Automatic Pressure Measuremtn and Controlling Ssytem

8/13/2019 Automatic Pressure Measuremtn and Controlling Ssytem

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AUTOMATIC PRESSURE MEASUREMTN AND CONTROLLING SSYTEM

Introduction

The notion behind the implementation of Pressure Sensing System is to learn by doing, the application

and functionality of microcontroller. Pressure sensing and controlling has a wide variety of applications

in industry and microcontroller is the most suitable device that can be dedicated for the task.

This project discusses the circuitry and the programming involve in the implementation of Pressure

Sensing System. The project also includes each component and IC involve in the circuitry. The purpose of

this project is to introduce the use of microcontrollers as instrumentation controllers. The

microcontroller will be programmed using an embedded C language and will familiarize us with

hardware and programming of an 8051 microcontroller. This system will generate alarm signal in case

of excess pressure and hence control the application of excess pressure


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Microcontroller (AT89S52)

1 About 8052 (AT89S52) microcontroller

The AT89S52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K bytes of

downloadable Flash programmable and erasable read only memory and 2K bytes of EEPROM. The

device is manufactured using Atmels high-density non volatile memory technology and is compatible

with the industry-standard 80C51 instruction set and pin out. The on-chip downloadable Flash allows

the program memory to be reprogrammed in-system through an SPI serial interface or by a

conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with downloadable

Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcomputer which provides a highly-

flexible and cost-effective solution to many embedded control applications.

The AT89S52 provides the following standard features: 8K bytes of downloadable Flash, 2K bytes of

EEPROM, 256 bytes of RAM, 32 I/O lines, programmable 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 AT89S8252 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. The downloadable Flash can be changed a single byte at a

time and is accessible through the SPI serial interface. Holding RESET active forces the SPI bus into a

serial programming interfaces and allows the program memory to be written to or read from unless

Lock Bit 2 has been activated


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Analog to Digital Conversion process in Pressure Monitoring Project

Analog to Digital Conversion process in 8051 Microcontroller Based Pressure Monitoring Project:-

The output of the pressure transducer is an analog signal .To interface with the microcontroller it is

needed to change this signal in to digital value because the microcontroller and other digital devices

works on the digital data . For this purpose ADC is used. We used an IC(ADC0804) which gave an 8 bit

digital value for the input analog valued signal.

Analog signals are very common inputs to embedded systemsMost transducers and sensors are

analog. Special devices needed to interface the analog systems to digital systems. ADC (Analog to Digital

Converter) is used between signal input and the embedded system. DAC (Digital to Analog Converter)

between embedded system and analog signal output

An analog-to-digital converter (ADC) is a circuit that converts an analog voltage into a digital word. A

typical ADC consists of a single IC with a few support components.


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Applications of pressure sensor

2.1 Pressure sensing in the Water industry.

Pressure monitoring is widely used in the water industry to provide level measurement in reservoirs and

bore boles, leak detection in distribution networks, as well as control data for a wide range of process

functions. Pressure transducers can also be used for 'drop testing' when measuring leakage from

reservoirs. There are many reasons for the popularity of pressure transducers, within the water and

waste industry. Pressure transducers are the first choice for level measurement in boreholes, due to

their compact size, and offer the

most reliable solution for applications involving 'foamy' water. This gives them an advantage over

ultrasonic equipment in wastewater applications, where the conditions can lead to false readings. As

transducers are submerged, they are also ideal for remote sites where vandalism can potentially present

a problem.

.2 Critical pressure measurements throughout Jaguar's test cars.

Jaguar Cars Limited are using the latest PMP 317 series of Druck automotive pressure transducers for

monitoring performance critical pressure measurements on their preproduction test cars. The sensors

provide pressure data during a series of intensive climatic and durability tests to analyse performance

under extremes of temperature and high-speed operation.

2.3 Aerospace industry.

It was during the early seventies that the concept of an "integrated" micromachined silicon sensor

proved its ability to deliver a substantially better performance for aerospace pressure measurement

than other traditional technologies available at that time. Due to its inherent operating characteristics

and solid state construction, it offered high accuracy, response and overload capability coupled with a

virtual insensitivity to severe environmental effects such as vibration, shock and acceleration. Exploiting

the piezo-resistive properties of a monolithic silicon diaphragm, with atomically diffused strain gauges

arranged in a wheatstone bridge configuration, a continuous, high millivoltage output could be achieved

proportional to applied pressures ranging from tens of millibars upwards. The compact nature of this

sensor technology also enabled a modular approach to packaging design which could be readily

modified for many different purposes including built-in signal conditioning where required. Also, by the

use of low thermal coefficient materials such as a glass mount, together with fully encapsulated


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passively or actively temperature compensated electronics, its performance could be maintained even

across wide extremes of temperature. For the aerospace industry, effectively this technology offered all

the benefits of improved performance, reliability, efficiency and safety, which were then of course, soon

applied within the industry led by specialist manufacturers such as Druck.

Automatic Pressure Measuremtn and Controlling Ssytem

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