Where Do I Download Bluno Arduino Software

Note: this page is no longer being maintained. For up to date documentation on this library, visit the new ArduinoBLE library page.

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This library supports all the Arduino boards that accept the hardware enabled for BLE and Bluetooth® 4.0 and in a higher place; these include Nano 33 BLE, Arduino NANO 33 IoT, Uno WiFi Rev 2, MKR WiFi 1010.

To use this library
#include <ArduinoBLE.h>

A quick introduction to BLE

Bluetooth® 4.0 includes both traditional Bluetooth®, now labeled "Bluetooth® Classic", and the Bluetooth® Low Free energy. Bluetooth® Low Free energy is optimized for depression ability use at low data rates, and was designed to operate from unproblematic lithium coin cell batteries.

Unlike standard bluetooth® communication basically based on an asynchronous series connection (UART) a Bluetooth® LE radio acts like a community bulletin board. The computers that connect to it are like community members that read the bulletin board. Each radio acts every bit either the bulletin board or the reader. If your radio is a bulletin lath (chosen a peripheral device in Bluetooth® LE parlance) information technology posts data for all radios in the community to read. If your radio is a reader (chosen a central device in Blueooth LE terms) information technology reads from any of the bulletin boards (peripheral devices) that have information about which it cares. Y'all tin can also think of peripheral devices as the servers in a client-server transaction, because they contain the information that reader radios inquire for. Similarly, cardinal devices are the clients of the Bluetooth® LE world considering they read information available from the peripherals.

Think of a Bluetooth® LE peripheral device as a bulletin board and cardinal devices equally viewers of the board. Key devices view the services, become the data, and then motion on. Each transaction is quick (a few milliseconds), so multiple central devices can become data from one peripheral.

The information presented by a peripheral is structured every bit services, each of which is subdivided into characteristics. You tin call back of services as the notices on a bulletin lath, and characteristics as the individual paragraphs of those notices. If you're a peripheral device, you just update each service characteristic when it needs updating and don't worry almost whether the central devices read them or non. If yous're a central device, y'all connect to the peripheral and then read the boxes you lot want. If a given characteristic is readable and writable, and then the peripheral and central can both alter it.

Notify

The Bluetooth® LE specification includes a mechanism known as notify that lets you know when data'south inverse. When notify on a characteristic is enabled and the sender writes to information technology, the new value is automatically sent to the receiver, without the receiver explicitly issuing a read command. This is commonly used for streaming information such as accelerometer or other sensor readings. In that location'southward a variation on this specification called betoken which works similarly, only in the point specification, the reader sends an acknowledgement of the pushed data.

The client-server structure of Bluetooth® LE, combined with the notify feature, is generally called a publish-and-subscribe model.

Update a characteristic

Your peripheral should update characteristics when at that place's a pregnant change to them. For case, when a switch changes from off to on, update its characteristic. When an analog sensor changes by a pregnant amount, update its characteristic.

Only as with writing to a characteristic, you could update your characteristics on a regular interval, but this wastes processing ability and energy if the characteristic has non changed.

Central and Peripheral Devices

Central devices are clients. They read and write data from peripheral devices. Peripheral devices are servers. They provide data from sensors as readable characteristics, and provide read/writable characteristics to control actuators like motors, lights, and and then forth.

Services, characteristics, and UUIDs

A BLE peripheral will provide services, which in plow provide characteristics.

Services are identified by unique numbers known as UUIDs. You know nearly UUIDs from other contexts. Standard services have a 16-bit UUID and custom services have a 128-fleck UUID. The ability to define services and characteristics depends on the radio you're using and its firmware.

Service pattern patterns

A characteristic value can be up to 512 bytes long. This is a fundamental constraint in designing services. Given this limit, you should consider how best to store data virtually your sensors and actuators most effectively for your awarding. The simplest design pattern is to store 1 sensor or actuator value per characteristic, in ASCII encoded values.

Characteristic	Value
Accelerometer X	200
Accelerometer Y	134
Accelerometer Z	150

This is also the most expensive in memory terms, and would take the longest to read. But it's the simplest for development and debugging.

You could also combine readings into a single characteristic, when a given sensor or actuator has multiple values associated with it.

Characteristic	Value
Motor Speed, Direction	150,one
Accelerometer 10, Y, Z	200,133,150

This is more efficient, but you need to exist careful not to exceed the 512-byte limit. The accelerometer characteristic above, for example, takes eleven bytes as a ASCII-encoded string.

Read/write/notify/indicate

There are four things a central device can do with a characteristic:

Read: ask the peripheral to send back the current value of the characteristic. Often used for characteristics that don't alter very frequently, for example characteristics used for configuration, version numbers, etc.
Write: modify the value of the feature. Oft used for things that are like commands, for example telling the peripheral to turn a motor on or off.
Point and Notify: ask the peripheral to continuously transport updated values of the characteristic, without the central having to constantly ask for it.

Advertising and GAP

BLE devices let other devices know that they be by advert using the Full general Advert Profile (GAP). Advertizing packets can contain a device proper name, some other information, and as well a list of the services it provides.

Advertizement packets take a express size. Yous volition just be able to fit a unmarried 128-bit service UUID in the packet. Brand certain the device name is non too long, or you won't even be able to fit that.

Yous can provide additional services that are not advertised. Central devices will learn about these through the connection/bonding process. Non-advertised services cannot be used to discover devices, though. Sometimes this is not an issue. For instance, you may have a custom peripheral device with a custom service, but in your primal device app yous may know that it also provides the Battery Service and other services.

GATT

The Bluetooth® LE protocol operates on multiple layers. General Attribute Contour (GATT) is the layer that defines services and characteristics and enables read/write/notify/signal operations on them. When reading more about GATT, you may encounter GATT concepts of a "server" and "client". These don't always correspond to central and peripherals. In most cases, though, the peripheral is the GATT server (since it provides the services and characteristics), while the cardinal is the GATT client.

Library structure

As the library enables multiple types of functionality, there are a number of different classes.

BLE used to enable the Bluetooth® Low Energy module
BLEDevice used to get information about the devices connected or discovered while scanning
BLEService used to enable the services board provides or interact with services a remote lath provides.
BLECharacteristic used to enable the characteristics lath offers in a service or interact with characteristics a remote board provides.
BLEDescriptor used to depict a characteristic the board offers

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