Monitor And Control Of Greenhouse Environment [automated Green House] Final Documentation 6oss

A Project Report on

MONITOR AND CONTROL OF GREEN HOUSE ENVIRONMENT (Green House Efect ) Submitted in partial fulfillment of the requirements for the award of the DIPLOMA OF ASSOCIATE ENGINEER In

ELECTRONICS Submitted By:

IMRAN JAVED

10919103

WAQAR HAIDER

10919110

RASHID IQBAL

10919116

ANWAR YASIN

10919132

MUHAMMAD ALI

10919237

Under the esteemed guidance of

Mr. IMRAN KHAN

ELECTRONICS TECHNOLOGY SWEDISH INISTITUTE OF TECHNOLOGIES (AFFLIATED WITH PUNJAB BOARD OF TECHNICAL EDUCATION, LAHORE) CAMPUS-III, COMMERCIAL MARKET, RAWALPINDI 2012

CERTIFICATE

DEPARTMENT OF

ELECTRONICS AND COMMUNICATION ENGINEERING

This is to certify that the project report entitled

MONITOR AND CONTROL OF GREEN HOUSE ENVIRONMENT is Submitted by IMRAN JAVED

10919103

WAQAR HAIDER

10919110

RASHID IQBAL

10919116

ANWAR YASIN

10919132

MUHAMMAD ALI

10919237

In partial fulfillment for the award of the Diploma of Associate Engineer in Electronics . It is a record of bonafide work carried out by above mentioned students under the esteemed guidance and supervision of Mr. IMRAN KHAN

Project Guide

Head of the Department

( Mr. IMRAN KHAN )

( Mr. IMRAN KHAN )

Project Incharge

Head of Department

External Examiner

ACKNOWLEDGEMENTS

We are very grateful to our guide Mr. IMRAN KHAN who laid the time bound program for the successful completion of this project. He initiated and channeled our thoughts and extended timely suggestions for which we are deeply indebted to him. We are thankful to him for his comments and insights in the preparation of this report. We express my heart felt gratitude and thanks to the Head of Department of Electronics Mr. HAFEEZ AHMED for his technical and valuable suggestions.

We expres s my sincere thanks to

Mr. MAJID KHAN

principal of Swedish Institute

of Technology, for his enriching thoughts and profound knowledge, which brought

our project

work to its completion. We express my sincere thanks to our microprocessor teacher

Mr. HAFEEZ AHMED

and our lab incharge Mr. MUHAMMAD HAFEEZ for providing necessary in the lab and for helping us in the microcontroller programming. We thank sincerely and profusely to all staff of our College, for their valuable guidance. We also express my gratitude to the college Management and to all those who have indirectly helped us in the successful completion of our project. Last but not the least We are deeply indebted to our parents for what We are today, because this project w ould not have been a reality without their love and .

Yours Sincerely,

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ABSTRACT Appropriate environmental conditions are necessary for optimum plant growth, improved crop yields, and efficient use of water and other resources. Automating the data acquisition process of the soil conditions and various climatic parameters that govern plant growth allows information to be collected at high frequency with less labor requirements. The existing systems employ PC or SMS-based systems for keeping the continuously informed of the conditions inside the greenhouse; but are unaffordable, bulky, difficult to maintain and less accepted by the technologically unskilled workers.

The objective of this project is to design a simple, easy to install, microcontrollerbased circuit to monitor and record the values of temperature, humidity, soil moisture and sunlight of the natural environment that are continuously modified and controlled in order optimize them to achieve maximum plant growth and yield. The controller used is a low power, cost efficient chip manufactured by ATMEL having 8K bytes of on-chip memory. It communicates with the various sensor modules in real-time in order to control the light, aeration and drainage process efficiently inside a greenhouse by actuating a cooler, fogger, dripper and lights respectively according to the necessary condition of the crops. An integrated Liquid crystal display (LCD) is also used for real time display of data acquired from the various sensors and the status of the various devices. Also, the use of easily available components reduces the manufacturing and maintenance costs. The design is quite flexible as the software can be changed any time. It can thus be tailormade to the specific requirements of the . This makes the proposed system to be an economical, portable and a low maintenance solution for greenhouse applications, especially in rural areas and for small scale agriculturists.

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Contents 1. INTRODUCTION........................................................................................................................... 11 1.1 CURRENT SCENARIO .............................................................................................................. 11 1.1.1 MANUAL SET-UP: ........................................................................................................... 11 1.1.2 PARTIALLY AUTOMATED SET-UP: ................................................................................... 11 1.1.3 FULLY- AUTOMATED:...................................................................................................... 11 1.2 PROPOSED MODEL FOR AUTOMATION OF GREENHOUSE ...................................................... 12 2. SYSTEM MODEL .......................................................................................................................... 14 2.1 BASIC MODEL OF THE SYSTEM............................................................................................... 14 2.2 PARTS OF THE SYSTEM: ......................................................................................................... 14 2.2.1 TRANSDUCERS (Data acquisition system): ...................................................................... 15 2.2.2 ANALOG TO DIGITAL CONVERTER (ADC): ........................................................................ 15 2.2.3 MICROCONTROLLER: ...................................................................................................... 15 2.2.4 ACTUATORS: .................................................................................................................. 15 2.2.5 DISPLAY UNIT: ............................................................................................................... 15 2.3 STEPS FOLLOWED IN DEG THE SYSTEM: ...................................................................... 16 3. HARDWARE DESCRIPTION ........................................................................................................... 19 3.1 TRANSDUCERS:...................................................................................................................... 19 3.1.1 SOIL MOISTURE SENSOR................................................................................................. 19 3.1.2 LIGHT SENSOR ................................................................................................................ 20 3.1.3

HUMIDITY SENSOR .................................................................................................. 22

3.1.4

TEMPERATURE SENSOR ........................................................................................... 23

3.2 ANALOG TO DIGITAL CONVERTER (ADC 0808) ....................................................................... 24 3.2.1 DESCRIPTION .................................................................................................................. 25 3.2.2 FEATURES ....................................................................................................................... 25 3.2.3 CONVERSION METHOD USED ......................................................................................... 26 3.2.4 PIN DIAGRAM OF ADC 0808/0809................................................................................... 27 3.2.5

SELECTING AN ANALOG CHANNEL ........................................................................... 28

3.3 CLOCK CIRCUITRY FOR ADC: .................................................................................................. 30 3.3.1 Functional Description: .................................................................................................. 30 3.4 MICROCONTROLLER (AT89S52) ............................................................................................. 31 3.4.1 CRITERIA FOR CHOOSING A MICROCONTROLLER ........................................................... 31 3.4.2 DESCRIPTION: ................................................................................................................ 32 5|P ag e `

3.4.3 FEATURES: ...................................................................................................................... 33 3.4.4 PIN CONFIGURATION ..................................................................................................... 33 3.4.5 BLOCK DIAGRAM ............................................................................................................ 34 3.4.6 PIN DESCRIPTION ........................................................................................................... 34 3.4.7 SPECIAL FUNCTION S....................................................................................... 37 3.4.8 MEMORY ORGANIZATION .............................................................................................. 38 3.4.9 WATCHDOG TIMER (One-time Enabled with Reset-out) ................................................. 39 3.4.10 TIMERS AND COUNTERS ............................................................................................... 40 3.4.11 INTERRUPTS ................................................................................................................. 41 3.5 LIQUID CRYSTAL DISPLAY ...................................................................................................... 43 3.5.1

SIGNALS TO THE LCD................................................................................................ 43

3.5.2 PIN DESCRIPTION ........................................................................................................... 44 3.6 ALARM CIRCUITRY ................................................................................................................. 45 3.7 RELAYS .................................................................................................................................. 46 3.8 POWER SUPPLY CONNECTION .............................................................................................. 49 CIRCUIT SCHEMATIC OF THE SYSTEM ............................................................................................. 51 4. SYSTEMS USED IN WORK MODE .................................................................................................. 53 4.1 DRIP IRRIGATION SYSTEM FOR CONTROLLING SOIL MOISTURE ............................................. 53 4.2 ARTIFICIAL GROWING LIGHTS FOR CONTROLLING ILLUMINATION ........................................ 54 4.3 TEMPERATURE CONTROLLERS .............................................................................................. 55 4.3.1 COOLING EQUIPMENT .................................................................................................... 55 4.3.2 HEATING EQUIPMENT .................................................................................................... 55 4.4 HUMIDIFCATION SYSTEMS .................................................................................................... 55 5. SOFTWARE .................................................................................................................................. 58 5.1 INTRODUCTION TO KEIL SOFTWARE ...................................................................................... 58 5.1.1 WHAT IS µVision3? ......................................................................................................... 58 5.1.2 STEPS FOLLOWED IN CREATING AN APPLICATION IN uVision3: ...................................... 58 5.1.3 DEVICE DATABASE .......................................................................................................... 62 5.1.4 PERIPHERAL SIMULATION............................................................................................... 63 5.2 PROGRAMMER...................................................................................................................... 63 5.3 ProLoad PROGRAMMING SOFTWARE ................................................................................... 64 6. Flowcharts .................................................................................................................................. 66 6.1 FLOWCHART REPRESENTING THE WORKING OF THE SYSTEM ................................................ 66 6.2 FLOWCHART FOR LCD INITIALIZATION ................................................................................... 67 7. RESULT ANALYSIS ........................................................................................................................ 72 6|P ag e `

7.1 TRANSDUCER READINGS ....................................................................................................... 72 7.1.1 SOIL MOISTURE SENSOR................................................................................................. 72 7.1.2 LIGHT SENSOR............................................................................................................... 73 7.1.3 HUMIDITY SENSOR ....................................................................................................... 73 7.1.4 TEMPERATURE SENSOR .................................................................................................. 74 8. ADVANTAGES AND DISADVANTAGES .......................................................................................... 76 8.1 ADVANTAGES ........................................................................................................................ 76 8.2 DISADVANTAGES ................................................................................................................... 76 9. SCOPE FOR FURTHER DEVELOPMENT .......................................................................................... 78 10. CONCLUSION ............................................................................................................................ 80 11. REFERENCES .............................................................................................................................. 82 Books .......................................................................................................................................... 82 Web Resources ........................................................................................................................... 82 12. Source Code: ............................................................................................................................. 84 FINAL PROTOTYPE: .......................................................................................................................... 99

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LIST OF FIGURES Figure 2.1: Block diagram of the system ……………………………………………………………………………....5 Figure 3.1 :Soil moisture sensor ………………………………………………………………………………………10 Figure 3.2: Light Dependent Resistor …………………………………………………………………………………11 Figure 3.2.1: Structure of a Light Dependent Resistor ……………………………………………………………….12 Figure 3.3: Light sensor circuit ………………………………………………………………………………….…….12 Figure 3.4: Humidity sensor …..………………………………………………………………………………….……13 Figure 3.5: Humidity sensor circuit ……………………………..…………………………………………………….13 Figure 3.6: LM35 temperature sensor …………………………….…………………………………………………..14 Figure 3.7: Temperature sensor circuit ………………………….……………………………………………………15 Figure 3.8: Getting data from the analog world ……………………..……………………………………………….16 Figure 3.9: Block diagram of ADC 0808 ……………………………..………………………………………………17 Figure 3.10: Successive approximation method ………………………………………………………………………18 Figure 3.11: Pin diagram of ADC 0808 ………………………………………..……………………………………..18 Figure 3.12: ADC 0808 pin details as used for this application ………………………..……………………………20 Figure 3.13: Timing diagram of ADC 0809 ……………………………………………….………………………….21 Figure 3.14: Clock circuitry for ADC …………………………………………………………………………………21 Figure 3.15: The effect of using a Schmitt trigger …………………………………………..………………………22 Figure 3.16: Pin diagram of AT89S52 ……………………………………………………………..………………….24 Figure 3.17: Block diagram of the microcontroller ………………………………………………………….………..25 Figure 3.18: Power-on reset circuit …………………………………………………………………………………….27 Figure 3.19: The AT89S52 oscillator clock circuit ……………………………………………………………………28 Figure 3.20: Internal memory block …………………………………………………………………………………...30 Figure 3.21: Microcontroller pin details ……………………………………………………………………………….33 Figure 3.22: Address locations for a 2x16 line LCD ………………………………………………………………….34 Figure 3.23: Pin diagram of 2x16 line LCD …………………………………………………………………………...36 Figure 3.24: Electrical symbol of a buzzer …………………………………………………………………………….36 Figure 3.25: Buzzer circuitry ………………………………………………………………………….……………….37 Figure 3.26: Sugar cube relay ………………………………………………………………………………………….37 Figure 3.27: Different types of Relays …………………………………………………………………….………….38 Figure 3.28: Relay circuitry ……………………………………………………………………………………………39 Figure 3.29: +5V Power supply circuit ………………………………………………………………………………..40 Figure 3.30: +12V Power supply Circuit ………………………………………………………………………………41 Figure: CIRCUIT SCHEMATIC OF THE SYSTEM …………………………………………………………..……..42 Figure 4.1: Drip irrigation system ………………………………………………………………………………..……44 Figure 5.1: Window for choosing the target device …………………………………………………………………..50 Figure 5.2: Project Workspace Pane …………………………………………………………………………………..51 Figure 5.3 Project Options Dialog……………………………………………………………………………………..51 Figure 5.4: “Save All” and “Build All Target Files” Buttons ……………………………………………………….51 Figure 5.5: µVision3 Debugger window ……………………………………………………………………………..52 Figure 5.6: ‘Reset’, ‘Run’ and ‘Step into’ options ………………………………………………………………….53 Figure 5.7: Programming window …………………………………………………………………………………..55 Figure: FINAL PROTOTYPE …………………………………………………………………………………………90

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LIST OF TABLES Table 2.1 Importance of the various parameters ................. ................... .................. .............7 Table 3.1 Selection of the input channels ..................... ................... .....................................19 Table 3.2 Alternate functions of Port-3 ........................ .................. ......................................26 Table 3.3 Pin description of the LCD ........................... .................. ......................................36 Table 7.1 Soil moisture sensor readings .................. .................. ...........................................63 Table 7.2 Light sensor readings . .................. .................. ......................................................64 Table 7.3 Temperature sensor readings . .................................................................................65

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CHAPTER 1

INTRODUCTION

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1. INTRODUCTION We live in a world where everything can be controlled and operated automatically, but there are still a few important sectors in our country where automation has not been adopted or not been put to a full-fledged use, perhaps because of several reasons one such reason is cost. One such field is that of agriculture. Agriculture has been one of the primary occupations of man since early civilizations and even today manual interventions in farming are inevitable. Greenhouses form an important part of the agriculture and horticulture sectors in our country as they can be used to grow plants under controlled climatic conditions for optimum produce. Automating a greenhouse envisages monitoring and controlling of the climatic parameters which directly or indirectly govern the plant growth and hence their produce. Automation is process control of industrial machinery and processes, thereby replacing human operators.

1.1 CURRENT SCENARIO Greenhouses in India are being deployed in the high-altitude regions where the subzero temperature up to -40° C makes any kind of plantation almost impossible and in arid regions where conditions for plant growth are hostile. The existing set-ups primarily are: 1.1.1 MANUAL SET-UP:

This set-up involves visual inspection of the plant growth, manual irrigation of plants, turning ON and OFF the temperature controllers, manual spraying of the fertilizers and pesticides. It is time consuming, vulnerable to human error and hence less accurate and unreliable. 1.1.2 PARTIALLY AUTOMATED SET-UP:

This set-up is a combination of manual supervision and partial automation and is similar to manual set-up in most respects but it reduces the labor involved in of irrigating the set-up. 1.1.3 FULLY- AUTOMATED:

This is a sophisticated set-up which is well equipped to react to most of the climatic changes occurring inside the greenhouse. It works on a system which helps it to 11 | P a g e `

respond to the external stimuli efficiently.

Although this set-up overcomes the

problems caused due to human errors it is not completely automated and expensive.

1.2 PROPOSED MODEL FOR AUTOMATION OF GREENHOUSE The proposed system is an embedded system which will closely monitor and control the microclimatic parameters of a greenhouse on a regular basis round the clock for cultivation of crops or specific plant species which could maximize their production over the whole crop growth season and to eliminate the difficulties involved in the system by reducing human intervention to the best possible extent. The system comprises of sensors, Analog to Digital Converter, microcontroller and actuators.

When any of the above mentioned climatic parameters cross a safety threshold which has to be maintained to protect the crops, the sensors sense the change and

the microcontroller reads this from the data at its input ports after being

converted to a digital form by the ADC. The microcontroller then performs the needed actions by employing relays until the strayed-out parameter has been brought back to its optimum level. Since a microcontroller is used as the heart of the system, it makes the setup low-cost and effective nevertheless. As the system also employs an LCD display for continuously alerting the about the condition inside the greenhouse, the entire set-up becomes friendly.

Thus, this system eliminates the drawbacks of the existing set-ups mentioned in the previous section and is designed as an easy to maintain, flexible and low cost solution.

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CHAPTER 2

SYSTEM MODEL

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2. SYSTEM MODEL 2.1 BASIC MODEL OF THE SYSTEM

Figure 2.1 Block diagram of the system

2.2 PARTS OF THE SYSTEM: i.

Sensors (Data acquisition system) a. Temperature sensor (LM35) b. Humidity sensor (HH10D) c. Light sensor (LDR) d. Moisture sensor

ii.

Analog to Digital Converter (ADC 0808/0809)

iii. Microcontroller (AT89S52) iv. Liquid Crystal Display (Hitachi's HD44780) v.

Actuators – Relays

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vi. Devices controlled a. Water Pump (simulated as a bulb) b. Sprayer (simulated as a bulb) c. Cooler (simulated as a fan) d.Artificial Lights (simulated as 2 bulbs) vii. Buzzer 2.2.1 TRANSDUCERS (Data acquisition system):

This part of the system consists of various sensors, namely soil moisture, humidity, temperature and light. These sensors sense various parameters- temperature, humidity, soil moisture and light intensity and are then sent to the Analog to Digital Converter. 2.2.2 ANALOG TO DIGITAL CONVERTER (ADC):

The analog parameters measured by the sensors are then converted to corresponding digital values by the ADC. 2.2.3 MICROCONTROLLER:

The microcontroller is the heart of the proposed embedded system. It constantly monitors the digitized parameters of the various sensors and verifies them with the predefined threshold values and checks if any corrective action is to be taken for the condition at that instant of time. In case such a situation arises, it activates the actuators to perform a controlled operation. 2.2.4 ACTUATORS:

An array of actuators can be used in the system such as relays, ors, and change over switches etc. They are used to turn on AC devices such as motors, coolers, pumps, fogging machines, sprayers. For the purpose of demonstration relays have been used to drive AC bulbs to simulate actuators and AC devices. A complete working system can be realized by simply replacing these simulation devices by the actual devices. 2.2.5 DISPLAY UNIT:

A Liquid crystal display is used to indicate the present status of parameters and the respective AC devises (simulated using bulbs). The information is displayed in two 15 | P a g e `

modes which can be selected using a push button switch which toggles between the modes. Any display can be interfaced to the system with respective changes in driver circuitry and code.

2.3 STEPS FOLLOWED IN DEG THE SYSTEM: Three general steps can be followed to appropriately select the control system: Step #1: Identify measurable variables important to production. It is very important to correctly identify the parameters that are going to be measured by the controller’s data acquisition interface, and how they are to be measured. The set of variables typically used in greenhouse control is shown below:

Sl. No.

Variable to be monitored

Its Importance

1

Temperature

Affects all plant metabolic functions.

2

Humidity

Affects transpiration rate and the plant's thermal

3

Soil moisture

control mechanisms. Affects salinity, and pH of irrigation water

4

Solar Radiation

Affects photosynthetic rate, responsible for most

thermal load during warm periods Table 2.1 Importance of the various parameters An electronic sensor for measuring a variable must readily available, accurate, and reliable and low in cost. If a sensor is not available, the variable cannot be incorporated into the control system, even if it is very important. Many times variables that cannot be directly or continuously measured can be controlled in a limited way by the system. For example, fertility levels in nutrient solutions for greenhouse production are difficult to measure continuously. Step #2: Investigate the control strategies. An important element in considering a control system is the control strategy that is to be followed. The simplest strategy is to use threshold sensors that directly affect actuation of devices. For example, the temperature inside a greenhouse can be affected by controlling heaters, fans, or window openings once it exceeds the maximum allowable limit. The light intensity can be controlled using four threshold levels. As the light intensity decreases one light may be turned on. With a further decrease 16 | P a g e `

in its intensity a second light would be powered, and so on; thus ensuring that the plants are not deprived of adequate sunlight even during the winter season or a cloudy day. More complex control strategies are those based not only on the current values of the controlled variables, but also on the previous history of the system, including the rates at which the system variables are changing. Step #3: Identify the software and the hardware to be used. It is very important that control system functions are specified before deciding what software and hardware system to purchase. The model chosen must have the ability to: 1. Expand the number of measured variables (input subsystem) and controlled devices (output subsystem) so that growth and changing needs of the production operation can be satisfied in the future. 2. Provide a flexible and easy to use interface. 3. It must ensure high precision measurement and must have the ability resist noise. Hardware must always follow the selection of software, with the hardware required being ed by the software selected. In addition to functional capabilities, the selection of the control hardware should

include factors such as reliability,

, previous experiences with the equipment (successes and failures), and cost.

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CHAPTER 3

HARDWARE DESCRIPTION

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3. HARDWARE DESCRIPTION 3.1 TRANSDUCERS: A transducer is a device which measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. Monitoring and controlling of a greenhouse environment involves sensing the changes occurring inside it which can influence the rate of growth in plants. The parameters which are of importance are the temperature inside the greenhouse which affect the photosynthetic and transpiration processes are humidity, moisture content in the soil, the illumination etc. Since all these parameters are interlinked, a closed loop () control system is employed in monitoring it. The sensors used in this system are: 1. Soil Moisture Sensor (Transistor amplifier) 2. Light Sensor (LDR (Light Dependent Resistor)) 3. Humidity Sensor (HH10D) 4. Temperature Sensor (LM35) 3.1.1 SOIL MOISTURE SENSOR 3.1.1.1 Features of the Soil moisture sensor:

1. The circuit designed uses a 5V supply, fixed resistance of 100Ω, variable resistance of 10ΚΩ, two copper leads as the sensor probes, 2N222N transistor. 2. It gives a voltage output corresponding to the conductivity of the soil. 3. The conductivity of soil depends upon the amount of moisture present in it. It increases with increase in the water content of the soil. 4. The voltage output is taken at the transmitter which is connected to a variable resistance. This variable resistance is used to adjust the sensitivity of the sensor. SENSOR LEADS VCC

3.1 Soil moisture sensor

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3.1.1.2 Functional description of Soil moisture sensor:

The two copper leads act as the sensor probes. They are immersed into the specimen soil whose moisture content is under test. The soil is examined under three conditions: Case #1: Dry condition- The probes are placed in the soil under dry 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 voltage output of the emitter in this case ranges from 0 to 0.5V. Case #2: Optimum condition- When water is added to the soil, it percolates through the successive layers of it and spreads across the layers of soil due to capillary force. This water increases the moisture content of the soil. This leads to an increase in its conductivity which forms a conductive path between the two sensor probes leading to a close path for the current flowing from the supply to the transistor through the sensor probes. The voltage output of the circuit taken at the emitter of the transistor in the optimum case ranges from 1.9 to 3.4V approximately. Case #3: Excess water condition- With the increase in water content beyond the optimum level, the conductivity of the soil increases drastically and a steady conduction path is established between the two sensor leads and the voltage output from the sensor increases no further beyond a certain limit. The maximum possible value for it is not more than 4.2V. 3.1.2 LIGHT SENSOR

Light Dependent Resistor (LDR) also known as photoconductor or photocell, is a device which has a resistance which varies according to the amount of light falling on its surface. Since LDR is extremely sensitive in visible light range, it is well suited for the proposed application.

Fig. 3.2 Light Dependent Resistor 3.1.2.1 Features of the light sensor:

The Light Dependent Resistor (LDR) is made using the semiconductor Cium 20 | P a g e `

Sulphide (CdS).The light falling on the brown zigzag lines on the sensor causes the resistance of the device to fall. This is known as a negative co-efficient. There are some LDRs that work in the opposite way i.e. their resistance increases with light (called positive co- efficient). The resistance of the LDR decreases as the intensity of the light falling on it increases. Incident photons drive electrons from the valence band into the conduction band.

Fig. 3.2.1 Structure of a Light Dependent Resistor, showing Cium Sulphide track and an atom to illustrate electrons in the valence and conduction bands

3.1.2.2 Functional description

An LDR and a normal resistor are wired in series across a voltage, as shown in the circuit below. Depending on which is tied to the 5V and which to 0V, the voltage at the point between them, call it the sensor node, will either rise or fall with increasing light. If the LDR is the component tied directly to the 5V, the sensor node will increase in voltage with increasing light The LDR's resistance can reach 10 k ohms in dark conditions and about 100 ohms in full brightness. The circuit used for sensing light in our system uses a 10 kΩ fixed resistor which is tied to +5V. Hence the voltage value in this case decreases with increase in light intensity.

Fig. 3.3 Light sensor circuit 21 | P a g e `

The sensor node voltage is compared with the threshold voltages for different levels of light intensity corresponding to the four conditions- Optimum, dim, dark and night. The relationship

between

the

resistance

RL

and

light

intensity

Lux

for a

typical LDR is: RL = 500 / Lux kΩ

…(3.1)

With the LDR connected to 5V through a 10K resistor, the output voltage of the LDR is: Vo = 5*RL / (RL+10)

… (3.2)

In order to increase the sensitivity of the sensor we must reduce the value of the fixed resistor in series with the sensor. This may be done by putting other resistors in parallel with it. 3.1.3

HUMIDITY SENSOR The humidity sensor HH10D is used for sensing humidity. Relative humidity is a

measure, in percentage, of the vapour in the air compared to the total amount of vapour that could be held in the air at a given temperature.HH10D gives the output in of frequency at a range of 5 kHz to 10 kHz from frequency out pin.

Fig 3.4 Humidity sensor 3.1.3.1 Features:

i.

Relative humidity sensor

ii.

Two point calibrated with capacitor type sensor, excellent performance

iii.

Frequency output type, can be easily integrated with application system

iv.

Very low power consumption

v.

No extra components needed

HH10D

Fig 3.5 Humidity sensor circuit

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3.1.4

TEMPERATURE SENSOR

National Semiconductor’s LM35 IC has been used for sensing the temperature. It is an integrated circuit sensor that can be used to measure temperature with an electrical output proportional to the temperature (in oC). The temperature can be measured more accurately with it than using a thermistor. The sensor circuitry is sealed and not subject to oxidation, etc.

Fig. 3.6 LM35 temperature sensor 3.1.4.1 Features:

Calibrated directly in ° Celsius (Centigrade) Linear + 10.0 mV/°C scale factor 0.5°C accuracy guaranteed (at +25°C) Rated for full −55° to +150°C range Suitable for remote applications Low cost due to wafer-level trimming Operates from 4 to 30 volts Less than 60 µA current drain Low self-heating, 0.08°C in still air Nonlinearity only ±1⁄4°C typical

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Fig. 3.7 Temperature sensor circuit

3.1.4.2 Functional description:

The sensor has a sensitivity of 10mV / oC. The output of LM35 is amplified using a LM324 single power supply (+5V) op-amp. The op-amp is designed to have a gain of 5. The circuitry measures temperatures with a resolution of up to 0.5 degree Celsius. The output voltage is converted to temperature by a simple conversion factor. The general equation used to convert output voltage to temperature is:

Temperature ( oC) = (Vout * 100) / 5 oC

…(3.3)

So if Vout is 5V, then, Temperature = 100 oC The output voltage varies linearly with temperature.

3.2 ANALOG TO DIGITAL CONVERTER (ADC 0808) In physical world parameters such as temperature, pressure, humidity, and velocity are analog signals. A physical quantity is converted into electrical signals. We need an analog to digital converter (ADC), which is an electronic circuit that converts continuous signals into discrete form so that the microcontroller can read 24 | P a g e `

the data. Analog to digital converters are the most widely used devices for data acquisition.

Fig. 3.8 Getting data from the analog world

3.2.1 DESCRIPTION

The ADC0808 data acquisition component is a monolithic CMOS device with an 8- bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible control logic. The 8-bit A/D converter uses successive approximation as the conversion technique. The converter features a high impedance chopper stabilized comparator, a 256R voltage divider with analog switch tree and a successive approximation . The 8-channel multiplexer can directly access any of 8-single-ended analog signals. The design of the ADC0808 has been optimized by incorporating the most desirable aspects of several A/D conversion techniques. The device offers high speed, high accuracy, minimal temperature dependence, excellent long-term accuracy and repeatability, and consumes minimal power. These features make it ideally suited for applications from process and machine control to consumer and automotive applications.

3.2.2 FEATURES

1. Easy interface to all microcontrollers. 2. Operates ratio metrically or with 5 VDC or analog span adjusted voltage reference. 3. No zero or full-scale adjust required. 4. 8-channel multiplexer with address logic. 5. 0V to 5V input range with single 5V power supply. 6.

Outputs meet TTL voltage level specifications.

7.

28-pin molded chip carrier package. 25 | P a g e

`

Block diagram of ADC0808:

Fig. 3.9 Block diagram of ADC 0808

3.2.3 CONVERSION METHOD USED

Following are the most used conversion methods: i.

Digital-Ramp ADC

ii.

Successive Approximation ADC

iii.

Flash ADC Successive approximation ADC is suitable for the proposed application. It is much faster than the digital ramp ADC because it uses digital logic to converge on the value closest to the input voltage. A comparator and a DAC (Digital to Analog Converter) are used in the process. A flowchart explaining the working is shown below.

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Fig. 3.10 Flowchart explaining the Successive approximation method 3.2.4 PIN DIAGRAM OF ADC 0808/0809

Fig. 3.11 Pin diagram of ADC 0808

We use A, B, C addresses to select IN0-IN7 and activate Address latch enable (ALE) to latch in the address. SC is for Start Conversion. EOC is for End of Conversion and OE is for Output Enable. The output pins D0-D7 provides the digital output from the chip. Vref (-) and Vref (+) are the reference voltages.

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3.2.5

SELECTING AN ANALOG CHANNEL

How to select the channel using three address pins A, B, C is shown in Table below: Select Analog Channel

C

B

A

IN0

0

0

0

IN1

0

0

1

IN2

0

1

0

IN3

0

1

1

IN4

1

0

0

IN5

1

0

1

IN6

1

1

0

IN7

1

1

1

Table 3.1 Selection of the input channels

The ADC 0804 is most widely used chip, but since it has only one anaput, ADC 0808 is chosen as this chip allows the monitoring of up to 8 different transducers using only a single chip. The 8 anaput channels are multiplexed and selected according to the requirement. But for the proposed application only the last 4 channels i.e., IN4, IN5, IN6 and IN7 are used to monitor the four parameters- temperature, humidity, soil moisture and light intensity. Hence the address line ADD_C is given to Vcc (+ 5V) as it is always high in this case. Vref (+) and Vref (-) set the reference voltages. If Vref (-) = Gnd and Vref (+) =5V, the step size is 5V/256=19.53. Since there is no self clocking in this chip, the clock must be provided from an external source to the Clock (CLK) pin. The 8-bit output from the ADC is given to Port 0 of the microcontroller and the control signals ADD_A, ADD_B, ADD_C, ALE, START, OE, EOC are given to Port 1 as shown in the figure below.

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Fig. 3.12 ADC 0808 pin details as used for this application

At a certain point of time, even though there is no conversion in progress the ADC0809 is still internally cycling through 8 clock periods. A start pulse can occur any time during this cycle but the conversion will not actually begin until the converter internally cycles to the beginning of the next 8 clock period sequence. As long as the start pin is held high no conversion begins, but when the start pin is taken low the conversion will start within 8 clock periods. The EOC output is triggered on the rising edge of the start pulse. It, too, is controlled by the 8 clock period cycle, so it will go low within 8 clock periods of the rising edge of the start pulse. One can see that it is entirely possible for EOC to go low before the conversion starts internally, but this is not important, since the positive transition of EOC, which occurs at the end of a conversion, is what the control logic is looking for. Once EOC does go high this signals the interface logic that the data resulting from the conversion is ready to be read. The output enable (OE) is then raised high. 29 | P a g e `

Fig 3.13 Timing diagram of ADC 0809

3.3 CLOCK CIRCUITRY FOR ADC: 3.3.1 Functional Description:

The clock for the ADC is generated using the IC CD4093, which is a 2-input Schmitt triggered NAND gate. A Schmitt trigger is a comparator circuit that incorporates positive . The Control pin is pulled high and the capacitor charges and discharges producing alternate patterns of 0’s and 1, generating a square waveform. When the input is higher than a certain chosen threshold, the output is high; when the input is below another (lower) chosen threshold, the output is low; when the input is between the two, the output retains its value. The trigger is so named because the output retains its value until the input changes sufficiently to trigger a change. This dual threshold action is called hysteresis, and implies that the Schmitt trigger has some memory.

Fig. 3.14 Clock circuitry for ADC 30 | P a g e `

The benefit of a Schmitt trigger over a circuit with only a single input threshold is greater stability (noise immunity). With only one input threshold, a noisy input signal near that threshold could cause the output to switch rapidly back and forth from noise alone. A noisy Schmitt Trigger input signal near one threshold can cause only one switch in output value, after which it would have to move to the other threshold in order to cause another switch.

Fig. 3.15 The effect of using a Schmitt trigger (B) instead of a comparator (A)

3.4 MICROCONTROLLER (AT89S52) 3.4.1 CRITERIA FOR CHOOSING A MICROCONTROLLER

The basic criteria for choosing a microcontroller suitable for the application are: 1) The first and foremost criterion is that it must meet the task at hand efficiently and cost effectively. In analyzing the needs of a microcontroller-based project, it is seen whether an 8- bit, 16-bit or 32-bit microcontroller can best handle the computing needs of the task most effectively. Among the other considerations in this category are: i. Speed: The highest speed that the microcontroller s. ii. Packaging: It may be a 40-pin DIP (dual inline package) or a QFP (quad flat package), or some other packaging format. This is important in of space, assembling, and prototyping the end product. iii. Power consumption: This is especially critical for battery-powered products. iv. The number of I/O pins and the timer on the chip. v. How easy it is to higher –performance or lower consumption versions. vi. Cost per unit: This is important in of the final cost of the product in which a microcontroller is used. 2) The second criterion in choosing a microcontroller is how easy it is to develop products around it. Key considerations include the availability of an assembler, debugger, compiler, technical . 31 | P a g e `

3) The third criterion in choosing a microcontroller is its ready availability in needed quantities both now and in the future. Currently of the leading 8-bit microcontrollers, the 8051 family has the largest number of diversified suppliers. By supplier is meant a producer besides the originator of the microcontroller. In the case of the 8051, this has originated by Intel several companies also currently producing the 8051. Thus the microcontroller AT89S52, satisfying the criterion necessary for the proposed application is chosen for the task. 3.4.2 DESCRIPTION:

The 8051 family of microcontrollers is based on an architecture which is highly optimized for embedded control systems. It is used in a wide variety of applications from military equipment to automobiles to the keyboard. Second only to the Motorola 68HC11 in eight bit processors sales, the 8051 family of microcontrollers is available in a wide array of variations from manufacturers such as Intel, Philips, and Siemens. These manufacturers have added numerous features and peripherals to the 8051 such as I2C interfaces, analog to digital converters, watchdog timers, and pulse width modulated outputs. Variations of the 8051 with clock speeds up to 40MHz and voltage requirements down to 1.5 volts are available. This wide range of parts based on one core makes the 8051 family an excellent choice as the base architecture for a company's entire line of products since it can perform many functions and developers will only have to learn this one platform. The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry- standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit U with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost- effective solution to many embedded control applications. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and s two software selectable power saving modes. The Idle Mode stops the U while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset. 32 | P a g e `

3.4.3 FEATURES:

•

Compatible with MCS-51 Products

•

8K Bytes of In-System Programmable (ISP) Flash Memory

•

4.0V to 5.5V Operating Range

•

Fully Static Operation: 0 Hz to 33 MHz

•

256 x 8-bit Internal RAM

•

32 Programmable I/O Lines

•

Three 16-bit Timer/Counters

•

Eight Interrupt Sources

•

Full Duplex UART Serial Channel

•

Low-power Idle and Power-down Modes

•

Interrupt Recovery from Power-down Mode

•

Watchdog Timer

•

Fast Programming Time

3.4.4 PIN CONFIGURATION

Fig. 3.16 Pin diagram of AT89S52

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3.4.5 BLOCK DIAGRAM

Fig. 3.17 Block diagram of the microcontroller 3.4.6 PIN DESCRIPTION

VCC: Supply voltage. GND: Ground. Port 0: Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal 34 | P a g e `

pull-ups. In addition, P1.0 and P1.1 can be configured to be the timer/counter2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively. Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16- bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull- ups when emitting 1s. During accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function . Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port3 pins that are externally being pulled low will source current (IIL) because of the pullups. Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S52, as shown in the following table. Alternate functions of Port 3:

Table 3.2 Alternate functions of Port 3

RST: Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives high for 98 oscillator periods after the watchdog times out.

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3.4.6.1 Power-On Reset circuit

Fig. 3.18 Power-on reset circuit

In order for the RESET input to be effective, it must have a minimum duration of two machine cycles. ALE/PROG: Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode. PSEN: Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. EA: External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming.

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XTAL1: Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2: Output from the inverting oscillator amplifier. 3.4.6.2 Oscillator clock circuit

•

It uses a quartz crystal oscillator.

•

We can observe the frequency on the XTAL2 pin.

Fig 3.19 The AT89S52 oscillator clock circuit

•

The crystal frequency is the basic internal frequency of the microcontroller.

•

The

internal

counters

must

divide

the

basic

clock

rate

to

yield

standard communication bit per second (baud) rates. •

An 11.0592 megahertz crystal, although seemingly an odd value, yields a

crystal frequency of 921.6 kilohertz, which can be divided evenly by the standard communication baud rates of 19200, 9600, 4800, 2400, 1200, and 300 hertz.

3.4.7 SPECIAL FUNCTION S

The Special Function s (SFRs) contain memory locations that are used for special tasks. Each SFR occupies internal RAM from 0x80 to 0xFF.They are 8-bits wide. • The A (accumulator) or accumulator is used for most ALU operations and Boolean Bit manipulations. • B is used for multiplication & division and can also be used for general purpose storage. • PSW (Program Status Word) is a bit addressable . 37 | P a g e `

• PC or program counter is a special 16-bit . It is not part of SFR. Program instruction bytes are fetched from locations in memory that are addressed by the PC. • Stack Pointer (SP) is eight bits wide. It is incremented before data is stored during PUSH and CALL executions. While the stack may reside anywhere in onchip RAM, the Stack Pointer is initialized to 07H after a reset. This causes the stack to begin at location 08H.

• DPTR or data pointer is a special 16-bit that is accessible as two 8- bit s: DPL and DPH, which are used to used to furnish memory addresses for internal and external code access and external data access. • Control s: Special Function s IP, IE, TMOD, TCON, SCON, and PCON contain control

and

status

bits for the interrupt system, the

Timer/Counters, and the serial port. • Timer s: pairs (TH0, TL0) and (TH1, TL1) are the 16-bit Counter s for Timer/Counters 0 and 1, respectively.

3.4.8 MEMORY ORGANIZATION

MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes each of external Program and Data Memory can be addressed. • Program Memory: If the EA pin is connected to GND, all program fetches are directed to external memory. On the AT89S52, if EA is connected to VCC, program fetches to addresses 0000H through 1FFFH are directed to internal memory and fetches to addresses 2000H through FFFFH are to external memory. • Data Memory: The AT89S52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function s. This means that the upper 128 bytes have the same addresses as the SFR space but are physically separate from SFR space. When an instruction accesses an internal location above address 7FH, the address mode used in the instruction specifies whether the U accesses the upper 128 bytes of RAM or the SFR space. Instructions which use direct addressing access the SFR space. The lower 128 bytes of RAM can be divided into three segments: 1. Banks 0-3: locations 00H through 1FH (32 bytes). The device after reset defaults to bank 0. To use the other banks, the must select them in software. Each bank contains eight 1-byte s R0-R7. Reset initializes the 38 | P a g e `

stack point to location 07H, and is incremented once to start from 08H, which is the first of the second bank. 2. Bit Addressable Area: 16 bytes have been assigned for this segment 20H-2FH. Each one of the 128 bits of this segment can be directly addressed (0-7FH). Each of the 16 bytes in this segment can also be addressed as a byte. 3. Scratch Pad Area: 30H-7FH are available to the as data RAM. However, if the data pointer has been initialized to this area, enough bytes should be left aside to prevent SP data destruction.

Fig. 3.20 Internal memory block 3.4.9 WATCHDOG TIMER (One-time Enabled with Reset-out)

The WDT is intended as a recovery method in situations where the U may be subjected to software upsets. The WDT consists of a 14-bit counter and the Watchdog Timer Reset (WDTRST) SFR. The WDT is defaulted to disable from exiting reset. To enable the WDT, a must write 01EH and 0E1H in sequence to the WDTRST (SFR location 0A6H). When the WDT is enabled, it will increment every machine cycle while the oscillator is running. The WDT timeout period is dependent on the external clock frequency. There is no way to disable the WDT except through reset (either hardware reset or WDT overflow reset). When WDT over-flows, it will drive an output RESET HIGH pulse at the RST pin.

39 | P a g e `

3.4.10 TIMERS AND COUNTERS

Many microcontroller applications require the counting of external events such as the frequency of a pulse train, or the generation of precise internal time delays between computer actions. Both of these tasks can be accomplished using software techniques, but software loops for counting or timing keep the processor occupied so that, other perhaps more important, functions are not done. Hence the better option is to use interrupts & the two 16- bit count- up timers. The microcontroller can programmed for either of the following: 1. Count internal - acting as timer 2. Count external - acting as counter All counter action is controlled by the TMOD (Timer Mode) and the TCON (Timer/Counter Control) s. TCON Timer control SFR contains timer 1& 2 overflow flags, external interrupt flags, timer control bits, falling edge/low level selector bit etc. TMOD timer mode SFR comprises two four-bit s (timer #1, timer #0) used to specify the timer/counter mode and operation. The timer may operate in any one of four modes that are determined by modes bits M1 and M0 in the TMOD : TIMER MODE-0: Setting timer mode bits to 00b in the TMOD results in using the TH as an 8-bit counter and TL as a 5-bit counter. Therefore mode0 is a 13-bit counter. TIMER MODE-1: Mode-1 is similar to mode-0 except TL is configured as a full 8-bit counter when the mode bits are set to 01b in TMOD. TIMER MODE-2: Setting the mode bits to 10b in TMOD configures the timer to use only the TL counter as an 8-bit counter. TH is used to hold a value that is loaded into TL every time TL overflows from FFh to 00h. The timer flag is also set when TL overflows. TIMER MODE-3: In mode-3, timer-1 simply hold its count, where as timer 0 s TL0 and TH0 are used as two separate 8-bit counters. TL0 uses the Timer-0 control bits. TH0 counts machine cycles and takes over the use of TR1 and TF1 from Timer-1.

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3.4.11 INTERRUPTS

A computer has only two ways to determine the conditions that exist in internal and external circuits. One method uses software instructions that jump to subroutines on the states of flags and port pins. The second method responds to hardware signals, called interrupts that force the program to call a subroutine. The AT89S52 has a total of six interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. Each of these interrupt sources can be individually enabled or disabled by setting or clearing a bit in Special Function IE. IE also contains a global disable bit, EA, which disables all interrupts at once. Each interrupt forces the processor to jump at the interrupt location in the memory. The interrupted program must resume operation at the instruction where the interrupt took place. Program resumption is done by storing the interrupted PC address on to stack. RETI instruction at the end of ISR will restore the PC address. 3.4.12 MICROCONTROLLER CONFIGURATION USED IN THE SET-UP

The microcontroller is interfaced with the ADC in polling mode. INT0 is used for the LCD mode selection switch in order to switch between two modes of display: 1) Sensor output display 2) Actuator status display Port details: • Port 0: Interfaced with the LCD data lines. • Port 1: Interfaced with the ADC data lines • Port 2: Interfaced with the LCD Control lines and AC Interface control • Port 3: Interfaced with the ADC control lines

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Fig. 3.21 Microcontroller pin details

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3.5 LIQUID CRYSTAL DISPLAY A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. Each pixel consists of a column of liquid crystal molecules suspended between two transparent electrodes, and two polarizing filters, the axes of polarity of which are perpendicular to each other. Without the liquid crystals between them, light ing through one would be blocked by the other. The liquid crystal twists the polarization of light entering one filter to allow it to through the other. Many microcontroller devices use 'smart LCD' displays to output visual information. LCD displays designed around Hitachi's LCD HD44780 module, are inexpensive, easy to use, and it is even possible to produce a readout using the 8x80 pixels of the display. They have a standard ASCII set of characters and mathematical symbols. For an 8-bit data bus, the display requires a +5V supply plus 11 I/O lines. For a 4bit data bus it only requires the supply lines plus seven extra lines. When the LCD display is not enabled, data lines are tri-state and they do not interfere with the operation of the microcontroller. Data can be placed at any location on the LCD. For 16×2 LCD, the address locations are: First line

80

81

Second line

C0 C1

82

83

84

85

C2 C3

C4

C5

86

through

8F

C6 through CF

Fig 3.22 Address locations for a 2x16 line LCD

3.5.1

SIGNALS TO THE LCD

The LCD also requires 3 control lines from the microcontroller: 1) Enable (E) This line allows access to the display through R/W and RS lines. When this line is low, the LCD is disabled and ignores signals from R/W and RS. When (E) line is high, the LCD checks the state of the two control lines and responds accordingly. 2) Read/Write (R/W) This line determines the direction of data between the LCD and microcontroller. When it is low, data is written to the LCD. When it is high, data is read from the LCD. 43 | P a g e `

3) selects (RS) With the help of this line, the LCD interprets the type of data on data lines. When it is low, an instruction is being written to the LCD. When it is high, a character is being written to the LCD. 3.5.1.1 Logic status on control lines:

•

E - 0 Access to LCD disabled - 1 Access to LCD enabled

•

R/W - 0 Writing data to LCD - 1 Reading data from LCD

•

RS - 0 Instructions - 1 Character

3.5.1.2 Writing and reading the data from the LCD:

1. Writing data to the LCD is done in several steps: 1) Set R/W bit to low 2) Set RS bit to logic 0 or 1 (instruction or character) 3) Set data to data lines (if it is writing) 4) Set E line to high 5) Set E line to low 2. Read data from data lines (if it is reading): 1) Set R/W bit to high 2) Set RS bit to logic 0 or 1 (instruction or character) 3) Set data to data lines (if it is writing) 4) Set E line to high 5) Set E line to low 3.5.2 PIN DESCRIPTION

Most LCDs with 1 controller has 14 Pins and LCDs with 2 controller has 16 Pins (Two pins are extra in both for back-light LED connections).

44 | P a g e `

Fig 3.23 Pin diagram of 2x16 line LCD

Table 3.23 Pin description of the LCD

3.6 ALARM CIRCUITRY BUZZER: A buzzer or beeper is a signaling device, usually electronic, typically used in automobiles, household appliances such as a microwave oven.

Fig. 3.24 Electrical symbol of a buzzer

45 | P a g e `

It is connected to the control unit through the transistor that acts as an electronic switch for it. When the switch forms a closed path to the buzzer, it sounds a warning in the form of a continuous or intermittent buzzing or beeping sound.

The transistor acts as a normal controlled by the base connection. It switches ON when a positive voltage from the control unit is applied to the base. If the positive voltage is less than 0.6V, the transistor switches OFF. No current flows through the buzzer in this case and it will not buzz. As can be seen in the buzzer circuitry given below, a protection resistor of 10k ohm is used in order to protect the transistor from being damaged in case of excessive current flow. In our system, the buzzer is designed to give a small beep whenever one of the devices such as a cooler or a bulb turns on in order to alert the .

Fig. 3.25 Buzzer circuitry

3.7 RELAYS A relay is an electrical switch that opens and closes under the control of another electrical circuit. In the original form, the switch is operated by an electromagnet to open or close one or many sets of s. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered to be, in a broad sense, a form of an electrical amplifier.

Fig. 3.26 Sugar cube relay 46 | P a g e `

Despite the speed of technological developments, some products prove so popular that their key parameters and design features remain virtually unchanged for years. One such product is the ‘sugar cube’ relay, shown in the figure above, which has proved useful to many designers who needed to switch up to 10A, whilst using relatively little PCB area

Since relays are switches, the terminology applied to switches is also applied to relays. A relay will switch one or more poles, each of whose s can be thrown by energizing the coil in one of three ways:

1. Normally - open (NO) s connect the circuit when the relay is activate d; the circuit is disconnected when the relay is inactive. It is also called a FORM A or “make” .

2. Normally - closed (NC) s disconnect the circuit when the relay is activated; the circuit is connected when relay is inactive. It is also called FORM B or” break” .

3. Change-over or double-throw s control two circuits; one

normally open

and one normally –closed with a common terminal. It is also called a Form C “transfer “. The following types of relays are commonly encountered:

"C" denotes the common terminal in SPDT and DPDT types Fig. 3.27 Different types of Relays 47 | P a g e `

•

SPST - Single Pole Single Throw: These have two terminals which can be

connected or disconnected. Including two for the coil, such a relay has four terminals in total. It is ambiguous whether the pole is normally open or normally closed. The terminology "SPNO" and "SPNC" is sometimes used to resolve the ambiguity.

•

SPDT - Single Pole Double Throw: A common terminal connects to either of

two others. Including two for the coil, such a relay has five terminals in total.

•

DPST - Double Pole Single Throw: These have two pairs of terminals. Equivalent

to two SPST switches or relays actuated by a single coil. Including two for the coil, such a relay has six terminals in total. It is ambiguous whether the poles are normally open, normally closed, or one of each.

•

DPDT - Double Pole Double Throw: These have two rows of change-over

terminals. Equivalent to two SPDT switches or relays actuated by a single coil. Such a relay has eight terminals, including the coil.

•

QPDT - Quadruple Pole Double Throw: Often referred to as Quad Pole Double

Throw, or 4PDT. These have four rows of change-over terminals. Equivalent to four SPDT switches or relays actuated by a single coil or two DPDT relays. In total, fourteen terminals including the coil.

The Relay interfacing circuitry used in the application is:

Fig. 3.28 Relay circuitry

48 | P a g e `

3.8 POWER SUPPLY CONNECTION The power supply section consists of step down transformers of 230V primary to 9V and 12V secondary voltages for the +5V and +12V power supplies respectively. The stepped down voltage is then rectified by 4 1N4007 diodes. The high value of capacitor 1000 µF charges at a slow rate as the time constant is low, and once the capacitor charges there is no resistor for capacitor to discharge. This gives a constant value of DC. IC 7805 is used for regulated supply of +5 volts and IC 7812 is used to provide a regulated supply of +12 volts in order to prevent the circuit ahead from any fluctuations. The filter capacitors connected after this IC filters the high frequency spikes. These capacitors are connected in parallel with supply and common so that spikes filter to the common. These give stability to the power supply circuit. As can be seen from the above circuit diagrams, the rectified voltage from the 4 diodes is given to pin 1 of the respective regulators. Pin 2 of the regulators is connected to ground and pin 3 to Vcc. With adequate heat sinking the regulator can deliver 1A output current. If internal power dissipation becomes too high for the heat sinking provided, the thermal shutdown circuit takes over preventing the IC from overheating.

Fig. 3.29 +5V Power supply circuit

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Fig. 3.30 +12V Power supply Circuit

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CIRCUIT SCHEMATIC OF THE SYSTEM

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CHAPTER 4

SYSTEMS USED IN WORK MODE

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4. SYSTEMS USED IN WORK MODE 4.1 DRIP IRRIGATION SYSTEM FOR CONTROLLING SOIL MOISTURE Drip, or micro-irrigation, technology uses a network of plastic pipes to carry a low flow of water under low pressure to plants. Polyethylene tubing is run from the source of water to the plant, where the emitter is attached for dripping water. Emitter line (poly tubing with pre-installed emitters) is used where a continuous band of water is needed. Fittings are available to make sharp turns (elbows), branch lines (tees), and to make the transition between different sizes of tubing. When plants are removed or die, drip lines should be plugged.

Fig. 4.1 Drip irrigation system

Drip irrigation (sometimes called trickle irrigation) works by applying water slowly, directly to the soil. The high efficiency of drip irrigation results from two primary factors. The first is that the water soaks into the soil before it can evaporate or run off. The second is that the water is only applied where it is needed, (at the plant's roots) rather than sprayed everywhere. A drip irrigation system slowly provides water to the plant's root system. Regular watering prevents plant dehydration, but roots don't get overly soaked and in turn, plant growth can increase up to 50%. Drip systems irrigate all types of landscape: shrubs, trees, perennial beds, ground covers, annuals and lawns. Drip is the best choice to water roof gardens, containers on decks and patios, row crops and kitchen gardens, orchards, and vineyards.

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4.2 ARTIFICIAL GROWING LIGHTS FOR CONTROLLING ILLUMINATION Growing lights enable cultivators to extend daylight hours - useful for winter and spring growing when levels of natural lights can be low, and one can therefore improve plant growth. Three basic types of lamps used in greenhouse lighting are:

1.

Fluorescent lamps - These have the advantage of higher light efficiency with low heat. This type of lamp is the most widely used for supplemental light. It is available in a variety of colors but cool-white lamps are the most common. High intensity (1500 ma) fluorescent tubes that require higher wattage are also commonly used to reach 2000 foot candles.

2.

Incandescent lamps - These vary in size from 60 watts to 500 watts. The grower can vary foot-candle levels by adjusting the spacing and mounting height above the plants.

3.

High-Intensity Discharge (HID) lamps - These have a long life (5000 hours or more). With improvements made possible by the addition of sodium and metal- halides, the lamp has a high emission of light in the regions utilized by plants.

The following generally accepted cultural divisions describe light levels: •

Very high: Over 5000 foot candles--nearly full sun except at midday, when full summer sun in most latitudes may reach 10,000 fc.

•

High: 4000-5000 foot candles--bright light, just under 50% of the full midday sun.

•

Intermediate: 1800-4000 foot candles--dappled sunlight.

•

Low: 1000-1800 foot candles--reduced sunlight, so that if a hand is ed over the leaves it does not produce a shadow.

One foot candle is equal to 10.76 lux, although in the lighting industry, typically this is approximated as 1 foot candle being equal to 10 lux.

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4.3 TEMPERATURE CONTROLLERS 4.3.1 COOLING EQUIPMENT

There are three primary cooling devices in most greenhouses. These are the vent system, exhaust fan, and swamp cooler. Some greenhouses may make use of air conditioners and/or misting systems as well. Vents are hinged or track connected s in the roof or sides of greenhouses. They open up the greenhouse to outside natural air. Hot air that builds up in the greenhouse can escape, and fresh air can enter the house. The microcontroller can be used to automate the opening and closing of these vents depending upon requirement. But during hot summer days, venting alone will not get the job done.

Exhaust fans can move a large volume of the hot greenhouse air out and pull fresh air in through the rear vent. They're powerful for a reason, as full sun on a hot summer day can cause temperatures inside the greenhouse to superheat. An exhaust fan must be able to pull this air out, or the temperatures will continue to rise.

Swamp coolers: come in different widths and lengths. They can be configured to the appropriate size, as this varies depending on the length and width of the greenhouse, location where you live, and type of plants you wish to grow. 4.3.2 HEATING EQUIPMENT

Hot-water or steam heater: A hot-water system with circulator or a steam system linked with automatic ventilation will give adequate temperature control. In some areas, coal or natural gas is readily available at low cost. This fuel is ideal for hot- water or a central steam system. Steam has an advantage in that it can be used to sterilize growing beds and potting soils. Electric heaters: Overhead infrared heating equipment combined with soil cable heat provides a localized plant environment, which allows plants to thrive even though the surrounding air is at a lower than normal temperature. Electric resistance-type heaters are used as space heaters or in a forced air system.

4.4 HUMIDIFCATION SYSTEMS 55 | P a g e `

Many evaporative cooling and humidifying systems are available: Foggers, Mist systems, Roof Sprinklers, and Pan & Fan Systems. They add water vapour to the air, and may subsequently reduce the amount of water that the plants need to transpire.

1. Roof sprinklers add water vapour and cool the incoming air. On large ranges, it is possible to decrease the temperature by 3 - 5 C and increase the humidity by 5-10%. 2. Pad and fan systems consist of porous wet pads at the inlet end of a fan ventilated Greenhouse. As the exhaust fans draw air through the wet pads, water evaporates, cooling and humidifying the air. Temperatures tend to be coolest nearer the fans and hottest at the exhaust when using these systems. 3. Mist and fog systems produce tiny water droplets that evaporate, thereby cooling and humidifying t he greenhouse air. A misting syst em can provide needed mo ist ure to maintain a healthy humidity level of 50 to 70%.

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CHAPTER 5

SOFTWARE

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5. SOFTWARE 5.1 INTRODUCTION TO KEIL SOFTWARE Keil MicroVision is an integrated development environment used to create software to be run on embedded systems (like a microcontroller). It allows for such software to be written either in assembly or C programming languages and for that software to be simulated on a computer before being loaded onto the microcontroller. 5.1.1 WHAT IS µVision3?

µVision3 is an IDE (Integrated Development Environment) that helps write, compile, and debug embedded programs. It encapsulates the following components: o

A project manager.

o

A make facility.

o

A Tool configuration.

o

A n Editor.

o

A powerful debugger.

5.1.2 STEPS FOLLOWED IN CREATING AN APPLICATION IN uVision3:

To create a new project in uVision3: 1. Select Project - New Project. 2. Select a directory and enter the name of the project file. 3. Select Project –Select Device and select a device from Device Database. 4. Create source files to add to the project 5. Select Project - Targets, Groups, and Files. Add/Files, select Source Group1, and add the source files to the project. 6. Select Project - Options and set the tool options. Note that when the target device is selected from the Device Database™ all-special options are set automatically. Default memory model settings are optimal for most applications. 7. Select Project - Rebuild all target files or Build target To

create

a

new

project,

simply

start

Micro Vision

and

select

“Project”=>”New Project” from the pull–down menus. In the file dialog that appears, choose a name and base directory for the project. It is recommended that a new directory be created for each project, as several files will be generated. Once the project has been named, the dialog shown in the figure below will appear, prompting the to select a 58 | P a g e `

target device. In this lab, the chip being used is the “AT89S52,” which is listed under the heading “Atmel”.

Fig. 5.1 Window for choosing the target device

Next, Micro Vision must be instructed to generate a HEX file upon program compilation. A HEX file is a standard file format for storing executable code that is to be loaded onto the microcontroller. In the “Project Workspace” pane at the left, right–click on “Target 1” and select “Options for ‘Target 1’ ”.Under the “Output” tab of the resulting options dialog, ensure that both the “Create Executable” and “Create HEX File” options are checked. Then click “OK” as shown in the two figures below.

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Fig. 5.2 Project Workspace Pane

Fig. 5.3 Project Options Dialog

Next, a file must be added to the project that will contain the project code. To do this, expand the “Target 1” heading, right–click on the “Source Group 1” folder, and select “Add files…” Create a new blank file (the file name should end in “.asm”), select it, and click “Add.” The new file should now appear in the “Project Workspace” pane under the “Source Group 1” folder. Double-click on the newly created file to open it in the editor. All code for this lab will go in this file. To compile the program, first save all source files by clicking on the “Save All” button, and then click on the “Rebuild All Target Files” to compile the program as shown in the figure below. If any errors or warnings occur during compilation, they will be displayed in the output window at the bottom of the screen. All errors and warnings will reference the line and column number in which they occur along with a description of the problem so that they can be easily located. Note that only errors indicate that the compilation failed, warnings do not (though it is generally a good idea to look into them anyway).

Fig. 5.4 “Save All” and “Build All Target Files” Buttons 60 | P a g e `

When the program has been successfully compiled, it can be simulated using the integrated

debugger

in

Keil

Micro

Vision.

To

start

the

debugger,

select

“Debug”=>”Start/Stop Debug Session” from the pull–down menus. At the left side of the debugger window, a table is displayed containing several key parameters about the simulated microcontroller, most notably the elapsed time (circled in the figure below). Just above that, there are several buttons that control code execution. The “Run” button will cause the program to run continuously until a breakpoint is reached, whereas the “Step Into” button will execute the next line of code and then pause (the current position in the program is indicated by a yellow arrow to the left of the code).

Fig. 5.5 µVision3 Debugger window

Breakpoints can be set by double–clicking on the grey bar on the left edge of the window containing the program code. A breakpoint is indicated by a red box next to the 61 | P a g e `

line of code.

Fig. 5.6 ‘Reset’, ‘Run’ and ‘Step into’ options

The current state of the pins on each I/O port on the simulated microcontroller can also be displayed. To view the state of a port, select “Peripherals”=>”I/O Ports”=>”Port n” from the pull–down menus, where n is the port number. A checked box in the port window indicates a high (1) pin, and an empty box indicates a low (0) pin. Both the I/O port data and the data at the left side of the screen are updated whenever the program is paused. The debugger will help eliminate many programming errors, however the simulation is not perfect and code that executes properly in simulation may not always work on the actual microcontroller. 5.1.3 DEVICE DATABASE

A unique feature of the Keil µVision3 IDE is the Device Database, which contains information a bo ut more t han 400 ed m icr o co nt ro ller s. When you creat e 62 | P a g e `

a new µVision3 project and select the target chip from the database, µVision3 sets all assembler, compiler, linker, and debugger options for you. The only option you must configure is the memory map. 5.1.4 PERIPHERAL SIMULATION

The µVision3 Debugger provides complete simulation for the U and on-chip peripherals of most embedded devices. To discover which peripherals of a device are ed, in µVision3 select the Simulated Peripherals item from the Help menu. You may also use the web-based Device Database. We are constantly adding new devices and simulation for on-chip peripherals so be sure to check Device Database often.

5.2 PROGRAMMER The programmer used is a powerful programmer for the Atmel 89 series of microcontrollers that includes 89C51/52/55, 89S51/52/55 and many more. It is simple to use & low cost, yet powerful flash microcontroller programmer for the Atmel 89 series. It will Program, Read and Code Data, Write Lock Bits, Erase and Blank Check. All fuse and lock bits are programmable. This programmer has intelligent onboard firmware and connects to the serial port. It can be used with any type of computer and requires no special hardware. All that is needed is a serial communication port which all computers have. All devices also have a number of lock bits to provide various levels of software and programming protection. These lock bits are fully programmable using this programmer. Lock bits are useful to protect the program to be read back from microcontroller only allowing erase to reprogram the microcontroller. Major parts of this programmer are Serial Port, Power Supply and Firmware microcontroller. Serial data is sent and received from 9 pin connector and converted to/from TTL logic/RS232 signal levels by MAX232 chip. A Male to Female serial port cable, connects to the 9 pin connector of hardware and another side connects to back of computer. All the programming ‘intelligence’ is built into the programmer so you do not need any special hardware to run it. Programmer comes with window based software for easy programming of the devices.

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5.3 ProLoad PROGRAMMING SOFTWARE ‘ProLoad’ is a software working as a friendly interface for programmer boards from Sunrom Technologies. ProLoad gets its name from “Program Loader” term, because that is what it is supposed to do. It takes in compiled HEX file and loads it to the hardware. Any compiler can be used with it, Assembly or C, as all of them generate compiled HEX files. ProLoad accepts the Intel HEX format file generated from compiler to be sent to target microcontroller. It auto detects the hardware connected to the serial port. It also auto detects the chip inserted and bytes used. The software is developed in Delhi and requires no overhead of any external DLL. The programmer connects to the computer’s serial port (Comm 1, 2, 3 or 4) with a standard DB9 Male to DB9 Female cable. Baud Rate - 57600, COMx Automatically selected by window software. No PC Card Required. After making the necessary selections, the ‘Auto Program’ button is clicked as shown in the figure below which burns the selected hex file onto the microcontroller.

Fig. 5.7 Programming window

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CHAPTER 6

FLOWCHART

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6. Flowcharts 6.1 FLOWCHART REPRESENTING THE WORKING OF THE SYSTEM

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6.2 FLOWCHART FOR LCD INITIALIZATION

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CHAPTER 7

RESULT ANALYSIS

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7. RESULT ANALYSIS o

All readings are taken at room temperature of 32 C

7.1 TRANSDUCER READINGS 7.1.1 SOIL MOISTURE SENSOR

Tolerance= ± 0.2 V

Soil Condition

Transducer Optimum Range

Soil is dry

Optimum level of

0-1.5V

1.9- 3.5V

soil moisture

Slurry soil

>3.5V

Table 7.1 Soil moisture sensor readings

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7.1.2 LIGHT SENSOR

Tolerance = ±0.1V

Illumination Status

Transducer Optimum Range

OPTIMUM ILLUMINATION

0V-0.69V

DIM LIGHT

0.7V-2.5V

DARK

2.5V- 3V

NIGHT

3V-3.47V Table 7.2 Light sensor readings

7.1.3 HUMIDITY SENSOR

At normal room conditions the humidity can range between 35% and 45% of Relative Humidity (RH). Our Test results were observed at temperature ranging between 32oC and 36oC and the observed RH range was between 38% and 42%, which is within the possible conditions.

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7.1.4 TEMPERATURE SENSOR 7.1.4.1 FORMULA:

Temperature ( oC ) = (Vout/5) *100( oC/V)

(Ref. Eq.3.3)

Temperature range in

Temperature

degree Celsius

output(V out)

100 C

0.5V

150 to 200 C

0.75-1.0V

20 0to 250 C

1.0-1.25V

250 to 30 0C

1.25-1.5V

30 0to 35 0C

1.5-1.75V

350 to 400 C

1.75-2.0V

400 to 45 0C

2.0-2.25V

450 to 500 C

2.25-2.5V

500 to 55 0C

2.5-2.75V

550 to 600C

2.75-3.0V

600 to 650 C

3.0-3.25V

650 to 70 0C

3.25-3.5V

70 0to 750 C

3.5-3.75V

75 0to 80 0C

3.75-4.0V

80 0to 850 C

4.0-4.25V

85 0to 900 C

4.25-4.5V

900 to 95 0C

4.5-4.75V

950 to 1000 C

4.75-5V

sensor

Table 7.3 Temperature sensor readings 74 | P a g e `

CHAPTER 8

ADVANTAGES AND DISADVANTAGES

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8. ADVANTAGES AND DISADVANTAGES 8.1 ADVANTAGES 1. Sensors used have high sensitivity and are easy to handle. 2. Low cost system, providing maximum automation. 3. Closed loop design prevents any chances of disturbing the greenhouse environment. 4. is indicated for changes in actuator state thereby giving an option for manual override. 5. Low maintenance and low power consumption. 6. The system is more compact compared to the existing ones, hence is easily portable. 7. Can be used for different plant species by making minor changes in the ambient environmental parameters. 8. Can be easily modified for improving the setup and adding new features. 9. Labour saving. 10. Provides a -friendly interface hence will have a greater acceptance by the technologically unskilled workers. 11. In response to the sensors, the system will adjust the heating, fans, lighting, irrigation immediately, hence protect greenhouse from damage. 12. Malfunctioning of single sensor will not affect the whole system. 13. Natural resource like water saved to a great extent.

8.2 DISADVANTAGES 1. Complete automation in of pest and insect detection and eradication cannot be achieved. 2. No self-test system to detect malfunction of sensors. 3. Requires uninterrupted power supply. 4. Facility to remotely monitor the greenhouse is not possible.

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CHAPTER 9

FUTURE SCOPE

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9. SCOPE FOR FURTHER DEVELOPMENT 1. The performance of the system can be further improved in of the operating speed, memory capacity, and instruction cycle period of the microcontroller by using other controllers such as AVRs and PICs. The number of channels can be increased to interface more number of sensors which is possible by using advanced versions of Microcontrollers. 2. The system can be modified with the use of a data logger and a graphical LCD showing the measured sensor data over a period of time. 3. A speaking voice alarm could be used instead of the normal buzzer. 4. This system can be connected to communication devices such as modems, cellular phones or satellite terminal to enable the remote collection of recorded data or alarming of certain parameters. 5. The device can be made to perform better by providing the power supply with the help of battery source which can be rechargeable or non-rechargeable, to reduce the requirement of main AC power. 6. Time bound istration of fertilizers, insecticides and pesticides can be introduced. 7.

A multi-controller system can be developed that will enable a master controller along with its slave controllers to automate multiple greenhouses simultaneously.

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CHAPTER 10

CONCLUSION

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10. CONCLUSION A system

step-by-step

approach

in

deg

the

microcontroller

based

for measurement and control of the four essential parameters for plant

growth, i.e. temperature, humidity, soil moisture, and light intensity, has been followed. The results obtained from the measurement have shown that the system performance is quite reliable and accurate. The system has successfully overcome quite a few shortcomings of the existing systems by reducing the power consumption, maintenance and complexity, at the same time providing a flexible and precise form of maintaining the environment. The continuously decreasing costs of hardware and software, the wider acceptance of electronic systems in agriculture, and an emerging agricultural control system industry in several areas of agricultural production, will result in reliable control systems that will address several aspects of quality and quantity of production. Further improvements will be made as less expensive and more reliable sensors are developed for use in agricultural production.

Although the enhancements mentioned in the previous chapter may seem far in the future, the required technology and components are available, many such systems have been independently developed, or are at least tested at a prototype level. Also, integration of all these technologies is not a daunting task and can be successfully carried out.

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CHAPTER11

11. REFERENCES

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11. REFERENCES

Books Muhammad Ali Mazidi, Janice Gillispie Mazidi, Rolin D. Mc Kinlay , The 8051 Microcontroller & Embedded Systems, Pearson Education Inc. 2nd Edition, 2008.

Web Resources http://www.google.com http://www.8052.com http://www.8051projects.net/forum http://www.roboticsindia.com http://www.electro-tech-online.com http://www.datasheetdirect.com http://www.keil.com/appnotes http://freewebs.com/maheshwankede http://www.faludi.com

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CHAPTER 12

SOURCE CODE

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12. Source Code: #include // ADC pins Initialisation: sbit OE = P3^0; sbit start= P3^1; //sbit EOC = P3^3; sbit ADD_A= P3^4; sbit ADD_B= P3^5; // ADD_C directly connected to VCC in hardware; sbit ALE = P3^7; //humidity pins: sbit freqOut = P3^3; //LCD pins: sbit rs=P2^5; sbit rw=P2^6; sbit en=P2^7; // MODE Selection: sbit sw=P3^2; // switch to change mode // Relay control pins sbit cooler=

P2^4;

sbit pump=

P2^3;

sbit sprayer=

P2^2;

sbit light1=

P2^1;

sbit light2=

P2^0;

sbit buzzer=

P3^6;

// SFR initialisations: sfr ldata=0x80;

// port 0 LCD data

sfr ADC_data = 0x90;// port 1 ADC input //Gobal vaiables unsigned char value_binary; //ADC output value char LDR_Level,MOIST_Level; bit coolerOnOff; bit timeout;

// humidity time out of 1sec

unsigned int timeCount; unsigned char comm[] = {0x38,0x0E,0x01,0x06,0x80,0};

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bit P3_2flag; //functions proto-types void ADC_value(void); void MOIST(void); void LDR_sensor(void); void temp_Sensor(void); int convertBinToDecimal(unsigned char value); void lcdcmd(unsigned char value); void lcddata(unsigned char value1); void msdelay(unsigned int itime); // Delay of 1mesc void humiditySensor(void); void Display(unsigned char[]); void modeStatus(void); void buzzerON(); void buzzer2ON();

// Timer ISR void timer0_isr(void) interrupt 3 { timeCount= timeCount+1; if(timeCount==10000) // 0.1m*10000=1sec { timeCount=0; // Reset the TimeCount after every 1 Second timeout=1; // Set the timeout=1 ( variable to start the Pulse count in the While loop) ET1 = 0; } }

void Ext0_isr (void) interrupt 0

// port3.2 =0

{ EA=0; P3_2flag=1; EA=1; }

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void main(void) { //gobal variables: unsigned int i; buzzerON(); value_binary=0; LDR_Level=0; MOIST_Level=0; cooler=0; sprayer=0; coolerOnOff=0; pump=0; light1=0; light2=0; IE=0x83;// enable timer 0 and int0 interrupts // port pins ADC_data = 0xff;

// input port1

freqOut=1;

// act as input port

ALE=0; // ALE should be low to high OE=0; start=0; // Start of conv should be low to high for(i=0;comm[i]!=0;i++) { lcdcmd(comm[i]); } Display(" WELCOME To $"); lcdcmd(0xc0); //second line in LCD Display("Project GreenBee $"); msdelay(250); lcdcmd(0x01); //clear line in LCD lcdcmd(0x80); //first line in LCD Display(" A Final Year $"); lcdcmd(0xc0); //second line in LCD Display(" Project by: $"); msdelay(175); lcdcmd(0x01); //clear line in LCD

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lcdcmd(0x80); //second line in LCD Display("Sekhar, Ravi $"); lcdcmd(0xc0); //first line in LCD Display("Paul & Feroze

$");

msdelay(250); lcdcmd(0x01); //clear line in LCD lcdcmd(0x80); //first line in LCD Display(" Initialising$"); lcdcmd(0xc0); //second line in LCD Display(" the Sensors...

$");

msdelay(2000); while(1) { if(P3_2flag==0) { while(1) { humiditySensor(); if(P3_2flag==1) break; // Soil Moisture: MOIST_Level=0; ADD_A=1; ADD_B=0; ADC_value();//value_binary = ADC_value(); MOIST(); msdelay(1); if(P3_2flag==1) break; // Temperature: ADD_A=0; ADD_B=0; ADC_value(); temp_Sensor(); if(P3_2flag==1) break;

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//Light Sensor: LDR_Level=0; ADD_A=1; ADD_B=1; ADC_value(); LDR_sensor(); msdelay(1); if(P3_2flag==1 break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; msdelay(50); if(P3_2flag==1) break; } }

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if(P3_2flag==1) { modeStatus(); P3_2flag=0; } } } void modeStatus(void) { lcdcmd(0x01); //clear line in LCD lcdcmd(0x80); //first line in LCD if(sprayer==1) Display("SP:ON $"); else Display("SP:OFF $"); lcdcmd(0x88); if(MOIST_Level==1) Display("SM:ON$"); if(MOIST_Level==2) Display("SM:OFF$"); if(MOIST_Level==3) Display("SM:OFF$"); lcdcmd(0xc0); if(cooler==1) Display("C :ON$"); else Display("C :OFF$"); lcdcmd(0xc8); if(LDR_Level==1) Display("LI:OFF

$");

if(LDR_Level==2) Display("LI:ON

$");

if(LDR_Level==3) Display("LI:ON

$");

if(LDR_Level==4) Display("LI:OFF

$");

msdelay(3000);

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} void humiditySensor(void) { unsigned char DTa[30]="RH:@"; unsigned char DTb[30]="**.* @"; unsigned int count=0;

//count=0x00;

bit c=0,flag=0; unsigned int i,d,y,z; timeout=0; timeCount=0; TMOD = 0x20; // Set Mode (8-bit timer0 with reload)

(.1m/1.085u)=92.16=256-n =>n= 163.83=164d= A4

TH1 = 0xA4;

// Reload TL1 to count 100 clocks

TL1 = TH1; ET1 = 1;

// Enable Timer 1 Interrupts

TR1 = 1;

// Start Timer 1 Running

EA = 1; //Counting the Pulses: while(timeout!=1) { c=freqOut; if(c==1) { if(flag==0) { count = count+1; flag=1; } } else flag=0; }

//Checking the Humidity Limits: //LOGIC: //RH% ranges from 0 to 100 through 5k to 10k freq.. So change in freq = 5K. //5K/100 = 50. So for every increment of freq count by 50, there is one increment in RH value in % if (count>4999 && count<10001) // Limiting the calculations to the desired limits of 5k to 10k) { d=count-5000; // Obtaining the Difference in the Freq.

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d=d/50; // Divide with 50 to get the RH value if(d<=40) { buzzer2ON(); sprayer=1; } else sprayer=0; y=d/10; // obtaining the tens position integer and asg to variable y z=d%10; // Modulo Division to obtain the Remainder value (the ONEs place) and Asg the value to variable z y=y+48; // converting the integer to its equivalent ASCII code z=z+48; // converting the integer to its equivalent ASCII code lcdcmd(0x01); //clear line in LCD lcdcmd(0x80); for(i=0;DTa[i]!='@';i++) { lcddata(DTa[i]); // ing the data "RH% =" to the LCD } lcddata(y); // ing the value of y to the LCD lcddata(z); // ing the value of z to the LCD lcddata(37); // ing the symbol "%" using its ASCII code (37) to the LCD } if(count<5000 || count>10000) // If the Freq. is below 5k or greater than 10k ERROR message is displayed { lcdcmd(0x01); //clear line in LCD lcdcmd(0x80); for(i=0;DTa[i]!='@';i++) { lcddata(DTa[i]); // ing the data "RH% =" to the LCD } for(i=0;DTb[i]!='@'; i++) { lcddata(DTb[i]); // ing the data "**.*" to the LCD } }

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} void LDR_sensor(void) { lcdcmd(0xc8); //first line in LCD Display("LI:$"); if(value_binary<0x25)

// dec=37

{ LDR_Level=1; // mode= OFF Display("Opt

$");

light1=0; light2=0; // send data onto LCD - optimum } else if(value_binary<0x82)

// dec=130

{ LDR_Level=2; //mode= ON Display("Dim

$");

buzzer2ON(); light1=1; light2=0; // send data onto LCD -dim } else if(value_binary<0x9d) { LDR_Level=3; //mode = ON Display("Dark

$");

buzzer2ON(); light1=1; light2=1; // send data onto LCD - dark } else if(value_binary>0x9d) { LDR_Level=4; //mode=OFF Display("Night

$");

light1=0;

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light2=0; // send data onto LCD - night } else { Display("**.*

$");

light1=0; light2=0; // send data onto LCD - night } } void MOIST(void) { lcdcmd(0x88); //first line in LCD Display("SM:$"); if(value_binary<0x67) { MOIST_Level=1; // mode =ON Display("Dry$"); pump=1; // send data onto LCD - Dry } else if(value_binary<0x78) { MOIST_Level=2; // mode =OFF Display("Opt$"); pump=0; // send data onto LCD -optimum } else if(value_binary>0x78) { MOIST_Level=3;//

mode=OFF

Display("Excs$"); pump=0; // send data onto LCD - excs } else

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{ Display("**.* $"); // send data onto LCD - **.* as default case pump=0; } } void ADC_value(void) { value_binary=0; msdelay(1); ALE=1; msdelay(1); start=1; msdelay(1); ALE=0; start=0; //can have delay of 1msec - since ADC converstion delay is 100usec msdelay(1); // 1msec delay OE=1; msdelay(1); value_binary=ADC_data; OE=0; }

void temp_Sensor(void) { unsigned int temp=0; float temp_float=0; unsigned int ones_position=0,tens_position=0; lcdcmd(0xc0); //first line in LCD Display("T :$"); temp=convertBinToDecimal(value_binary); temp_float=(float) temp/50; temp_float= temp_float *100 / 5; temp= (int) temp_float; // temp value that has to be displayed on to the LCD // in order to display the charater on to LCD we need to send tens postion //first and then units postion; tens_position=temp/10; // obtaining the tens position integer and asg to variable y ones_position=temp%10; // Modulo Division to obtain the Remainder value (the ONEs place) and Asg the value to variable z

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tens_position=tens_position+48; // converting the integer to its equivalent ASCII code ones_position=ones_position+48; // converting the integer to its equivalent ASCII code lcddata(tens_position); lcddata(ones_position); lcddata(223);

//Displaying the Symbol for Degrees Centigrate

lcddata('C'); lcddata(' '); //LCD Display if(temp<32) { cooler=0; coolerOnOff=0; //Mode= OFF } else { buzzer2ON(); cooler=1; coolerOnOff=1;// mode = ON } } int convertBinToDecimal(unsigned char value) { unsigned char x1=0,x2=0,x3=0,x4=0; int decimal=0; // x1, x2, x4 are decimal numbers with MSB X4 X2 X1 LSB x1=value%10; x2=value/10; x3=x2%10; x4=x3/10; decimal=

x4*100+x2*10+x1;

return decimal; } //LCD Functions: void lcdcmd(unsigned char value) // LCD Commands {

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ldata=value; rs=0; rw=0; en=1; msdelay(1); en=0; return; } void lcddata(unsigned char value1) // Data to LCD { ldata=value1; rs=1; rw=0; en=1; msdelay(1); en=0; return; } void msdelay(unsigned int itime ) // Delay of 1mesc { unsigned int i, j; for(i=0;i
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void buzzerON()

// Welcome Note Buzzer

{ buzzer=1; msdelay(10); buzzer=0; } void buzzer2ON()

// Warnings Buzzer

{ buzzer=1; msdelay(2); buzzer=0; }

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FINAL PROTOTYPE

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FINAL PROTOTYPE:

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