monitor and control ofgreenhouse environment-greenbee

8/12/2019 Monitor and Control OfGreenhouse Environment-GreenBee

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Biju Patnaik University of Technology

Rourkela

PROJECT REPORT ON

M o n i tor and C on t rol o f Gree n h ou se

E nvir o nment

The Project GreenBee

A Project report submitted in partial fulfillment of the requirement for the award of

Bachelor of Engineering

In

Applied Electronics and Instrumentation Engineering

Submitted by:

Chinmayananda Das !egd "o#$%$&''($)*+

,nder the guid a nce of

-rof# Subhendu BeheraDept# of Applied Electronics . Instrumentation Engineering

Dhanes/ar !ath Institute of Engineering . Management Studies0 Cuttac1

DE-A!2ME"2 34 A--5IED E5EC2!3"ICS A"D I"S2!,ME"2A2I3" E"GI"EE!I"G

D6A"ES7A! !A26 I"S2I2,2E 34 E"GI"EE!I"G . MA"AGME"2 S2,DIES

C,22AC8


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D6A"ES7A! !A26 I"S2I2,2E 34 E"GI"EE!I"G . MA"AGME"2 S2,DIES

C,22AC8

!Affiliated To "iju Patnai# $ni%ersit& of Technolo'&(

Dept# of Applied Electronics . Instrumentation

Engineering

CertificateCertified that the project wor# entitled 9Monitor and Control of Greenhouse

Environment is a bonafide wor# carried outb&)

Chinmayananda Das !egd "o#$%$&''($)*+

in partial fulfillment for the award of the de'ree of "achelor of En'ineerin' in Applied

Electronics and Instrumentation Engineering under "iju Pattnai# $ni%ersit& Of

Technolo'&* Rour#ela* durin' the &ear +,,-.+,,/ It is certified that all corrections0 su''estions

indicated for Internal Assessment ha%e been incorporated in the report and deposited in the

departmental librar& The project report has been appro%ed as it satisfies the academic

requirements in respect of the project wor# prescribed for the said de'ree

Signature:

Proj e ct 1 u id e) 2O 3 3 e pt of AE 4 I) Project Inchar'e)

Name) Name) Name)

3ate) 3ate) 3ate)

Internal e5aminer) E5ternal

e5aminer)Name) Name)


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AC8"375EDGEME"2

The completion of an& project brin's with it a sense of satisfaction* but it is ne%er

complete without than#in' those people who made it possible and whose constant support

has crowned our efforts with success

One cannot e%en ima'ine the power of the force that 'uides us all and neither can we

succeed without ac#nowled'in' it Our deepest 'ratitude to Almi'ht& 1od for holdin' our

hands and 'uidin' us throu'hout our li%es

I would also li#e to e5press our 'ratitude to -rof# Subhendu Behera 2ead of the

3epartment* Appl ied Electronics and Instrumentation 3RIE67* Cuttac# for encoura'in'

and inspirin' us to carr& out the project in the department lab

I would also li#e to than# our 'uide* Er# ;# " Mishra3ept of A p p l i e d Electronics

andCommunication for his e5pert 'uidance* encoura'ement and %aluable su''estions at

e%er& step

8e also would li#e to than# all the staff members of AE4I dept for pro%idin' us with

the required facilities and support towards the completion of the project

8e are e5tremel& happ& to ac#nowled'e and e5press our sincere 'ratitude to our

parents for their constant support and encoura'ement and last but not the least* friends and

well wishers for their help and cooperation and solutions to problems durin' the course of

the project

Also our friends at )$%&pro


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6ONITOR AN3 CONTRO9 O: 1REEN2O$7E EN;IRON6ENT

S="3-SIS

Appropriate en%ironmental conditions are necessar& for optimum plant 'rowth* impro%ed

crop &ields* and efficient use of water and other resources Automatin' the data acquisition

process of the soil conditions and %arious climatic parameters that 'o%ern plant 'rowth allows

information to be collected at hi'h frequenc& with less labor requirements The e5istin' s&stems

emplo& PC or 767.based s&stems for #eepin' the user continuousl& informed of the conditions

inside the 'reenhouse< but are unaffordable* bul#&* difficult to maintain and less accepted b& the

technolo'icall& uns#illed wor#ers

The objecti%e of this project is to desi'n a simple* eas& to install* microcontroller.based

circuit to monitor and record the %alues of temperature* humidit&* soil moisture and sunli'ht of

the natural en%ironment that are continuousl& modified and controlled in order optimi=e them to

achie%e ma5imum plant 'rowth and &ield The controller used is a low power* cost efficient chip

manufactured b& AT6E9 ha%in' >? b&tes of on.chip flash memor& It communicates with the

%arious sensor modules in real.time in order to control the li'ht* aeration and draina'e process

efficientl& inside a 'reenhouse b& actuatin' a cooler* fo''er* dripper and li'hts respecti%el&

accordin' to the necessar& condition of the crops An inte'rated 9iquid cr&stal displa& !9C3( is

also used for real time displa& of data acquired from the %arious sensors and the status of the

%arious de%ices Also* the use of easil& a%ailable components reduces the manufacturin' and

maintenance costs The desi'n is quite fle5ible as the software can be chan'ed an& time It can

thus be tailor.made to the specific requirements of the user

This ma#es the proposed s&stem to be an economical* portable and a low maintenance

solution for 'reenhouse applications* especiall& in rural areas and for small scale a'riculturists

3EPART6ENT O: AE 4 I i% +,,/.+,@,


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3EPART6ENT O: AE 4 I %iii +,,/.+,@,


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5IS2 34 4IG,!ESI :i'ure +@ "loc# dia'ram of the s&stem

II :i'ure + "loc# dia'ram ofphotos&nthesis@+

III :i'ure + Transpiration@D

I; :i'ure D@ 7oil moisture sensor circuit@F

; :i'ure D+ 9i'ht 3ependent Resistor@>

;I :i'ure D+@ 7tructure of a 9i'ht 3ependent Resistor@>

;II :i'ure D 9i'ht sensor circuit@/

;III :i'ure DD 2I2.D,,,.,,@ 2umidit& sensor+,

I :i'ure D- 2umidit& sensor circuit+@

:i'ure D 96- temperature sensor++

I :i'ure DF Temperature sensor circuit+

II :i'ure D> 1ettin' data from the analo' world+D

III :i'ure D/ "loc# dia'ram of A3C ,>,/+-

I; :i'ure D@, :lowchart e5plainin' the 7uccessi%e Appro5imation method+

; :i'ure D@@ Pin dia'ram of A3C ,>,/+

;I :i'ure D@+ A3C ,>,/ pin details for the s&stem+>

;II :i'ure D@ Timin' dia'ram of A3C ,>,/+/

;III :i'ure D@D Cloc# circuitr& for the A3C,

I :i'ure D@- The effect of usin' a 7chmitt tri''er instead of a comparator,

:i'ure D@ Pin dia'ram of AT>/7-+

I :i'ure D@F "loc# dia'ram of the microcontrollerD

II :i'ure D@> Power.on reset circuit

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III :i'ure D@/ Oscillator cloc# circuit>

I; :i'ure D+, Internal memor&bloc#D,

; :i'ure D+@ 6icrocontroller Pin 3etailsD

;I :i'ure D++ Address locations for a +5@ line 9C3DD

;II :i'ure D+ Pin dia'ram of +5@ line 9C3D

;III :i'ure D+D Electrical s&mbol of abu==erD

I :i'ure D+- "u==er circuitr&DF

:i'ure D+ 7u'ar Cube Rela&D>

I :i'ure D+F Circuit s&mbols of rela&sD/

II :i'ure D+> Rela& circuitr&-,

III :i'ure D+/ K-; Power suppl& circuit-@

I; :i'ure D, K@+; Power suppl& circuit-@

; :i'ure -@ 3rip irri'ation s&stem-D

;I :i'ure @ 8indow for choosin' the tar'et de%ice,

;II :i'ure + Project wor#spacepane@

;III :i'ure Project options dialo'@

I :i'ure D L7a%e AllM and L"uild All Tar'et :ilesMbuttons@

9 :i'ure - ;ision 3ebu''er window+

9I :i'ure Reset* Run and 7tep into options

9II :i'ure F Pro'rammin' window

9III Anne5ure.I) 7napshots of the 7&stem>>./,

3EPART6ENT O: AE 4 I 5 +,,/.+,@,


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5IS2 34 2AB5ES

I Table +@ Importance of the %ariousparameters>

II Table D@ 7election of the input channels+F

III Table D+ Alternate functions of Port

I; Table D Pin description of the 9C3D

; Table >@ 7oil moisture sensor readin'sFD

;I Table >+ 9i'ht sensor readin'sF-

;II Table > 2umidit& sensor readin'sF

;III Table >D Temperature sensor readin'sFF

3EPART6ENT O: AE 4 I 5i +,,/.+,@,


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C2APTER @

INTRO3$CTION

3epartment of AE 4 I Pa'e @ +,,/.+,@,


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I"2!3D,C2I3"

8e li%e in a world where e%er&thin' can be controlled and operated automaticall&*but there are still a few important sectors in our countr& where automation has not been

adopted or not been put to a full.fled'ed use* perhaps because of se%eral reasons one such

reason is cost One such field is that of a'riculture A'riculture has been one of the primar&

occupations of man since earl& ci%ili=ations and e%en toda& manual inter%entions in farmin'

are ine%itable 1reenhouses form an important part of the a'riculture and horticulture sectors

in our countr& as the& can be used to 'row plants under controlled climatic conditions for

optimum produce. Automatin' a 'reenhouse en%isa'es monitorin' and controllin' of the

climatic parameters which directl& or indirectl& 'o%ern the plant 'rowth and hence their

produce Automation is process control of industrial machiner& and processes* thereb&

replacin' human operators

& C ,! ! E " 2 S C E " A!I3

1reenhouses in India are bein' deplo&ed in the hi'h.altitude re'ions where the sub.=ero temperature up to .D,Q C ma#es an& #ind of plantation almost impossible and in arid

re'ions where conditions for plant 'rowth are hostile The e5istin' set.ups primaril& are)

& MA", A5 SE2 , -:

This set.up in%ol%es %isual inspection of the plant 'rowth* manual irri'ation ofplants*

turnin' ON and O:: the temperature controllers* manual spra&in' of the fertili=ers and

pesticides It is time consumin'* %ulnerable to human error and hence less accurate and

unreliable

' - A! 2 I A5 5 = A, 2 3 M A 2E D SE2,-:

This set.up is a combination of manual super%ision and partial automation and is

similar to manual set.up in most respects but it reduces the labor in%ol%ed in terms of

irri'atin' the set.up

3epartment of AE 4 I Pa'e + +,,/.+,@,


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> 4 ,55= A ,2 3MA 2ED :

This is a sophisticated set.up which is well equipped to react to most of the climatic

chan'es occurrin' inside the 'reenhouse It wor#s on a feedbac# s&stem which helps it to

respond to the e5ternal stimuli efficientl& Althou'h this set.up o%ercomes the problems

caused due to human errors it is not completel& automated and e5pensi%e

' -!3B5EM D E4I"I2I 3 "

A number of problems associated with the abo%e mentioned s&stems are enumerated

asbelow)

@ Comple5it& in%ol%ed in monitorin' climatic parameters li#e humidit&* soil moisture*

illumination* soil p2* temperature* etc which directl& or indirectl& 'o%ern the plant

'rowth

+ In%estment in the automation process are hi'h* as toda&s 'reenhouse control s&stems are

desi'ned for onl& one parameter monitorin' !as per 1?;? research center(< to control

more than one parameter simultaneousl& there will be a need to bu& more than one

s&stem

2i'h maintenance and need for s#illed technical labor# The modern proposed s&stems use

the mobile technolo'& as the communication schemes and wireless data acquisition

s&stems* pro%idin' 'lobal access to the information about ones farms "ut it suffers from

%arious limitations li#e desi'n comple5it&* incon%enient repairin' and hi'h price Also

the reliabilit& of the s&stem is relati%el& low* and when there are malfunctions in local

de%ices* all local and tele data will be lost and hence the whole s&stem collapses 6ore

o%er farmers in India do not wor# under such sophisticated en%ironment and find no

necessit& of such an ad%anced s&stem* and cannot afford the same

?eepin' these issues in %iew* a microcontroller based monitorin' and control s&stem is

desi'ned to find implementation in the near future that will help Indian farmers

3epartment of AE 4 I Pa'e +,,/.+,@,


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> -!3-3SED M3 DE5 43 ! A,23MA2I3" 34 G!EE"63,SE

The proposed s&stem is an embedded s&stem which will closel& monitor and control

the microclimatic parameters of a 'reenhouse on a re'ular basis round the cloc# for

culti%ation of crops or specific plant species which could ma5imi=e their production o%er the

whole crop 'rowth season and to eliminate the difficulties in%ol%ed in the s&stem b& reducin'

human inter%ention to the best possible e5tent The s&stem comprises of sensors* Analo' to

3i'ital Con%erter* microcontroller and actuators

8hen an& of the abo%e mentioned climatic parameters cross a safet& threshold which

has to be maintained to protect the crops* the sensors sense the chan'e and the

microcontroller reads this from the data at its input ports after bein' con%erted to a di'ital

form b& the A3C The microcontroller then performs the needed actions b& emplo&in' rela&s

until the stra&ed.out parameter has been brou'ht bac# to its optimum le%el 7ince a

microcontroller is used as the heart of the s&stem* it ma#es the set.up low.cost and effecti%e

ne%ertheless As the s&stem also emplo&s an 9C3 displa& for continuousl& alertin' the user

about the condition inside the 'reenhouse* the entire set.up becomes user friendl&

Thus* this s&stem eliminates the drawbac#s of the e5istin' set.ups mentioned in thepre%ious section and is desi'ned as an eas& to maintain* fle5ible and low cost solution

3epartment of AE 4 I Pa'e D +,,/.+,@,


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C2APTER +

7B7TE6 6O3E9

3epartment of AE 4 I Pa'e - +,,/.+,@,


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BASIC M3DE5 34 26E S=S2EM

4 ig # ' #& B lo c1 d iag ram of the s

ystem



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'#& -A !2S 34 26E S= S2EM:

R 7ensors !3ata acquisition s&stem(

Temperature sensor !96-(

2umidit& sensor !2I2D,,,(

9i'ht sensor !93R(

6oisture sensor

R Analo' to 3i'ital Con%erter ! A3C ,>,>0,>,/(

R 6icrocontroller !AT>/7-+(

R 9iquid Cr&stal 3ispla& !2itachiSs 23DDF>,(

R Actuators Rela&s

R 3e%ices controlled

8ater Pump !simulated as abulb(

7pra&er !simulated as abulb(

Cooler !simulated as a fan(

Artificial 9i'hts !simulated as +bulbs(

R "u==er

2 ! A" S D , CE!S D a t a acui s it ion s

ystem+:

This part of the s&stem consists of %arious sensors* namel& soil moisture* humidit&*

temperature and li'ht These sensors sense %arious parameters. temperature* humidit&* soil

moisture and li'ht intensit& and are then sent to the Analo' to 3i'ital Con%erter

A "A 53G 23 DIG I2A5 C3" ?E !DE! AD C

+:

The analo' parameters measured b& the sensors are then con%erted to correspondin'

di'ital %alues b& the A3C

MIC! 3 C 3"2!355E!:

The microcontroller is the heart of the proposed embedded s&stem It constantl&

monitors the di'iti=ed parameters of the %arious sensors and %erifies them with the

predefined threshold %alues and chec#s if an& correcti%e action is to be ta#en for the

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condition at that instant of time In case such a situation arises* it acti%ates the actuators to

perform a controlled operation

A C2,A2 3! S:

An arra& of actuators can be used in the s&stem such as rela&s* contactors* and chan'e

o%er switches etc The& are used to turn on AC de%ices such as motors* coolers* pumps*

fo''in' machines* spra&ers :or the purpose of demonstration rela&s ha%e been used to dri%e

AC bulbs to simulate actuators and AC de%ices A complete wor#in' s&stem can be reali=ed

b& simpl& replacin' these simulation de%ices b& the actual de%ices

DIS - 5A= ,"I2:

A 9iquid cr&stal displa& is used to indicate the present status of parameters and the

respecti%e AC de%ises !simulated usin' bulbs( The information is displa&ed in two modes

which can be selected usin' a push button switch which to''les between the modes An&

displa& can be interfaced to the s&stem with respecti%e chan'es in dri%er circuitr& and code

'#' S2E-S 435537ED I" DESIG"I"G 26E S=S2EM:

Three 'eneral steps can be followed to appropriatel& select the control s&stem)

Step F &: I d enti f y mea s urable variabl e s im

p o r t a n t to

production#

R It is %er& important to correctl& identif& the parameters that are 'oin' to be measured

b& the controllers data acquisition interface* and how the& are to be measured The

set of %ariables t&picall& used in 'reenhouse control is shown below)

Sl# "o# ?ariable to be monitored Its Importance

@ Temperature Affects all plant metabolic functions

+ 2umidit& Affects transpiration rate and the plantSs thermal

control mechanisms

7oil moisture Affects salinit&* and p2 of irri'ation water

D 7olar Radiation Affects photos&nthetic rate* responsible for most

thermal load durin' warmperiods

2a ble ' #& Impo rta nce o f t he var io us para me ters

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An electronic sensor for measurin' a %ariable must readil& a%ailable* accurate* reliable

and low in cost If a sensor is not a%ailable* the %ariable cannot be incorporated into the

control s&stem* e%en if it is %er& important 6an& times %ariables that cannot be directl& or

continuousl& measured can be controlled in a limited wa& b& the s&stem :or e5ample*

fertilit& le%els in nutrient solutions for 'reenhouse production are difficult to measure

continuousl&

StepF ': Inve stig ate the co nt ro l strateg ies#

R An important element in considerin' a control s&stem is the control strate'& that is to

be followed The simplest strate'& is to use threshold sensors that directl& affect

actuation of de%ices :or e5ample* the temperature inside a 'reenhouse can be

affected b& controllin' heaters* fans* or window openin's once it e5ceeds the

ma5imum allowable limit. The li'ht intensit& can be controlled usin' four threshold

le%els As the li'ht intensit& decreases one li'ht ma& be turned on 8ith a further

decrease in its intensit& a second li'ht would be powered* and so on< thus ensurin'

that the plants are not depri%ed of adequate sunli'ht e%en durin' the winter season or

a cloud& da&R 6ore comple5 control strate'ies are those based not onl& on the current %alues of the

controlled %ariables* but also on the pre%ious histor& of the s&stem* includin' the rates

at which the s&stem %ariables are chan'in'

Step F>: Id e n t if y the soft/are and t he hard/a r e to be used#

R It is %er& important that control s&stem functions are specified before decidin' what

software and hardware s&stem to purchase The model chosen must ha%e the abilit&to)

@ E5pand the number of measured %ariables !input subs&stem( and controlled

de%ices !output subs&stem( so that 'rowth and chan'in' needs of the

production operation can be satisfied in the future

+ Pro%ide a fle5ible and eas& to use interface

It must ensure hi'h precision measurement and must ha%e the abilit& resist

noise

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2ardware must alwa&s follow the selection of software* with the hardware required

bein' supported b& the software selected In addition to functional capabilities* the selection

of the control hardware should include factors such as reliabilit&* support* pre%ious

e5periences with the equipment !successes and failures(* and cost

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C2APTER "A7IC T2EORB

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BASIC 26E3!=

>#& 5 I 4E -!3CESSES I "S I D E G!EE"63,SE:

>#& - 6323 S= "2 6E2IC -! 3CESS

The two major life.processes occurrin' in plants are photos&nthesis and transpiration

Photos&nthesis is the con%ersion of li'ht ener'& into chemical ener'& b& li%in' or'anisms

The raw materials are carbon dio5ide and water< the ener'& source is sunli'ht< and the end.

products are o5&'en and !ener'& rich( carboh&drates* for e5ample sucrose* 'lucose and

starch This process is ar'uabl& the most important biochemical pathwa&* since nearl& all

life on Earth either directl& or indirectl& depends on it

4i g > #& B loc1 diag ram o f p hot osynthe sis

3epartment of AE 4 I Pa'e @+ +,,/.+,@,


24/298


A commonl& used but sli'htl& simplified equation for photos&nthesis is)

C3'g+ &' 6'3l+ photons H C6&'3a#+ 3'g+ 6'3l+ >#&+

Carbon dio5ide K water K li'ht ener'& U 'lucose K o5&'en K water

9i'ht ener'& obtained from the sun is %er& essential for photos&nthesis The photons

present in li'ht are responsible for tri''erin' the li'ht.reaction in plants Plants need an

optimum amount of e5posure to li'ht in a da& This optimum period is called its photo.

period The plant sensiti%it& cur%e for photos&nthesis has its pea# at the red side of the

spectrum This indicates that pro%idin' plants with the wa%elen'ths best suited to

photos&nthesis is most efficient with the use of artificial li'ht Tests show a mean de%iation

from the a%era'e sensiti%it& cur%e of less than -V for a wide %ariet& of plants The cur%e

shows that the ma5imum sensiti%it& for photos&nthesis lies in the far red at appro5imatel&

F- nm The plant sensiti%it& cur%e disputes two common misconceptions The first is that an

WidealW plant 'rowin' lamp duplicates the spectral ener'& distribution of the sun 7unli'ht has

a continual spectrum* radiatin' ener'& in wa%elen'ths that contribute less to photos&nthesis*

and are therefore WwastedW on the plant :or this reason* man& lamps are more efficient than

sunli'ht forplants

Plants need dar# periods Periods of li'ht !called photo.periods( and dar# periods and

their relati%e len'ths ha%e an effect on plant maturit& The dar# period of each da& affects

flowerin' and seedin' of most plants Althou'h man& plants can 'row under continuous

li'ht* nearl& all plants prefer a dar# period each da& for normal 'rowth All plants need some

dar#ness to 'row well or to tri''er flowerin' The ideal photoperiods of plants %ar&* some

preferrin' lon' da&s and short ni'hts< others the re%erse< and some do best when the len'th of

the ni'ht and da& periods are equal

>#' 2!A"S- I !A2 I 3"

2ranspiration is the e%aporation of water from the aerial parts of plants* especiall&

lea%es but also stems* flowers and roots Transpiration also cools plants and enables mass

flow of mineral nutrients and water from roots to shoots 6ass flow is caused b& the decrease

in h&drostatic !water( pressure in the upper parts of the plants due to the diffusion of water

out of stomata into the atmosphere 8ater is absorbed at the roots b& osmosis* and an&

dissol%ed mineral nutrients tra%el with it throu'h the 5&lem



25/298


The rate of transpiration is directl& related to the de'ree of stomatal openin'* and to

the e%aporati%e demand of the atmosphere surroundin' the leaf The amount of water lost b&

a plant depends on its si=e* alon' with the surroundin' li'ht intensit&* temperature* humidit&*

and wind speed !all of which influence e%aporati%e demand( 7oil water suppl& and soil

temperature can influence stomatal openin'* and thus the transpiration rate

4 i g > #' 2rans

pi ration

The moisture content in the soil is a %er& crucial factor in the process of transpiration

as the absorption of mineral salts from the soil throu'h the process of osmosis is directl&

dependent on the moisture content in the soil#

The 'reenhouse wor#s best when the temperature is not too hot and not too cold

Thou'h it sounds simple in the sprin' and autumn we can easil& ha%e a wide ran'e of

temperatures from the cold in the middle of the ni'ht to the e5cessi%e heat of the da& when

the sun is shinin' 3urin' the da& the ra&s from the sun penetrate the 'reenhouse and warm

up and li'ht up the surroundin's 9i'ht escapes throu'h the 'lass walls but the heat in form

of infra.red radiations 'ets trapped inside the 'reen house leadin' to an incubatin' effect and

the temperature inside 'raduall& increases This increased temperature leads to an increase in

the rate of transpiration which is harmful to theplants

3epartment of AE 4 I Pa'e @D +,,/.+,@,


26/298


C2APTER D

2AR38ARE 3E7CRIPTION

3epartment of AE 4 I Pa'e @- +,,/.+,@,


27/298


6 A!D7A!E DESC!I-2I3"

*#& 2!A"S D , C E!S:

A transducer is a de%ice which measures a ph&sical quantit& and con%erts it into a

si'nal which can be read b& an obser%er or b& an instrument 6onitorin' and controllin' of a

'reenhouse en%ironment in%ol%es sensin' the chan'es occurrin' inside it which can

influence the rate of 'rowth in plants The parameters which are of importance are the

temperature inside the 'reenhouse which affect the photos&nthetic and transpiration

processes are humidit&* moisture content in the soil* the illumination etc 7ince all these

parameters are interlin#ed* a closed loop !feedbac#( control s&stem is emplo&ed in

monitorin' it The sensors used in this s&stem are)

@ 7oil 6oisture 7ensor!Transistor amplifier(

+ 9i'ht 7ensor ! 93R !9i'ht 3ependent Resistor( (

2umidit& 7ensor !2I2D,,,(

D Temperature 7ensor !96-(

*#& S3I5 M3IS2,!E SE"S3!

*#& 4ea t ures of the So il m o ist u re sensor:

@ The circuit desi'ned uses a -; suppl&* fi5ed resistance of @,,X* %ariable resistance

of @,YX* two copper leads as the sensor probes* +N+++N transistor

+ It 'i%es a %olta'e output correspondin' to the conducti%it& of the soil

The conducti%it& of soil depends upon the amount of moisture present in it It

increases with increase in the water content of the soil

D The %olta'e output is ta#en at the transmitter which is connected to a %ariable

resistance This %ariable resistance is used to adjust the sensiti%it& of the sensor



28/298


VCC

SENSOR LEADS

@,, X

2N222N

ADC IN 5

@, # X

4 i g# * #& S o il moistu r e sensor

*#' 4unct io n al d e s c ript io n of S o il m oistu r e sensor:

The two copper leads act as the sensor probes The& are immersed into the specimen soil

whose moisture content is under test The soil is e5amined under three conditions)

CaseF&: D r

y condit ion The probes are placed in the soil under dr& conditions and are

inserted up to a fair depth of the soil As there is no conduction path between the two copper

leads the sensor circuit remains open The %olta'e output of the emitter in this case ran'es

from , to ,-;

CaseF': 3ptimum c o ndition 8hen water is added to the soil* it percolates throu'h the

successi%e la&ers of it and spreads across the la&ers of soil due to capillar& force This water

increases the moisture content of the soil This leads to an increase in its conducti%it& which

forms a conducti%e path between the two sensor probes leadin' to a close path for the current

flowin' from the suppl& to the transistor throu'h the sensor probes The %olta'e output of thecircuit ta#en at the emitter of the transistor in the optimum case ran'es from @/ to D;

appro5imatel&

CaseF>: E J cess /ater cond it ion 8ith the increase in water content be&ond the optimum

le%el* the conducti%it& of the soil increases drasticall& and a stead& conduction path is

established between the two sensor leads and the %olta'e output from the sensor increases no

further be&ond a certain limit The ma5imum possible %alue for it is not more than D+;

3epartment of AE 4 I Pa'e @F +,,/.+,@,


29/298

CadmiumSulphide


*#' 5I G6 2 SE" S3!

5ight Dependent !esistor !93R( also #nown as photoconductor or photocell* is a

de%ice which has a resistance which %aries accordin' to the amount of li'ht fallin' on its

surface 7ince 93R is e5tremel& sensiti%e in %isible li'ht ran'e* it is well suited for the

proposed application

4 ig # * #' 5ight Depen d ent !esi stor

*#'#& 4eatures of the lig ht sensor:

R The 9i'ht 3ependent Resistor !93R( is made usin' the semiconductor Cadmium

7ulphide !Cd7(

R The li'ht fallin' on the brown =i'=a' lines on the sensor causes the resistance of

thede%ice to fall This is #nown as a ne'ati%e co.efficient There are some 93Rs that

wor# in the opposite wa& ie their resistance increases with li'ht !called positi%e co.

efficient(

R he resistance of the 93R decreases as the intensit& of the li'ht fallin' on it increases

Incident photons dri%e electrons from the %alence band into the conduction band

conduction band

CadmiumSulphide

track

Band gapvalence band

4 i g# * #'#& Structure of a 5ight Dependent !esistor0 s h o/ing C a d m ium Su lphide trac1

a nd a n atom to il l ust r a t e ele c tr o n s i n t he va l e nce and c o nd uction bands

3epartment of AE 4 I Pa'e @> +,,/.+,@,


30/298


*#'#' 4unct io nal de script io n

R An 93R and a normal resistor are wired in series across a %olta'e* as shown in the

circuit below 3ependin' on which is tied to the -; and which to ,;* the %olta'e at

the point between them* call it the sensor node* will either rise or fall with increasin'

li'ht If the 93R is the component tied directl& to the -;* the sensor node will

increase in %olta'e with increasin' li'ht

R The 93RSs resistance can reach @, # ohms in dar# conditions and about @,, ohms in

fullbri'htness

R The circuit used for sensin' li'ht in our s&stem uses a @, #X fi5ed resistor which is

tied to K-; 2ence the %olta'e %alue in this case decreases with increase in li'ht

intensit&

VCC

10K X

ADC_IN4

LDR

GND

4 i g# * #> 5ight sen s or circuit

R The sensor node %olta'e is compared with the threshold %olta'es for different le%els

of li'ht intensit& correspondin' to the four conditions. Optimum* dim* dar# and ni'ht

R The relationship between the resistance !5 and li'ht intensit& 5uJ for a

t&pical 93R is)

!5 Z -,, 0 5uJ #X !D@(

3epartment of AE 4 I Pa'e @/ +,,/.+,@,


31/298


R 8ith the 93R connected to -; throu'h a @,? resistor* the output %olta'e of the 93R

is )

;o Z -[R9 0 !R9K@,( !D+(

R In order to increase the sensiti%it& of the sensor we must reduce the %alue of the fi5ed

resistor in series with the sensor This ma& be done b& puttin' other resistors in

parallel with it

*#> 6,MIDI2= SE"S3!

The humidit& sensor 2I2D,,,* manufactured b& 2one&well is used for sensin' the

humidit& It deli%ers instrumentation qualit& R2 !Relati%e 2umidit&( sensin' performance in

alow cost* solder able 7IP !7in'le In.line Pac#a'e( Relati%e humidit& is a measure* in

percenta'e* of the %apour in the air compared to the total amount of %apour that could be held

in the air at a 'i%en temperature

4ig# * #* 6 I 6 * $$ $ $ $& 6umidi t

y Sensor

*#>#& 4 e a t u r es:

R 9inear %olta'e output %s VR2

R 9aser trimmed interchan'eabilit&

R 9ow power desi'n

R 2i'h accurac&

R :ast response time

3epartment of AE 4 I Pa'e +, +,,/.+,@,


32/298

12


R 7table* low driftperformance

R Chemicall& resistant

R The R2 sensor is a laser trimmed* thermoset pol&mer capaciti%e sensin' element with

on.chip inte'rated si'nal conditionin' The sensin' elementSs multila&er construction

pro%ides e5cellent resistance to most application ha=ards such as wettin'* dust* dirt*

oils and common en%ironmental chemicals

VCC

&'#% 1 X

Vin6I6*$$$ GND

Vout3

To ADC IN6

4ig * #% 6 u midi t y s e n s or circuit

*#>#' 4unct io nal de script io n

R The sensor de%elops a linear %olta'e %s R2 output that is ratiometric to the suppl&

%olta'e That is* when the suppl& %olta'e %aries* the sensor output %olta'e follows in

the same proportion It can operate o%er a D.-> suppl& %olta'e ran'e At -; suppl&

%olta'e* and room temperature* the output %olta'e ran'es from ,> to /; as the

humidit& %aries from ,V to @,,V !noncondensin'(

R The humidit& sensor functions with a resolution of up to ,-V of relati%e humidit&

!R2(

R 8ith a t&pical current draw of onl& +,, A* the 2I2.D,,, 7eries is ideall& suited for

low drain* batter& operated s&stems

R The chan'e in the R2 of the surroundin's causes an equi%alent chan'e in the %olta'e

output The output is an analo' %olta'e proportional to the suppl& %olta'e

3epartment of AE 4 I Pa'e +@ +,,/.+,@,


33/298


Consequentl&* con%ertin' it to relati%e humidit& !R2( requires that both the suppl&

and sensor output %olta'es be ta#en into account accordin' to the formula)

R2 Z !!;out 0 ;suppl&( ,@( 0,,,+* t&pical at +-QC !D(

R This %olta'e is con%erted to the di'ital form b& the A3C and then sent as input to the

microcontroller which reads the data

*#* 2E M-E !A2, !E SE"S 3!

National 7emiconductors 96- IC has been used for sensin' the temperature It isan inte'rated circuit sensor that can be used to measure temperature with an electrical output

proportional to the temperature !inoC( The temperature can be measured more accuratel&

with it than usin' a thermistor The sensor circuitr& is sealed and not subject to o5idation* etc

4 i g# * # 5 M >% temperature sensor

*#*#& 4 e a t u r es:

R Calibrated directl& in Q Celsius !Centi'rade(

R 9inear K @,, m;0QC scale factor

R ,-QC accurac& 'uaranteed !at K+-QC(

R Rated for full \--Q to K@-,QC ran'e

R 7uitable for remote applications

R 9ow cost due to wafer.le%el trimmin'

R Operates from D to , %olts

R 9ess than , A current drain

3epartment of AE 4 I Pa'e ++ +,,/.+,@,


34/298


R 9ow self.heatin'* ,,>QC in still air

R Nonlinearit& onl& ]@^DQC t&pical

4ig# * # 2 empe ratu re s ensor ci rcuit

*#*#' 4un c t io n al descri ption:

R The sensor has a sensiti%it& of @,m; 0oC

R The output of 96- is amplified usin' a 96+D sin'le power suppl& !K-;( op.amp

R The op.amp is desi'ned to ha%e a 'ain of -

R The circuitr& measures temperatures with a resolution of up to ,- de'ree Celsius

RThe output %olta'e is con%erted to temperature b& a simple con%ersion factor The'eneral equation used to con%ert output %olta'e to temperature is)

Temperature !oC( Z !;out [ @,, ( 0 -

oC !DD(

7o if ;out is -;* then* Temperature Z @,,oC

R The output %olta'e %aries linearl& with temperature



35/298


*#' A"A 5 3G 23 DIG I 2A5 C 3 " ? E ! 2E! A D C $ ) $ (+

In ph&sical world parameters such as temperature* pressure* humidit&* and %elocit&

are analo' si'nals A ph&sical quantit& is con%erted into electrical si'nals 8e need an analo'

to di'ital con%erter !A3C(* which is an electronic circuit that con%erts continuous si'nals

into discrete form so that the microcontroller can read the data Analo' to di'ital con%erters

are the most widel& used de%ices for data acquisition

Analo' world

!temperature*

pressure* etc(Transducer

7i'nal

Conditionin'

Analo' to

3i'ital Con%erter 6icrocontroller

4 ig# * #) G e t ti n g d a t a f r om the a n a log /orl d

*#'#& DESC!I-2I3"

The A3C,>,/ data acquisition component is a monolithic C6O7 de%ice with an >.

bit analo'.to.di'ital con%erter* >.channel multiple5er and microprocessor compatible control

lo'ic The >.bit A03 con%erter uses successi%e appro5imation as the con%ersion technique

The con%erter features a hi'h impedance chopper stabili=ed comparator* a +-R %olta'e

di%ider with analo' switch tree and a successi%e appro5imation re'ister The >.channel

multiple5er can directl& access an& of >.sin'le.ended analo' si'nals

The desi'n of the A3C,>,/ has been optimi=ed b& incorporatin' the most desirable

aspects of se%eral A03 con%ersion techniques The de%ice offers hi'h speed* hi'h accurac&*

minimal temperature dependence* e5cellent lon'.term accurac& and repeatabilit&* and

consumes minimal power These features ma#e it ideall& suited for applications from process

and machine control to consumer and automoti%e applications

*#'#' 4 EA 2 , ! ES

@ Eas& interface to all microcontrollers

+ Operates ratiometricall& or with - ;3C or analo' span adjusted %olta'e reference

No =ero or full.scale adjust required

D >.channel multiple5er with address lo'ic

- ,; to -; in

put ran'e with sin'le -; power suppl&

3epartment of AE 4 I Pa'e +D +,,/.+,@,


36/298


Outputs meet TT9 %olta'e le%el specifications

F +>.pin molded chip carrierpac#a'e#

4ig # * #( B loc1 diag ram o f ADC $)$ (

*#'#> C 3 " ?E!S I 3" ME 2 6 3D ,SED

:ollowin' are the most used con%ersion methods)

3i'ital.Ramp A3C

7uccessi%e Appro5imation A3C

:lash A3C

Successive approJimation ADC is suitable for the proposed application It is much

faster than the di'ital ramp A3C because it uses di'ital lo'ic to con%er'e on the %alue closest

to the input %olta'e A comparator and a 3AC !3i'ital to Analo' Con%erter( are used in the

process A flowchart e5plainin' the wor#in' is shownbelow

3epartment of AE 4 I Pa'e +- +,,/.+,@,


37/298


4ig # *#&$ 4lo/ chart eJplaining the Successive approJimation method

*#'#* - I " DI AG! A M 34 A D C $)$)K$)$(

4ig # * #& & -in diag ram o f ADC $)$(



38/298


8e use A* "* C addresses to select IN,.INF and acti%ate Address latch enable !A9E(

to latch in the address 7C is for 7tart Con%ersion EOC is for End of Con%ersion and OE is

for Output Enable The output pins 3,.3F pro%ides the di'ital output from the chip ; ref !.(

and ;ref !K( are the reference %olta'es

*#'#% S E 5EC 2 I"G A" A " A5 3 G C6A""E5

2ow to select the channel usin' three address pins A* "* C is shown in Table below)

7elect Analo' Channel C " A

IN, , , ,

IN@ , , @

IN+ , @ ,

IN , @ @

IND @ , ,

IN- @ , @

IN @ @ ,

INF @ @ @

2a bl e *#& Sel ection o f the input cha nnel s

The A3C ,>,D is most widel& used chip* but since it has onl& one analo' input* A3C

,>,/ is chosen as this chip allows the monitorin' of up to > different transducers usin' onl& a

sin'le chip The > analo' input channels are multiple5ed and selected accordin' to the

requirement "ut for the proposed application onl& the last D channels ie* IND* IN-* IN and

INF are used to monitor the four parameters. temperature* humidit&* soil moisture and li'ht

intensit& 2ence the address line A33_C is 'i%en to ;cc !K -;( as it is alwa&s hi'h in this

case ;ref !K( and ;ref !.( set the reference %olta'es If ;ref !.( Z1nd and ;ref !K( Z-;* the step

si=e is -;0+-Z@/-

7ince there is no self cloc#in' in this chip* the cloc# must be pro%ided from an

e5ternal source to the Cloc# !C9?( pin The >.bit output from the A3C is 'i%en to Port , of

3epartment of AE 4 I Pa'e +F +,,/.+,@,


39/298

3,

3@

3+


the microcontroller and the control si'nals A33_A* A33_"* A33_C* A9E* 7TART* OE*

EOC are 'i%en to Port @ as shown in the fi'ure below

!V

+

+F

+>

@

+

TE6PERAT$RE 7EN7OR

6OI7T$RE 7EN7OR

D

2$6I3ITB 7EN7OR

-

9I12T 7EN7OR

IN,

IN@

IN+

IN

IND

IN-

IN

INF

@@

;CC

A3C,>,/

@F

@D

@-

>

3

@>3D

@/

3-

+,

3

+@3F

PIN @, O: 6C

PIN @@ O: 6C

PIN @+ O: 6C

PIN @ O: 6C

PIN @D O: 6C

PIN @- O: 6C

PIN @ O: 6C

PIN @F O: 6C

@+

K-%

@

;refK A33_A+-

PIN D O: 6C

+D

@,

/

PIN , O: 6C

F

PIN O: 6C

;ref.

C9OC?

OE

EOC

1N3

A33_"

+

A33_C

7TART

++

A9E

PIN - O: 6C

;CC

PIN @ O: 6C

PIN F O: 6C

@

4i g# *#&' ADC $)$( pin details as used for this application

At a certain point of time* e%en thou'h there is no con%ersion in pro'ress the

A3C,>,/ is still internall& c&clin' throu'h > cloc# periods A start pulse can occur an& time

durin' this c&cle but the con%ersion will not actuall& be'in until the con%erter internall&

c&cles to the be'innin' of the ne5t > cloc# period sequence As lon' as the start pin is held

hi'h no con%ersion be'ins* but when the start pin is ta#en low the con%ersion will start within

3epartment of AE 4 I Pa'e +> +,,/.+,@,


40/298


> cloc# periods The EOC output is tri''ered on the risin' ed'e of the start pulse It* too* is

controlled b& the > cloc# period c&cle* so it will 'o low within > cloc# periods of the risin'

ed'e of the start pulse One can see that it is entirel& possible for EOC to 'o low before the

con%ersion starts internall&* but this is not important* since the positi%e transition of EOC*

which occurs at the end of a con%ersion* is what the control lo'ic is loo#in' for Once EOC

does 'o hi'h this si'nals the interface lo'ic that the data resultin' from the con%ersion is

read& to be read The output enable !OE( is then raised hi'h

4 i g * #&> 2i m ing dia g r a m of ADC $)$(

* #> C 53 C8 C I! C,I2 != 4 3! A DC:

*#>#& 4un c t io n a l Description:

The cloc# for the A3C is 'enerated usin' the IC C3D,/* which is a +.input 7chmitt

tri''ered NAN3 'ate A 7chmitt tri''er is a comparator circuit that incorporates positi%e

feedbac#

The Control pin is pulled hi'h and the capacitor char'es and dischar'es producin'

alternate patterns of ,s and @* 'eneratin' a square wa%eform 8hen the input is hi'her than a

certain chosen threshold* the output is hi'h< when the input is below another !lower( chosen

threshold* the output is low< when the input is between the two* the output retains its %alue

The tri''er is so named because the output retains its %alue until the input chan'es

3epartment of AE 4 I Pa'e +/ +,,/.+,@,


41/298


sufficientl& to tri''er a chan'e This dual threshold action is called h&steresis* and implies

that the 7chmitt tri''er has some memor&

4ig# * #&* C lo c1 ci rcu it ry for AD C

The benefit of a 7chmitt tri''er o%er a circuit with onl& a sin'le input threshold is

'reater stabilit& !noise immunit&( 8ith onl& one input threshold* a nois& input si'nal near

that threshold could cause the output to switch rapidl& bac# and forth from noise alone A

nois& 7chmitt Tri''er input si'nal near one threshold can cause onl& one switch in output

%alue* after which it would ha%e to mo%e to the other threshold in order to cause another

switch

4ig # *#&% 2he effect of using a Schmitt t rigger B+ i nstea d of a co mpa rato r A+

3epartment of AE 4 I Pa'e , +,,/.+,@,


42/298


*#* MIC!3C3 "2!355E! A2)(S%'+

*#*#& C! I 2E! I A 4 3! C633SI " G A MIC!3C3"2!355E!

The basic criteria for choosin' a microcontroller suitable for the application are)

@( The first and foremost criterion is that it must meet the tas# at hand efficientl& and cost

effecti%el& In anal&=in' the needs of a microcontroller.based project* it is seen whether an >.

bit* @.bit or +.bit microcontroller can best handle the computin' needs of the tas# most

effecti%el& Amon' the other considerations in this cate'or& are)

!a( Speed: The hi'hest speed that the microcontroller supports

!b( - a c 1a g in g : It ma& be a D,.pin 3IP !dual inline pac#a'e( or a H:P !quad flatpac#a'e(* or some other pac#a'in' format This is important in terms of space*

assemblin'* and protot&pin' the endproduct

!c( -o/er c o nsumptio n : This is especiall& critical for batter&.powered products

!d( The number of I0O pins and the timer on the chip

!f( 2ow eas& it is to up'rade to hi'her performance or lower consumption %ersions

!'( C o s t

per uni t) This is important in terms of the final cost of the product in which

a microcontroller is used

+( The second criterion in choosin' a microcontroller is how eas& it is to de%elop products

around it ?e& considerations include the a%ailabilit& of an assembler* debu''er* compiler*

technical support

( The third criterion in choosin' a microcontroller is its read& a%ailabilit& in needed

quantities both now and in the future Currentl& of the leadin' >.bit microcontrollers* the

>,-@ famil& has the lar'est number of di%ersified suppliers "& supplier is meant aproducer

besides the ori'inator of the microcontroller In the case of the >,-@* this has ori'inated b&

Intel se%eral companies also currentl& producin' the >,-@

Thus the microcontroller AT>/7-+* satisf&in' the criterion necessar& for the proposed

application is chosen for the tas#

*#*#' DE SC !I - 2 I 3 " :

The >,-@ famil& of microcontrollers is based on an architecture which is hi'hl&

optimi=ed for embedded control s&stems It is used in a wide %ariet& of applications from



43/298


militar& equipment to automobiles to the #e&board 7econd onl& to the 6otorola >2C@@ in

ei'ht bit processors sales* the >,-@ famil& of microcontrollers is a%ailable in a wide arra& of

%ariations from manufacturers such as Intel* Philips* and 7iemens These manufacturers ha%e

added numerous features and peripherals to the >,-@ such as I+C interfaces* analo' to di'ital

con%erters* watchdo' timers* and pulse width modulated outputs ;ariations of the >,-@ with

cloc# speeds up to D,62= and %olta'e requirements down to @- %olts are a%ailable This

wide ran'e of parts based on one core ma#es the >,-@ famil& an e5cellent choice as the base

architecture for a compan&Ss entire line of products since it can perform man& functions and

de%elopers will onl& ha%e to learn this oneplatform

The AT>/7-+ is a low.power* hi'h.performance C6O7 >.bit microcontroller with

>? b&tes of in.s&stem pro'rammable :lash memor& The de%ice is manufactured usin'

Atmels hi'h.densit& non%olatile memor& technolo'& and is compatible with the industr&.

standard >,C-@ instruction set and pinout The on.chip :lash allows the pro'ram memor& to

be repro'rammed in.s&stem or b& a con%entional non%olatile memor& pro'rammer "&

combinin' a %ersatile >.bit CP$ with in.s&stem pro'rammable :lash on a monolithic chip*

the Atmel AT>/7-+ is a powerful microcontroller which pro%ides a hi'hl&.fle5ible and cost.

effecti%e solution to man& embedded control applications In addition* the AT>/7-+ is

desi'ned with static lo'ic for operation down to =ero frequenc& and supports two software

selectable power sa%in' modes The Idle 6ode stops the CP$ while allowin' the RA6*

timer0counters* serial port* and interrupt s&stem to continue functionin' The Power.down

mode sa%es the RA6 con.tents but free=es the oscillator* disablin' all other chip functions

until the ne5t interrupt or hardware reset

*#*#> 4 EA 2 , ! ES:

The basic architecture of AT>/C-@ consists of the followin' features)R Compatible with 6C7.-@ Products

R >? "&tes of In.7&stem Pro'rammable !I7P( :lash 6emor&

R D,; to --; Operatin' Ran'e

R :ull& 7tatic Operation) , 2= to 62=

R +- 5 >.bit Internal RA6

R + Pro'rammable I0O 9ines



44/298


R Three @.bit Timer0Counters

R Ei'ht Interrupt 7ources

R :ull 3uple5 $ART 7erial Channel

R 9ow.power Idle and Power.down 6odes

R Interrupt Reco%er& from Power.down 6ode

R 8atchdo' Timer

R :ast Pro'rammin' Time

R :le5ible I7P Pro'rammin' !"&te and Pa'e 6ode(

*#*#* - I" C3"4I G,!A2 I3"

4ig# * #& -in di ag ram of A2)(S%'



45/298


*#*#% B53 C8 D IA G! AM

4ig# * #& B lo c1 di ag ram of the mic ro co ntro ller



46/298


*#*# - I " DESC!I-2I3"

R ?CC: 7uppl& %olta'e

R G"D: 1round

R -ort $: Port , is an >.bit open drain bidirectional I0O port As an output port* each pin

can sin# ei'ht TT9 inputs 8hen @s are written to port , pins* the pins can be used as

hi'h.impedance inputs Port , can also be confi'ured to be the multiple5ed low.order

address0data bus durin' accesses to e5ternal pro'ram and data memor& In this mode*

P, has internalpull.ups

R -ort &: Port @ is an >.bit bidirectional I0O port with internal pull.ups The Port @

output buffers can sin#0source four TT9 inputs 8hen @s are written to Port @ pins*

the& are pulled hi'h b& the internal pull.ups and can be used as inputs As inputs* Port

@ pins that are e5ternall& bein' pulled low will source current !II9( because of the

internal pull.ups In addition* P@, and P@@ can be confi'ured to be the timer0counter

+ e5ternal count input !P@,0T+( and the timer0counter + tri''er input !P@@0T+EJ(*

respecti%el&* as shown in the followin' table

R -ort ': Port + is an >.bit bidirectional I0O port with internal pull.ups The Port +output buffers can sin#0source four TT9 inputs 8hen @s are written to Port + pins*


+ pins that are e5ternall& bein' pulled low will source current !II9( because of the

internal pull.ups Port + emits the hi'h.order address b&te durin' fetches from

e5ternal pro'ram memor& and durin' accesses to e5ternal data memor& that use @.

bit addresses !6O; ` 3PTR( In this application* Port + uses stron' internal pull.

ups when emittin' @s 3urin' accesses to e5ternal data memor& that uses >.bit

addresses !6O; ` RI(* Port + emits the contents of the P+ 7pecial :unction

re'ister

R -ort >: Port is an >.bit bidirectional I0O port with internal pull.ups The Port

output buffers can sin#0source four TT9 inputs 8hen @s are written to Port pins*


pins that are e5ternall& bein' pulled low will source current !II9( because of the

pull.ups Port recei%es some control si'nals for :lash pro'rammin' an %erification



47/298


Port also ser%es the functions of %arious special features of the AT>/7-+* as shown in

the followin' table

Alt er nate funct io ns of -ort >:

2 a ble * #' Alt e rn a t e fun c ti o ns of -ort >

R !S2: Reset input A hi'h on this pin for two machine c&cles while the oscillator

is runnin' resets the de%ice This pin dri%es hi'h for /> oscillator periods after the

watchdo' times out

*#*##& -o /e r 3n ! eset ci rcuit

4ig# * #&) -o /er on re set ci rcu it



48/298


In order for the RE7ET input to be effecti%e* it must ha%e a minimum duration of two

machine c&cles

R A5EK-!3G: Address 9atch Enable !A9E( is an output pulse for latchin' the

low b&te of the address durin' accesses to e5ternal memor& This pin is also the

pro'ram pulse input !PRO1( durin' :lash pro'rammin' In normal operation*

A9E is emitted at a constant rate of @0 the oscillator frequenc& and ma& be used

for e5ternal timin' or cloc#in' purposes Note* howe%er* that one A9E pulse is

s#ipped durin' each access to e5ternal data memor& If desired* A9E operation

can be disabled b& settin' bit , of 7:R location >E2 8ith the bit set* A9E is

acti%e onl& durin' a 6O; or 6O;C instruction Otherwise* the pin is wea#l&

pulled hi'h 7ettin' the A9E.disable bit has no effect if the microcontroller is in

e5ternal e5ecution mode

R -SE": Pro'ram 7tore Enable !P7EN( is the read strobe to e5ternal pro'ram

memor& 8hen the AT>/7-+ is e5ecutin' code from e5ternal pro'ram memor&*

P7EN is acti%ated twice each machine c&cle* e5cept that two P7EN acti%ations

are s#ipped durin' each access to e5ternal data memor&

R EA: E5ternal Access Enable EA must be strapped to 1N3 in order to enable the

de%ice to fetch code from e5ternal pro'ram memor& locations startin' at ,,,,2

up to ::::2 Note* howe%er* that if loc# bit @ is pro'rammed* EA will be

internall& latched on reset EA should be strapped to ;CC for internal pro'ram

e5ecutions This pin also recei%es the @+.%olt pro'rammin' enable %olta'e !;PP(

durin' :lashpro'rammin'

R 2A5&: Input to the in%ertin' oscillator amplifier and input to the internal cloc#

operatin' circuit

R 2A5': Output from the in%ertin' oscillator amplifier

*#*##' 2he A 2)( S%' osci lla tor clo c1 cir cuit

" It uses a quart= cr&stal oscillator

" 8e can obser%e the frequenc& on the TA9+pin

3epartment of AE 4 I Pa'e F +,,/.+,@,


49/298


C2

>$p4

C1

>$p4

#$%&2

#$%&1

GN D

4ig * #&( 2 he A2)( S%' oscillator cloc1 circuit

" The cr&stal frequenc& is the basic internal frequenc& of the microcontroller

" The internal counters must di%ide the basic cloc# rate to &ield standard

communication bit per second !baud( rates

" An @@,-/+ me'ahert= cr&stal* althou'h seemin'l& an odd %alue* &ields a cr&stal

frequenc& of /+@ #ilohert=* which can be di%ided e%enl& b& the standard

communication baud rates of @/+,,* /,,* D>,,* +D,,* @+,,* and ,, hert=

*#*# S- EC IA5 4 , "C 2 I 3" !EGIS2E!S

The 7pecial :unction Re'isters !7:Rs( contain memor& locations that are used for

special tas#s Each 7:R occupies internal RA6 from ,5>, to ,5::The& are >.bits wide

R The A !accumulator( re'ister or accumulator is used for most A9$ operations and

"oolean "it manipulations

R Re'ister " is used for multiplication 4 di%ision and can also be used for 'eneral

purpose stora'e

R P78 !Pro'ram 7tatus 8ord( is a bit addressable re'ister

R PC or pro'ram counter is a special @.bit re'ister It is not part of 7:R Pro'ram

instruction b&tes are fetched from locations in memor& that are addressed b& the

PC

3epartment of AE 4 I Pa'e > +,,/.+,@,


50/298


R 7tac# Pointer !7P( re'ister is ei'ht bits wide It is incremented before data is

stored durin' P$72 and CA99 e5ecutions 8hile the stac# ma& reside an&where

in on.chip RA6* the 7tac# Pointer is initiali=ed to ,F2 after a reset This causes

the stac# to be'in at location ,>2

R 3PTR or data pointer is a special @.bit re'ister that is accessible as two >. bit

re'isters) 3P9 and 3P2* which are used to used to furnish memor& addresses for

internal and e5ternal code access and e5ternal data access

R Control Re'isters) 7pecial :unction Re'isters IP* IE* T6O3* TCON* 7CON* and

PCON contain control and status bits for the interrupt s&stem* the

Timer0Counters* and the serialport

R Timer Re'isters) Re'ister pairs !T2,* T9,( and !T2@* T9@( are the @.bit

Counter re'isters for Timer0Counters , and @* respecti%el&

*#*#) ME M3 != 3! GA"I LA2I 3"

6C7.-@ de%ices ha%e a separate address space for Pro'ram and 3ata 6emor& $p to

D? b&tes each of e5ternal Pro'ram and 3ata 6emor& can be addressed

R - r og r am M e m o r y : If the EA pin is connected to 1N3* all pro'ram fetches are

directed to e5ternal memor& On the AT>/7-+* if EA is connected to ;CC*

pro'ram fetches to addresses ,,,,2 throu'h @:::2 are directed to internal

memor& and fetches to addresses +,,,2 throu'h ::::2 are to e5ternal memor&

R D a ta M e mo r y: The AT>/7-+ implements +- b&tes of on.chip RA6 The upper

@+> b&tes occup& a parallel address space to the 7pecial :unction Re'isters This

means that the upper @+> b&tes ha%e the same addresses as the 7:R space but are

ph&sicall& separate from 7:R space 8hen an instruction accesses an internal

location abo%e address F:2* the address mode used in the instruction specifies

whether the CP$ accesses the upper @+> b&tes of RA6 or the 7:R space

Instructions which use direct addressin' access the 7:R space The lower @+>

b&tes of RA6 can be di%ided into three se'ments)

3epartment of AE 4 I Pa'e / +,,/.+,@,


51/298


! e g i st e r B a n 1 s $ >: locations ,,2 throu'h @:2 !+ b&tes( The de%ice after reset

defaults to re'ister ban# , To use the other re'ister ban#s* the user must select them

in software Each re'ister ban# contains ei'ht @.b&te re'isters R,.RF Reset initiali=es

the stac# point to location ,F2* and is incremented once to start from ,>2* which is

the first re'ister of the second re'isterban#

'# B i t Address a b l e Ar e a : @ b&tes ha%e been assi'ned for this se'ment +,2.+:2

Each one of the @+> bits of this se'ment can be directl& addressed !,.F:2( Each of

the @ b&tes in this se'ment can also be addressed as ab&te

># Sc r a tch - a d Area: ,2.F:2 are a%ailable to the user as data RA6 2owe%er* if

the data pointer has been initiali=ed to this area* enou'h b&tes should be left aside to

pre%ent 7P data destruction

4ig# * #'$ I n ter n a l m e m o ry bloc1

*#*#( 7A2C6D3G 2IME! 3netime Enabled /ith !esetout+

The 83T is intended as a reco%er& method in situations where the CP$ ma& be

subjected to software upsets The 83T consists of a @D.bit counter and the 8atchdo' Timer

3epartment of AE 4 I Pa'e D, +,,/.+,@,


52/298


53/298


2IME! M3D E > : In mode.* timer.@ simpl& hold its count* where as timer , re'isters T9,

and T2, are used as two separate >.bit counters T9, uses the Timer., control bits T2,

counts machine c&cles and ta#es o%er the use of TR@ and T:@ from Timer.@

*#*#&& I " 2 E ! !, - 2S

A computer has onl& two wa&s to determine the conditions that e5ist in internal and

e5ternal circuits One method uses software instructions that jump to subroutines on the

states of fla's and port pins The second method responds to hardware si'nals* called

interrupts that force the pro'ram to call a subroutine

The AT>/7-+ has a total of si5 interrupt %ectors) two e5ternal interrupts !INT, and

INT@(* three timer interrupts !Timers ,* @* and +(* and the serial port interrupt Each of these

interrupt sources can be indi%iduall& enabled or disabled b& settin' or clearin' a bit in

7pecial :unction Re'ister IE IE also contains a 'lobal disable bit* EA* which disables all

interrupts at once

Each interrupt forces the processor to jump at the interrupt location in the memor&

The interrupted pro'ram must resume operation at the instruction where the interrupt too#

place Pro'ram resumption is done b& storin' the interrupted PC address on to stac#

RETI instruction at the end of I7R will restore the PC address

*#*#&' MIC!3C3" 2!3 55 E! C3"4IG,!A2 I3" , SED I" 26E SE2,-

The microcontroller is interfaced with the A3C in pollin' mode INT, is used for the

9C3 mode selection switch in order to switch between two modes of displa&)

@( 7ensor output displa&

+( Actuator status displa&

Port details)

R Port ,) Interfaced with the 9C3 data lines

R Port @) Interfaced with the A3C data lines

R Port +) Interfaced with the 9C3 Control lines and AC Interface control

R Port ) Interfaced with the A3C control lines

3epartment of AE 4 I Pa'e D+ +,,/.+,@,


54/298


A3C_3,

A3C_3@

A3C_3+

A3C_3

A3C_3D

A3C_3-

A3C_3

A3C_3F

-$

-&

-'

->

-*

-%

-

-

VCC

-$#$

-$#&

-$#'

-$#>

-$#*

-$#%

-$#

9E3K

3",

3"@

3"+

3"

3"D

3"-

3"

A3C_A

A3C_"

A3C_7TART

A3C_A9E

A3C_EOC

A3C_OE

"$GGER

6O3E 7E9ECTION 78ITC2

->#*

->#%

->#&

->#

->#>

->#$

->#

->#'

AT>/7-+

-$#

EA

A5E

-SE"

-'#

-'#

-'#%

-'#*

3"F

ENA"9E

R08 !Read08rite(

R7 !Re'ister select(

COO9ER

>$ p4

>$ p4

@,u:

>+ #

R7T

1N3

2A5'

2A5&

!S2

G"D

-'#>

-'#'

-'#&

-'#$

P$6P

7PRABER

9I12T @

9I12T +

4i g# *#'& Microco ntro ller pi n details



55/298


*#% 5I@, I D C!= S 2A5 DIS-5A=

A liquid cr&stal displa& !9C3( is a thin* flat displa& de%ice made up of an& number of

color or monochrome pi5els arra&ed in front of a li'ht source or reflector Each pi5el consists

of a column of liquid cr&stal molecules suspended between two transparent electrodes* and

two polari=in' filters* the a5es of polarit& of which are perpendicular to each other 8ithout

the liquid cr&stals between them* li'ht passin' throu'h one would be bloc#ed b& the other

The liquid cr&stal twists the polari=ation of li'ht enterin' one filter to allow it to pass throu'h

the other

6an& microcontroller de%ices use Ssmart 9C3S displa&s to output %isual information

9C3 displa&s desi'ned around 2itachiSs 9C3 23DDF>, module* are ine5pensi%e* eas& to

use* and it is e%en possible to produce a readout usin' the >5>, pi5els of the displa& The&

ha%e a standard A7CII set of characters and mathematical s&mbols

:or an >.bit data bus* the displa& requires a K-; suppl& plus @@ I0O lines :or a D.bit

data bus it onl& requires the suppl& lines plus se%en e5tra lines 8hen the 9C3 displa& is not

enabled* data lines are tri.state and the& do not interfere with the operation of the

microcontroller

3ata can be placed at an& location on the 9C3 :or @+ 9C3* the address locations

are)

4irst line )$ )& )' )> )* )% ) through )4

Second line C$ C& C' C> C* C% C through C4

4ig * #'' Addr ess lo cations for a ' J& li ne 5CD

*#%#& SIG"A5S 23 26E 5CD

The 9C3 also requires control lines from the microcontroller)

&+ E n a b le E+

This line allows access to the displa& throu'h R08 and R7 lines 8hen this line

is low* the 9C3 is disabled and i'nores si'nals from R08 and R7 8hen !E( line is

hi'h* the 9C3 chec#s the state of the two control lines and responds accordin'l&

'+ !eadK7rite !K7+

This line determines the direction of data between the 9C3 and microcontroller

3epartment of AE 4 I Pa'e DD +,,/.+,@,


56/298


8hen it is low* data is written to the 9C3 8hen it is hi'h* data is read from the

9C3

>+ ! e gi ster s e le ct !S+

8ith the help of this line* the 9C3 interprets the t&pe of data on data lines 8hen it is

low* an instruction is bein' written to the 9C3 8hen it is hi'h* a character is bein' written

to the 9C3

*#%#& 5ogic s t atus on c o n t r o l lines:

" E . , Access to 9C3 disabled

. @ Access to 9C3 enabled

" R08 . , 8ritin' data to 9C3

. @ Readin' data from 9C3

" R7 . , Instruction

. @ Character

*#%#' 7 r i t in g a n d r e ad ing the d a t a f r om the 5CD:

8ritin' data to the 9C3 is done in se%eral steps)

@( 7et R08 bit to low

+( 7et R7 bit to lo'ic , or @ !instruction or character(

( 7et data to data lines !if it is writin'(

D( 7et E line to hi'h

-( 7et E line to low

Read data from data lines !if it is readin'()

@( 7et R08 bit to hi'h

+( 7et R7 bit to lo'ic , or @ !instruction or character(

( 7et data to data lines !if it is writin'(

D( 7et E line to hi'h-( 7et E line to low

*#%#' - I " DESC!I-2I3"

6ost 9C3s with @ controller has @D Pins and 9C3s with + controller has @ Pins

!two pins are e5tra in both for bac#.li'ht 9E3 connections(

3epartment of AE 4 I Pa'e D- +,,/.+,@,


57/298


4ig * #'> -in d ia g ram o f ' J & li ne 5CD

2able * #'> - i n descri p tion o f t he 5CD

*# A 5A !M C I!C, I2!=

B,L L E!:

A buer or beeper is a si'nalin' de%ice* usuall& electronic* t&picall& used in

automobiles* household appliances such as a microwa%e o%en

4ig # *#'* Elec trical symbol of a bu er



58/298


It is connected to the control unit throu'h the transistor that acts as an electronic

switch for it 8hen the switch forms a closed path to the bu==er* it sounds a warnin' in the

form of a continuous or intermittent bu==in' or beepin' sound

The transistor acts as a normal controlled b& the base connection It switches ON

when a positi%e %olta'e from the control unit is applied to the base If the positi%e %olta'e is

less than ,;* the transistor switches O:: No current flows throu'h the bu==er in this case

and it will not bu== As can be seen in the bu==er circuitr& 'i%en below* a protection resistor

of @,# ohm is used in order to protect the transistor from bein' dama'ed in case of e5cessi%e

current flow In our s&stem* the bu==er is desi'ned to 'i%e a small beep whene%er one of the

de%ices such as a cooler or a bulb turns on in order to alert the user

4i g# * #'% Buer circuitry

*# ! E 5 A =S

A rela& is an electrical switch that opens and closes under the control of another

electrical circuit In the ori'inal form* the switch is operated b& an electroma'net to open or

close one or man& sets of contacts It was in%ented b& Joseph 2enr& in @>- "ecause a rela&

is able to control an output circuit of hi'her power than the input circuit* it can be considered

to be* in a broad sense* a form of an electrical amplifier

3epartment of AE 4 I Pa'e DF +,,/.+,@,


59/298


4ig # * #' Suga r cube relay

3espite the speed of technolo'ical de%elopments* some products pro%e so popular

that their #e& parameters and desi'n features remain %irtuall& unchan'ed for &ears One suchproduct is the su'ar cube rela&* shown in the fi'ure abo%e* which has pro%ed useful to

man& desi'ners who needed to switch up to @,A* whilst usin' relati%el& little PC" area

7ince rela&s are switches* the terminolo'& applied to switches is also applied to

rela&s A rela& will switch one or more poles* each of whose contacts can be thrown b&

ener'i=in' the coil in one of three wa&s)

@" o rmally open " 3 + contacts connect the circuit when the rela& is acti%ate d< the circuit

is disconnected when the rela& is inacti%e It is also called a :OR6 A contact or Lma#eM

contact

+" o rmally c lo s ed " C+ contacts disconnect the circuit when the rela& is acti%ated < the

circuit is connected when rela& is inacti%e It is also called :OR6 " contact orM

brea#M contact

Cha n g e o ver or dou b l e th r o/ contacts control two circuits < one normall& open contact

and one normall& closed contact with a common terminal It is also called a :orm C

LtransferLcontact

The followin' t&pes of rela&s are commonl& encountered)

3epartment of AE 4 I Pa'e D> +,,/.+,@,


60/298


WCW denotes the common terminal in 7P3T and 3P3T t&pes

4i g # * #' Di f ferent t

y

p e s of !elays

R S-S2 . Sin ' le -ole Sin ' le 2hr o w ) These ha%e two terminals which can be connected

or disconnected Includin' two for the coil* such a rela& has four terminals in total It

is ambi'uous whether the pole is normall& open or normall& closed The terminolo'&

W7PNOW and W7PNCW is sometimes used to resol%e the ambi'uit&

R S-D2 . Sin ' le -ole Dou b le 2hr o w ) A common terminal connects to either of twoothers Includin' two for the coil* such a rela& has fi%e terminals in total

R D-S2 . Dou b le -ole Sin ' le 2hr o w ) These ha%e two pairs of terminals Equi%alent to

two 7P7T switches or rela&s actuated b& a sin'le coil Includin' two for the coil* such

a rela& has si5 terminals in total It is ambi'uous whether the poles are normall& open*

normall& closed* or one of each

R D-D2 . Dou b le -ole Dou b le 2hrow) These ha%e two rows of chan'e.o%er terminals

Equi%alent to two 7P3T switches or rela&s actuated b& a sin'le coil 7uch a rela& has

ei'ht terminals* includin' the coil

R @-D2 . @uadr up le -o l e Do uble 2h r ow ) Often referred to as Huad Pole 3ouble

Throw* or DP3T These ha%e four rows of chan'e.o%er terminals Equi%alent to four

7P3T switches or rela&s actuated b& a sin'le coil* or two 3P3T rela&s In total*

fourteen terminals includin' the coil

The Rela& interfacin' circuitr& used in the application is)

3epartment of AE 4 I Pa'e D/ +,,/.+,@,


61/298


1N4148

4ig# *#') ! el ay ci rcuit r

y

*#) -3 7 E! S ,- - 5= C3""EC2I3"

The power suppl& section consists of step down transformers of +,; primar& to /;

and @+; secondar& %olta'es for the K-; and K@+; power supplies respecti%el& The stepped

down %olta'e is then rectified b& D @ND,,F diodes The hi'h %alue of capacitor @,,, :

char'es at a slow rate as the time constant is low* and once the capacitor char'es there is no

resistor for capacitor to dischar'e This 'i%es a constant %alue of 3C IC F>,- is used for

re'ulated suppl& of K- %olts and IC F>@+ is used to pro%ide a re'ulated suppl& of K@+ %olts in

order to pre%ent the circuit ahead from an& fluctuations The filter capacitors connected after

this IC filters the hi'h frequenc& spi#es These capacitors are connected in parallel with

suppl& and common so that spi#es filter to the common These 'i%e stabilit& to the power

suppl& circuit

As can be seen from the abo%e circuit dia'rams* the rectified %olta'e from the D

diodes is 'i%en to pin @ of the respecti%e re'ulators Pin + of the re'ulators is connected to

'round and pin to ;cc 8ith adequate heat sin#in' the re'ulator can deli%er @A output

current If internal power dissipation becomes too hi'h for the heat sin#in' pro%ided* the

thermal shutdown circuit ta#es o%er pre%entin' the IC from o%erheatin'

3epartment of AE 4 I Pa'e -, +,,/.+,@,


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3


1Vin '()! Vout

GND

2

23)V* !)+,

1)))u-

1)u- 1u-

4i g # *#'( %? -o/er supply circuit

4ig # * #>$ &'? -o/er suppl

y Circui t

3epartment of AE 4 I Pa'e -@ +,,/.+,@,


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CI!C,I2 SC6EMA2IC 34 26E S=S2EM


64/298


C2APTER -

7B7TE67 $7E3 IN 8OR? 6O3E



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%#& D!I- I! !IGA2I3" S= S2EM 43 ! C3"2!355I" G S3I5 M3IS2,!E

3rip* or micro.irri'ation* technolo'& uses a networ# of plastic pipes to carr& a low

flow of water under low pressure toplants

-olyethylene tubing is run from the source of water to the plant* where the emitter is

attached for drippin' water Emitter line !pol& tubin' with pre.installed emitters( is used

where a continuous band of water is needed 4ittings are a%ailable to ma#e sharp turns

!elbows(* branch lines !tees(* and to ma#e the transition between different si=es of tubin'

8hen plants are remo%ed or die* drip lines should beplu''ed

4ig# % #& D r ip irrigation s

ystem

3rip irri'ation !sometimes called tric#le irri'ation( wor#s b& appl&in' water slowl&*

directl& to the soil The hi'h efficienc& of drip irri'ation results from two primar& factors

The first is that the water soa#s into the soil before it can e%aporate or run off The second is

that the water is onl& applied where it is needed* !at the plantSs roots( rather than spra&ed

e%er&where

A drip irri'ation s&stem slowl& pro%ides water to the plantSs root s&stem Re'ular

waterin' pre%ents plant deh&dration* but roots donSt 'et o%erl& soa#ed and in turn* plant

'rowth can increase up to -,V 3rip s&stems irri'ate all t&pes of landscape) shrubs* trees*

perennial beds* 'round co%ers* annuals and lawns 3rip is the best choice to water roof 'ar.

3epartment of AE 4 I Pa'e -D +,,/.+,@,


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dens* containers on dec#s and patios* row crops and #itchen 'ardens* orchards* and

%ine&ards

%#' A !2I 4ICIA5 G!37 I" G 5IG62S 4 3! C3" 2!3 55I"G I55,M I"A2I3"

1rowin' li'hts enable culti%ators to e5tend da&li'ht hours . useful for winter and

sprin' 'rowin' when le%els of natural li'hts can be low* and one can therefore impro%e plant

'rowth Three basic

monitor and control ofgreenhouse environment-greenbee

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