Bluetooth Smart Technology - Meetupfiles.meetup.com/18517946/Introduction to Bluetooth Smart...

Bluetooth® Smart Technology

Krisztián Kovács | May 26, 2016

2 Silicon Labs Confidential

Silicon Labs:

Global mixed-signal semiconductor company

Founded in 1996; public since 2000 (NASDAQ: SLAB)

~1,200 employees and 12 R&D locations worldwide

Strong track record of innovation and differentiation

Pioneering mixed-signal and RF technologies for the past twenty

years

Fabless model with >6 billion devices shipped and >1,500

patents issued and pending

Introduction

My role:

„Help customers to find their ways within Wireless technologies”

Senior Applications Engineering Director, Wireless product

https://hu.linkedin.com/in/krkovacs

Twitter: @krkovacs_hu

https://hu.linkedin.com/in/krkovacs


Segítünk megismerni a trendi Wireless technológiákat – előadás sorozat

45 perc előadás / 15 perc demó

Minden előadáson kisorsolunk egy develoment Kit-et

Dedikált, magyar nyelvű fórum csatorna:

http://community.silabs.com/Hungary

Megosztani a tapasztalatokat

Kérdésed van, elfelejtettél megkérdezni valamit a meetup-on: mérnökeink válaszolnak!

SZERETNÉL valami másról is hallani? JELEZD a fórumon!

VERSENY:

Oszd meg IoT project ötletedet a magyar fórumon

A legjobb ötletet 3 havonta díjazzuk a következő meetup-on:

A technológiához kapcsolódó development kit-el és IC / modul mintákkal.

Meetup sorozat


Április 28: Wireless technológiák - hogyan válasszam ki a megfelelőt?

Demó: egyszerű garázsnyitó 15 perc alatt - lehetséges!

Május 26: BLE technológia rejtelmei - hogyan tudok egy BLE eszközt fejleszteni mobiltelefonhoz

Demó: iBeacon és egy BLE szenzor fejlesztése

Nyáriszünet, ősszel folytatjuk!

Alacsony fogyasztású, embedded WiFi technológia

bemutatása

Demó: hogyan küldjük el a páratartalom és hőmérséklet értéket emailben?

Apple HomeKit: "Siri, turn on the light!"

Demó: hogyan fejlesszünk egy intelligens lámpát HomeKithez

Soron következő témák (1/2)


Bluetooth Smart Intro

The Bluetooth Smart Architecture

Radio

Topologies

Device Discovery and Broadcast Data

Connections

Bluetooth Smart Security

Transferring Data - The ATT Protocol

Exposing Data – The GATT Database

Bluetooth Versions

TOPICS


1994. Ericsson - Classic Bluetooth (Short distance wireless data exchange)

1998. Bluetooth SIG v1.0 / 1.1 / 1.2 / 2.0 / 2.1 / 3.0 / 4.0 / 4.1 / 4.2 / (5.0) High throughput!

BR(1.2) ~ 700 kbps

EDR – Enhanced Data Rate (2.0) ~ 2.1 Mbps

HS – High Speed (3.0) ~ 24 Mbps

2006. Nokia - Wibree

2010. BT 4.0 Core Spec – Bluetooth Low Energy (BLE) Low current consumption (ave/high) Low bandwidth Not compatible (different design)



BT SIG classifies BT Devices:

BR/EDR = Classic Bluetooth

LE only = BLE = Single Mode LE Device = Bluetooth Smart

Sensors

Low power

Low cost

BR/EDR/LE = Dual Mode Device = Bluetooth Smart Ready

Smart phones, tablets, PCs

Communication with BR/EDR and LE even at the same time

High power consumption



Ultra low power: Ability to run months on coin cell batteries

Lower cost: 2 x lower cost

Reliable and robust – AFH, retransmissions, 24-bit CRCs

Secure – pairing, bonding, privacy, MITM protection and AES-128 encryption

Standardized profiles for key use cases (HR, HID, Glucose, Proximity etc.): Enables profiles to be developed as Apps: fast deployment

Customer specific profiles: no need to wait OS developers

Connectivity to Smart phones, tablets, PCs

Supported by all major platforms - iOS, Android 4.3, Windows 8, OSX and Linux

Bluetooth Smart Intro - Benefits


Building blocks:

Application

Host

Upper layers of stack

Controller

Lower layers of stack + radio

Bluetooth Smart Typical Implementations

Application

Host

Controller

Application

Host

Controller

Host

Controller

ApplicationSoC

Dual IC over HCIDual IC with NCP

NCP - Target

NCP - Host

Proprietary Protocol(BGAPI over UART)

HCI over UART/USB

Different use cases:

SoC: low cost sensors / end nodes

Dual IC with NCP: complex system with a host

processor

Dual IC over HCI: smartphones


GATT Organization of Attributes into services

ATT Data exchange protocol

SMP Bonding, privacy and encryption

GAP Advertising, device discovery and

connections

L2CAP Data multiplexing, fragmentation and reassembly

HCI Interface between controller and

host.

Link Layer Basic packets, state machine and radio control

Link layer security and privacy

Radio Receives and transmits bits

The Bluetooth Smart Architecture

Blue Gecko Bluetooth Smart radio

Link Layer

API

Application

Attribute Protocol (ATT)

Generic Attribute Profile (GATT)Security Manager

(SM)

Generic Access Profile

(GAP)

L2CAP


2.4GHz ISM Band

License free in most countries

Uses Adaptive Frequency Hopping (AFH)

Reliable

Robust

Adapts to interference

Radio 40 channels

3 advertisement channels

37 data channels

2 MHz wide


1 Mbps bit rate

Typical throughput <= 100kbps

due to small packets

Changes in 4.2 and 5.0

TX power up to +20 dBm

Was limited by CE and FCC regulations

Addendum 5 (Dec 2016) increases to +20 dBm

Also re-introduces power class designations

Range

0 – 500 meters

Typically 0-50 meters to a smart phone

Radio

Power Class Max Output Power Min Output Power

1 100 mW (+20 dBm) 10 mW (+10 dBm)

1.5 10 mW (+10 dBm)

0.1 mW (-20 dBm)2 2.5 mW (+4 dBm)

3 1 mW (0 dBm)

Core Addendum 5 LE Power Class


Advertiser

Only sends out advertisements i.e.

broadcast data

Can allow or disallow connections

Scanner

Only listens for advertisements

Can also connect an advertiser

Slave

Connected to one master (BT 4.0)

Connected to multiple masters (BT 4.1)

Master

Connected to one or multiple slaves

Topologies


Device advertisement

Devices advertise themselves

They broadcast advertisement packets on

one, two or three ADV channels

Scanners listen for advertisements to discover devices

Data broadcast

Advertisement can carry up to 31B of data

Typically device name, TX power, supported services

Can also be vendor specific data

Benefits of advertisements

Low power – Radio is active <1ms during

advertisement

Quick – ADV operation takes just 1.3 ms

Flexible - ADV interval ranges from 20ms to 10.2s

Device Discovery & Broadcast Data


Connections

Enable reliable data transfer

Connections use ACKs, re-transmits, 24-bit

CRC to ensure correct data delivery

Connections enable the use of encryption

and protection of data confidentiality

Connections

10ms connection interval + ACK allow data to be sent every 20ms.At 20B payload this is about 1000B/sec.


Connection interval varies from 7.5ms to 4000ms

Data payload between 20 to 22 bytes (including header)

Connection Properties

Slave devices can use slave latency – enables them to skip N connection

intervals when there is no data to transmit

Connection request

Data

Connection window

Data150us

Connection interval

Master Slave

time

Data Data Data Data Data150us

Connection interval

Connection interval

Connection interval

Connection request Data

Connection window(from 1.25ms to 3998.75 ms)

Data150us Data

Connection interval(7.5ms to 4000ms)

Data150us

Master Slave

time

Data Data150us

Connection interval(7.5ms to 4000ms)


Example with acknowledgement:

Connection interval of 20ms

Acknowledged ATT operation : read, write,

indicate

1000ms/(20ms * 2) * 21B = 525B/sec (4200bps)

Throughput

Example without acknowledgement

Connection interval of 20ms

Unacknowledged ATT operation : write no

response, notify

5 packets in a connection interval

1000ms/(20ms) * 21B * 5 = 5250B/sec

(42000bps)

Main factors affecting throughout: Connection interval

The used ATT protocol operation – Acknowledged vs. Unacknowledged

Acknowledged operations must be ACKed, before new one can be sent

One or multiple unacknowledged operations can be made in a single connection interval

Note: below calculation doesn’t take into account some delay / turnaround parameters!


The Attribute Protocol is the only data transfer protocol in BLE

Uses Client – Server architecture

Server stores the data

Client requests data from the server

Data is stored in attributes

From 0 up to 64kB

Can be fixed or variable length

Data can be accessed with the following operations

Read - reads data up to 22B

Read long - reads longer than 22B attributes

Write - writes data up to 20B

Write command - Just like write, but no ACK

Indicate - server indicates the data has changed

Notify - server notifies the data has changed

Transfering Data – The ATT Protocol


Data is organized and described with the GATT database

Service – Describes a set of data like Health Thermometer

Bluetooth SIG standardized services identified by unique

16-bit UUIDs

Vendor specific services identified by 128-bit UUIDs

Services contain one or more characteristics

Characteristic – Describes data within a service

Describe data like Temperature Measurement

Standardized characteristics identified by unique 16-bit

UUIDs

Vendor specific characteristics identified by 128-bit UUIDs

Characteristic properties

Tell which operations can be used to access the data

(Read, Write, Notify etc.)

Tell which security means must be used to access the data

(bonding, encryption etc.)

Data Organization with the GATT Database


Health Thermometer profile


The most common threats in wireless communications are: Passive eavesdropping

Man-in-the-Middle (MITM) protection

Privacy

Bluetooth Smart provides three basic security services: Authentication and authorization: Establishing trusted relationships between devices

Encryption and data protection: Protecting data integrity and confidentiality

Privacy and confidentiality: Preventing device tracking

The Bluetooth security model includes five security features: Pairing: the process for creating shared secret keys

Bonding: storing the keys created during pairing so they can be used later

Device authentication: verification of stored keys

Encryption: data confidentiality

Message integrity: protection against data alteration

All security algorithms or mechanisms used in Bluetooth Smart are either FIPS or NIST approved

Note: ecosystem providers don’t use BLE security, but dedicated secure elements Apple – HomeKit, Samsung SmarThings

Bluetooth Smart Security


Pairing Is the process of creating trusted relationships between devices

Used to generate and exchange security keys

Used to exchange identity information

Bluetooth Smart uses Secure Simple Pairing (SSP) pairing model Just works For devices without UI. No user interaction required. No MITM protection.

Passkey entry User needs to enter a passkey the remote party displays. Provides MITM protection.

Numeric comparison User needs to confirm passkeys both devices display. Provides MITM protection.

Out-of-band Encryption keys exchanged e.g. using NFC

Bonding Storing of security keys for future use

E.g. authentication of connections or verifying devices identity

Pairing & Bonding


Bluetooth v4.2 (highlights)

Security improvements

IPv6 – Enables the use of 6LoWPAN and IPv6 packets over BLE (IPSP)

Bluetooth 5.0 (highlights)

Main target is either longer range or higher data throughput

2Mbps PHY – 2Mbps physical layer for faster data transmission

LE long range – 250kbps and 500kbps PHYs for better sensitivity and longer range connections

Bluetooth MESH capabilities

Simple home automation use cases

Main advantage is the simple installation vs. ZigBee / Thread

Where the Bluetooth Standard is going? Versions

How Silicon Labs can help You?


Wireless Gecko SoCs


ARM Cortex-M4 MCU

256kB flash & 32kB RAM

Multi-band, multi-protocol radio

Ultra low power

63 uA/MHz (active), 1.4 uA (sleep)

Highly integrated (+20 dBm PA)

Advanced security

Rich peripherals

Multiple package options

Wireless Gecko SoCs

QFN487x7 mm

QFN325x5 mm

WLCSP~3x3 mm

2.4 GHz<1 GHz


Wireless Gecko Portfolio

Development ToolsSoCs SDKs and Stacks

Proprietary

Modules

„Not just an SoC, but a complete platform!”

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