water level indicator

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automatic water level controller using at895c1

March 16, 2013 //0

1.1 Introduction

Water level controller is automatic electronic circuit. This circuit monitor the condition of water tank and control the motor used topump water from ground tank to roof tank using microcontroller. The control panel, i.e. the main control unit of the system which consist ofthe primary control switches. The programed logic in microcontroller gives the output which is connected the relay which controls theswitching of the pump, using of siren and LCD to indicate the present condition of controller. Beside the program logic and its functions, oneimportant thing regard the level monitoring is its sensor. In this project we will use self-make sensor which is consist of metallic strip.Among different strips one will be connect with dc voltage, when water reaches and touches any of the strip the circuit is completed andrespective Optocoupler is activated which gives will signal to microcontroller. When all strip is dipped in water motor will off. Optocouplerwill be used to make circuit safe from outside signal. We will need two different power supplies, one for smooth running of microcontrollerand another for input and optocoupler

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1.2 Objectives

v To observe the water level of tank

v To control motor automatically

v To save energy and natural resources

1.3 Problem statement

Most of the people in the context of our country, they are still using manual process for water pumping and motor control thatused in home, office and industries. Manual controlling process is difficult when the water tank is located at higher buildings and controllingfrom ground level. Due to more time consuming on manual operation it is total loss of our valuable time. If we are unable to continuousmonitoring there are loss of energy sources for pumping water as well as loss of natural resources by overflowing water from tank.

With invention of different technology and automatic system, people wants to do such a task without touching it. Forfulfillment of people desire we have design this system which control the motor used to pump. Motor is automatically start and stops as ourrequirement. Our system is not only motor controlling system it also check the condition of water tank and display the present status.

The proposed approach for this system is based on microcontroller controlling system with simple self-made water level sensor.Microcontroller reads the status of system and give desired output by switching motor and displaying LCD and LED.

.


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1.4 Theory

The embedded system is a combination of computer hardware, software and perhaps additional mechanical or other parts,designed to perform a specific function within a given time frame. The embedded software is required for all real-time applications and isdeveloped using a real time operating system (RTOS), as it helps to schedule and execute tasks based on priority in a predictable manner.

This project is based on the embedded systems technology using microcontroller. The objective of this project is to controlthe motor used in home and office for water pumping with the help of switching function of microcontroller with observing status by simpleself-made sensor. In this project we interface LCD and Microcontroller to show the status of whole system. When water tank is empty motoris automatically start and when tank is full motor is stop and all condition in you are system will be display in LCD.

The Microcontroller is the embedded device which has on chip program memory in which the machine control program is stored. Suppose ifsensor send signal to turn on the motor, then the Microcontroller activates the relay which is connected to motor. Now the Motor is switchedON by relay.

2.1 Parts of system

Fig 1: Block diagram of automatic water level controller

The figure shown above is the simple block diagram of our project. It is a simple illustration of how we have implemented our projectand the various parts involved in it. From the above representation, the sensor is used to read status of water level and sends different signalto the microcontroller. Explanation of each block are follow:

2.1.1Water level sensor:

In market, different water level sensor are available but in this project we have used self-made sensor. Water level sensor is thesimply group of wire. Separate wire conducts voltage from where the level of water is reached and this voltage is supplied to the signal


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conditioner.

2.1.2 Input signal conditioner:

The voltage from water level sensor is simply amplified by this section of our project. The output of sensor is very small so weprocess it using amplifier circuit. We have used emi=er follower amplifier in this project whose output is given to the microcontroller.

2.1.3 Microcontroller:

Microcontroller is programmable semiconductor device. This is 40 pins digital device. Microcontroller has in built RAM and ROMwith microprocessor. The microcontroller we used in this project is AT89C51.which is the main section of our project. Microcontroller arewidely used in embedded system.

2.1.4 Optoisolators:

Optocoupler is used to isolate two part of system. We have used motor in our projects, which can produce back EMF, a highvoltage spike produced by a sudden change of current. In this situation, we can reduce the effect of this unwanted voltage spike by usingoptocoupler. Optoisolator has an LED transmi=er and a photo sensor receiver, separated from each other by air gap.

2.1.5 Relay driving circuit:

Microcontroller pins lack sufficient current to drive relay. While the relay’s coil needs around 10mA to be energized, themicrocontroller pin can provide a maximum 1-2 mA current. For this reason, we placed a driver as ULN2803. Which is Darlington pair circuitwhose gain is very high, input impedance is very high and output impedance is low.

2.1.6 Relay:

A relay is an electrically controllable switch widely used in industrial controls, automobiles and appliances. It allows isolation of twoseparate section of system with two different voltage source. We have used electromechanical relay, when current flows through the coilmagnetic field is induced around the coil which causes the armature to be a=racted to the coil.

2.1.7 Indicator:

Indicator are the electronic devices which shows the condition of the system. It indicates what is happening in our system. LCDand LED are the indicators used in our system. We have added LED indicator together with LCD because uneducated people cannotunderstand LCD’s output.

2.1.8 Power supply:

Power supply provides all necessary voltage and current for our system to operate. Power supply used in this projects convert220v AC supply in to 5v and 12v dc supply using transformer, diodes, capacitor and regulator IC. A power supply can by broken down intoa series of blocks, each of which performs a particular function. For example a 5V regulated supply:

Fig 2: block diagram of power supply


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3.1 Component used

3.1.1Microcontroller

Microcontroller is a microprocessor designed specifically for control applications, and is equipped with ROM, RAM and facilities Input/Output on a single chip. The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmableand erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and iscompatible with the industry-standard MCS-51 instruction set and pin out. The on-chip Flash allows the program memory to bereprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on amonolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to manyembedded control applications.

Features:

• Compatible with MCS-51™ Products

• 4K Bytes of In-System Reprogrammable Flash Memory

– Endurance: 1,000 Write/Erase Cycles

• Fully Static Operation: 0 Hz to 24 MHz

• Three-level Program Memory Lock

• 128 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Two 16-bit Timer/Counters

• Six Interrupt Sources

• Programmable Serial Channel

• Low-power Idle and Power-down Modes

Pin configuration:

AT89C51 microcontroller has 40 pins with a single 5 Volt power supply. The pin 40 is illustrated as follows:

Fig 3: AT89C51 pin configuration


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The function of each pin AT89C51 is:

Pin 1 to 8 (Port 1) is an 8-bit parallel port of a two-way (bidirectional) that can be used for different purposes (general purpose).

Pin 9 is a pin reset, reset is active if a high ration.

P3.0 (10): RXD (serial port data receiver)P3.1 (11): TXD (serial port data sender)P3.2 (12): INT0 (external interrupt 0 input, active low)P3.3 (13): INT1 (external an interrupt input, active low)P3.4 (14): T0 (external input timer / counter 0)P3.5 (15): T1 (external input timer / counter 1) P3.6 (16): WR (Write, active low) control signal from port 0 write data to memory and input-output data externally.P3.7 (17): RD (Read, active low) control signal of the reading of input-output data memory external to the port 0. XTAL pin 18 as thesecond, the output is connected to the crystal oscillator. XTAL pin 19 as the first, high input to the oscillator, connected to the crystal.

3.1.2Relay

A relay is an electrical switch that opens and closes under the control of another electrical circuit. In the original form, the switch isoperated by an electromagnet to open or close one or many sets of contacts. Because a relay is able to control an output circuit of higherpower than the inputcircuit, it can be considered to be, in a broad sense, a form of an electrical amplifier.

Fig 4: Relay

Operation

When a current flows through the coil, the resulting magnetic field a=racts an armature that is mechanically linked to a movingcontact. The movement either makes or breaks a connection with a fixed contact. When the current to the coil is switched off, the armature isreturned by a force approximately half as strong as the magnetic force to its relaxed position. Usually this is a spring, but gravity is also usedcommonly in industrial motor starters. Most relays are manufactured to operate quickly. In a low voltage application, this is to reduce noise.In a high voltage or high current application, this is to reduce arcing. If the coil is energized with DC, a diode is frequently installed across thecoil, to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a spike of voltage and mightcause damage to circuit components. Some automotive relays already include that diode inside the relay case. Alternatively a contactprotection network, consisting of a capacitor and resistor in series, may absorb the surge. If the coil is designed to be energized with AC, asmall copper ring can be crimped to the end of the solenoid. This “shading ring” creates a small out-of-phase current, which increases theminimum pull on the armature during the AC cycle.

3.1.3 ULN2803A

The ULN2803A is a high-voltage, high-current Darlington transistor array. The device consists of eight NPN

Darlington pairs that feature high-voltage outputs with common-cathode clamp diodes for switching inductive loads. The

collector-current rating of each Darlington pair is 500mA. The Darlington pairs may be connected in parallel for higher

current capability. Applications include relay drivers, hammer drivers, lamp drivers, display drivers (LED and gas

discharge), line drivers, and logic buffers. The ULN2803A has a 2.7-k series base resistor for each Darlington pair for

operation directly with TTL or 5-V CMOS devices.

Fig 5: Logical diagram of ULN2803

Features:

500-mA Rated Collector Current (Single Output)High-Voltage Outputs 50 VOutput Clamp Diodes


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Inputs Compatible With Various Types of LogicRelay Driver Applications

3.1.4 Capacitor

A capacitor is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called “plates”).The process of storing energy in the capacitor

is known as “charging”, and involves electric charges of equal magnitude, but opposite polarity, building up on each plate. Capacitors areoccasionally referred to as condensers. Capacitors are often used in electrical circuit and electronic circuits as energy-storage devices. Theycan also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters.

Capacitance: The capacitor’s capacitance (C) is a measure of the amount of charge (Q) stored on each plate for a given potential difference orvoltage (V) which appears between the plates:

In SI units, a capacitor has a capacitance of one farad when one coulomb of charge is stored due to one volt applied potential difference acrossthe plates. Since the farad is a very large unit, values ofcapacitors are usually expressed in microfarads (µF), Nano farads (nF), or Pico farads (pF).

When there is a difference in electric charge between the plates, an electric field is created in the region between the plates that isproportional to the amount of charge that has been moved from one plate to the other. This electric field creates a potential difference V = E·dbetween the plates of this simple parallel-plate capacitor.

The capacitance is proportional to the surface area of the conducting plate and inversely proportional to the distance between the plates. It isalso proportional to the permi=ivity of the dielectric (that is, non-conducting) substance that separates the plates.

The capacitance of a parallel-plate capacitor is given by:

Where ε is the permi=ivity of the dielectric (see Dielectric constant), A is the area of the plates and d is the spacing between them.

Polarized capacitors (large values, 1µF +):

Fig 7: circuit symbol of capacitor

3.1.5 Diode

The P-N junction diode is a normal semiconductor la=ice formed by combining a p-type & a n-type extrinsic semiconductormaterials. It permits the easy flow of current only in one direction but restricts it in the other direction. Hence it is popularly used inrectification purposes of the a.c. supply. The P-N junction diode is symbolized in the circuit as shown:

The Anode (A) is the p- type material & the cathode (K) is the n- type material. A

normal diode has basically two states of operation. These are: the forward bias & the reverse

bias. In the forward mode anode is positive & cathode is negative. Here high current flows

heavily known as forward current. In the reverse mode anode is negative & cathode is

positive. Here very little current


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known as reverse current flows.

Fig 8: diode

3.1.6 Transistor

A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. The transistor is thefundamental building block of the circuitry in computers, cellular phones, and all other modern devices. Because of its fast response andaccuracy, the transistor is used in a wide variety of digital and analog functions, including amplification, switching, voltage regulation, signalmodulation, and oscillators. There are mainly two groups of transistors the BJT & the FET. The BJT has both polarity carriers i.e. Holes andElectrons, while the FET is a special transistor having only one type of carrier responsible for conduction. Generally there are two types oftransistors. They are the NPN & the PNP which are symbolized as shown below. The NPN type has p-type material sandwiched between then- type materials while the PNP has n- type material sandwiched between the p- type materials. The transistor has three terminals namelyBase, Collector & Emi=er.

Fig 9: circuit symbol of transistor

3.1.7 Resistor

Fig 10: resistor

Resistors restrict the flow of electric current, for example a resistor is placed in series with a light-emi=ing diode (LED) to limit thecurrent passing through the LED.

Resistor values – the resistor color code:

Resistance is measured in ohms; the symbol for ohm is an omega .1 is quite small so resistor values are often given in k and M .1 k = 1000 1 M = 1000000 .

The ResistorColor Code

Color Number

Black 0

Brown

1

Red 2

Orange

3

Yellow 4


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Green

5

Blue 6

violet

7

Grey 8

White 9

Resistor values are normally shown using colored bands.Each color represents a number as shown in the table.

Most resistors have 4 bands:

The first band gives the first digit.The second band gives the second digit.The third band indicates the number of zeros.The fourth band is used to shows the tolerance (precision) of the resistor, this may be ignored for almost all circuits but further details aregiven below.

This resistor has red (2), violet (7), yellow (4 zeros) and gold bands.So its value is 270000 = 270 k .

On circuit diagrams the is usually omi=ed and the value is wri=en 270K.

3.1.8 Transformer

Transformers convert AC electricity from one voltage to another with li=le loss of power. Transformers work only with AC and thisis one of the reasons why mains electricity is AC.

Step-up transformers increase voltage, step-down transformers reduce voltage. Most power supplies use a step-down transformer to reducethe dangerously high mains voltage (230V in UK) 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, insteadthey are linked by an alternating magnetic field created in the soft-iron core of the transformer. The two lines in the middle of the circuitsymbol represent the core.

Transformers waste very li=le power so the power out is (almost) equal to the power in. Note that as voltage is stepped down current isstepped up.

The ratio of the number of turns on each coil, called the turn’s ratio, determines the ratio of the voltages. A step-down transformer has a largenumber of turns on its primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on itssecondary (output) coil to give a low output voltage.

turns ratio = Vp = Np and power out = power in

Vs Ns Vs × Is = Vp × Ip

Vp = primary (input) voltageNp = number of turns on primary coilIp = primary (input) current

Vs = secondary (output) voltageNs = number of turns on secondary coilIs = secondary (output) current


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Fig 11: transformer

3.1.8 Preset

Preset Symbol

These are miniature versions of the standard variable resistor. They are designed to be mounted directly onto the circuit board and adjustedonly when the circuit is built. For example to set the frequency of an alarm tone or the sensitivity of a light-sensitive circuit. A smallscrewdriver or similar tool is required to adjust presets.

Presets are much cheaper than standard variable resistors so they are sometimes used in projects where a standard variable resistor wouldnormally be used.

Multiturn presets are used where very precise adjustments must be made. The screw must be turned many times (10+) to move the sliderfrom one end of the track to the other, giving very fine control.

Fig 12: preset

3.1.10 Crystal Oscillator

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric

material to create an electrical signal with a very precise frequency.[This frequency is commonly used to keep track of time (as in quarY

wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmi=ers and receivers.The most common type of piezoelectric resonator used is the quarY crystal, so oscillator circuits incorporating them became known as crystaloscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.

QuarY crystals are manufactured for frequencies from a few tens of kiloherY to tens of megaherY. More than two billion crystals aremanufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. QuarY crystalsare also found inside testand measurement equipment, such as counters, signal generators, and oscilloscopes.

Fig 13: Crystal oscillator

3.1.11 LCD

This 16-character, 2-line parallel liquid crystal display achieves a large viewing area in a compact package. It features a yellow-green LEDbacklight and uses the common HD44780 interface (330k pdf), so sample interface code is widely available for a variety of microcontrollers.This LCD is also available without a backlight.

The DDRAM address 0x00 corresponds to the first character of the top line, address 0x0F corresponds to the last character of the top line,address 0x40 corresponds to the first character of the second line, and address 0x4F corresponds to the last character of the second line.

You can find sample HD44780 LCD interface code wri=en for a variety of AVR microcontrollers as part of the Pololu AVR library.


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Pinout

Pin Symbol Function

1 Vss ground (0 V)

2 Vdd 5 V logic supply voltage

3 Vo contrast adjustment

4 RS H/L register select signal

5 R/W H/L read/write signal

6 E H/L enable signal

7-14 DB0 – DB7 H/L data bus for 4- or 8-bit mode

15 A (LED+) backlight anode

16 K (LED-) backlight cathode

Fig 14: LCD display

3.1.12 LED

A light-emi=ing diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used forother lighting. Appearing as practical electronic components in 1962, early LEDs emi=ed low-intensity red light, but modern versions areavailable across the visible, ultraviolet, and infrared wavelengths, with very high brightness.

When a light-emi=ing diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasingenergy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon)

is determined by the energy gap of the semiconductor. A LED is often small in area (less than 1 mm2

), and integrated optical components

may be used to shape its radiation pa=ern.[6]

LEDs present many advantages over incandescent light sources including lower energy


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consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. LEDs powerful enough for room lighting arerelatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output.

Light-emi=ing diodes are used in applications as diverse as aviation lighting, automotive lighting, advertising, general lighting, and trafficsignals. LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful inadvanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products includingtelevisions, DVD players and other d

Fig : Light emmiting diode

3.1.13 Optoisolator

In electronics, an opto-isolator, also called an optocoupler, photocoupler, or optical isolator, is “an electronic device designed totransfer electrical signals by utilizing light waves to provide coupling with electrical isolation between its input and output”. The mainpurpose of an opto-isolator is “to prevent high voltages or rapidly changing voltages on one side of the circuit from damaging components ordistorting transmissions on the other side.” Commercially available opto-isolators withstand input-to-output voltages up to 10 kV andvoltage transients with speeds up to 10 kV/µs.

Fig 16: Optoisolator

3.2 Circuit diagrm

4.1 Software used

4.1.1Mide compiler

Mide Software is used which is provide with software development tools for 8051 based microcontrollers. With the Mide tools, wecan generate embedded applications for virtually every 8051 derivative. As well as we use it for debugging program and generating HexCode, this is understood by microcontroller.

4.1.2 ISP flash programmer


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It is an application program in computer which is used to burn program into Microcontroller.

4.1.3 Proteus

It is an application program for simulation of system using virtual hardware component with hex code generated by mide.

4.2 Flow chart

Dhara=1

?

Level<half

?

Level=full

?

Read from sensor

Turn on motor

Show status

Turn off motor

Show status

Show status

Start

Turn off motor

Show status


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No

Yes

No

Yes

Yes No

Fig 18: flow chart of program

5.1 Limitation

If the one wire of the sensor is broken system is halted1.

Sensor operated on the principle of water conduct electricity so sometimes it doesn’t work so we can change sensor type as our

requirement.

2.

System debugging is difficult for normal user3.


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5.2 Problem faced

Firstly due to lack of sufficient knowledge about programming, we faced problem on generating hex code for microcontroller. Laterwe have solved this problem learning book, e-book and consulting with teachers and friends.

The most difficulty we faced in the course of our project is implementation hardware due to lack of knowledge about some hardware likeULN2803 and optocoupler. At last we were more worry about our sensor which had worked in testing but not worked in all water at finaltesting. and power supply have created problem.

5.3 Application

The automatic water level controller system can be used broadly over different fields. Some of the major fields are listed below:

Personal useOffice useBusinessResearch

Education


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5.3 Cost of project:

particular Qty Unit price Amount

1 Microcontroller 1 175 140

2 Transformer 1 150 150

3 Relay 1 40 60

4 Regulator IC 1 50 50

5 Optoisolator 1 70 70

6 Diode 8 4 32

7 Capacitor (electrolytic) 2 10 20

8 Capacitor(ceramic) few 15

9 Resistor few 20

10 Transistor 5 10 50

11 Board 1 90 90

12 LCD 1 250 400

14 Crystal oscillator 1 40 40

15 ULN 2803 1 50 50

16 7404 1 35 35

17 IC base 4 10 40

13 Miscellaneous 250

Total 1512


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5.4 Conclusion

After analyzing and working in this project we concluded that project is very useful in daily life of people .We faced fewproblems while doing this project till. We did a group work and with the help of our supervisor and faculty members we are so close insuccess of our project. Thus, the project we have undertaken has helped us gain a be=er perspective on various aspects related to our courseof study as well as practical knowledge of electronic equipment. We became familiar with software analysis, designing, implementation,testing and maintenance concerned with our project. Really, we are developing a useful project.

5.5 References

www.google.comh=p://en.wikipedia.orgMicrocontroller51.blogspot.comh=p://www.engineergarage.comElectronic device and circuit , J.B. Gupta

Mazidi, M. and Mazidi, J. and McKinlay, R., The 8051 Microcontroller and Embedded Systems, 2nd

ed., Pearson education, 2009

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