Bluetooth Guideline for Starters

Overview

Bluetooth is a wireless technology standard for exchanging data over short distances from fixed and mobile devices, and building personal area networks (PANs).

BLE stands for Bluetooth Low Energy.

Through the following sections, you will get to know BLE.

• Introduction
• Protocol Basics
• GAP (Advertising and Connections)
• GATT (Services and Characteristics)

Introduction

BLE aims to have

• Low cost
• Low bandwidth
• Low power
• Low complexity

Two types of Bluetooth

• BR/EDR (Classic Bluetooth)
• BLE (Bluetooth Low Energy)

Two modes of Bluetooth

• Single-mode (BLE, Bluetooth Smart) device
• Dual-mode (BR/EDR/LE, Bluetooth Smart Ready) device

Three main building blocks

• Application

  The user application interfacing with the Bluetooth protocol stack to cover a particular use case.

• Host

  The upper layers of the Bluetooth protocol stack.

• Controller

  The lower layers of the Bluetooth protocol stack, including radio.

There most common configurations

• SoC (system on chip)
• Dual IC (Integrated Circuit) over HCI (Host Controller Interface)
• Dual IC with connectivity device

Key limitations

• Data throughput: 15960 bytes/s or ~0.125Mbit/s (~125bit/s)
• Operating Range: reliably 30 meters or more line-of-sight

Network topology

• Broadcasting and Observing

  Broadcaster and Observer

• Connections

  Central (master) and Peripheral (slave)

Protocols versus Profiles

• Protocols

  building blocks used by all devices conformant to the Bluetooth specification, protocols are the layers that implement the different packet formats, routing, multiplexing, encoding, and decoding that allow data to be sent effectively between peers.

• Profiles

  “Vertical slices” of functionality covering either basic modes of operation required by all devices (Generic Access Profile, Generic Attribute Profile) or specific use cases (Proximity Profile, Glucose Profile), profiles essentially define how protocols should be used to achieve a particular goal, whether generic or specific.

Protocol Basics

Protocols in Several layers

Layers
├── Application
├── Host
|    ├── Generic Access Profile (GAP)
|    ├── Generic Attribute Profile (GATT)
|    ├── Logical Link Control and Adaptation Protocol (L2CAP)
|    ├── Attribute Protocol (ATT)
|    └── Security Manager (SM)
|    └── Host Controller Interface (HCI), Host side
├── Host
|    └── Host Controller Interface (HCI), Controller side
|    ├── Link Layer (LL)
|    └── Physical Layer (PHY)

Physical Layer

• The radio uses the 2.4 GHz ISM (Industrial, Scientific, and Medical) band.

• 37 channels are used.

Link Layer

GAP (Advertising and Connections)

GATT (Services and Characteristics)

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