Lecture Programming Microcontrollers

8/9/2019 Lecture Programming Microcontrollers

1/22

Programming Microcontrollers

B. Furman19MAR2011


2/22

Learning Objectives

E!lain an" a!!l# best !ractices in $riting a!rogram %or a microcontroller

E!lain t&e structure o% a !rogram %or t&e

Ar"uino E!lain t&e conce!t o% a 'bit mas() an" use it to

"etermine i% a bit is clear or set *se bit+$ise logical o!erators to create bit

mas(s an" etract bits


3/22

Mec&atronics ,once!t Ma!

,ontroller -ar"$are / o%t$are

#stem to

,ontrol

ensor

ignal

,on"itioning

Po$er nter%ace

Actuator

*ser nter%ace

Po$er

ource

B3 Furman 223A411

ME 105ME 167

ME 168

ME 196

ME 120

ME 298A

ME 105

ME 120

ME 105

ME 190

ME 18

ME 110

ME 1:5

ME 167

ME 168

ME 12

ME 19

ME 196

ME 105

ME 120

ME 105

INTEGRATION


4/22

Reca! Last Lecture

Binar# an" &e numbers ; use &e<

=igital !ins can be in!uts or out!uts

;&at is t&e "i%%erence<

Pins are bidirectional %or "igital >O ;&ic& Ar"uino %unction "o #ou use<

==R - ? B@ ,@ or = %or Amega:2 register

"etermines "irection +bit register

a '1) in ==R means<

a '0) in ==R means<

012:7658


5/22

est Cour ,om!re&ension

;rite co"e to ma(e all !ins o% POR= to be

out!uts -Ar"uino an" alternate ==R= ?

==R= ? 0b11111111; ==R= ? 266D

;rite co"e to ma(e !ins 6@ :@ an" 1 o%

POR= to be out!uts@ an" t&e rest in!uts ==R= ? 0b00101010D

==R= ? 02AD ==R= ? -16 -1: -11D

0xFF;!inMo"e-0@ O*P*D

!inMo"e-8@ O*P*D

Ar"uino st#le

!inMo"e-1@ O*P*D

!inMo"e-:@ O*P*D

!inMo"e-6@ O*P*D

Ar"uino st#le


6/22

tructure o% an Ar"uino Program

An ar"uino !rogram ?? 'sketch)

Must &aveG setu!-

loo!-

setu!- con%igures !in mo"es an"

registers

loo!- runs t&e main bo"# o% t&e

!rogram %orever li(e $&ile-1 HI

;&ere is main- < Ar"uino sim!li%ies t&ings

=oes t&ings %or #ou

>J Blink + turns on an LE= %or =ELACKO4 msec@

t&en o%% %or =ELACKOFF msec@ an" re!eatsB3 Furman rev. 1.1 Last revG 223A42011

J>

"e%ine LE=KP4? 1:D >> LE= on "igital !in 1:

"e%ine =ELACKO4 ? 1000D

"e%ine =ELACKOFF ? 1000D

voi" setu!-

H

>> initialie t&e "igital !in as an out!utG

!inMo"e-LE=KP4@ O*P*D

I

>> loo!- met&o" runs %orever@

>> as long as t&e Ar"uino &as !o$er

voi" loo!-

H

"igital;rite-LE=KP4@ ND >> set t&e LE= on

"ela#-=ELACKO4D >> $ait %or =ELACKO4 msec

"igital;rite-LE=KP4@ LO;D >> set t&e LE= o%%

"ela#-=ELACKOFFD >> $ait %or =ELACKOFF msec

I


7/22

Best Practices an" Patterns +1

Programmer)s bloc( At a minimumG

Program name

=escri!tion o% $&at

t&e !rogram "oes Aut&or

Revision number

Revision "ate>time

Even betterG ,reation "ate

n!uts

Out!uts

Met&o">algorit&m

>J Blink + turns on an LE= %or =ELACKO4 msec@ t&en

o%% %or =ELACKOFF msec@ an" re!eats

B3 Furman rev. 1.1 Last revG 223A42011

J>


8/22

Best Practices an" Patterns +2

Avoi" '&ar" co"ing)constants *se "e%ine an"

s#mbolic names

instea" ;<

#mbolic names are

usuall# !ut in all

ca!s to "i%%erentiate%rom variables

ee me106.h

"e%ine LE=KP4 ? 1:D >> LE= on "igital !in 1:

"e%ine =ELACKO4 ? 1000D

"e%ine =ELACKOFF ? 1000D


9/22

o$ to $i""le Bits

Recall t&e eam!le o% t&e seat beltin"icator s#stem , co"e sni!!et -not %ull !rogram

ATmega328

D0, D1

VTG= +5V

0

1

D2

D3

"e%ine LA,E= 0

"e%ine E4NANE= 0

!inMo"e-0@ 4P*D >> (e# s$itc&!inMo"e-1@ 4P*D >> belt latc& s$itc&

!inMo"e-2@ O*P*D >> lam!

!inMo"e-:@ O*P*D >> buer

(e#Kstate?"igitalRea"-0D

beltKstate?"igitalRea"1D

i%-(e#Kstate??E4NANE= i%-beltKstate??LA,E=

"igital;rite-:@ LO;D

"igital;rite-2@ LO;D

else

"igital;rite-2@ ND

"igital;rite-:@ ND

else D


10/22

Bit Mani!ulation Practice

ee t&e &an"out on Bit Mani!ulation etting bits

,learing bits

oggling bits

Ma(e bits 6 an" : o% PORB &ig& an" t&e rest lo$

ChallengeG


11/22

ummar# o% Bit Mani!ulation

etting a bit -ma(ing it a '1) Bit$ise OR t&e POR register $it& t&e

corres!on"ing bit mas( E. PORTB | = B!"#$;

,learing a bit -ma(ing it a '0) Bit$ise A4= t&e POR register $it& t&e

corres!on"ing complemented bit mas( E. PORTB % = &" B!"#$ $;

oggling a bit -ma(ing it %li! Bit$ise OR t&e POR register $it& t&e

corres!on"ing bit mas( E. PORTB ' = B!"#$;


12/22

Bit $i""ling Practice

Ma(e Ar"uino !ins 11 1: to be out!uts an"

!ins 10 to be in!uts

1. *se t&e Ar"uino met&o"

2. *se t&e 'all+at+once) -general met&o"

,&ec( i% !in 9 is &ig& % !in 9 is &ig&@ ma(e !in 1: &ig& an" !in 11 lo$

Else bot& !ins 1: s&oul" be lo$

1. *se t&e Ar"uino met&o"

2. *se t&e general !ort+st#le met&o"


13/22

Pull+u! Resistors

Pins con%igure" as 4P* can be '!ulle"u!) to QN ; is t&is use%ul<

Puts an in!ut !in in a (no$n state -logic &ig& i% noeternal in%luence &as !ulle" it "o$n -to logic lo$ Eam!le o% a s$itc& connecte" bet$een a !in an"

groun"

o$ is it "one


14/22

Re"o eat Belt ensor #stem

*se !ort+st#le !rogrammingATmega328

D0, D1

VTG= +5V

0

1

D2

D3

"e%ine LA,E= 0

"e%ine E4NANE= 0

==R= ? KBQ-2 KBQ-:D >> =2 an" =: are O*P*s

POR= ? KBQ-0 KBQ-1D >> turn on !ull+u!s %or =0 an" =1currentKstate ? P4=D >> invert %or active+lo$ s$itc&es

(e#Kstate?currentKstate / - KBQ-0

beltKstate?currentKstate / - KBQ-1

i%-(e#Kstate??E4NANE=

i%-beltKstate??LA,E=

POR= / ? - KBQ-2 KBQ-: D >> buer an" lam! o%% else

POR= ? - KBQ-2 KBQ-: D >> buer an" lam! on

else

POR= / ? - KBQ-2 KBQ-: D >> buer an" lam! o%%

Key on D0Belt on D1


15/22

Reca! Amega =igital >O

Pins are bi+"irectional. ,an con%igure asG In)*ts KKKKKKK "etermines t&e !in voltage

O*t)*ts KKKKKK "etermines t&e !in voltage

=irection "etermine" b# bits in ++R register ;&ere is B@ ,@ = %or t&e Amega:2 -an" ==R

corres!on"s to all !ins associate" $it& t&e !ort

% con%igure" as output G Program can s!eci%# a !in to be &ig& -QN or lo$ -N4= b#

$riting a corres!on"ing 1 or 0 -res!ectivel# to POR

register E. o ma(e Port = !ins 8@ :@ an" 7 lo$@ an" t&e rest &ig&

POR=?KKKKKKKKKKKD -$rite in binar#@ t&en in &e


16/22

Reca! Amega =igital >O@ cont.

% !ins con%igure" as input @ t&is meansG Eternal "evice can !ull !in voltage &ig& or lo$

i.e. ta(e u! to QN or ta(e "o$n to N4=

Cou can "etermine t&e state o% t&e !ort

!ins b# rea"ing t&e P4 register Nrabs all eig&t logic levels at t&e same time

E. POR= con%igure" as in!uts

P=0

P=1

P=2

P=:

P=7

P=6

P=5

P=8

QN

uint8_t a_pins;

a_pins=PINDD

;&at is t&e content o% aK!insG

binar#GKKKKKKKKKK

&eGKKKKK


17/22

Reca! Amega =igital >O@ cont.

% !ins con%igure" as input @ cont.G ,an turn !ull+u! resistors on or o%% b#

$riting a 1 or 0 to corres!on"ing !insin POR A !ull+u! resistor internall# connects a

!in to QN to give it a "e%ine" state-logic &ig&@ i.e.@ 1

E. ;rite t&e co"e t&at $illG Ma(e Port = !ins inputs urn on !ull+u! resistors Rea" t&e voltages on t&e !ins an" store

t&em in a variable@ test=

;&at is t&e value o% test= in binar#an" &e< P=0

P=1

P=2

P=:P=7

P=6

P=5

P=8 QN


18/22

Rea"ing POR= Pins Eam!le

unsigne" c&ar test=D

==R=?0D

test=?P4=D

;&at is t&e content o% test=<

binar#G 11111001

&eG F9 P=0

P=1

P=2

P=:

P=7

P=6

P=5

P=8 QN


19/22

Amega:2 Features

Amega:2 "ata s&eet !. 1

&tt!G>>$$$.atmel.com>"#n>resources>!ro"K"ocuments>"oc281.!"%


20/22

Amega:2 nternal Arc&itecture

Amega:2 "ata s&eet !!. 2@ 6


21/22

POR Pin

c&ematics

Amega:2 "atas&eet@ !!. 85+88


22/22

Amega:2 Port Pin =etails

ee t&e Amega:2 "ata s&eet@ !!. 85+97 Port !in %unctionalit# is controlle" b# t&ree

register -s!ecial memor# location bitsG

==R =ata =irection bit in ==R register -rea">$rite

PORn PORn bit in POR "ata register -rea">$rite

P4n P4n bit in P4 register -rea" onl#

Lecture Programming Microcontrollers

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