AUTOMATIC METER READING USING GSM MODEM
Objective of Project-
- Primary objective to make this project is – Person Going home to home to collect meter reading need not to collect reading by visit. He will have to send sms to particular meters and he will get Reading on His
- Secondary to make electricity billing system Automated and protect from theft of electricity.
- Wirelss RF monitoring of System
Methodology– methodology behind the project first of all we will learn to make digital electricity meter using controller . secondly will connect controller with gsm modem serially using rs232 connection. We will learn how we cn send message from controller and how can we read message using AT commands. AT commands used to read and send message from gsm modem.
Introduction and Description of Project
The purpose of this project is the remote monitoring and control of the domestic energy meter by GSM NET-WORK. This system enables the Electricity Department to read the meter reading regularly without the person visiting each house. This can be achieved by the use of microcontroller unit that continuously monitors and records the Energy Meter reading in its permanent ( non-volatile) memory location. This system also makes use of a GSM model for remote monitoring and control of Energy meter.
The Microcontroller based system continuously records the reading and the live meter reading can be sent to the Electricity deoartment on request. This system also can be used to disconnect the power supply to the house in case of non payment of electricity bills. A dedicated Gsm modem with sim card is required for each energy meter. In project we will also use RF 434 Mhz modules to send wireless data to substation to protect from theft. User can change value of home display. He cant change value going to substation.
In this project we show that how we get a meter reading though a SMS. Energy meter is connected to the microcontroller via Opto-Coupler PC 817. Meter provide a pulse according to the load. Micro-controller counts the pulse and save this in the external memory . Microcontroller converts this data in to ASCII code and display the same on the LCD.. GSM modem is connected with the microcontroller through MAX 232 IC. MAX 232 IC converts TTL data into RS232 data . Non volatile memory is connected to .
For meter reading, fisrt of all we send a SMS to this unit from department ( company phone) . As the sms is received on this system then GSM modem transfer the sms to this unit via GSM MODEM .. Microcontroller save this sms and send back a sms with pulse and unit reading.
If the company want to stop . start the meter then company send a sms to this unit.
By sending a MESSAGE 4LF , UNIT is off automatically and by sending a message 4LN unit again restart automatically.
STEP DOWN TRANSFORMER
Step down transformer from 220 volt Ac to 9-0-9 ac. We use step down transformer to step down the voltage from 220 to 9 volt ac. This AC is further connected to the rectifier circuit for AC to DC conversion. Transformer current rating is 750 ma .
In this project we use IN 4007 diode as a rectifier. IN 4007 is special diode to convert the AC into DC
rectifier. Output of rectifier is pulsating DC. To convert the pulsating dc into smooth dc we use Electrolytic capacitor as a main filter. Capacitor converts the pulsating dc into smooth dc and this DC is connected to the Regulator circuit for Regulated 5 volt DC.
Pin no 40 of the controller is connected to the positive supply. Pin no 20 is connected to the ground. Pin no 9 is connected to external resistor capacitor to provide a automatic reset option when power is on.
Pin no 9 of the controller is connected to the reset circuit. On the circuit we connect one resistor and capacitor circuit to provide a reset option when power is on
As soon as you give the power supply the 8051 doesn’t start. You need to restart for the microcontroller to start. Restarting the microcontroller is nothing but giving a Logic 1 to the reset pin at least for the 2 clock pulses. So it is good to go for a small circuit which can provide the 2 clock pulses as soon as the microcontroller is powered.
This is not a big circuit we are just using a capacitor to charge the microcontroller and again discharging via resistor.
Pin no 18 and 19 is connected to external crystal oscillator to provide a clock to the circuit.
Crystals provide the synchronization of the internal function and to the peripherals. Whenever ever we are using crystals we need to put the capacitor behind it to make it free from noises. It is good to go for a 33pf capacitor.
We can also resonators instead of costly crystal which are low cost and external capacitor can be avoided.
But the frequency of the resonators varies a lot. And it is strictly not advised when used for communications projects.
How is this time then calculated?
The speed with which a microcontroller executes instructions is determined by what is known as the crystal speed. A crystal is a component connected externally to the microcontroller. The crystal has different values, and some of the used values are 6MHZ, 10MHZ, and 11.059 MHz etc.
Thus a 10MHZ crystal would pulse at the rate of 10,000,000 times per second.
The time is calculated using the formula
No of cycles per second = Crystal frequency in HZ / 12.
For a 10MHZ crystal the number of cycles would be,
This means that in one second, the microcontroller would execute 833333.33333 cycles.
LIQUID CRYSTAL DISPLAY
A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is prized by engineers because it uses very small amounts of electric power, and is therefore suitable for use in battery-powered electronic devices.
Reflective twisted nematic liquid crystal display.
- Vertical filter film to polarize the light as it enters.
- Glass substrate with ITO The shapes of these electrodes will determine the dark shapes that will appear when the LCD is turned on or off. Vertical ridges etched on the surface are smooth.
- Twisted nematic liquid crystals.
- Glass substrate with common electrode film (ITO) with horizontal ridges to line up with the horizontal filter.
- Horizontal filter film to block/allow through light.
- Reflective surface to send light back to viewer.
Each pixel of an LCD consists of a layer of liquid crystal molecules aligned between two transparent electrodes, and two polarizing filters, the axes of polarity of which are perpendicular to each other. With no liquid crystal between the polarizing filters, light passing through one filter would be blocked by the other.
The surfaces of the electrodes that are in contact with the liquid crystal material are treated so as to align the liquid crystal molecules in a particular direction. This treatment typically consists of a thin polymer layer that is unidirectionally rubbed using a cloth (the direction of the liquid crystal alignment is defined by the direction of rubbing).
Before applying an electric field, the orientation of the liquid crystal molecules is determined by the alignment at the surfaces. In a twisted nematic device (the most common liquid crystal device), the surface alignment directions at the two electrodes are perpendicular, and so the molecules arrange themselves in a helical structure, or twist. Because the liquid crystal material is birefringent (i.e. light of different polarizations travels at different speeds through the material), light passing through one polarizing filter is rotated by the liquid crystal helix as it passes through the liquid crystal layer, allowing it to pass through the second polarized filter. Half of the light is absorbed by the first polarizing filter, but otherwise the entire assembly is transparent.
When a voltage is applied across the electrodes, a torque acts to align the liquid crystal molecules parallel to the electric field, distorting the helical structure (this is resisted by elastic forces since the molecules are constrained at the surfaces). This reduces the rotation of the polarization of the incident light, and the device appears gray. If the applied voltage is large enough, the liquid crystal molecules are completely untwisted and the polarization of the incident light is not rotated at all as it passes through the liquid crystal layer. This light will then be polarized perpendicular to the second filter, and thus be completely blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts, correspondingly illuminating the pixel.
With a twisted nematic liquid crystal device it is usual to operate the device between crossed polarizers, such that it appears bright with no applied voltage. With this setup, the dark voltage-on state is uniform. The device can be operated between parallel polarizers, in which case the bright and dark states are reversed (in this configuration, the dark state appears blotchy).
Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided by applying either an alternating current, or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).
When a large number of pixels is required in a display, it is not feasible to drive each directly since then each pixel would require independent electrodes. Instead, the display is multiplexed. In a multiplexed display, electrodes on one side of the display are grouped and wired together (typically in columns), and each group gets its own voltage source. On the other side, the electrodes are also grouped (typically in rows), with each group getting a voltage sink. The groups are designed so each pixel has a unique, unshared combination of source and sink. The electronics, or the software driving the electronics then turns on sinks in sequence, and drives sources for the pixels of each sink.
Important factors to consider when evaluating an LCD monitor include resolution, viewable size, response time (sync rate), matrix type (passive or active), viewing angle, color support, brightness and contrast ratio, aspect ratio, and input ports (e.g. DVI or VGA).
Passive-matrix and active-matrix
A general purpose alphanumeric LCD, with two lines of 16 characters.
LCDs with a small number of segments, such as those used in digital watches and pocket calculators, have a single electrical contact for each segment. An external dedicated circuit supplies an electric charge to control each segment. This display structure is unwieldy for more than a few display elements.
Small monochrome displays such as those found in personal organizers, or older laptop screens have a passive-matrix structure employing supertwist nematic (STN) or double-layer STN (DSTN) technology (DSTN corrects a color-shifting problem with STN). Each row or column of the display has a single electrical circuit. The pixels are addressed one at a time by row and column addresses. This type of display is called a passive matrix because the pixel must retain its state between refreshes without the benefit of a steady electrical charge. As the number of pixels (and, correspondingly, columns and rows) increases, this type of display becomes less feasible. Very slow response times and poor contrast are typical of passive-matrix LCDs.
High-resolution color displays such as modern LCD computer monitors and televisions use an active matrix structure. A matrix of thin-film transistors (TFTs) is added to the polarizing and color filters. Each pixel has its own dedicated transistor, allowing each column line to access one pixel. When a row line is activated, all of the column lines are connected to a row of pixels and the correct voltage is driven onto all of the column lines. The row line is then deactivated and the next row line is activated. All of the row lines are activated in sequence during a refresh operation. Active-matrix displays are much brighter and sharper than passive-matrix displays of the same size, and generally have quicker response times, producing much better images.
Twisted nematic (TN)
LCD Display Technology
In-plane switching (IPS)
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, 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. Manufacturers have different standards for determining a maximum acceptable number of defective pixels. The maximum acceptable number of defective pixels for LCD varies a lot (such as zero-tolerance policy and 11-dead-pixel policy) from one brand to another, often a hot debate between manufacturers and customers. To regulate the acceptability of defects and to protect the end user, ISO released the ISO 13406-2 standard. However, not every LCD manufacturer conforms to the ISO standard and the ISO standard is quite often interpreted in different ways.
Examples of defects in LCD displays
LCD panels are more likely to have defects than most ICs due to their larger size. In this example, a 12″ SVGA LCD has 8 defects and a 6″ wafer has only 3 defects. However, 134 of the 137 dies on the wafer will be acceptable, whereas rejection of the LCD panel would be a 0% yield. The standard is much higher now due to fierce competition between manufacturers and improved quality control. An SVGA LCD panel with 4 defective pixels is usually considered defective and customers can request an exchange for a new one. Some manufacturers, notably in South Korea where some of the largest LCD panel manufacturers, such as LG, are located, now have “zero defective pixel guarantee” and would replace a product even with one defective pixel. Even where such guarantees do not exist, the location of defective pixels is important. A display with only a few defective pixels may be unacceptable if the defective pixels are near each other. Manufacturers may also relax their replacement criteria when defective pixels are in the center of the viewing area.
Comonents List Required
- GSM modem Sim 300 or SIM 900 RS232
- MAX 232
- LCD display 16×2
- RS232 connector
- IC base 40 pin and 16pin and 8 pin
- Soldering wire
- Soldering Iron
- Screw Driver
- Ribbon wire
- RESISTANCES- 100OHM,22K,220K,330K
- CAPACITORS- 1000µF,470µF,33PF,1µF
- TRANSFORMER 12 V 1Ampere
- REGULATOR- 7805
- Controller 89s52
- DECADE COUNTER IC 4017
- ELECTRICAL SWITCHES
- Electricity Meter Normal
- PC817 Optocoupler
- COPPER CLAD BOARD
- FECL3 anhyd Power for PCB design