05-03-2013, 03:13 PM
GSM Based periodical weather monitor system
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ABSTRACT
Aim of the project is to calculate humidity and temperature in particular environment (like textile mills, food processing units and market places)and display values in digital form by using embedded system technology.
Previously, like many other clean rooms, customer had been using the whirling hygrometer test to take manual readings of the environment at regular intervals. This simple method could not detect humidity and temperature drifts, which need to be monitored closely. The challenge was to provide a system that would do all of this without the need for constant supervision. ESD (electrostatic discharge), which occurs in drier atmospheres, can damage the components and therefore maximum and minimum amounts of humidity (30% minimum and 65% maximum) have to be maintained when testing.
There was a system of taking manual readings at regular intervals, with further management time required for collating and analyzing the information.
This project monitors the control of the clean room by measuring temperature and humidity across the whole building (metrology lab) and display in digital format. Now a day the display systems are in digital form, because it is easy way to identify values with their units if it has and control the systems automatically.
INTRODUCTION
The project report describes the design Development and Fabrication of One demo unit of the project work “GSM Based periodical weather monitor system”
Now a day, with the advancement technology, particularly in the field of Microcontrollers, all the activities in our daily living have become a part of Information technology and we find microcontrollers in each and every application. Thus, trend is directing towards Microcontrollers based project works. However, in this project work two sensors are used to sensing the signals, one is humidity sensor and the other is Gas Leakage sensor. The microcontroller receives the signal from the sensor. Then the decisions are taken with the help of microcontroller and associated software.
The microcontroller block is playing a major role in this project work. The micro controller chip used in this project work is PIC 16f877A and this is like heart of the project work. The PIC 16f877A microcontroller is a 40-pin IC.
Embedded Development Environment
PICC can be run entirely from the. This environment allows you to manage all of your PIC projects. You can compile, assemble and link your embedded application with a single step. Optionally, the compiler may be run directly from the command line, allowing you to compile, assemble and link using one command. This enables the compiler to be integrated into third party development environments, such as Microchip's MPLAB IDE.
Embedded system tools
ASSEMBLER
An assembler is a computer program for translating assembly language — essentially, a mnemonic representation of machine language — into object code. A cross assembler (see cross compiler) produces code for one type of processor, but runs on another. The computational step where an assembler is run is known as assembly time. Translating assembly instruction mnemonics into op codes, assemblers provide the ability to use symbolic names for memory locations (saving tedious calculations and manually updating addresses when a program is slightly modified), and macro facilities for performing textual substitution — typically used to encode common short sequences of instructions to run inline instead of in a subroutine. Assemblers are far simpler to write than compilers for high-level languages.
DETAILS ABOUT MICROCONTROLLER
The microcontroller is a chip, which has a omputer processor with all its support functions, memory (both program storage and RAM), and I/O built in to the device.These built in functions minimize the need for external circuits and devices to design in final applications.
Most microcontrollers do not require a substantial amount of time to learn how to efficiently program them, although many of them, which have quirks, which you will have to understand before you, attempt to develop your first application.
Along with microcontrollers getting faster, smaller and more power efficient they are also getting more and more features. Often, the first version of microcontroller will just have memory and digital I/O, but as the device family matures, more and more pat numbers with varying features will be available. In this project we used PIC 16f877A microcontroller. For most applications, we will be able to find a device within the family that meets our specifications with a minimum of external devices, or an external but which will make attaching external devices easier, both in terms of wiring and programming. For many microcontrollers, programmers can built very cheaply, or even built in to the final application circuit eliminating the need for a separate circuit. Also simplifying this requirement is the availability of micro-controllers wit SRAM and EEPROM for control store, which will allow program development without having to remove the micro controller fro the application circuit.
DESCRIPTION OF BLOCK DIAGRAM
The AC main Block is the power supply, which is of single-phase 230V ac. This should be given to step down transformer to reduce the 230V ac voltage to low voltage. i.e., to 6V or 12V ac this value depends on the transformer inner winding. The output of the transformer is given to the rectifier circuit. This rectifier converts ac voltage to dc voltage. But the voltage may consist of ripples or harmonics.
To avoid these ripples the output of the rectifier is connected to filter. The filter thus removes the harmonics. This is the exact dc voltage of the given specification. But the controller operates at 5V dc and the relays and driver operates at 12V dc voltage. So we need a regulator to reduce the voltage. 7805 regulator produces 5V dc and 7812 regulator produces 12V dc. Both are positive voltages.
POWER SUPPLY
Power supply unit consists of Step down transformer, Rectifier, Input filter, Regulator unit, Output filter.
The Step down Transformer is used to step down the main supply voltage from 230V AC to lower value. This 230 AC voltage cannot be used directly, thus it is stepped down. The Transformer consists of primary and secondary coils. To reduce or step down the voltage, the transformer is designed to contain less number of turns in its secondary core. The output from the secondary coil is also AC waveform. Thus the conversion from AC to DC is essential. This conversion is achieved by using the Rectifier Circuit/Unit.
The Rectifier circuit is used to convert the AC voltage into its corresponding DC voltage. There are Half-Wave, Full-Wave and bridge Rectifiers available for this specific function. The most important and simple device used in Rectifier circuit is the diode. The simple function of the diode is to conduct when forward biased and not to conduct in reverse bias.
The Forward Bias is achieved by connecting the diode’s positive with positive of the battery and negative with battery’s negative. The efficient circuit used is the Full wave Bridge rectifier circuit. The output voltage of the rectifier is in rippled form, the ripples from the obtained DC voltage are removed using other circuits available. The circuit used for removing the ripples is called Filter circuit.
OPERATION OF THE CIRCUIT
The input of the circuit is taken from the main. It is a single-phase 230V ac voltage. This 230 AC voltage cannot be used directly, thus it is stepped down. The Step down Transformer is used to step down the main supply voltage from 230V AC to lower value. Because the microcontroller and sensors are operated at +5V dc voltage and relays and drivers will be operate at +12V dc voltage. So first this 230C AC voltage should be stepped down and then it should be converted to dc. After converting to dc it is applied to controller, sensors, relays and drivers. In this project we used 230/12V step down transformer.
In this circuit we used two regulators. 7805 regulator for producing 5V dc, and 7812 regulator for 12V dc voltage. The output of 7805 regulator is given to PIC microcontroller and three sensors. The output of the 7812 regulator is connected to driver IC and Relay. The main parts of this project are sensors and PIC micro controller.
When the power supply given to the circuit then the LCD displays the humidity level and gas leakage level of the room. If the gas leakage level is crossing the prescribed limits then the controller activates the relays and dialed the particular number, which we are already inserted in the controller through coding.
RESULT AND CONCLUSION
The humidity and temperature levels are sensed by individual sensors, the sensed values are transmitted to through I2C communication protocol to micro controller. The controller calculates the level of humidity and temperature. This calculated value will be display on LCD display unit; the LCD displayed all the values in digital format. Now we can see the level of humidity and temperature.