CONTACTLESS LIQUID LEVEL CONTROLLER Project Title CONTACTLESS LIQUID LEVEL CONTROLLER Under the Guidance of Submitted by

ABSTRACT This ultrasonic level controller comprises of an ultrasonic module which detects precise range by reflection coming ahead of it. This module is interfaced with the serial port of microcontroller. Whenever level distance measured by cm falls below a set point the pump starts since by sensing the ultrasonic module signal coming out from the Tx sensor being reflected from the level and is received by the ultrasonic Rx sensor the output of which is fed to microcontroller. When the microcontroller receives the signal from ultrasonic receiver it activates the relay through a MOSFET that operated the pump on or off. The power supply consists of an electronic transformer (230V, 50Hz/12V, 25KHz) which steps down the voltage to 12V AC. This is converted to DC using a Bridge rectifier. The ripples are removed using a capacitive filter and it is then regulated to +5V using a voltage regulator 7805 which is required for the operation of the microcontroller and other components.  

PROJECT BLOCK DIAGRAM

HARDWARE REQUIREMENTS POWER SUPPLY BLOCK MICROCONTROLLER (AT89S52/AT89C51) ULTRASONIC MODULE PUSH BUTTONS LCD BC547 RESISTORS CAPACITORS IRFZ44 MOSFET

POWER SUPPLY Bridge rectifier 5v Regulator 230 V AC 50 Hz 5V DC Filter(470µf) 12V step down transformer

It is a smaller computer Has on-chip RAM, ROM, I/O ports... MICROCONTROLLER It is a smaller computer Has on-chip RAM, ROM, I/O ports... RAM ROM I/O Port Timer Serial COM Port Microcontroller CPU A single chip

INTERNAL STRUCTURE OF A MICRO CONTROLLER-AT89S52/51 CPU On-chip RAM On-chip ROM for program code 4 I/O Ports Timer 0 Serial Port OSC Interrupt Control External interrupts Timer 1 Timer/Counter Bus Control TxD RxD P0 P1 P2 P3 Address/Data Counter Inputs

Features of AT89S51/52 Compatible with MCS®-51 Products 8K Bytes of In-System Programmable (ISP) Flash Memory Endurance: 10,000 Write/Erase Cycles 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 Interrupt Recovery from Power-down Mode Watchdog Timer Dual Data Pointer

Pin Description

ULTRASONIC TRANSMITTER AND RECIVER Ultrasonic sensors (also known as transceivers) work on a principle similar to radar or sonar which evaluate attributes of a target by interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor.

Ultrasonic generators use piezoelectric materials such as zinc or lead zirconium tartrates or quartz crystal. The material thickness decides the resonant frequency when mounted and excited by electrodes attached on either side of it. The medical scanners used for abdomen or heart ultrasound are designed at 2.5 MHz. In this circuit, a 40 kHz transducer is used for object detection in the air medium. FEATURES Use for motion or distance sensing Frequency: 40kHz ±1.0kHz Aluminum case Capacitance: 2000Pf ±20% Transmitter: bandwidth 5.0kHz/100Db, sound pressure level 112Db/40 ±1.0kHz

MOSFET The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is a Voltage controlled device.    This means that a voltage at the gate control the current flows from the drain to the source. There are three terminals: Gate - connected to the input device. Drain - connected to the positive, since electrons drain away to the positive. Source - the source of the electrons

Contd.. USES OF MOSFETS High power devices like motors and light bulbs give a large current output for a very tiny current input.   So a MOSFET can act as the interface between an integrated circuit that can give only a tiny current, and the motor that takes a big current.   In complimentary pairs they are used in hi-fi power amplifiers.   They produce less distortion as they are more linear than bipolar transistors. Integrated circuits, as they can be made very compact.

BC547 (NPN –Transistor) The BC547 transistor is an NPN Epitaxial Silicon Transistor. It is used in general-purpose switching and amplification BC847/BC547 series 45 V, 100 mA NPN general-purpose transistors. The ratio of two currents (Ic/Ib) is called the DC Current Gain of the device and is given the symbol of hfe or nowadays Beta, (β).

The current gain from the emitter to the collector terminal, Ic/Ie, is called Alpha, (α), and is a function of the transistor itself

LIQUID CRYSTAL DISPLAY (LCD) Most common LCDs connected to the microcontrollers are 16x2 and 20x2 displays. This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively. The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (and communicates directly with the LCD.

If an 8-bit data bus is used the LCD will require 11 data lines LCD BACKGROUND If an 8-bit data bus is used the LCD will require 11 data lines (3 control lines plus the 8 lines for the data bus) The three control lines are referred to as EN, RS, and RW EN=Enable (used to tell the LCD that you are sending it data) RS=Register Select (When RS is low (0), data is treated as a command) (When RS is High(1), data being sent is text data ) R/W=Read/Write (When RW is low (0), the data written to the LCD) (When RW is low (0), the data reading to the LCD)

WORKING OF PROJECT The ultrasonic module attached to the board will check liquid level from reflecting ultrasonic waves. If the water falls below certain level, the sensor will sense it from the reflecting waves and gives the information to the microcontroller. The controller will switch on a lamp, indicating a pump, to start filing the water tank. If the water rises beyond a certain level the controller will switch off the lamp, indicating motor off. A relay is used to switch on and off the lamp. The relay is turned on or off by a switching mechanism consisting of a mosfet and a transistor. A zero logic from the MC maintains Q1(transistor) in off state such that R4 provides a voltage level to turn on the relay. A high logic from the controller switches on Q1 that provides zero voltage level at R4 to turn the device fully "OFF”.

Software Requirements Keil an ARM Company makes C compilers, macro assemblers, real-time kernels, debuggers, simulators, integrated environments, evaluation boards, and emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families. Compilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors.

i.e the programs written in one of the HLL like ‘C’ will compile the code to run on the system for a particular processor like x86 (underlying microprocessor in the computer). For example compilers for Dos platform is different from the Compilers for Unix platform  So if one wants to define a compiler then compiler is a program that translates source code into object code.

BIBILOGRAPHY “The 8051 Microcontroller and Embedded systems” by Muhammad Ali Mazidi and Janice Gillispie Mazidi , Pearson Education. ATMEL 89S52 Data Sheets. www.atmel.com www.beyondlogic.org www.wikipedia.org www.howstuffworks.com www.alldatasheets.com

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