Bluetooth

gatecircleΚινητά – Ασύρματες Τεχνολογίες

10 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

60 εμφανίσεις

Presented by:

Kedao

Wang, Shaun Levin, Dave Chen

A proprietary open wireless technology established by the:



Bluetooth® Special Interest Group (SIG)

Overview


History





3


Applications




4


Specifications



5
-
8


Components




9
-
12


States





13
-
15


Connection Setup



16
-
17


Development Kits



18
-
21


Conclusion




23


References




24

History & Creation


Created by telecoms vendor
Ericsson in 1994


Named after Scandinavian King
Bluetooth from 900's BCE


A wireless alternative to RS
-
232
data cables


Simple, secure, everywhere


Robust, low power, low cost


Simultaneously handle data and

voice transmissions

Applications

Audio

-

synchronization of separate stereo channels between devices


Mobile phone

-

Android and iPhone


Controls

-

Game Consoles, Mouse, Printer, Remote Controllers


Replacing RS
-
232
-

GPS receivers in medical equipment, barcode
scanners, and traffic control devices

Profiles: Overview

Provide standards which manufacturers follow to allow devices to use
Bluetooth in the intended manner

Profiles describe
:


Dependencies on other profiles


Suggested user interface formats


Specific parts of the Bluetooth protocol stack used by the profile

Profiles: Common Uses

Audio/Video Remote Control Profile (AVRCP)

Provide standard interface for a single device to
control several pieces of A/V equipment (TV,
VCR, DVD, etc)


Human Interface Device Profile (HID)

Send mice, keyboards, joysticks, and game
controllers presses. Low latency link with low
power. Used for Playstation 3 and Wii
controllers.


Advanced Audio Distribution Profile (A2DP)

High quality audio streamed from one device to
another

Basic Imaging Profile (BIP)

Designed for sending images
between devices and includes
the ability to resize and convert
images


Serial Port Profile (SPP)

Emulates a serial cable to
provide a simple substitute for
existing RS
-
232, including the
familiar control signals


GATT Profile

General development profile
installed on Texas Instrument
Development Kits


Version

Improvements

Power Advantages

1 (Basic Rate)

GFSK modulation
, 1 Mb/s

2 (Enhanced
Data Rate)

π/4
-
QPSK modulation
: 2 Mb/s

8DPSK modulation
: 3 Mb/s

Reduced Duty Cycle

3 (High Speed)

Bluetooth establishes and negotiates a
802.11 (WiFi) link at 24 Mb/s

Enhanced Power Controls

4 (Low Energy)

Low energ
y mode: 200 kbit/s over
Bluetooth

Ultra
-
low power idle mode

Versions

π/4
-
QPSK

GFSK

Range

Class

Expected Range

Power

1

42 meter

100 mW

2

16 meter

2.5 mW

3

10 meter

1 mW

Manufacturer can choose to create the device to match 1 of 3 class
models

Networks: Piconets and Scatternets

http://www.freeopenbook.com/upgrading
-
repairing
-
networks/ch22lev1sec3.html

Piconet
:

One master => up to
7

slaves

All devices share the master's clock

Up to 255 further slave devices can
be inactive

Scatternet
:

Two or more piconets to form a
scatternet

One device simultaneously is master
in one piconet and slave in another

Networks: Frequency Hopping


Versions use different modulations schemes

o
The modulation rate changes with Frequency
-
Hopping Spread
Spectrum (FHSS)



2.402 GHz to 2.480 GHz
, 79 frequency bands of 1 MHz each



To minimize interference between piconets, paired
-
up devices hop
among 79 frequency bands together
1600 times/sec



Data can be transferred between the master and one slave device
at a time



The master chooses the slave to address, and switches the slaves
through a round
-
robin fashion


Synchronization and Transmission


Time
-
division duplex (TDD)

scheme = alternately transmit and
receive data


To transmit data, need:

o
Channel Hopping Sequence = derived from BD_ADDR of master

o
Phase of Hopping Sequence = derived from clock of master

o
Channel Access Code (CAC) = derived from BD_ADDR of master


Piconet

is synchronized by master's clock

o
Slaves adapt internal clock with a timing offset to match master


Clocks

o
Basic
clock

rate is 3.2 KHz

o
2 clock ticks make up a
slot

o
1, 3, or 5 slots make up a
packet

Packets

Access Code:


72 bits


timing sync


offset compensation


paging


inquiry

Header:


54 bits


packet
acknowledgement


packet numbering


flow control


slave address


error check for header

Payload:


0
-
2745 bits


either voice field,
data field, or both


if it has a data field,
payload also
contains payload
header

There are 13 special packets for synchronizing and making connections

Four Types of Device Addressing

BD_ADDR

(Bluetooth Device
Address)

48
-
bit device address used to identify each
transceiver

AM_ADDR

(Active Member
Address)

3
-
bit MAC address of the active slave
device

PM_ADDR

(Parked Member
Address)

8
-
bit MAC address of the parked slave
device

AR_ADDR

(Access Request
Address)

Used by parked slaves

Determines when it can ask the master for
messages

Connection States

Devices have two major states

Standby (disconnected)


Default state


Low power


Only native clock is running


No interaction with any device

Connection


Master and slaves can
exchange packets


Uses master's clock


Uses master access code

Connection Modes

Active Mode

Actively participates on the channel

Master schedules the transmissions

Slaves only respond if addressed

Has AM_ADDR (unless it is the master)

Sniff Mode

(low power
-
saving)

(slave only)

Slave listens to piconet at programmable reduced rate

If addressed, switch to active mode

Has AM_ADDR

Hold Mode

(medium power
-
saving)

(slave only)

Slave waits until an internal timer runs out

Master and/or slave can put the slave on HOLD

Data transfer restarts instantly once HOLD finishes

Has AM_ADDR

Park Mode

(high power
-
saving)

(slave only)

Device is still synchronized to piconet, but does not participate

Has given up MAC (AM_ADDR)

Occasionally listens to master to re
-
synchronize and check on messages

Has PM_ADDR instead of AM_ADDR

Connection Setup: Step 1
(Discover)


Source

sends out inquiry packet and waits for an inquiry reply


If a
destination

receives an inquiry packet, it:

o
Enters the inquiry response state

o
Sends the inquiry reply to the source

Connection Setup: Step 2
(Connect)

1.
The source sends special ID packet (page) to the destination

2.
The destination receives the page

3.
The destination sends a reply to the source

4.
The source sends an FHS (Frequency Hopping Synchronization)
packet to the destination

a.
FHS contains BD_ADDR and clock of the source in 144
-
bit data
and 16
-
bit CRC

5.
The destination sends its second reply to the source

6.
The destination and source switch to modes where they can interact

http://www.palowireless.com/infotooth/tutorial.asp

Development Kits

GS
-
BT2416C1DB from ST Microelectronics


USB and RS 232

Serial Interface


$35
-

cheapest


Older Bluetooth version (1.2)


Development Kits

DEV
-
PC
-
1309C
-
ND from CSR


$93.75


Flexible Communication Protocol


Serial and Ethernet


CSR also develops software for
platforms with built in bluetooth
(Android, iPhone) and has multiple
development tools for multiple
profiles


Development Kits

CC2540 Mini Development Kit
from Texas Instruments


$99


Simple, flexible GATT Profile


Best documentation

Development Kits

CC2540 Development Kit From
Texas Instruments

$300

Complete hardware evaluation kit

Complete hardware performance
test platform

GATT Profile

Conclusions


Bluetooth is a wireless communication protocol with speeds between
1 Mbps and 24 Mbps



< 40m range



It avoids interfering with other devices by using FHSS



Its version designs have been driven by power



Its connection states are defined by power consumption



'Profiles' are provided for developing application specific uses

References

http://www.m2mgsm.com/download/BT/docs/general/Bluetooth_Overview.p
d
f


http://www.bluetooth.com/


http://grouper.ieee.org


http://www.palowireless.com/infotooth/tutorial.asp

Questions?