Automatic Gardening System

A PROJECT REPORT

on

AUTOMATIC GARDENING SYSTEM

Submitted by

Patel Jaydeep (120443111019)

Sanghani Kishor (120443111001)

Prikh Rutvik (120443111034)

In fulfillment for the award of the degree

Of

BACHELOR OF ENGINEERING

In

Electronics and Communications

C. U. Shah College of Engineering & Technology, Wadhwan city

Gujarat Technological University, Ahmedabad

OCT 2014

C. U. Shah College of Engg. & Tech. Page 2

C.U. Shah College of Engineering & Technology

C. U. Shah College of Engineering & Technology

Electronics and Communications

2014

CERTIFICATE

Date:

This is to certify that the dissertation entitled Automatic Gardening

System has been carried out by Patel Jaydeep, Sanghani Kishor & Prikh

Rutvik under my guidance in fulfillment of the degree of Bachelor of Engineering

in Electronics and Communications (7th Semester) of Gujarat Technological

University, Ahmedabad during the academic year 2013-14.

Guide: Prof. K.R.Ranipa

Head of the Department

Prof. D. N. Khandhar


ACKNOWLEDGEMENT

Initially, we would like to express our sincere gratitude and gratefulness to our professor

Mr. K.R.Ranipa for providing us with all sorts of basic ideas and techniques essential for

carrying out this project work from the very beginning to the end and enabled us to present this

dissertation in this form. The teaching staffs also deserve our sincere thanks for sharing their

discussion and exchange of ideas.

We are very much grateful to the C.U. Shah College of Engineering & Technology,

Wadhwan city Campus for providing us an enthusiastic support and opportunity. Also to the

Head of Department of Electronics and Communications Prof. D. N. Khandhar also must come

in special mention for their unstinting cooperation in completion of this project. We would like

to give heartily thanks to our friends who have provided a great help and cooperation for the

existence of this output. Our obligation goes to our family and all our friends who assisted us

directly and indirectly in completing this study.

Lastly, we would like to extend our sincere gratitude to the known and unknown writers

of the books and references that has been taken during the preparation of this project work.


LIST OF FIGURES

Sr. Chapter Name Pg. No.

No.

2.1 Block Diagram 10

3.1 Circuit Diagram 12

4.1 Power Supply Circuit 14

4.2 Transformer 15

4.3 Rectifier Operation 1 16



4.6 LM 7805 18

4.7 Pin Diagram of 8051 20

4.8 Block Diagram of 8051 21

4.9 Crystal Circuit of 8051 26

4.10 DS 1307 27

4.11 DS 1307 Block Diagram 28

4.12 DS1307 Pin Diagram 29

4.13 DS 1307 Interfacing 30

4.14 I2C Protocol 31

4.15 I2C Protocol Communication 33


4.16 2x16 LCD Display 35

4.17 2x16 LCD Pin Diagram 37

4.18 LCD Interfacing 40

4.19 Buzzer Interfacing Circuit 41

4.20 L293D Pin Diagram 43

4.21 L293D Interfacing 44

4.22 Relay Pin Diagram 47

4.23 Relay Interfacing 47

4.24 Relay ON 48

4.25 Relay OFF 48

4.26 Relay 50

4.27 Different Types of Relay 51


TABLE OF CONTENTS

Sr. No. Page No

Acknowledgement 3

Abstract 7

1. Introduction 8

2. Block Diagram 10

3. Circuit Diagram 12

4. Circuit Working 13

4.1 Power Supply 14

4.2 Sensor Signaling Conditioning 19

4.3 Microcontroller 19

4.4 RTC DS 1307 27

4.5 LCD 35

4.6 Buzzer 41

4.7 Motor Driver IC (L293D) 42

4.8 Relay 46

5. Result & Conclusion 53

6. Application 54

7. Advantages 55

8. Reference 56


ABSTRACT

The most important problems faced in Garden automation are the misusage of electricity

and its wastage. Sometimes due to carelessness of the authorities and the workers lamps are left

ON which results in wastage of electricity. Water wastage is another problem which needs to be

dealt with. Our project helps to overcome all these problems.

Firstly the Microcontroller around 4.00pm switches on the water supply once to water the

entire garden few hours before opening of the garden for public. Next the gate is opened by

running the motor which is driven by a motor driver operated by the Microcontroller. At around

6.00pm the two lights are switched on depending upon the output of the LDR and the lights

remain functional till the garden remains open for visitors.

The garden remains open for about three hours and so around 8.50 pm a buzzer is

sounded to indicate closure of the garden and alert the visitors. The gate is then closed at 9.00pm

and one of the two lamps is switched off. One lamp is kept on throughout the night. In the

morning the remaining lamp is switched off as the depending upon the signal sent by the light

dependent resistor to the Microcontroller. These are the step involved in the operation of the

circuit and the public garden automation. Microcontroller is used to supervise the actions of all

other devices and to control the entire set of operations.


Chapter 1

Introduction

The most important problems faced are the misusage of electricity and its wastage.

Sometimes due to carelessness of the authorities and the workers lamps are left ON which results

in wastage of electricity. Water wastage is another problem which needs to be dealt with. Our

project helps to overcome all these problems.

Firstly the Microcontroller around 4.00pm switches on the water supply once to water the

entire garden few hours before opening of the garden for public. Next the gate is opened by

running the motor which is driven by a motor driver operated by the Microcontroller. At around

6.00pm the lights are switched on depending upon the output of the LDR and the lights remain

functional till the garden remains open for visitors.

The garden remains open for about three hours and so around 8.50 pm a buzzer is

sounded to indicate closure of the garden and alert the visitors. The gate is then closed at 9.00pm

and three of the four lamps are switched off. One lamp is kept on throughout the night. In the

morning the remaining lamp is switched off as the depending upon the signal sent by the light

dependent resistor to the Microcontroller. These are the step involved in the operation of the

circuit and the public garden automation. Microcontroller is used to supervise the actions of all

other devices and to control the entire set of operations.

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 user 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, microcontroller-based

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 flash 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 tailor-made to the specific requirements of the user.

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.


Chapter 2

Block Diagram

Block Diagram of Automatic Gardening System

Figure 2.1 Block Diagram

LDR

Micro Controller

Unit 8051

Family

Relay 1

Keypad Motor

Driver

Buzzer DC

Motor

(For Gate)

Relay 2

Motor

Driver

DC Motor

(For Water

Supply)

Lamp 1

Lamp 2

RTC

DS1307


Description of Block Diagram

LDR:

The output of LDR is given as input to the signal conditioning circuit the output of which is

given to 89C51 on input side to control the state of lamps.

RTC:

A real time clock is basically just like a watch - it runs on a battery and keeps time for you even

when there is a power outage! Using an RTC, you can keep track of long timelines, even if you

reprogram your microcontroller or disconnect it from USB or a power plug.

MICRO CONTROLLER AT 89C51:

It processes the calculated digital values by converting it to ASCII & sends it to the LCD display

in order to display the data. Also depending upon the setting at the input, it controls the output

LIQUID CRYSTAL DISPLAY:

As the name suggests, it is used for displaying purpose. It displays the current date, time.

RELAY:

It is used to control the flow of water in the garden just like any simple valve and is driven by a

relay driver.

KEYPAD:

The keypad is used for entering the time and date and also can be used for manual over ride.

POWER SUPPLY UNIT:

Power supply unit provides a 5V regulated supply to the micro controller AT 89C51, ADC 0804,

LCD, MUX 4051, serial memory. It provides a 12V unregulated supply to the relays.


Chapter 3

Circuit Diagram

Figure 3.1 Circuit Diagram


Chapter 4

Circuit Working

OUR complete project is to be divided into 6 sections.

1. Power supply.

2. Sensor signal conditioning

3. Analogue to digital converter.

4. Microcontroller

5. RTC (Real Time Clock)

6. LCD connectivity.

7. Output interface.


4.1 POWER SUPPLY

In this project firstly we use one step down transformer. Step down transformer step

down the voltage from 220 volt Ac to 12 volt Ac. This Ac voltage is further converted into DC

with the help of rectifier circuit. In rectifier circuit we use four diode. All the diodes are arranges

as a bridge rectifier circuit. Output of this rectifier is pulsating Dc. To convert this pulsating DC

into smooth dc we use one capacitor as a filter components. Capacitor converts the pulsating Dc

into smooth DC with the help of its charging and discharging effect.

Output of the rectifier is now regulated with the help of IC regulator circuit. In this

project we use positive voltage regulator circuit. Here we use three pin regulator. Output of this

regulator is regulated voltage. If we use 7805 regulator then its means its is 5 volt regulator and

if we use 7808 regulator then its means that it is 8 volt regulator circuit. In this project we use 5

volt dc regulated power supply for the complete circuit.

5 VOLT REGULATED POWER SUPPLY CIRCUIT

Figure 4.1 Power Supply Circuit


Transformer:

A transformer is an electrical device which is used to convert electrical power from one

electrical circuit to another without change in frequency. Transformers convert AC electricity

from one voltage to another with little loss of power. Transformers work only with AC and this

is one of the reasons why mains electricity is AC. Most power supplies use a step-down

transformer to reduce the dangerously high mains voltage to a safer low voltage. The input coil is

called the primary and the output coil is called the secondary. There is no electrical connection

between the two coils; instead they are linked by an alternating magnetic field created in the soft-

iron core of the transformer. The two lines in the middle of the circuit symbol represent the core.

Transformers waste very little power so the power out is (almost) equal to the power in. Note

that as voltage is stepped down current is stepped up. The ratio of the number of turns on each

coil, called the turns ratio, determines the ratio of the voltages. A step-down transformer has a

large number of turns on its primary (input) coil which is connected to the high voltage mains

supply, and a small number of turns on its secondary (output) coil to give a low output voltage.

Figure 4.2 Transformer

Rectifier:

A circuit which is used to convert a.c to dc is known as RECTIFIER. The process of

conversion a.c to d.c is called rectification

Types of Rectifiers:

Half wave Rectifier

Full wave rectifier


1. Centre tap full wave rectifier.

2. Bridge type full bridge rectifier.

Full-wave Rectifier:

In our project we are using full wave bridge rectifier circuit. Bridge Rectifier: A bridge

rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. This

is a widely used configuration, both with individual diodes wired as shown and with single

component bridges where the diode bridge is wired internally.

A bridge rectifier makes use of four diodes in a bridge arrangement as shown in fig(a) to

achieve full-wave rectification. This is a widely used configuration, both with individual diodes

wired as shown and with single component bridges where the diode bridge is wired internally.

Figure 4.3 Transformer Operation1


Figure 4.4 Transformer Operation

Figure 4.5 Transformer Operation

Filter:

A Filter is a device which removes the a.c component of rectifier output but allows the

d.c component to reach the load.


Regulator:

Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or variable output

voltages. The maximum current they can pass also rates them. Negative voltage regulators are

available, mainly for use in dual supplies. Most regulators include some automatic protection

from excessive current ('overload protection') and overheating ('thermal protection'). Many of the

fixed voltage regulator ICs have 3 leads and look like power transistors, such as the 7805 +5V

1A regulator shown on the right. The LM7805 is simple to use. You simply connect the positive

lead of your unregulated DC power supply (anything from 9VDC to 24VDC) to the Input pin,

connect the negative lead to the Common pin and then when you turn on the power, you get a 5

volt supply from the output pin.

Figure 4.6 LM 7805 IC


4.2 SENSOR SIGNAL CONDITIONING

Light Sensor:

In the light sensor we use one LDR. LDR is a light dependent resistor. Resistance of the

ldr is depend on the intensisty of the light. As the light on the ldr is change , resistance of ldr is

also change. Resistance of the ldr is varies from 1k ohm to 500 k ohm. In full llight resistance of

the ldr is very low below then 1 k ohm and in no light resistance of the ldr is become very high

above then 500k ohm.

In this project we use ldr with only one 10k ohm variable resistor. This 10 k ohm resistor

is connected to the positive voltage 5volt.

4.3 MICROCONTROLLER


Figure 4.7 Pin Diagram

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 Atmels

high-density nonvolatile memory technology and is compatible with the industry- standard

80C51 instruction set and pinout. 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 CPU 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. The AT89S52 provides the following standard

features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers,

three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port,

on-chip oscillator,and clock circuitry. In addition, the AT89S52 is designed with static logic for

operation down to zero frequency and supports two software selectable power saving modes. The

Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt

system to continue functioning. The Power-down mode saves the RAM contents but freezes the

oscillator, disabling all other chip functions until the next interrupt or hardware reset.


Figure 4.8 Block Diagram

Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pullups. 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 pullups 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 pullups. In addition, P1.0 and P1.1 can be

configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2

trigger input (P1.1/T2EX), respectively.Port 1 also receives the low-order address bytes during

Flash programming and verification.

Port 2




low will source current (IIL) because of the internal pullups. 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 use 8-bit addresses (MOVX

@ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the

highorder address bits and some control signals during Flash programming and verification.

Port 3




low will source current (IIL) because of the pullups. Port 3 also serves the functions of various

special features of the AT89S52. Port 3 also receives some control signals for Flash

programming and verification.

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 96 oscillator periods after the Watchdog times out.

The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default

state of bit DISRTO, the RESET HIGH out feature is enabled.

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/VPP

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.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

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 Registers. 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 CPU accesses the upper 128 bytes of RAM or the SFR space.

Instructions which use direct addressing access of the SFR space. For example, the following


direct addressing instruction accesses the SFR at location 0A0H (which is P2) MOV 0A0H,

#data, Instructions that use indirect addressing access the upper 128 bytes of RAM.

For example, the following indirect addressing instruction, where R0 contains 0A0H,

accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H). MOV @R0,

#data, Note that stack operations are examples of indirect addressing, so the upper 128 bytes of

data RAM are available as stack space.

Timers

Watchdog Timer

The WDT is intended as a recovery method in situations where the CPU may be

subjected to software upsets. The WDT consists of a 13-bit counter and the Watchdog Timer

Reset (WDTRST) SFR. The WDT is defaulted to disable from exiting reset. To enable the WDT,

a user must write 01EH and 0E1H in sequence to the WDTRST register (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 overflows, it will drive an output RESET HIGH pulse at the RST pin.

Using the WDT

To enable the WDT, a user must write 01EH and 0E1H in sequence to the WDTRST

register (SFR location 0A6H). When the WDT is enabled, the user needs to service it by writing

01EH and 0E1H to WDTRST to avoid a WDT overflow. The 13-bit counter overflows when it

reaches 8191 (1FFFH), and this will reset the device. When the WDT is enabled, it will

increment every machine cycle while the oscillator is running. This means the user must reset the

WDT at least every 8191 machine cycles. To reset the WDT the user must write 01EH and 0E1H

to WDTRST. WDTRST is a write-only register. The WDT counter cannot be read or written.

When WDT overflows, it will generate an output RESET pulse at the RST pin. The RESET

pulse duration is 96xTOSC, where TOSC=1/FOSC. To make the best use of the WDT, it should

be serviced in those sections of code that will periodically be executed within the time required

to prevent a WDT reset. The UART in the AT89S52 operates the same way as the UART in the

AT89C51 and AT89C52.


Timer 0 and 1: Timer 0 and Timer 1 in the AT89S52 operate the same way as Timer 0

and Timer 1 in the AT89C51 and AT89C52.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that

can be configured for use as an on-chip oscillator, as shown in Figure Either a quartz crystal or

ceramic resonator may be used. To drive the device from an external clock source, XTAL2

should be left unconnected while XTAL1 is driven, as shown in Figure There are no

requirements on the duty cycle of the external clock signal, since the input to the internal

clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high

and low time specifications must be observed. Idle Mode : In idle mode, the CPU puts itself to

sleep while all the onchip peripherals remain active. The mode is invoked by software. The

content of the on-chip RAM and all the special functions registers remain unchanged during this

mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset. Note

that when idle mode is terminated by a hardware reset, the device normally resumes program

execution from where it left off, up to two machine cycles before the internal reset algorithm

takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the

port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when

idle mode is terminated by a reset, the instruction following the one that invokes idle mode

should not write to a port pin or to external memory. Power-down Mode: In the Power-down

mode, the oscillator is stopped, and the instruction that invokes Powerdown is the last instruction

executed. The on-chip RAM and Special Function Registers retain their values until the Power-

down mode is terminated. Exit from Power-down mode can be initiated either by a hardware

reset or by an enabled external interrupt. Reset redefines the SFRs but does not change the on-

chip RAM. The reset should not be activated before VCC is restored to its normal operating level

and must be held active long enough to allow the oscillator to restart and stabilize.


Figure 4.9 Crystal Circuit


4.4 RTC - DS 1307 REAL TIME CLOCK:

A real time clock is basically just like a watch - it runs on a battery and keeps time for

you even when there is a power outage! Using an RTC, you can keep track of long timelines,

even if you reprogram your microcontroller or disconnect it from USB or a power plug.

Most microcontrollers, including the Arduino, have a built-in timekeeper called millis ()

and there are also timers built into the chip that can keep track of longer time periods like

minutes or days. So why would you want to have a seperate RTC chip? Well, the biggest reason

is that millis () only keeps track of time since the Arduino was last powered - . That means that

when the power is turned on, the millisecond timer is set back to 0. The Arduino doesn't know

that it's 'Tuesday' or 'March 8th', all it can tell is 'It's been 14,000 milliseconds since I was last

turned on'.

Figure 4.10 DS1307

OK so what if you wanted to set the time on the Arduino? You'd have to program in the

date and time and you could have it count from that point on. But if it lost power, you'd have to

reset the time. Much like very cheap alarm clocks: every time they lose power they blink 12:00

While this sort of basic timekeeping is OK for some projects, some projects such as data-

loggers, clocks, etc will need to have consistent timekeeping that doesn't reset when the

Arduino battery dies or is reprogrammed. Thus, we include a seperate RTC! The RTC chip is

a specialized chip that just keeps track of time. It can count leap-years and knows how many


days are in a month, but it doesn't take care of Daylight Savings Time (because it changes from

place to place)

The RTC we'll be using is the DS1307. It's low cost, easy to solder, and can run for years

on a very small coin cell.

GENERAL DESCRIPTION

The DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal

(BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially

through an I2C, bidirectional bus. The clock/calendar provides seconds, minutes, hours, day,

date, month, and year information. The end of the month date is automatically adjusted for

months with fewer than 31 days, including corrections for leap year. The clock operates in either

the 24-hour or 12- hour format with AM/PM indicator. The DS1307 has a built-in power-sense

circuit that detects power failures and automatically switches to the backup supply. Timekeeping

operation continues while the part operates from the backup supply.

TYPICAL OPERATING CIRCUIT

Figure 4.11 DS1307 Block Diagram


FEATURES

Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of

the week, and Year with Leap-Year Compensation Valid Up to 2100

56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes

I2C Serial Interface

Programmable Square-Wave Output Signal

Automatic Power-Fail Detect and Switch Circuitry

Consumes Less than 500nA in Battery-Backup Mode with Oscillator Running

Optional Industrial Temperature Range:

-40C to +85C

Available in 8-Pin Plastic DIP or SO

Underwriters Laboratories (UL) Recognized

PIN CONFIGURATIONS

Figure 4.12 DS1307 Pin Diagram


DS 1307 Interface with Microcontroller

Figure 4.13 DS1307 interface

I2C Protocol

At the low end of the spectrum of communication options for "inside the box"

communication is I2C ("eye-squared-see"). The name I

2C is shorthand for a standard Inter-IC

(integrated circuit) bus.

I2C provides good support for communication with various slow, on-board peripheral

devices that are accessed intermittently, while being extremely modest in its hardware resource

needs. It is a simple, low-bandwidth, short-distance protocol. Most available I2C devices operate

at speeds up to 400Kbps, with some venturing up into the low megahertz range. I2C is easy to

use to link multiple devices together since it has a built-in addressing scheme.


Philips originally developed I2C for communication between devices inside of a TV set.

Examples of simple I2C-compatible devices found in embedded systems include EEPROMs,

thermal sensors, and real-time clocks. I2C is also used as a control interface to signal processing

devices that have separate, application-specific data interfaces. For instance, it's commonly used

in multimedia applications, where typical devices include RF tuners, video decoders and

encoders, and audio processors. In all, Philips, National Semiconductor, Xicor, Siemens, and

other manufacturers offer hundreds of I2C-compatible devices.

Inside the box

I2C is appropriate for interfacing to devices on a single board, and can be stretched across

multiple boards inside a closed system, but not much further. An example is a host CPU on a

main embedded board using I2C to communicate with user interface devices located on a

separate front panel board. A second example is SDRAM DIMMs, which can feature an I2C

EEPROM containing parameters needed to correctly configure a memory controller for that

module.

I2C is a two-wire serial bus, as shown in Figure 1. There's no need for chip select or

arbitration logic, making it cheap and simple to implement in hardware.

Figure 4.14 I2C Protocol

The two I2C signals are serial data (SDA) and serial clock (SCL). Together, these signals

make it possible to support serial transmission of 8-bit bytes of data-7-bit device addresses plus

control bits-over the two-wire serial bus. The device that initiates a transaction on the I2C bus is


termed the master. The master normally controls the clock signal. A device being addressed by

the master is called a slave.

In a bind, an I2C slave can hold off the master in the middle of a transaction using what's

called clock stretching (the slave keeps SCL pulled low until it's ready to continue). Most I2C

slave devices don't use this feature, but every master should support it.

The I2C protocol supports multiple masters, but most system designs include only one.

There may be one or more slaves on the bus. Both masters and slaves can receive and transmit

data bytes.

Each I2C-compatible hardware slave device comes with a predefined device address, the

lower bits of which may be configurable at the board level. The master transmits the device

address of the intended slave at the beginning of every transaction. Each slave is responsible for

monitoring the bus and responding only to its own address. This addressing scheme limits the

number of identical slave devices that can exist on an I2C bus without contention, with the limit

set by the number of user-configurable address bits (typically two bits, allowing up to four

identical devices).

Communication

As you can see in Figure 2, the master begins the communication by issuing the start

condition (S). The master continues by sending a unique 7-bit slave device address, with the

most significant bit (MSB) first. The eighth bit after the start, read/not-write (), specifies whether

the slave is now to receive (0) or to transmit (1). This is followed by an ACK bit issued by the

receiver, acknowledging receipt of the previous byte. Then the transmitter (slave or master, as

indicated by the bit) transmits a byte of data starting with the MSB. At the end of the byte, the

receiver (whether master or slave) issues a new ACK bit. This 9-bit pattern is repeated if more

bytes need to be transmitted.


Figure 4.15 I2C Protocol Communication

In a write transaction (slave receiving), when the master is done transmitting all of the

data bytes it wants to send, it monitors the last ACK and then issues the stop condition (P). In a

read transaction (slave transmitting), the master does not acknowledge the final byte it receives.

This tells the slave that its transmission is done. The master then issues the stop condition.

A simple bus

As we've seen, the I2C signaling protocol provides device addressing, a read/write flag,

and a simple acknowledgement mechanism. There are a few more elements to the I2C protocol,

such as general call (broadcast) and 10-bit extended addressing. Beyond that, each device defines

its own command interface or address-indexing scheme.

Standard I2C devices operate up to 100Kbps, while fast-mode devices operate at up to 400Kbps.

A 1998 revision of the I2C specification (v. 2.0) added a high-speed mode running at up

to 3.4Mbps. Most of the I2C devices available today support 400Kbps operation. Higher-speed

operation may allow I2C to keep up with the rising demand for bandwidth in multimedia and

other applications.

Most often, the I2C master is the CPU or microcontroller in the system. Some

microcontrollers even feature hardware to implement the I2C protocol. You can also build an all-

software implementation using a pair of general-purpose I/O pins (single master implementations

only).

Since the I2C master controls transaction timing, the bus protocol doesn't impose any

real-time constraints on the CPU beyond those of the application. (This is in contrast with other


serial buses that are timeslot-based and, therefore, take their service overhead even when no real

communication is taking place.)


4.5 LIQUID CRYSTAL DISPLAY

Introduction to LCD:

In recent years the LCD is finding widespread use replacing LED s (seven-segment LED

or other multi segment LED s).

This is due to the following reasons:

1. The declining prices of LCD s.

2. The ability to display numbers, characters and graphics. This is in contract to LEDs, which are

limited to numbers and a few characters.

3. Incorporation of a refreshing controller into the LCD, there by relieving the CPU of the task of

refreshing the LCD. In the contrast, the LED must be refreshed by the CPU to keep displaying

the data.

4. Ease of programming for characters and graphics.

Figure 4.16 2x16 Display


Specifications

Number of Characters: 16 characters x 2 Lines

Character Table: English-European (RS in Datasheet)

Module dimension: 80.0mm x 36.0mm x 13.2mm(MAX)

View area: 66.0 x 16.0 mm

Active area: 56.2 x 11.5 mm

Dot size: 0.56 x 0.66 mm

Dot pitch: 0.60 x 0.70 mm

Character size: 2.96 x 5.46 mm

Character pitch: 3.55 x 5.94 mm

LCD type: STN, Positive, Transflective, Yellow/Green

Duty: 1/16

View direction: Wide viewing angle

Backlight Type: yellow/green LED

RoHS Compliant: lead free

Operating Temperature: -20C to + 70C


LCD PIN DIAGRAM:

Figure 4.17 2x16 LCD Pin Diagram

Pinout Connections

Pin No Symbol Level Description

1 VSS 0V Ground

2 VCC 5V Supply Voltage for logic

3 VEE (Variable) Operating voltage for LCD

4 RS H/L H: DATA, L: Instruction code

5 R/W H/L H: Read(MPU?Module) L: Write(MPU?Module)

6 E H,H->L Chip enable signal

7 DB0 H/L Data bus line








15 A 5V LED +


Description

The HD44780U dot-matrix liquid crystal display controller and driver LSI displays

alphanumeric, Japanese kana characters, and symbols. It can be configured to drive a dot-matrix

liquid crystal display under the control of a 4- or 8-bit microprocessor. Since all the functions

such as display RAM, character generator, and liquid crystal driver, required for driving a dot-

matrix liquid crystal display are internally provided on one chip, a minimal system can be

interfaced with this controller/driver.

A single HD44780U can display up to one 8-character line or two 8-character lines. The

HD44780U has pin function compatibility with the HD44780S which allows the user to easily

replace an LCD-II with an HD44780U. The HD44780U character generator ROM is extended to

generate 2085 8 dot character fonts and 32 5 10 dot character fonts for a total of 240 different

character fonts.

The low power supply (2.7V to 5.5V) of the HD44780U is suitable for any portable

battery-driven product requiring low power dissipation.

Features

5 8 and 5 10 dot matrix possible

Low power operation support:

2.7 to 5.5V

3.0 to 11V

Liquid crystal drive waveform

A (One line frequency AC waveform)

Correspond to high speed MPU bus interface

2 MHz (when VCC = 5V)

4-bit or 8-bit MPU interface enabled

80 8-bit display RAM (80 characters max.)


9,920-bit character generator ROM for a total of 240 character fonts

208 character fonts (5 8 dot)


64 8-bit character generator RAM



16-common 40-segment liquid crystal display driver

Programmable duty cycles

1/8 for one line of 5 8 dots with cursor

1/11 for one line of 5 10 dots with cursor

1/16 for two lines of 5 8 dots with cursor

Display clear, cursor home, display on/off, cursor on/off, display character blink,

cursor shift,

display shift

Pin function compatibility with HD44780S

Automatic reset circuit that initializes the controller/driver after power on

Internal oscillator with external resistors

Low power consumption


LCD Interface with Microcontroller

Figure 4.18 16*4 LCD Interface


4.6 BUZZER

Figure 4.19 Buzzer Circuit

To interface a buzzer the standard transistor interfacing circuit is used. Note that if a

different power supply is used for the buzzer, the 0V rails of each power supply must be

connected to provide a common reference.

If a battery is used as the power supply, it is worth remembering that piezo sounders draw

much less current than buzzers. Buzzers also just have one tone, whereas a piezo sounder is

able to create sounds of many different tones.

To switch on buzzer - high

To switch off buzzer - low


4.7 MOTOR DRIVER IC (LM 293D)

L293D is a typical Motor driver or Motor Driver IC which allows DC motor to drive on

either direction. L293D is a 16-pin IC which can control a set of two DC motors simultaneously

in any direction. It means that you can control two DC motor with a single L293D IC. Dual H-

bridge Motor Driver integrated circuit (IC).

The l293d can drive small and quiet big motors as well, check the Voltage Specification

at the end of this page for more info.

Concept

It works on the concept of H-bridge. H-bridge is a circuit which allows the voltage to be

flown in either direction. As you know voltage need to change its direction for being able to

rotate the motor in clockwise or anticlockwise direction, Hence H-bridge IC are ideal for driving

a DC motor.

In a single l293d chip there two h-Bridge circuit inside the IC which can rotate two dc

motor independently. Due its size it is very much used in robotic application for controlling DC

motors. Given below is the pin diagram of a L293D motor controller.

There are two Enable pins on l293d. Pin 1 and pin 9, for being able to drive the motor,

the pin 1 and 9 need to be high. For driving the motor with left H-bridge you need to enable pin 1

to high. And for right H-Bridge you need to make the pin 9 to high. If anyone of the either pin1

or pin9 goes low then the motor in the corresponding section will suspend working. Its like a

switch.


Figure 4.20 Pin Diagram of L293D

Working of L293D

The there 4 input pins for this l293d, pin 2,7 on the left and pin 15 ,10 on the right as

shown on the pin diagram. Left input pins will regulate the rotation of motor connected across

left side and right input for motor on the right hand side. The motors are rotated on the basis of

the inputs provided across the input pins as LOGIC 0 or LOGIC 1.

In simple you need to provide Logic 0 or 1 across the input pins for rotating the motor.

L293D Logic Table.

Lets consider a Motor connected on left side output pins (pin 3,6). For rotating the motor

in clockwise direction the input pins has to be provided with Logic 1 and Logic 0.

Pin 2 = Logic 1 and Pin 7 = Logic 0 | Clockwise Direction

Pin 2 = Logic 0 and Pin 7 = Logic 1 | Anticlockwise Direction


Pin 2 = Logic 0 and Pin 7 = Logic 0 | Idle [No rotation] [Hi-Impedance state]

Pin 2 = Logic 1 and Pin 7 = Logic 1 | Idle [No rotation]

In a very similar way the motor can also operated across input pin 15,10 for motor on the right

hand side.

Circuit Diagram For l293d motor driver IC controller.

Figure 4.21 Interfacing Diagram of L293D

Voltage Specification

VCC is the voltage that it needs for its own internal operation 5v; L293D will not use this

voltage for driving the motor. For driving the motors it has a separate provision to provide motor

supply VSS (V supply). L293d will use this to drive the motor. It means if you want to operate a

motor at 9V then you need to provide a Supply of 9V across VSS Motor supply.


The maximum voltage for VSS motor supply is 36V. It can supply a max current of

600mA per channel.Since it can drive motors Up to 36v hence you can drive pretty big motors

with this l293d.

VCC pin 16 is the voltage for its own internal Operation. The maximum voltage ranges

from 5v and upto 36v.


4.8 RELAY

Relay is an electromagnetic device which is used to isolate two circuits electrically and

connect them magnetically. They are very useful devices and allow one circuit to switch another

one while they are completely separate. They are often used to interface an electronic circuit

(working at a low voltage) to an electrical circuit which works at very high voltage. For example,

a relay can make a 5V DC battery circuit to switch a 230V AC mains circuit. Thus a small sensor

circuit can drive, say, a fan or an electric bulb.

A relay switch can be divided into two parts:

1. Input

2. Output

The input section has a coil which generates magnetic field when a small voltage from an

electronic circuit is applied to it. This voltage is called the operating voltage. Commonly used

relays are available in different configuration of operating voltages like 6V, 9V, 12V, 24V etc.

The output section consists of contactors which connect or disconnect mechanically. In a basic

relay there are three contactors: normally open (NO), normally closed (NC) and common

(COM). At no input state, the COM is connected to NC. When the operating voltage is applied

the relay coil gets energized and the COM changes contact to NO. Different relay configurations

are available like SPST, SPDT and DPDT etc, which have different number of changeover

contacts. By using proper combination of contactors, the electrical circuit can be switched on and

off. Get inner details about structure of a relay switch.


PIN DIAGRAM:

Figure 4.22 Relay Basic Pin Diagram

RELAY INTERFACING WITH 89C51

Figure 4.23 Relay Interfacing with 89c51


RELAY ON

Figure 4.24 Relay On

RELAY OFF

Figure 4.25- Relay Off


RELAY APPLICATIONS

Relays are used to and for:

Amplify a digital signal, switching a large amount of power with a small operating

power. Some special cases are:

A telegraph relay, repeating a weak signal received at the end of a long wire

Controlling a high-voltage circuit with a low-voltage signal, as in some types

of modems or audio amplifiers,

Detect and isolate faults on transmission and distribution lines by opening and

closing circuit breakers (protection relays),

Isolate the controlling circuit from the controlled circuit when the two are at different

potentials, for example when controlling a mains-powered device from a low-voltage

switch. The latter is often applied to control office lighting as the low voltage wires are

easily installed in partitions, which may be often moved as needs change. They may also

be controlled by room occupancy detectors to conserve energy,

Logic functions. For example, the Boolean AND function is realized by connecting

normally open relay contacts in series, the OR function by connecting normally open

contacts in parallel. The change-over or Form C contacts perform the XOR (exclusive or)

function. Similar functions for NAND and NOR are accomplished using normally closed

contacts. The Ladder programming language is often used for designing relay

logic networks.

Safety-critical logic. Because relays are much more resistant than semiconductors to

nuclear radiation, they are widely used in safety-critical logic, such as the control panels

of radioactive waste-handling machinery.

Time delay functions. Relays can be modified to delay opening or delay closing a set of

contacts. A very shorts (a fraction of a second) delay would use a copper disk between

the armature and moving blade assembly. Current flowing in the disk maintains magnetic

field for a short time, lengthening release time. For a slightly longer (up to a minute)

delay, a dashpot is used. A dashpot is a piston filled with fluid that is allowed to escape


slowly. The time period can be varied by increasing or decreasing the flow rate. For

longer time periods, a mechanical clockwork timer is installed.

Figure 4.26- Relay

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 contacts

can be thrown by energizing the coil in one of three ways:

1. Normally - open (NO) contacts 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 contact or make contact.

2. Normally - closed (NC) contacts disconnect the circuit when the relay is

activated ; the circuit is connected when relay is inactive. It is also called

FORM B contact or break contact


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

open contact and one normally closed contact with a common terminal. It is

also called a Form C transfer contact.

The following types of relays are commonly encountered:

Figure 4.27 DIFFERENT TYPES OF RELAYS

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 hange-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.


Chapter 5

Result & Conclusion

The most important problems faced are the misusage of electricity and its wastage.

Sometimes due to carelessness of the authorities and the workers lamps are left ON which results

in wastage of electricity. Water wastage is another problem which needs to be dealt with. Our

project helps to overcome all these problems.


Chapter 6

Applications

1. This small scale project can be implemented with minimum cost and resources in any public

garden which are generally maintained by municipal corporations.

2. This project can also be used at private gardens like company or universities or educational

premises like school / colleges

3. With little modifications, this project can be used in industries. By this the light bulbs can be

controlled with respect to intensity of light in the environment. Also, various industrial

devices can be turned on/off with respect to desired time for the specific interval of time.


Chapter 7

Advantages

1. This project saves electricity because lights are turned on only when there is insufficient light

in the environment. Thus it avoids wastage of electricity.

2. This project also saves water because water supply is turned on only for specific time period.

Thus it avoids wastage of water. Thus it helps in proper utilization of the available resources

3. All process in Garden like Gate opening, water supply, light controlling are fully automated.

Thus it does not require any human attention.


Chapter 8

Reference

1. The 8051 Micro controller and Embedded Systems by Muhammad Ali Mazidi and Janice

Gillispie Mazidi

2. The 8051 Micro controller Architecture, Programming & Applications by Kenneth J. Ayala

3. Fundamentals of Micro processors and Micro computers by B. Ram

4. Electronic Components -D.V. Prasad

5. Wireless Communications - Theodore S. Rappaport

Documents

Automatic Gardening System