IrDA and Bar Code IR

7/21/2019 IrDA and Bar Code IR

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IrDA

• The Infrared Data Association (IrDA)defines physical specificationscommunications protocol standards for theshortran!e e"chan!e of data o#erinfrared li!ht$ for uses such as personalarea net%or&s ('As)



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IrDA

• IrDA is a #ery shortran!e e"ample of freespaceoptical communication o !o#ernmentre!ulation*

• IrDA interfaces are used in palmtop computers$mo+ile phones$ and laptop computers

• ,any laptops no lon!er offer IrDA in fa#or of

Bluetooth or -i.i %hich don/t need line of si!ht• .or the de#ices to communicate #ia IrDA theymust ha#e a direct line of si!ht



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Bluetooth

• Bluetooth is a shortran!e %ireless communicationsstandard that utilies radiofreuency transmissions inthe 204

• R. 5 not line of si!ht

• 6on!er distance$ so can +e monitored 5 eeds encryption

• Industrial7cientific,edical (I7,) +and 5 potentially su+8ect to !o#ernment re!ulation

• De#ices li&e !ara!e door openers$ +a+y monitors$ andhi!hend cordless phones already inha+it the I7, +and$thou!h$ so it9s a potentially noisy part of the spectrum



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IrDA-Data Bluetooth

Physical Media Infrared R. (20 4)

CommunicationsRange

;p to at least 1m 1<cm to 1<<m

Connection Type,

Direction

'ointto'oint$ arro% An!le

(3< de!rees)

,ultipoint$ =mnidirectional

Maximum DataRate

0,+ps (1>,+ps on the %ay) 1,+ps (a!!re!ate)

ecurity

'hysical limitations offer some

+uiltin protection

Authentication$ encryption$

spread spectrum

ApproximateCost

under ?2 under ?:

Table 1. IrDA and Bluetooth Feature Comparison



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• Can send document from 'DA to printer

%ithout any %ires connected*

• ;se soft%are protocol stac&

similar to TC'@I'

• IrDA11 standard

5 ma" data sie is 2<0 +ytes 5 ma"imum mit rate is 0 ,+ps



• ou ne#er ha#e to %onder %hich de#ice you areactually tal&in! to

• The infrared si!nal is emitted in a narro% cone ofli!ht and %ith #ery little si!nal stren!th

• ou9#e !enerally !ot to +e %ithin one meter ofthe other de#ice and ha#e your infraredtranscei#er pointed in its appro"imate direction

• 7o there9s not much fear of interference fromother IrDA de#ices (e"cept from fluorescentli!hts and other +ac&!round producers ofinfrared radiation) or ea#esdroppin!



0 6ayers to IrDA

• Ir'4 6o%est 6ayer 5 a physical layer that defines data rates$ the encodin! of indi#idual

+its$ and the %ay that +its are com+ined into frames

• Ir6A' 2nd 6ayer 5

6in& Access 'rotocol 5 Data 6in& 6ayer of the =7I model 5 pro#ides addressin!$ error detection$ and retransmission

capa+ilities to ensure the relia+le deli#ery of all pac&ets

• Ir6,' 3rd 6ayer 5 6in& ,ana!ement 'rotocol layer that ena+les multiple

simultaneous con#ersations +et%een the t%o connected systems• Tiny T' Top 6ayer

5 Tiny Transport 'rotocol 5 7e!mentation and Reassem+ly of lar!e messa!es



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IrP!"

• Infrared 'hysical 6ayer 7pecification• 6o%est layer of the IrDA specifications• Ran!e (7tandardF 1 m$

lo%po%er to lo%po%erF <2 m$7tandard to lo% po%erF <3 m)• An!le (minimum cone G@1:H)• 7peed (20 &+it@s to 1> ,+it@s)

• ,odulation (Base +and$ no carrier)• halfduple" mode +ecause %hile transmittin!recei#er is +linded +y the li!ht of its o%ntransmitter$ so full duple" not possi+le



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7IR

• 7erial Infrared (7IR) speeds co#er thosetransmission speeds normally supported+y an R7232 port

5 E><< +it@s$

5 1E2 &+it@s$

5 30 &+it@s$

5 :> &+it@s$

5 11:2 &+it@s



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Bit Rates

• 7erial Infrared (7IR) J 11:2 &+it@s

• ,IR (,edium Infrared) <:> ,+it@s

and 11:2 ,+it@s

• .ast Infrared (.IR) 0 ,+it@s

• Kery .ast Infrared (K.IR) 1> ,+it@s

• ;.IR (;ltra .ast Infrared) 1<< ,+it@s



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Bar Code IR

• ,odern +ar code +e!an in 1E0

• Bernard 7il#er$ a !rad student at Dre"el Institute ofTechnolo!y in 'hiladelphia$

• =#erheard president of a local food chain as&in! one ofthe deans to underta&e research to de#elop a system toautomatically read product information durin! chec&out

• 7il#er told his friend orman Loseph -oodland a+out thefood chain president9s reuest

• -oodland %as a t%enty se#en year old !raduate studentand teacher at Dre"el The pro+lem fascinated-oodland and he +e!an to %or& on the pro+lem



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;'C

• ;ni#ersal 'roduct Code

• httpF@@electronicsho%stuff%or&scom@upchtm

• ;'C sym+ol printed on a pac&a!e has t%o partsF 5

The machine-reada#le #ar code 5 The human-reada#le $%-digit &PC num#er• B 'u+lishin!9s manufacturer identification num+er is the first si"

di!its of the ;'C num+er >3E32• The ne"t fi#e di!its <<<3E are the item num#er • The last di!it$ 3$ of the ;'C code is called a chec' digit

http://electronics.howstuffworks.com/upc.htm

http://electronics.howstuffworks.com/upc.htm



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Chec& Di!it

• 4ere is ho% the chec& di!it is calculated for the other 11 di!its$usin! the code >3E32<<<3E from MThe Teena!er9s uide to theReal -orldM e"ample sho%n a+o#eF

• 7tep 1 Add to!ether the #alue of all of the di!its in odd positions(di!its 1$ 3$ :$ $ E and 11)> G E G G < G < G E J 32

• 7tep 2 ,ultiply that num+er +y 332 N 3 J E>• 7tep 3 Add to!ether the #alue of all of the di!its in e#en positions

(di!its 2$ 0$ >$ and 1<)3 G 3 G 2 G < G 3 J 11

• 7tep 0 Add this sum to the #alue in step 2

E> G 11 J 1<• 7tep : Ta&e the num+er in 7tep 0 To create the chec& di!it$determine the num+er that$ %hen added to the num+er in step 0$ isa multiple of 1<1< G 3 J 11< The chec& di!it is therefore 3



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;'C

• =ne thin! you %ill notice if you startloo&in! at ;'C codes in detail is that the+i! manufactures ha#e manufacturer IDs

%ith lots of eros in them 4ere are a fe%F

• Post - ()*(((

• +eneral Mills - ($(((

• Del Monte - (%)(((

• ua'er .ats - (*((((



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Decodin! the Bars

• .irst of all$ loo& at any 12di!it +ar code Itis made up of +lac& +ars and %hite spaces+et%een the +ars Assume that the

thinnest +ar or space that you see can +ecalled Mone unit %ideM The +ars andspaces can therefore +e seen to ha#e

proportional %idths of one$ t%o$ three orfour units If you loo& at any +ar code youcan see e"amples of these four %idths



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7tart Code

• The start of any +ar code is M111M Thatis$ startin! at the left you find a oneunit%ide +lac& +ar follo%ed +y a oneunit%ide

%hite space follo%ed +y a oneunit%ide+lac& +ar (+arspace+ar)



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Bar Code

.ollo%in! the start code$ the di!its are encoded as follo%sF

< J 32111 J 22212 J 2122

3 J 10110 J 1132: J 1231> J 1110 J 1312

J 1213E J 3112

otice that all of these encodin!s add up to



1E

The code em+edded in the +ars is()*((($/$0(



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Decodin! the Bar Code

The code em+edded in the +ars is ()*((($/$0(• The #ar code starts 1ith the standard start code of $-$-$ 2#ar-space-#ar34• The 5ero is *-%-$-$ 2space-#ar-space-#ar34• The four is $-$-*-% 2space-#ar-space-#ar34• The three is $-)-$-$ 2space-#ar-space-#ar34• The next three 5eros are *-%-$-$ 2space-#ar-space-#ar34



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• In the middle there is a standard $-$-$-$-$ 2space-#ar-space-#ar-space3, 1hich is important #ecause itmeans the num#ers on the right are optically

in6erted7• o no1 1e ha6e #ar-space-#ar-space,

rather than space-#ar-space-#ar



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• The one is %-%-%-$ 2#ar-space-#ar-space34• The eight is $-%-$-* 2#ar-space-#ar-space34• The one is %-%-%-$ 2#ar-space-#ar-space34

• The se6en is $-*-$-% 2#ar-space-#ar-space34• The 5ero is *-%-$-$ 2#ar-space-#ar-space34• The six is $-$-$-) 2#ar-space-#ar-space34• The stop character is a $-$-$ 2#ar-space-#ar34



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IrDA and Bar Code IR