10-09-2014, 11:02 AM
GSM BASED DATA AQUISATION SYSTEM
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INTRODUCTION
The “GSM BASED DATA AQUISATION SYSTEM” is an example of embedded system. An embedded system includes both hardware and software. In its simplest form, these consist of a microcontroller with software written in either high level language compilers/assembly language. Here we are written the program code in TASM (assembly language) and then dumped it into the controller/chip.
Our kit consists the microcontroller 89C52 to which the input data is given from ADC8089.For the ADC; the input signal is coming from the sensors like temperature, frequency etc. The User phone obtains information from the SIM (Subscriber Index Module) present in the GSM module. The input to the GSM modem is coming from microcontroller connected by using MAX232. So by using this we got information at any place.
Our kit gives three parameters. The three parameters are temperature, voltage, frequency. Temperature is calculated by using thermister. Voltage, frequency is calculated by using other two sensors
GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS (GSM)
INTRODUCTION
GSM (Global System for Mobile communications) is the technology that underpins most of the world's mobile phone networks. The GSM platform is a hugely successful wireless technology and an unprecedented story of global achievement and cooperation. GSM has become the world's fastest growing communications technology of all time and the leading global mobile standard, spanning 214 countries.
Global System for Mobile communications (GSM) is the most popular standard for mobile phones in the world.GSM differs from its predecessors in that both signaling and speech channels are digital call quality, and thus is considered a second generation (2G) mobile phone system. This has also meant that data communication was easy to build into the system. The ubiquity of the GSM standard has been advantageous to both consumers (who benefit from the ability to roam and switch carriers without switching phones) and also to network operators (who can choose equipment from any of the many vendors implementing GSM. GSM also pioneered a low-cost alternative to voice calls, the Short message service (SMS, also called "text messaging"), which is now supported on other mobile standards as well. One of the key features of GSM is the Subscriber Identity Module (SIM), commonly known as a SIM card. The SIM is a detachable smart card containing the user's subscription information and phonebook. This allows the user to retain his or her information after switching handsets. Alternatively, the user can also change operators while retaining the handset simply by changing the SIM. Some operators will block this by allowing the phone to use only a single SIM, or only a SIM issued by them. This practice is known as SIM locking, and is illegal in some countries.
GSM ARCHITECTURE
A GSM network is composed of several functional entities, whose functions and interfaces are specified. The GSM network can be divided into three broad parts. The Mobile Station is carried by the subscriber. The Base Station Subsystem controls the radio link with the Mobile Station. The Network Subsystem, the main part of which is the Mobile services Switching Center (MSC), performs the switching of calls between the mobile users, and between mobile and fixed network users. The MSC also handles the mobility management operations. Not shown is the Operations and Maintenance Center, which oversees the proper operation and setup of the network. The Mobile Station and the Base Station Subsystem communicate across the Um interface, also known as the air interface or radio link. The Base Station Subsystem communicates with the Mobile services Switching Center across the A interface.
MOBILE STATION
The mobile station (MS) consists of the mobile equipment (the terminal) and a smart card called the Subscriber Identity Module (SIM). The SIM provides personal mobility, so that the user can have access to subscribed services irrespective of a specific terminal. By inserting the SIM card into another GSM terminal, the user is able to receive calls at that terminal, make calls from that terminal, and receive other subscribed services.
The Base Station Subsystem is composed of two parts, the Base Transceiver Station (BTS) and the Base Station Controller (BSC). The Base Transceiver Station
NETWORK SUBSYSTEM
The central component of the Network Subsystem is the Mobile services Switching Center (MSC). It acts like a normal switching node of the PSTN or ISDN, and additionally provides all the functionality needed to handle a mobile subscriber, such as registration, authentication, location updating, handovers, and call routing to a roaming subscriber. These services are provided in conjuction with several functional entities, which together form the Network Subsystem
SERVICES PROVIDED BY GSM
From the beginning, the planners of GSM wanted ISDN compatibility in terms of the services offered and the control signaling used. However, radio transmission limitations, in terms of bandwidth and cost, do not allow the standard ISDN B-channel bit rate of 64 kbps to be practically achieved. The most basic teleservice supported by GSM is telephony. As with all other communications, speech is digitally encoded and transmitted through the GSM network as a digital stream. There is also an emergency service, where the nearest emergency-service provider is notified by dialing three digits.
A variety of data services is offered. GSM users can send and receive data, at rates up to 9600 bps, to users on POTS (Plain Old Telephone Service), ISDN, Packet Switched Public Data Networks, and Circuit Switched Public Data Networks using a variety of access methods and protocols, such as X.25 or X.32. Since GSM is a digital
POINT TO MULTIPOINT MESSAGING
Point to multipoint messaging is the process of sending data, text or alphanumeric messages from one communication device to several communication devices. To send point to multipoint messages, a message is copied and sent to each communication device that is listed in the multipoint distribution list. An example of a point to multipoint message is sending a message to a company project team informing them of a change in staff meeting time.
PIN DIAGRAM AND ITS DESCRIPTION
The microcontroller generic part number actually includes a whole family of microcontrollers that have numbers ranging from 8031to 8751 and are available in N-Channel Metal Oxide Silicon (NMOS) and Complementary Metal Oxide Silicon (CMOS) construction in a variety of package types. With 4Kbytes of Flash Programmable and Erasable Read Only Memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard MCS-51 instruction set and pin out. 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 Flash on a monolithic chip, the Atmel AT89C52 is a powerful microcomputer
ALE/PROG
Address Latch Enable 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.
Program Memory Lock Bits
On the chip there are three lock bits which can be left unprogrammed (U) or can be programmed (P) to obtain the additional features .When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the latch initializes to a random value, and holds that value until reset is activated. It is necessary that the latched value of EA be in agreement with the current logic level at that pin in order for the device to function properly.
The Stack and Stack Pointer:
The stack refers to an area of internal RAM that is used in conjunction with certain opcodes to store and retrieve data quickly. The 8-bit stack pointer register is used by the 89C52 to hold an internal RAM address that is called the top of the stack. The address held in the SP register is the location in internal RAM where the last byte of data was stored by a stack operation. When data is to be placed on the stack, the SP increments before storing data on the stack, so that the stack grows up as data is stored.
POWER SUPPLY
INTRODUCTION
The supply given is the +5V D.C. The incoming power is 230V A.C.; there is a need to convert it into +5V D.C.
The input A.C. supply is stepped down from 230V to 9-0-9V. The rectifier consists of diodes D1 and D2 makes the supply D.C. that is, unidirectional waveform. The output from rectifier is a URDC, whose value is 12.726V peak to peak. The voltage regulator makes this URDC to RDC of +5V. The capacitor C1 is used to maintain constant voltage between two consecutive positive cycles where as C2 is used to remove the fluctuations caused by regulator. Here we are selecting 12.726V as a peak value. Because of fluctuations, the peak voltage may decrease, then regulator cannot step up to +5V. If we select peak value, a higher one, then the problem can be overcome.
LM 78XX SERIES VOLTAGE REGULATOR
The LM 78XXX series of the three terminal regulations is available with several fixed output voltages making them useful in a wide range of applications. One of these is local on card regulation. The voltages available allow these regulators to be used in logic systems, instrumentation and other solid state electronic equipment. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents. The LM78XX series is available in aluminum to 3 packages which will allow over 1.5A load current if adequate heat sinking is provided. Current limiting is included to limit the peak output current to a safe value. The LM 78XX is available in the metal 3 leads to 5 and the plastic to 92. For this type with adequate heat sinking, the regulator can deliver 100mA output current.
LIQUID CRYSTAL DISPLAY
INTRODUCTION
In 1968, RCA Laboratories developed the first liquid crystal display (LCD). Since then, LCD’s have been implemented on almost all types of digital devices, from watches to computer to projection TVs .LCD’s operate as a light “valve”, blocking light or allowing it to pass through. An image in an LCD is formed by applying an electric field to alter the chemical properties of each LCC (Liquid Crystal Cell) in the display in order to change a pixel’s light absorption properties. These LCC’s modify the image produced by the backlight into the screen output requested by the controller. Through the end output may be in color, the LCC’s are monochrome, and the color is added later through a filtering process. Modern laptop computer displays can produce 65,536 simultaneous colors at resolution of 800 X 600.
To understand the operation of an LCD, it is easiest to trace the path of a light ray from the backlight to the user. The light source is usually located directly behind the LCD, and can use either LED or conventional fluorescent technology. From this source, the light ray will pass through a light polarizer to uniformly polarize the light so it can be acted upon by the liquid crystal (LC) matrix. The light beam will then pass through the LC matrix, which will determine whether this pixel should be “on” or “off”. If the pixel is “on”, the liquid crystal cell is electrically activated, and the molecules in the liquid will align in a single direction. This will allow the light to pass through unchanged. If the pixel is “off”, the electric field is removed from the liquid, and the molecules with in scatter. This dramatically reduces the light that will pass through the display at that pixel. In a color display, after the light passes through the liquid crystal matrix, it passes through a color filter (usually glass). This filter blocks all wavelengths of light except those within the range of that pixel. In a typical RGB
INTERFACING LCD TO THE MICROCONTROLLER
This is the first interfacing example for the parallel port. We will star with something simple. This example does not use the Bi-directional feature found on newer ports, thus it should work with most, if no all Parallel Ports. It however does not show the use of the status port as an input. So what are we interfacing? A 16 Character, 2 Line LCD Module to the Parallel Port. These LCD Modules are very common these days, and are quite simple to work with, as all the logic required running them is on board
QUALITY CONTROL
Some LCD panels have defective transistors, causing permanently lit or unlit pixels which are commonly referred to as stuck pixels or dead pixels respectively.
Unlike integrated circuits (ICs), LCD panels with a few defective pixels are usually still usable. It is also economically prohibitive to discard a panel with just a few defective pixels because LCD panels are much larger than ICs
COLOUR DISPLAYS
In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters (pigment filters, dye filters and metal oxide filters). Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel. CRT monitors employ a similar 'subpixel' structures via phosphors, although the analog electron beam employed in CRTs do not hit exact 'subpixels'.
Color components may be arrayed in various pixel geometries, depending on the monitor's usage. If software knows which type of geometry is being used in a given LCD, this can be used to increase the apparent resolution of the monitor through sub pixel rendering. This technique is especially useful for text anti-aliasing.
To reduce smudging in a moving picture when pixels do not respond quickly enough to color changes, so-called pixel overdrive may be used.
THERMISTOR
A thermistor is a type of resistor whose resistance varies significantly with temperature more so than in standard resistors. The word is portmanteau of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors, self-resetting over current protectors, and self-regulating heating elements.
Thermistors differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different. RTDs are useful over larger temperature ranges, while thermistors typically achieve a higher precision within a limited temperature range [usually −90 °C to 130 °C].
DESCRIPTION
Serial RS-232 communication works with voltages (between -15V ... -3V are used to transmit a binary '1' and +3V ... +15V to transmit a binary '0') . On the other hand, external interfacing hardware like microprocessors and microcontrollers of modern VLSI technology are made of TTL logic operates between 0V ... +5V (roughly 0V ... +0.8V referred to as low for binary '0', +2V ... +5V for high binary '1' ). Modern low-power logic operates in the range of 0V ... +3.3V or even lower. So, the maximum RS-232 signal levels are far too high for today's TTL logic electronic hardware and the negative
RS-232 voltage can't be grokked at all by the TTL logic. Therefore, to receive serial data from an RS-232 interface the voltage has to be reduced, and the 0 and 1voltage levels inverted. In the other direction (sending data from some logic over RS-232) the low logic voltage has to be "bumped up", and a negative voltage has to be generated, too.
SETTING THE SERIAL PORT BAUD RATE
Once the Serial Port Mode has been configured, as explained above, the program must configure the serial port’s baud rate. This only applies to Serial Port modes 1 and 3. The Baud Rate is determined based on the oscillator’s frequency when in mode 0 and 2. In mode 0, the Baud rate is always the oscillator frequency divided by 12. This means if you’re crystal is 11.0592 MHz; mode 0 baud rate will always be 921,583 baud. In mode 2 the baud rate is always the oscillator frequency divided by 64, so an 11.059 MHz crystal speed will yield a baud rate of 172,797. In modes 1 and 3, the baud rate is determined by how frequently timer 1 overflows. The more frequently timer 1 overflows, the higher the baud rate. There are many ways one can cause timer 1 to overflow at a rate that determines a baud rate, but the most common method is to put timer 1 in 8-bit auto-reload mode (timer mode2) and set a reload value (TH1) that causes Timer 1 to overflow at a frequency appropriate to generate a baud rate. To determine the value that must be placed in TH1 to generate a given baud rate, we may use the following equation (assuming PCON.7 is clear).
WRITING TO THE SERIAL PORT
Once the Serial Port has been properly configured as explained above, the serial port is ready to be used to send data and receive data. If you thought that configuring the serial port was simple, using the serial port will be breeze .To write a byte to the serial port one must simply write the value to the SBUF (99h) SFR. For example, if you wanted to send the letter "A" to the serial port, it could be accomplished as easily as: MOV SBUF, #’An’ on execution of the above instruction the 8051 will begin transmitting the character via the serial port. Obviously transmission is not instantaneous--it takes a measurable amount of time to transmit. And since the 8051 does not have a serial output buffer we need to be sure that a character is completely transmitted before we try to transmit the next character. The 8051 lets us know when it is done transmitting a character by setting the TI bit in SCON. When this bit is set we know that the last character has been transmitted and that we may send the next character, if any. Consider the following code segment:
CLR TI; be sure the bit is initially clear
MOV SBUF, #’A’; Send the letter ‘A’ to the serial port
JNB TI, $; Pause until the RI bit is set.
The above three instructions will successfully transmit a character and wait for the TI bit to be set before continuing. The last instruction says "Jump if the TI bit is not set to $"-- $, in most assemblers, means "the same address of the current instruction." Thus the 8051 will pause on the JNB instruction until the TI bit is st by the 8051 upon successful transmission of the character.
CONCLUSION
Our kit consists the microcontroller 89C52 to which the input data is given from ADC8089.For the ADC; the input signal is coming from the sensors like temperature, frequency etc. The input to the GSM modem coming from microcontroller connected by using MAX232 So by using this we got information at any place. Our kit gives three parameters. The three parameters are temperature, voltage, frequency. Temperature is calculated by using thermister. Voltage, frequency is calculated by using other two sensors
Here we provide the acknowledgement a beep sound for sending data to the phone. Also the information sends to only prescribed numbers that embedded in microcontroller. Here we examined the detailed description of working and hardware components in our project.