Getting Started With BLE – A Complete Guide

Going down the memory lane, Bluetooth and its applications are in use since the 2000s. Since the time of its development and usage, Bluetooth has undergone numerous changes and advancements. One among the most important of them all is the development and introduction of Bluetooth Low Energy.

Bluetooth Low Energy is abbreviated as BLE (Bluetooth Low Energy, and is additionally also marketed as Bluetooth Smart). Bluetooth Low Energy (BLE), sometimes known as Bluetooth Smart, may be a lightweight subset of original Bluetooth that debuted with the Bluetooth 4.0 core specification. 

In this article, we are going to talk about Bluetooth Low Energy Technology which will help you in getting started with BLE.

Related Read:- Integrate BLE Technology In Mobile Apps With React Native BLE Manager

What Is Bluetooth?

Before diving into the small print of Bluetooth Low Energy, it is essential for us to understand the meaning and dealing of Bluetooth. The Bluetooth specifications specify the technical components that developers utilize to build the interoperable devices that structure the thriving Bluetooth ecosystem.

The Bluetooth Special Interest Group (SIG) oversees Bluetooth specifications, which are updated and improved on an everyday basis by Bluetooth SIG Working Groups to satisfy changing technology and market needs.

The majority of people associate Bluetooth with a wireless headset or another gadget that connects you to the information that you are transmitting. Bluetooth is a wireless connection that exists between your phone and the device to which you are linked. This mechanism allows data to be sent over small distances without the utilization of cables.

What Is Bluetooth Low Energy?

Bluetooth gadgets are continually being developed and reinvented. Do you recall when Apple initially released AirPods? There are now various different versions of this Bluetooth connectivity device, including innovations that help with battery life, which leads us to Bluetooth Low Energy. BLE (Bluetooth Low Energy) is a type of wireless communication that is designed for short-range communication. Like Wi-Fi, BLE allows devices that are connected to interact with one another. 

BLE is designed for circumstances where battery life is more important than high data transfer speeds. Assume you would like to broadcast marketing campaigns within the vicinity of a just introduced headset. As the quantity of data and information that you would send to a visitor’s smartphone is so minimal, BLE-enabled beacons can do the task fast and without exhausting the battery. 

Bluetooth Low Energy vs. Bluetooth Classic

• Both are accustomed Connect the devices and Transferring the info for private and commercial use.
• The main difference is how they’re distributing data for low-energy power.
• Bluetooth classic is employed to transfer many data continuously but contains high power and more cost.
• BLE transfers smaller packets of information over short periods of your time using low battery power.

Key Terms And Concepts

1. Generic Attribute Profile (GATT) :
   The GATT profile could be a general specification for sending and receiving short pieces of information called “attributes” over a BLE link. GATT supports all current BLE app profiles.
2. Generic Access Profile (GAP) :
   GAP is mandatory for BLE devices as it defines a framework for enabling device discovery, security, connectivity, and related network technologies. This defines the role that the Connection can implement.
3. Profiles :
   Profiles can be specifications that show how the tool works in a particular application. Note that a tool can implement quite one profile. For example, a tool could contain a vital sign monitor and battery level detector.
4. Attribute Protocol (ATT) :
   GATT is made on top of the Attribute Protocol (ATT). ATT is optimized to run on BLE devices. Up to this point, use as few bytes as possible. Each attribute is uniquely identified by a Universally Unique Identifier (UUID). This can be in the standardized 128-bit format of the string identifier used to identify the information uniquely. The attributes transported by ATT are formatted as characteristics and services.
5. Characteristic :
   The lowest level concept in GATT transactions is the Characteristic, which encapsulates one datum. Similar to Services, each Characteristic distinguishes itself via a pre-defined 16-bit or 128-bit UUID. Characteristics are the most point that you will interact with along with your BLE peripheral, so it is vital to grasp the concept. They’re also wont to send data back to the BLE peripheral since you’re also ready to write to characteristics.
6. Descriptor :
   Descriptors are defined attributes that describe a characteristic value.
   For example, a descriptor might specify a human-readable description, an appropriate range for a characteristic’s value, or a unit of measure specific to a characteristic’s value.
7. Service :
   Services are accustomed to breaking data into logical entities and containing specific chunks of information called characteristics. A service can have one or more characteristics. Every service distinguishes itself from others using a singular numeric ID called a UUID, which may be either 16-bit or 128-bit.

BLE Operations

To perform any action or operation, you must communicate with the BLE device. Therefore, BLE communication can be combined into three operations.

1. Read:
   When this property is enabled, the app will read the value of the property or descriptor of the BLE device and interpret it based on the previously created protocol.
2. Write :
   We can write data 2 ways:-
   Write with the response: If you enable this property, you can write characteristic values ​​and get confirmation from the BLE device after completing the process.
   Write without response: If you enable this property, you can write characteristic values, but you will not receive confirmation from the BLE device after the operation is complete.
3. Notify / Indicate:
   Both are a way for the peripheral to notify the medium when the feature value changes. The only difference between notifications and indications is that notifications need to be accepted by the client when receiving a package, while indicators require this type of acceptance. So it moves slowly.

GAP Roles

GAP is a topology for maintaining connectivity between BLE devices and the devices that control BLE devices. GAP roles can be defined in two ways.

The first one is Broadcasting or connectionless.
The second one is Connecting or connection-oriented.

Broadcasting OR ConnectionLess:

1. Broadcaster :
   Devices with the sender role only send data to this environment. This is done through continuous advertising and usually contains useful data in your ad package, that is, data that is visible to everyone. Such devices do not require a receiver and do not accept connections, as their sole job is to send to others.
2. Observer :
   Observers are the opposite of broadcasters. Observers passively listen to nearby BLE devices and process the data in the ad packets they receive. No transmitter is needed as it does not broadcast anything and does not connect.

Connecting OR Connection-Oriented:

1. Peripheral devices :
   BLE peripherals are generally low-power devices. Peripherals can be scanned with a Bluetooth central device. When Connection is established, the peripheral act as an enslaved person. Smartwatches, bracelets, sensors, fitness bands and smart light bulbs are examples of peripherals.
2. Central devices :
   The central device is usually a high-power energy device. A hub is a device that searches for Bluetooth devices and connects to and uses the information they contain. Central devices are typically richer in resources, such as computing power than peripheral devices. Pre-attached: The device is designated as the central device at boot time and as the master after it is connected. Laptop, mobile, and tablet devices are examples of core devices.

How Does Bluetooth Low Energy Work?

GATT is an acronym for Generic Attribute Profile, which uses services and characteristics to define how two Bluetooth Low Energy devices exchange data. GATT works when a dedicated connection is established between the two devices. This means that you have already completed the GAP-regulated advertising process.

The most important thing to note about GATT and connections is that the connections are exclusive. BLE peripherals can only connect to one central device (such as a mobile phone). When a peripheral connects to a central device, it stops advertising itself, and other devices cannot recognize or connect to it until the existing connection is broken.

Establishing a connection is also the only way to enable two-way communication. In this case, the central device can send meaningful data to peripheral devices and vice versa. The operation of BLE can be divided into three sections described below and will help you to understand how does Bluetooth low energy works?

Attribute And Data Hierarchy:

Attributes are the smallest data entity defined by GATT (and ATT). These are addressable information that may contain relevant user data (or metadata) about the structure and grouping of the various attributes contained in the server. Both GATT and ATT work only on attributes, so all information must be organized in this format for the client and server to interact.

The attributes of the GATT server are grouped into services, and each service may contain zero or more characteristics. These features can contain zero or more descriptors. The “Important Terms” section above has discussed the relationship between services and features.

Most data types in the GATT hierarchy must distinguish between their definitions (the entire set of attributes that make them up) and their declarations. Declarations are the single attribute that always comes first (in ascending order of handles) in the definition and introduces most of the metadata for subsequent data.

All declarations have read-only permissions that do not require security because they cannot contain sensitive data. These are just structural attributes that allow the client to understand and discover the server’s layout and type of attributes.

Central And Peripheral Communication:

A central device and peripheral devices are required to perform BLE operations. Peripherals advertise themselves and contain information. The central device scans for ad packages. Once connected, you can perform BLE operations. The central device can perform read and write operations if peripheral functions give this permission.

BLE technology acts as an intermediary between both types of devices. When operating with BLE peripherals, notification/display operations can be performed on the central device. This type of surgery is useful for all kinds of emergencies.

Example Service:

This section provides examples of specific services found in many commercial products today. Heart rate service (HRS) relays your heart rate to a monitoring device.

This heart service has several features, each with a descriptor. The structure of the attributes is as follows:

Attribute Handle:

The attribute handle is a 16-bit unique identifier:

• Makes the attribute “addressable.”
• Does not change.

Handle values ​​grow in an ordered order on the server (gap allowed) and during the discovery process Detected by the client.

Attribute Type (Universally Unique Identifier (UUID))

The attribute type determines the type of data present in the attribute’s value and uses a 2-byte or 16-byte UUID. Here is an example:

• Service UUID
• Characteristic UUID
• Profile UUID
• Vendor-Specific UUID

Attribute Value

The attribute value contains the actual data content that the client can access. You can also include metadata about the attribute (depending on the type).

Attribute Permissions

Attribute permissions are attribute metadata that specifies:

• ATT access operations are allowed on attribute values. The allowed operations are read and write, no operations.
• Security requirements. In this case, encryption is required. Cryptography has different types of layers that are also needed for security. Authentication is also required for security, such as biometrics and password authentication.