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Chapter 5: Measuring RotationChapter 5: Measuring Rotation

Presentation based on:

"What's a Microcontroller ?"By Andy LindsayParallax, Inc

Presentation developed by:Presentation developed by:

Martin A. ebelMartin A. ebel!othern Illinois #niversity $arbondale!othern Illinois #niversity $arbondale

$olle%e o& Applied !ciences and Arts$olle%e o& Applied !ciences and Arts

lectronic !yste(s )echnolo%ieslectronic !yste(s )echnolo%ies*++-

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Presentation IndexPresentation Index

#se and $opyri%ht

Ad/stin% 0ials and Monitorin% #sin% a potentio(eter as a variable resistor

Activity 1: Bildin%+)estin% Potentio(eter $ircit

Activity 12: Measrin% #sin% )i(e

Introdcin% the $apacitor Polled 3$ )i(e

Activity 1: 3eadin% 4ith BA!I$ !ta(p

3$)IM Pro%ra( xplanation

Activity 15: !ervo $ontrol 4ith Potentio(eter

$hapter 15 3evie4

Lin6s

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Use and CopyrightUse and Copyright

 )his presentation spple(ents "What's aMicrocontroller" by Andy Lindsay. 7Lin6 to text at

Parallax8 )his presentation is not a replace(ent &or the text.

I(portant concepts o& the text are hi%hli%hted.

In so(e cases, additional (aterial has been added

to a%(ent the text. 0enoted by titles colored %old%old. 9ll pro%ra( listin%s are %enerally not provided in

the presentation.

Distribution:

 )his presentation (ay be &reely distribted 4ithot(odications. Modications are per(itted byschools and or%ani;ations &or internal se only.$redits, se and copyri%ht slides (st re(ain.

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CP!RI#$% &D $R&D(M&R)%

 )his doc(entation is $opyri%ht 2-- by Parallax, Inc. By do4nloadin% orobtainin% a printed copy o& this doc(entation or so&t4are yo a%ree that itis to be sed exclsively 4ith Parallax prodcts. Any other ses are notper(itted and (ay represent a violation o& Parallax copyri%hts, le%allypnishable accordin% to 9ederal copyri%ht or intellectal property la4s. Anydplication o& this doc(entation &or co((ercial ses is expressly prohibitedby Parallax, Inc. $hec6 4ith Parallax &or approval prior to dplicatin% any o&or doc(entation in part or 4hole &or any se.

BA!I$ !ta(p is a re%istered trade(ar6 o& Parallax, Inc. I& yo decide to se thena(e BA!I$ !ta(p on yor 4eb pa%e or in printed (aterial, yo (st statethat "BA!I$ !ta(p is a re%istered trade(ar6 o& Parallax, Inc." <ther brandand prodct na(es are trade(ar6s or re%istered trade(ar6s o& theirrespective holders.

DI%C*&IM(R + *I&,I*I$! 

Parallax, Inc. and !othern Illinois #niversity are not responsible &or special,

incidental, or conse=ential da(a%es resltin% &ro( any breach o& 4arranty,or nder any le%al theory, incldin% lost prots, do4nti(e, %ood4ill, da(a%e

to or replace(ent o& e=ip(ent or property, or any costs o& recoverin%,repro%ra((in%, or reprodcin% any data stored in or sed 4ith Parallax

prodcts. Parallax is also not responsible &or any personal da(a%e, incldin%that to li&e and health, resltin% &ro( se o& any o& or prodcts. >o ta6e &ll

responsibility &or yor BA!I$ !ta(p application, no (atter ho4 li&ethreatenin% it (ay be.

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&d-usting Dials and Monitoring&d-usting Dials and Monitoring

0ials are ideal inpt devices &or

ad/st(ents sch as roo( li%htin%and vol(e levels.

 )hey are also sed inside devices &or

&eedbac6, sch as inside the servo tosense actal position.

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Using a potentio.eter as a /ariableUsing a potentio.eter as a /ariable

resistorresistor )he device inside the dial is called a

variable resistor or potentio(eter. )hey are sed in dials, /oystic6s, and(any other devices 4hich need to

prodce an otpt in re&erence to aposition.

Potentio(eters can be pac6a%ed(any dierent 4ays.

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 )he potentio(eter is a resistor 4ith

t4o ter(inals si(ilar to a re%larresistor, bt also has a 4iperter(inal to ad/st 4here contact is

(ade.

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 )he distance &ro( the 4iper to each ter(inal

deter(ines the resistance &or that path. )he (ini(( resistance 4ill be - oh(s,and the (axi(( 4ill be the ratin% o& thepotentio(eter, sch as -@  .

Low resistance

High resistance

High resistance

Low resistance

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&cti/ity 01: ,uilding2$esting Potentio.eter&cti/ity 01: ,uilding2$esting Potentio.eter

CircuitCircuit

$onstrct the circit and observe the

L0's bri%htness at dierent settin%so& the potentio(eter.

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When the L0 4as bri%htest, 4as the

potentio(eter resistance hi%hest orlo4est in the path to the L0?

When the L0 4as bri%htest, 4as thepotentio(eter 4iper closest or &rthest

&ro( ter(inal connected to dd?

7clic6 &or ans4ers8

Lowest

Closest

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&cti/ity 03: Measuring Using $i.e&cti/ity 03: Measuring Using $i.e

In this activity an 3$net4or6

73esistor$apacitor8 is sed to &or( acircit. )he capacitor is char%ed anddischar%ed at dierent rates

deter(ined by the resistor and thecapacitor si;es.

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Introducing the CapacitorIntroducing the Capacitor

 )he capacitor is a device 4hich can store an

electron char%e. Its si;e is expressedtypically in (icro&arads 7µ98 or (illionthso& 9arads.

$ertain types o& capacitors are polaritysensitive, that is, they can only beconnected in one direction.

$onnectin% a polarity sensitivecapacitor bac64ards can casethe device to explode.

CWear sa4ety glassesC(nsure proper polarity6hen connecting

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Polled RC $i.ePolled RC $i.e

In the Polled 3$ )i(e circit the &ollo4in% occrs:

Btton is pressed char%in% the capacitor.

5V

 )he btton is released, the BA!I$!ta(p

be%ins ti(in% and the capacitor be%ins todischar%e.

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. )he BA!I$ !ta(p contines ti(in% ntil

inpt PD chan%es to a lo4 7drops belo4.58.L<<P #E)IL IEDF-

5. )i(e is displayed in tenths o& seconds.

V => 1.4V

Logic 1

V < 1.4V

Logic 0

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 )he ti(e to dischar%e the capacitor is

in proportion to the si;e o& theresistor and capacitor net4or6 73$8.

 )he lar%er the capacitance 7$8, the%reater the char%e it can hold,increasin% ti(e.

 )he lar%er the resistance 738, theslo4er the capacitor 4ill dischar%e,increasin% ti(e.

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&cti/ity 07: Reading 6ith ,&%IC&cti/ity 07: Reading 6ith ,&%IC

%ta.p%ta.p )he BA!I$ !ta(p has an instrction to

per&or( (ch o& the ti(in% operationato(atically:

RC$IM( Pin, State, Variable

Where:

Pin is the pin the 3$ net4or6 is connected.

State is the initial state 4hen ti(in%be%ins.

Variable is the (e(ory location to storethe reslts. Gst li6e P#L!<#) the ti(e isthe n(ber o& 2! incre(ents.

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ReadPotWithRC$i.e Progra.ReadPotWithRC$i.e Progra.

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RC$IM( Progra. (xplanationRC$IM( Progra. (xplanation

0eclare variable ti(e to hold reslts.

0<L<<P code bloc6:C !et I+< PD IH 78.

C Wait -- (! to char%e capacitor and

stabili;e 0B#H screen.C xecte 3$)i(e instrction:

 )i(e ntil capacitor dischar%es andPD leaves dened state 78.

!tore reslts in variable )i(e.

C 0isplay )i(e reslts.

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%cope Capture%cope Capture

End of High,RCTime begins timing.

1.4V threshod crossed

!fter "m# $5m#%&i'(

"m# % )*# = co*nt of 4500

i i % C l i h& ti it 08 % C t l ith

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&cti/ity 08: %er/o Control 6ith&cti/ity 08: %er/o Control 6ith

Potentio.eterPotentio.eterIn this activity the vale o& 3$)i(e is

sed to control a servo. )he 3$)i(e readin% is oset to be

4ithin the controllable ran%e o& the

servo 7-----8.A constant is sed to hold the oset

vale:

9set C 7Pin I+<'s are na(ed sin% $<E:

rcPI C ;

h i

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Chapter 08 Re/ie6Chapter 08 Re/ie6

A potentio(eter is a variable resistor 4herethe 4iper is sed to ad/st the resistance.

$apacitors are sed to hold a char%e.

A resistor and capacitor are sed to &or( an3$ net4or6.

 )he rate o& char%e or dischar%e is dependenton the vales o& 3 and $.

An inpt pin 4ill read hi%h 78 ntil volta%edrops belo4 .5.

Pollin% can be sed to (easre ho4 lon% itta6es the capacitor to reach .5.

3$)i(e (easres the dischar%e ti(e andstores the reslts in a variable as 2!incre(ents.

*i <

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*in<s*in<s

BA!I$ !ta(p o(e

!ta(ps In $lass o(eBA!I$ !ta(p !o&t4are

BA!I$ !ta(p 3obots

BA!I$ !ta(p >ahoo Hrop

!ta(ps In $lass >ahoo Hrop

!I#$ !) 0e%ree