
上述表格搬運自core spec，該表格所列出的內容是針對純ble設備，需要區別於br/edr 和ble 共存的設備。
所涉及到的章節，後續會依次展開對spec的研讀。