CHAPTER 1

INTRODUTION

1.1 Introduction:-

Automatic meter reading (AMR) is the technology of automatically collecting data from energy metering devices (water, gas, and electric) and transferring that data to a central database for billing and/or analyzing. This saves employee trips, and means that billing can be based on actual consumption rather than on an estimate based on previous consumption, giving customers better control of their use of electric energy, gas usage, or water consumption.

This means that billing can be based on actual consumption rather than on an estimate based on previous consumption, giving customers better control of their use of electric energy. The Transmitter is connected to the meter and it counts the pulses from it and displays it over the seven segment display. It transmits the data over radio frequency. At the receiver end the data is received by an receiver module and the microcontroller will display it over the seven segment display.

1.2 Brief History: -

The primary driver for the automation of meter reading is not so much to reduce labor costs, but to obtain data that is otherwise unattainable. Many meters, especially water meters, are located in areas that require an appointment with the homeowner. Gas and Electricity tend to be more valuable commodities than water, and the need to offer actual readings instead of estimated readings can drive a utility to consider automation. While early systems consisted of walk-by, and drive-by AMR for residential.

Remote meter reading (or AMR) refers to the system that uses a communication technique to automatically collect the meter readings and other relevant data from utilities’ gas meters, without the need to physically visit the gas meters. The development of AMR technology has catapulted meter data to center stage of the utility business plan.

1.3 Benefits of AMR:-

The automatic meter reading (AMR) technology is very useful in many applications. By using AMR technology we can accommodate a lot of benefits. Some benefits of AMR are as follow-

1.3.1 Electrical Company Benefits:-

1. Smart automated processes instead of manual work.2. Accurate information from the network load to optimize maintenance and

investments.3. Customized rates and billing dates.4. Streamlined high bill investigations.5. Detection of tampering of Meters.6. Accurate measurement of transmission losses.

7. Better network performance and cost efficiency.8. Demand and distribution management.9. More intelligence to business planning.

1.3.2 Customer Benefits:-

1. Precise consumption information.2. Clear and accurate billing.3. Automatic outage information and faster recovery.4. Better and faster customer service.5. Flag potential high consumption before customer gets a high bill.

1.4 AMR Applications:-

As technology continues to improve in price/performance, the number of municipal utilities implementing automatic meter reading (AMR) systems continues to grow. Today, most AMR deployments are “walk-by” or “drive-by” systems. A battery-operated transmitter in each meter sends a radio frequency (RF) signal that is read by a special receiver either carried by hand or mounted in a vehicle. These solutions require a much smaller sta of meter readers, who merely need to walk or drive by the manyff meters in any neighborhood. Although this form of AMR is an enormous improvement over manual meter reading, continued high labor and vehicle costs are driving the industry to an even better solution.

Among the many advantages are the ability to monitor daily demand, implement conservation programs, create usage profiles by time of day, and detect potentially hazardous conditions, such as leaks or outages. But there is still one drawback with these AMR deployments: the costly network backhaul required by leased lines or cellular services from a local telephone company, or Power Line Carrier (PLC) solutions from the local power company.

AMR is the remote collection of consumption data from customers’ utility meters using telephony, radio frequency, power lines and satellite communications technologies. AMR provides water, gas and electric utility-service companies the opportunity to increase operational efficiency, improve customer service, reduce data-collection costs and quickly gather critical information that provides insight to company decision-makers. [4]

1.5 Different AMR Technologies:-

There are many different technologies which are used in the AMR. Using these technologies data can be send from transmitting end to the receiving end. In our project we are using RF technology for transmitting the meter reading from one point to other point. The different types of technologies are described below. Out of which handheld technology is uses rarely. [1]

1.5.1 Handheld:-

In handheld AMR, a meter reader carries a handheld computer with a built-in or attached receiver/transceiver (radio frequency or touch) to collect meter readings from an AMR capable meter. This is sometimes referred to as "walk-by" meter reading since the

meter reader walks by the locations where meters are installed as they go through their meter reading route. Handheld computers may also be used to manually enter readings without the use of AMR technology.

1.5.2 Touch Based:-

With touch based AMR, a meter reader carries a handheld computer or data collection device with a wand or probe. The device automatically collects the readings from a meter by touching or placing the read probe in close proximity to a reading coil enclosed in the touchpad. When a button is pressed, the probe sends an interrogate signal to the touch module to collect the meter reading. The software in the device matches the serial number to one in the route database, and saves the meter reading for later download to a billing or data collection computer.

1.5.3 Mobile:-

Mobile or "Drive-by" meter reading is where a reading device is installed in a vehicle. The meter reader drives the vehicle while the reading device automatically collects the meter readings. With mobile meter reading, the reader does not normally have to read the meters in any particular route order, but just drives the service area until all meters are read components often consist of a laptop or proprietary computer, software, RF receiver or transceiver, and external vehicle antennas.

1.5.4 Fixed Network:-

Fixed Network AMR is a method where a network is permanently installed to capture meter readings. This method can consist of a series of antennas, towers, collectors, repeaters, or other permanently installed infrastructure to collect transmissions of meter readings from AMR capable meters and get the data to a central computer without a person in the field to collect it. [2]

There are several types of network topologies in use to get the meter data back to a central computer. A star network is the most common, where a meter transmits its data to a central collector or repeater. Some systems use only collectors which receive and store data for processing. Others also use a repeater which forwards a reading from a more remote area back to a main collector without actually storing it. A repeater may be forwarded by RF signal or sometimes is converted to a wired network such as telephone or IP network to get the data back to a collector. Some manufacturers are developing mesh networks where meters themselves act as repeaters passing the data to nearby meters until it makes it to a main collector. A mesh network may save the infrastructure of many collection points, but is more data intensive on the meters. One issue with mesh networks it that battery operated ones may need more power for the increased frequency of transmitting. [7]

1.5.5 Radio Frequency Network:-

Radio frequency based AMR can take many forms. The more common ones are Handheld, Mobile, and Fixed network. There are both two-way RF systems and one-way RF systems in use that use both licensed and unlicensed RF bands. In a two-way or "wake up" system, a radio transceiver normally sends a signal to a particular transmitter serial number, telling it to wake up from a resting state and transmit its data. The Meter attached transceiver and the reading transceiver both send and receive radio signals and data. In a one-way “bubble-up” or continuous broadcast type system, the transmitter broadcasts readings continuously every few seconds. This means the reading device can be a receiver only, and the meter AMR device a transmitter only.

Data goes one way, from the meter AMR transmitter to the meter reading receiver. There are also hybrid systems that combine one-way and two-way technologies, using one-way communication for reading and two way communication for programming functions.RF based meter reading usually eliminates the need for the meter reader to enter the property or home, or to locate and open an underground meter pit. The utility saves money by increased speed of reading, has lower liability from entering private property, and has less chance of missing reads because of being locked out from meter access.

1.5.6 Power Line Communication:-

AMR is a method where electronic data is transmitted over power lines back to the substation, then relayed to a central computer in the utility's main office. This would be considered a type of fixed network system the network being the distribution network which the utility has built and maintains to deliver electric power. Such systems are primarily used for electric meter reading. Some providers have interfaced gas and water meters to feed into a PLC type system.

1.5.7 Wireless Fidelity(Wi-Fi):-

Today many meters are designed to transmit using Wi-Fi even if a Wi-Fi network is not available, and they are read using a drive-by local Wi-Fi hand held receiver. Narrow-banded signal has a much greater range than Wi-Fi so the numbers of receivers required for the project are far fewer the number of Wi-Fi access points covering the same area. These special receiver stations then take in the narrow-band signal and report their data via Wi-Fi Most of the automated utility meters installed in the Corpus Christi area are battery powered. Compared to narrow-band burst telemetry, Wi-Fi technology uses far too much power for long-term battery-powered operation. Thus Wi-Fi is the efficient mean of communication in AMR technologies, which allows communication between the central data base and the end users, and defines the efficient reliability of the system. Thus offering a ultimate mean to fulfill the requirement.

1.6 Description of RF Based AMR:-

1. Originally AMR devices just collected meter readings electronically & matched them with accounts.

2. As technology has advanced, additional data could then be captured, stored, and transmitted to the main computer, and often the metering devices could be controlled remotely.

3. This can include events alarms such as tamper, leak detection, low battery, or reverse flow.

4. Many AMR devices can also capture interval data, and log meter events.5. Radio frequency based AMR can take many forms. The more common one are

Handheld, Mobile, and Fixed network.

CHAPTER 2Block diagram of Zigbee Based Automatic Meter Reading System

2.1 Transmitter Unit:-The transmitter circuit diagram and block diagram are shown in figure 2.1 & 2.2

respectively. The data is transmitted from transmitter unit to the receiver unit through RF channel.

Figure-2.1-Block diagram of transmitter unit

2.2 Receiver Unit:-The receiver unit circuit diagram and block diagram are shown in figure 2.3 and

2.4 respectively. The main purpose of the receiver unit is to receive the sending end data. The is finally display on the seven segment display.

Figure-2.2-Block diagram of receiver unit

CHAPTER 3

TRANSMITTER UNIT

3.1 Introduction:-

Transmitter unit is used to send the meter reading to the receiving end. The data is send to the receiver end through Zigbee channel. The transmitter unit consists of Zigbee transmitter module, microcontroller ATMEGA48V-18PU and an LCD. For display the meter reading we are using LCD. The supply which is given to the transmitter unit is +5 volt.

Figure-3.1-Circuit diagram of transmitter unit

3.2 Microcontroller ATMEGA48V-10PU:-

3.2.1 Features:- 4K byte Self-Programmable Flash 256 byte EEPROM 512 byte internal SRAM Two 8bit Timer/Counter 6 PWM Channel 6-channel 10-bit ADC Programmable Serial USART SPI interface WDT 23-programmable I/O lines 1.8-5.5V for ATMega48v/88v/168v (max 10MHz)

Figure-3.2-Pin configuration of ATMEGA48V-10PU

3.2.2 Description:-The ATmega48/88/168 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega48/88/168 achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speedThe AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than con-ventional CISC microcontrollers.

The ATmega48/88/168 provides the following features: 4K/8K/16K bytes of In-System Program-mable Flash with Read-While-Write capabilities, 256/512/512 bytes EEPROM, 512/1K/1K bytes SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible Timer/Counters with compare modes, internal and external interrupts, a serial programmable USART, a byte-oriented 2-wire Serial Interface, an SPI serial port, a 6-channel 10-bit ADC (8 channels in TQFP and QFN/MLF packages), a programmable Watchdog Timer with internal Oscillator, and five software selectable power saving modes. The Idle mode stops the CPU while allowing the SRAM, Timer/Counters, USART, 2-wire Serial Interface, SPI port, and inter-rupt system to continue functioning. The Power-down mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next interrupt or hardware reset. In Power-save mode, the asynchronous timer continues to run, allowing the user to maintain a timer base while the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except asynchronous timer and ADC, to minimize switching noise dur-ing ADC conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest of the device is sleeping. This allows very fast start-up combined with low power consumption.

The device is manufactured using Atmel’s high density non-volatile memory technology. The On-chip ISP Flash allows the program memory to be reprogrammed In-System through an SPI serial interface, by a conventional non-volatile memory programmer, or by an On-chip Boot pro-gram running on the AVR core. The Boot

program can use any interface to download the application program in the Application Flash memory. Software in the Boot Flash section will continue to run while the Application Flash section is updated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel ATmega48/88/168 is a powerful microcontroller that provides a highly flexible and cost effective solution to many embedded control applications.

The ATmega48/88/168 AVR is supported with a full suite of program and system development tools including: C Compilers, Macro Assemblers, Program Debugger/Simulators, In-Circuit Emu-lators, and Evaluation kits.

Figure-3.3-Block diagram of ATMEGA48V-10PU

3.2.3 Pin Description:-

1.1.1 VCC

Digital supply voltage.

1.1.2 GND

Ground.

1.1.3 Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running.

Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

Depending on the clock selection fuse settings, PB7 can be used as output from the inverting Oscillator amplifier.

If the Internal Calibrated RC Oscillator is used as chip clock source, PB7..6 is used as TOSC2..1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.

The various special features of Port B are elaborated in “Alternate Functions of Port B” on page 77 and “System Clock and Clock Options” on page 26.

1.1.4 Port C (PC5:0)

Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The PC5..0 output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running.

1.1.5 PC6/RESET

If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical char-acteristics of PC6 differ from those of the other pins of Port C.

If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this pin for longer than the minimum pulse length will generate a Reset, even if the clock is not running. The minimum pulse length is given in Table 26-3 on page 306. Shorter pulses are not guaran-teed to generate a Reset.

The various special features of Port C are elaborated in “Alternate Functions of Port C” on page 80.

1.1.6 Port D (PD7:0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running.

The various special features of Port D are elaborated in “Alternate Functions of Port D” on page 83.

1.1.7 AVCC

AVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. Note that PC6..4 use digital supply voltage, VCC.

1.1.8 AREF

AREF is the analog reference pin for the A/D Converter.

1.1.9 ADC7:6 (TQFP and QFN/MLF Package Only)

In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D converter. These pins are powered from the analog supply and serve as 10-bit ADC channels.

3.2.4 Oscillator Characteristics:-

The XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 5-1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 5-2. There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed.

3.7 Zigbee Transmitter Module:-

The XBee®/XBee-PRO® RF Modules interface to a host device through a logic-level asynchronous serial port. Through its serial port, the module can communicate with any logic and voltage com-patible UART; or through a level translator to any serial device (For example: Through a Digi pro-prietary RS-232 or USB interface board).

Fig: Zigbee mounting

UART Data Flow

Devices that have a UART interface can connect directly to the pins of the RF module as shown in the figure below.

Figure System Data Flow Diagram in a UART‐interfaced environment

(Low‐asserted signals distinguished with horizontal line over signal name.)

Serial Data

Data enters the module UART through the DI pin (pin 3) as an asynchronous serial signal. The sig-nal should idle high when no data is being transmitted.

Each data byte consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit (high). The following figure illustrates the serial bit pattern of data passing through the module.

Figure UART data packet 0x1F (decimal number 31) as transmitted through the RF module Example Data Format is 8‐N‐1 (bits ‐ parity ‐ # of stop bits)

Serial communications depend on the two UARTs (the microcontroller's and the RF module's) to be configured with compatible settings (baud rate, parity, start bits, stop bits, data bits).

The UART baud rate and parity settings on the XBee module can be configured with the BD and SB commands, respectively.

Transparent Operation

By default, XBee®/XBee-PRO® RF Modules operate in Transparent Mode. When operating in this mode, the modules act as a serial line replacement - all UART data received through the DI pin is queued up for RF transmission. When RF data is received, the data is sent out the DO pin.

Serial-to-RF Packetization

Data is buffered in the DI buffer until one of the following causes the data to be packetized and transmitted:

1. No serial characters are received for the amount of time determined by the RO (Packetization Timeout) parameter. If RO = 0, packetization begins when a character is received.

2. The maximum number of characters that will fit in an RF packet (100) is received.

3. The Command Mode Sequence (GT + CC + GT) is received. Any character buffered in the DI buffer before the sequence is transmitted.

If the module cannot immediately transmit (for instance, if it is already receiving RF data), the serial data is stored in the DI Buffer. The data is packetized and sent at any RO timeout or when 100 bytes (maximum packet size) are received.

If the DI buffer becomes full, hardware or software flow control must be implemented in order to prevent overflow (loss of data between the host and module).

Remote Configuration Commands

The API firmware has provisions to send configuration commands to remote devices using the Remote Command Request API frame (see API Operation). This API frame can be used to send commands to a remote module to read or set command parameters.

The API firmware has provisions to send configuration commands (set or read) to a remote mod-ule using the Remote Command Request API frame (see API Operations). Remote commands can be issued to read or set command parameters on a remote device.

Sending a Remote Command

To send a remote command, the Remote Command Request frame should be populated with val-ues for the 64 bit and 16 bit addresses. If 64 bit addressing is desired then the 16 bit address field should be filled with 0xFFFE. If any value other than 0xFFFE is used in the 16 bit address field then the 64 bit address field will be ignored and 16 bit addressing will be used. If a command response is desired, the Frame ID should be set to a non-zero value.

Applying Changes on Remote

When remote commands are used to change command parameter settings on a remote device, parameter changes do not take effect until the changes are applied. For example, changing the BD parameter will not change the actual serial interface rate on the remote until the changes are applied. Changes can be applied using remote commands in one of three ways:

Set the apply changes option bit in the API frame Issue an AC command to the remote deviceIssue a WR + FR command to the remote device to save changes and reset the device.

Remote Command Responses

If the remote device receives a remote command request transmission, and the API frame ID is non-zero, the remote will send a remote command response transmission back to the device that sent the remote command. When a remote command response transmission is received, a device sends a remote command response API frame out its UART. The remote command response indicates the status of the command (success, or reason for failure), and in the case of a command query, it will include the register value.

The device that sends a remote command will not receive a remote command response frame if: The destination device could not be reached

The frame ID in the remote command request is set to 0.

LCD 16*2:

Features

This LCD has 14 pins, an optional backlight and a simple parallel bus interface for easy communication.

+5v DC supply from pin Vdd This module operates in 8-bit mode and 4-bit mode. It contains eight data lines (D0-D7), three control lines (E, R/W & RS) and three

power lines (Vss, Vdd & Vee). Enable (E) pin is to latch information present to its data pins. Read/write(R/W) pin used to write and read information to LCD display. Register select (RS) decide either to send commands or data to LCD display. Using Vee pin contrast of display can be adjusted.

Liquid crystal displays (LCDs) offer several advantages over traditional cathode-ray tube displays that make them ideal for several applications. Of course, LCDs are flat and they use only a fraction of the power required by cathode-ray tubes. They are easier to read and more pleasant to work with for long periods of time than most ordinary video

monitors. There are several tradeoffs as well, such as limited view angle, brightness, and contrast, not to mention high manufacturing cost.

16x2 LCD is used in this project to display data to user. There are two rows and 16 columns. It is possible to display 16 characters on each of the 2 rows. It has two registers, command register and data register.LCDs can add a lot to your application in terms of providing an useful interface for the user, debugging an application or just giving it a "professional" look. The most common type of LCD controller is the Hitachi 44780 which provides a relatively simple interface between a processor and an LCD. Using this interface is often not attempted by inexperienced designers and programmers because it is difficult to find good documentation on the interface, initializing the interface can be a problem and the displays themselves are expensive.LCD has single line display, Two-line display, four line display. Every line has 16 characters

.Description of pins used:RS, Register Select (Pin 4):

This pin is used to select command register and data register.If RS=0, instruction command register is selected, allowing the user to send a command such as clear display, cursor at home, etc.If RS =1, the data register is selected, allowing the user to send data to be displayed on the LCD.

EN Enable (Pin 6):The LCD to latch information presented to its data pins uses the enable pin. When data is supplied to data pins, a high-to-low pulse must be applied to this pin in order for the LCD to latch in the data present at the data pins. This pulse must be a minimum of 450ns wide. __ _____R / W, Read/Write (Pin 5):This pin is connected to ground, as LCD is used only to display data.

D4 – D7 (Pin 11 – Pin 14):Data to be displayed is sent to LCD on these pins. First MSB is sent, followed by

LSB. D0 – D3 (Pin 7 – Pin 10):These pins are connected to ground, as they are not used to display data.

Vcc (Pin 2):This pin is connected to +5v power supply.

Vss (Pin 1): This pin is connected to ground.Description of pins used: IN 1 – IN 4 (Pin 1 – Pin 4):

These are input pins. These pins are connected to Port 2 (P 2.0 – P2.3) pins of microcontroller. OUT 1 – OUT 4 (Pin 15 – Pin18):

These are output pins. These pins are connected to devices to be controlled. GND (Pin 9):

This pin is connected to ground.Vcc (Pin 10):

This pin is connected to +12v power supply.

The OUT1 and OUT2 are connected to two bulbs. Two more relays are left free for future use.

INTRODUCTION TO I2C PROTOCOL

History of the I2C Bus:

The I2C bus was developed in the early 1980's by Philips semiconductors. Its purpose was to provide an easy way to connect a CPU to peripheral chips in a TV-set. Normal Computer systems use Byte Wide buses to accomplish this task. This results in lots of copper tracks on PCB's to route the Address and data lines. Not to mention a bunch of address decoders and glue logic to connect everything. In mass production items such as TV-sets, VCR's and audio equipment this is not acceptable. In these appliances every component counts. And a component less means more money for the producer and cheaper products for the customer.

Furthermore lots of control lines imply that the system is more susceptible to disturbances by EMC and ESD. The research done by Philips Labs in Eindhoven (The Netherlands) resulted in a 2-wire communication bus called the I2C bus.

I2C is an acronym for Inter-IC bus. Its name literally explains its purpose: to provide a communication link between Integrated Circuits.

Nowadays the extent of the bus goes much further than Audio and Video equipments .The bus is generally accepted in industry. Offspring’s like D2B and ACCESS bus find their ways into computer peripherals like keyboards, mice, printers, monitors, etc. The I2C Bus’s has been adopted by several leading chip manufacturers like Xicor, SGS-Thomson, Siemens, Intel, TI, Maxim, Atmel, Analog Devices and lots of others.

The I2C Bus Protocol

The BUS physically consists of 2 active wires and a ground connection. The active wires, SDA and SCL, are both bi-directional. Where SDA is the Serial Data line and SCL is the Serial Clock line.

Every component hooked up to the bus has its own unique address whether it is a CPU, LCD, driver, memory or complex function chip. Each of these chips can act as a receiver and/or transmitter depending on its functionality. Obviously an LCD driver is only a receiver, while a memory or I/O chip can both be transmitter and receiver. Furthermore there may be one or more BUS Master’s.

The BUS MASTER is the chip issuing the commands on the BUS. In the I2C protocol specification it is stated that the IC that initiates a data transfer on the bus is considered the BUS MASTER. At that time all the others are regarded to as the BUS SLAVE.

As mentioned before, the IC bus is a Multi-MASTER BUS. This means that more than one IC capable of initiating data transfer can be connected to it. As MASTERs are generally microcomputers let's take a look at a general 'inter-IC chat' on the bus.

Figure 4.22: EEPROM Internal block diagram

Lets consider the following setup: Case: The CPU wants to talk to one of its slaves.

The CPU will issue a START condition (see further on for description of all these conditions) this acts as and ’ATTENTION’ signal to all of the connected IC's. All IC's on the bus will listen to the bus for incoming data.

Then the CPU sends the address of the device he wants to access. This takes 8 clock pulses. At this moment in time all IC's will compare this address with their own. If it doesn't match they simply do nothing and wait until the bus is released by the STOP condition. If the address matches however the chip will produce a response called the ACKNOWLEDGE signal.

If the CPU gets this ACKNOWLEDGE then it can start transmitting or receiving data. In our case the CPU will transmit data. When all is done the CPU will issue a STOP condition. This is a signal that the bus has been released and that the IC's may expect another transmission to start any moment.

We have had several states on the BUS right now: START, address, ACKNOWLEDGE, DATA, STOP.

These are all unique conditions on the BUS. Before we take a closer look into these bus conditions we need to understand a bit about the physical structure and hardware of the bus.

The I2C bus physically consists of 2 active wires and a ground connection. The active wires, called SDA and SCL, are both bi-directional. SDA is the Serial Data line, and SCL is the Serial Clock line.

Every device hooked up to the bus has its own unique address, no matter whether it is an MCU, LCD driver, memory or ASIC. Each of these chips can act as a receiver, and /or transmitter, depending on the functionality. Obviously, an LCD driver is only a receiver, while a memory or I/O chip can be both transmitter and receiver.

The I2C bus is a multi-master bus. This means that more than one IC capable of initiating a data transfer can be connected to it. The I2C protocol specification states that the IC that initiates a data transfer on the bus is considered the Bus Master. Consequently, at that time, all the other ICs are regarded to be Bus Slaves.

As bus masters are generally micro controllers, let's take a look at a general 'inter-IC chat' on the bus. Lets consider the following setup and assume the MCU wants to send Data to one of its slaves (also see here for more information; click here for information on how to receive data from a slave).Table 1: Start and stop conditions

Table 1: Start and stop conditionsFirst, the MCU will issue a START condition. This acts as an 'Attention' signal to all of the connected devices. All ICs on the bus will listen to the bus for incoming data.

Then the MCU sends the ADDRESS of the device it wants to access, along with an indication whether the access is a Read or Write operation (Write in our example). Having received the address, all IC's will compare it with their own address. If it doesn’t match, they simply wait until the bus is released by the stop condition (see below). If the address matches, however, the chip will produce a response called the ACKNOWLEDGE signal. Once the MCU receives the acknowledgement, it can start transmitting or receiving DATA. In our case, the MCU will transmit data. When all is done, the MCU will issue the STOP condition. This is a signal that the bus has been released and that the connected ICs may expect another transmission to start any moment.

We have had several states on the bus in our example: START, ADDRESS,ACKNOWLEDGE, DATA, STOP. These are all unique conditions on the bus. Beforewe take a closer look at these bus conditions we need to understand a bit about thephysical structure and hardware of the bus.

STARTThe chip issuing the Start condition first pulls the SDA (data) line low and next pull the SCL (clock) line low.

STOPThe Bus MASTER first releases the SCL and then the SDA line.

CHAPTER 4

RECEIVER UNIT

4.1 Introduction:-

In this project the micro controller & the ZIGBEE unit is interfaced with the Energy meter of each house. Every house has a separate number, which is given by the corresponding authority. The ZIGBEE unit is fixed in the energy meter/water meter.

The amount of consumption is stored in an EEPROM and the authority can give request to get the reading from each house by giving the number assigned. On other end the modem will receive the data in the form of a command and informs the controller to do the readings. After the readings the controller will send data to the modem. Modem, in turn sends data to the authorities. In the office the receiver unit will receive the data. They will calculate the amount and they will send back the amount be paid and the last due date. After sending the Readings to the Main server the Microcontroller will resets the memory to get the fresh readings. Finally that bill is sent to the owner through post.

4.2 Zigbee Receiver Module:-

The receiver module has Zigbee module to receive the signals from the AMR and using the RS232C converter the signals from the Zigbee module is interfaced with the server computer. In the server computer using the software “Real Term” we monitor or control the AMR unit sitting in the main electricity station.

Microcontroller and MAX3232 interactions:

Microcontroller interacts with XBEE modem for sending and receiving SMS. Microcontroller interacts with XBEE modem serially. Microcontroller has built in UART (Universal Asynchronous Receiver Transmitter), which will help in asynchronous serial communication with XBEE modem. Serial communication takes place over RS232 cable.RS232 and microcontroller, are not compatible as the voltage levels to represent a bit are different for both. Therefore MAX232 is used to convert the voltage levels of microcontroller to that of RS232 while sending data and the other way while receiving data.

Serial communication:

To communicate serially, the baud rate has to be set. Configuring the special function registers (SCON and TMOD) of the microcontroller can set this.

SCON: Serial Port Control Register (Bit –Addressable)

One cost effective way to communicate is to send and receive bits serially. Asynchronous serial communication is widely used for character-oriented transmission. In Asynchronous serial communication, the data is placed in between a start bit and one or two stop bits. This is called Framing. During serial data communication, register

SUBF is used to hold data to be transmitted / received. SCON register controls data communication, PCON controls data rates.

SBUF is physically two registers. One is write only and is used to hold data to be transmitted out of 8051 via TXD. The other is read only and holds received data from external sources via RXD. Both mutually exclusive registers use address 99H. The serial port pins TXD and RXD (P3.1 (pin 11) and P3.0 (pin 10), respectively). A register called SCON at address 98H controls the serial port of microcontroller. Start bit is always 0 (low) and stop bit is 1 (high)

Space stop 0 1 0 0 0 0 0 1 start mark bit bit

d7 d0

goes out last goes out first

Figure 4.14: Framing ASCII “A” (41H)

LSB is sent out first. When there is no transfer, the signal is 1 (high) which is referred to as MARK.0 (low) is referred tom as space.

SM0 SM1 SM2 REN TB8 RB8 TI RI

0 1 0 1 0 0 0

0

SM0 = 0 and SM1 = 1, the microcontroller operates in mode 1 i.e., 8-bit UART, 1 Stop bit and 1 Start bit. REN = 1, i.e. microcontroller is enabled to send and receive data serially.

Timer Mode Control (TMOD) This register is used to select the timer to use and the mode of its operation.

< ----------------Timer 1 ----------------- >|< -----------------Timer 0 --------------->

GATE

C/T

M1

M0

GATE

C/T

M1

M0

0 0 1 0 0 0 0 0

Timer 1 is used in this project. Since M1 = 1 and M0 = 0, timer1 is used in mode 2 i.e. auto reload mode. C/T = 0, the timer 1 is used as a timer for time delay generation.

The crystal frequency is divided by 12 to get the machine cycle timei.e. (1/12) * 11.0592 MHz = 921.6 kHz.

Therefore clock tick T = 1/921.6 kHz = 1.085 s. The UART circuitry divides the machine cycle frequency of 921.6 kHz by 32 once more before timer 1 is used to set the baud rate.

Microcontroller can communicate serially at different baud rates.To generate a baud rate of 9600 bps, the TH1 is loaded with 0xfd (decimal value: -3). And then Timer 1 should be started by making TR1 = 1.Now, it is possible for serial communication at 9600 baud rate.

1. RS232:

RS-232 (Recommended standard-232) is a standard interface approved by the Electronic Industries Association (EIA) for connecting serial devices. In other words, RS-232 is a long established standard that describes the physical interface and protocol for relatively low-speed serial data communication between computers and related devices. An industry trade group, the Electronic Industries Association (EIA), defined it originally for teletypewriter devices. In 1987, the EIA released a new version of the standard and changed the name to EIA-232-D. Many people, however, still refer to the standard as RS-232C, or just RS-232. RS-232 is the interface that your computer uses to talk to and exchange data with your modem and other serial devices. The serial ports on most computers use a subset of the RS-232C standard.

2.1. RS232 on DB9 (9-pin D-type connector):

There is a standardized pinout for RS-232 on a DB9 connector, as shown below

Pin No Signal Description1 DCD Data carrier detect2 RxD Receive Data3 TxD Transmit Data4 DTR Data terminal ready5 GND Signal ground6 DSR Data set ready7 RTS Ready to send8 CTS Clear to send9 RI Ring Indicator25 -pin D-type connector Pin assignment

2.2. RS232 on DB25 (25-pin D-type connector):

In DB-25 connector most of the pins are not needed for normal PC communications, and indeed, most new PCs are equipped with male D type connectors having only 9 pins. Using a 25-pin DB-25 or 9-pin DB-9 connector, its normal cable limitation of 50 feet can be extended to several hundred feet with high-quality cable. RS-232 defines the purpose and signal timing for each of the 25 lines; however, many applications use less than a dozen. There is a standardized pin out for RS-232 on a DB25 connector, as shown below.Pin Number Signal Description1 PG Protective ground

2 TD Transmitted data3 RD Received data4 RTS Request to send5 CTS Clear to send6 DSR Data set ready7 SG Signal Ground8 CD Carrier detect9 + Voltage (testing)10 - Voltage (testing)11 Clear the CTS12 SCD Secondary CD13 SCS Secondary CTS14 STD Secondary TD15 TC Transmit Clock16 SRD Secondary RD17 RS Receiver clock18 Ready to Send19 SRS Secondary RTS20 DTR Data Terminal Ready21 SQD Signal Quality Detector22 RI Ring Indicator23 DRS Data rate select24 XTC External Clock25 -pin D-type connector Pin assignment

2.4. Signal Description:

TxD: - This pin carries data from the computer to the serial device

RXD: - This pin carries data from the serial device to the computer

DTR signals: - DTR is used by the computer to signal that it is ready to communicate with the serial device like modem. In other words, DTR indicates to the Dataset (i.e., the modem or DSU/CSU) that the DTE (computer) is ON.

DSR: - Similarly to DTR, Data set ready (DSR) is an indication from the Dataset that it is ON.

DCD: - Data Carrier Detect (DCD) indicates that carrier for the transmit data is ON.

RTS: - This pin is used to request clearance to send data to a modem

CTS: - This pin is used by the serial device to acknowledge the computer's RTS Signal. In most situations, RTS and CTS are constantly on throughout the communication session.

Clock signals (TC, RC, and XTC): - The clock signals are only used for synchronouscommunications. The modem or DSU extracts the clock from the data stream and provides a steady clock signal to the DTE. Note that the transmit and receive clock

signals do not have to be the same, or even at the same baud rate.CD: - CD stands for Carrier Detect. Carrier Detect is used by a modem to signal that it has a made a connection with another modem, or has detected a carrier tone. In other words, this is used by the modem to signal that a carrier signal has been received from a remote modem.

RI: - RI stands for Ring Indicator. A modem toggles(keystroke) the state of this line when an incoming call rings your phone. In other words, this is used by an auto answer modem to signal the receipt of a telephone ring signal.

The Carrier Detect (CD) and the Ring Indicator (RI) lines are only available in connections to a modem. Because most modems transmit status information to a PC when either a carrier signal is detected (i.e. when a connection is made to another modem) or when the line is ringing, these two lines are rarely used.

2.5. Limitations of RS-232:

RS-232 has some serious shortcomings as an electrical interface.Firstly, the interface presupposes a common ground between the DTE and DCE. This isa reasonable assumption where a short cable connects a DTE and DCE in the same room, but with longer lines and connections between devices that may be on different electrical busses, this may not be true. We have seen some spectacular electrical events causes by "uncommon grounds". Secondly, a signal on a single line is impossible to screen effectively for noise. By screening the entire cable one can reduce the influence of outside noise, but internally generated noise remains a problem. As the baud rate and line length increase, the effect of capacitance between the cables introduces serious crosstalk until a point is reached where the data itself is unreadable. Using low capacitance cable can reduce crosstalk. Also, as it is the higher frequencies that are the problem, control of slew rate in the signal (i.e., making the signal more rounded, rather than square) also decreases the crosstalk. The original specifications for RS-232 had no specification for maximum slew rate. Voltage levels with respect to ground represent the RS 232 signals. There is a wire for each signal, together with the ground signal (reference for voltage levels). This interface is useful for point-to-point communication at slow speeds. For example, port COM1 in a PC can be used for a mouse, port COM2 for a modem, etc. This is an example of point-to-point communication: one port, one device. Due to the way the signals are connected, a common ground is required. This implies limited cable length - about 30 to 60 meters maximum. (Main problems are interference and resistance of the cable.) Shortly, RS 232 was designed for communication of local devices, and supports one transmitter and one receiver.

Converters:

Converters in general can be used to change the electrical characteristic of onecommunications standard into another, to take advantage of the best properties of the alternate standard selected. For example, an Automatic RS232<=>RS485 converter, could be connected to a computer's RS232, full-duplex port, and transform it into an RS485 half-duplex, multi-drop network at distances up to 4000ft. Converters in most instances, pass data through the interface without changing the timing and/or protocol. While the conversion is "transparent" the software must be able to communicate with the

expanded network features. An "Automatic Converter" (RS232<=>RS485) will turn on the RS485 transmitter when data is detected on the RS232 port, and revert back into the receive mode after a character has been sent. This avoids timing problems (and software changes) that are difficult to deal with in typical systems. When fullduplex is converted into half-duplex only one device at a time can transmit data. Automatic Converters take care of the timing problems and allow fast communications without software intervention.

4.8 Regulated Power Supply:-

4.8.1 Features:- Output Current up to 1A Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V Thermal Overload Protection Short Circuit Protection Output Transistor Safe Operating Area Protection4.8.2 Description:-

The LM7805C series of three terminal positive regulators are available in the TO-220/D-PAK package and with several fixed output voltages, making them useful in a wide range of applications. Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. If adequate heat sinking is provided, they can deliver over 1A output current.

Figure-4.5-Circuit diagram of Regulated Power Supply

CHAPTER 5

AMR WORKING AND ITS SOFTWARE REQUIREMENTS

5.1 Working of Transmitter Unit:-

This project is useful for billing purpose in Electricity board. Instead of going to every house & taking the readings, in this project the system will continuously read the energy consumption and it will update the reading in EEPROM as well as the current reading will display on the meter in the house.

In this project the micro controller & the ZIGBEE unit is interfaced with the Energy meter of each house. Every house has a separate number, which is given by the corresponding authority. The ZIGBEE unit is fixed in the energy meter/water meter.

The amount of consumption is stored in an EEPROM and the authority can give request to get the reading from each house by giving the number assigned. On other end the modem will receive the data in the form of a command and informs the controller to do the readings. After the readings the controller will send data to the modem. Modem, in turn sends data to the authorities. In the office the receiver unit will receive the data. They will calculate the amount and they will send back the amount be paid and the last due date. After sending the Readings to the Main server the Microcontroller will resets the memory to get the fresh readings. Finally that bill is sent to the owner through post.

HARDWARE AND SOFTWARE REQUIREMENTS

HARDWARE REQUIREMENTS:

1. Atmega482. Relays3. Max232

SOFTWARE REQUIREMENTS:

1. Embedded C Embedded C is extensive and contains many advanced concepts. The range of

modules covers a full introduction to C, real-time and embedded systems concepts through to the design and implementation of real time embedded or standalone systems based on real-time operating systems and their device drivers. Real time Linux (RTLinux) is used as an example of such a system. The modules include an introduction to the development of Linux device drivers. Embedded C covers all of the important features of the C language as well as a good grounding in the principles and practices of real-time systems development including the POSIX threads (pthreads) specification.

The design of the modules is intended to provide an excellent working knowledge of the C language and its application to serious real time or embedded systems. Those wanting in-depth training specifically on RTLinux or Linux kernel internals should contact us to discuss their requirements; this set of modules is geared more towards

providing the groundwork for approaching those domains rather than as in-depth training on a specific approach.

Embedded C contains essential information for anyone developing embedded systems such as microcontrollers, real-time control systems, mobile device, PDAs and similar applications. This C course is based on many years experience of teaching C, extensive industrial programming experience and also participation in the ANSI X3J11 and BSI standards bodies that produced the standard for C. We focus on the needs of day-to-day users of the language with the emphasis being on practical use and delivery of reliable software.

Software’s used for Embedded C1. CodeVisionAVR VERSION 1.24.8

a. CodeVisionAVR is a C cross-compiler, Integrated Development Environment and Automatic Program Generator designed for the Atmel AVR family of microcontrollers.

b. The program is designed to run under the Windows 95, 98, Me, NT 4, 2000 and XP operating systems.

c. The C cross-compiler implements nearly all the elements of the ANSI C language, as allowed by the AVR architecture, with some features added to take advantage of specificity of the AVR architecture and the embedded system needs.

d. The compiled COFF object files can be C source level debugged, with variable watching, using the Atmel AVR Studio debugger.

The Integrated Development Environment (IDE) has built-in AVR Chip In-System Programmer software that enables to automatically transfer of the program to the microcontroller chip after successful compilation/assembly. The In-System Programmer software is designed to work in conjunction with the Atmel STK500/AVRISP/AVRProg (AVR910 application note), Kanda Systems STK200+/300, Dontronics DT006, Vogel Elektronik VTEC-ISP, Futurlec JRAVR and MicroTronics ATCPU/Mega2000 programmers/development boards.

For debugging embedded systems, which employ serial communication, the IDE has a built-in Terminal.

Besides the standard C libraries, the CodeVisionAVR C compiler has dedicated libraries for:

· Alphanumeric LCD modules· Philips I2C bus· National Semiconductor LM75 Temperature Sensor· Philips PCF8563, PCF8583, Maxim/Dallas Semiconductor DS1302 and DS1307

Real Time Clocks· Maxim/Dallas Semiconductor 1 Wire protocol· Maxim/Dallas Semiconductor DS1820, DS18S20, DS18B20 Temperature Sensors

· Maxim/Dallas Semiconductor DS1621 Thermometer/Thermostat· Maxim/Dallas Semiconductor DS2430 and DS2433 EEPROMs· SPI· Power management· Delays· Gray code conversionCodeVisionAVR also contains the CodeWizardAVR Automatic Program Generator that allows you to write, in a matter of minutes, all the code needed for implementing the following functions:· External memory access setup· Chip reset source identification· Input/output Port initialization· External Interrupts initialization· Timers/Counters initialization· Watchdog Timer initialization· UART (USART) initialization and interrupt driven buffered serial communication· Analog Comparator initialization· ADC initialization· SPI Interface initialization· Two Wire Interface initialization· CAN Interface initialization· I2C Bus, LM75 Temperature Sensor, DS1621 Thermometer/Thermostat and

PCF8563, PCF8583, DS1302, DS1307 Real Time Clocks initialization· 1 Wire Bus and DS1820, DS18S20 Temperature Sensors initialization· LCD module initialization.

2. AVR StudioAVR Studio is an Integrated Development Environment (IDE) for writing and

debugging AVR applications in Windows 9x/ME/NT/2000/XP/VISTA environments. AVR Studio provides a project management tool, source file editor, simulator, assembler and front-end for C/C++, programming, emulation and on-chip debugging.

AVR Studio supports the complete range of ATMEL AVR tools and each release will always contain the latest updates for both the tools and support of new AVR devices.AVR Studio 4 has a modular architecture which allows even more interaction with 3rd party software vendors.  GUI plug-ins and other modules can be written and hooked to the system.  AVR Simulator V2

The new simulator V2 offers a cycle correct and accurate simulator with complete peripheral support. The model are converted automatically from the real hardware source and therefore minimizes the risk of annoying conversion bugs. The goal is to offer early and accurate simulator support for all our new devices.

CHAPTER 6

FUTURE ADVANCEMENT AND CONCLUSION

6.1 Introduction:-

Originally AMR devices just collected meter readings electronically and matched them with accounts. As technology has advanced, additional data could then be captured, stored, and transmitted to the main computer, and often the metering devices could be controlled remotely. This can include events alarms such as tamper, leak detection, low battery, or reverse flow. Many AMR devices can also capture interval data, and log meter events. The logged data can be used to collect or control time of use or rate of use data that can be used for water or energy usage profiling, time of use billing, demand forecasting, demand response, rate of flow recording, leak detection, flow monitoring, water and energy conservation enforcement, remote shutoff, etc. Advanced Metering Infrastructure, or AMI is the new term coined to represent the networking technology of fixed network meter systems that go beyond AMR into remote utility management. The meters in an AMI system are often referred to as smart meters, since they often can use collected data based on programmed logic.

The AMR project has been more difficult than originally expected. Initially, the design was going to be much simpler than what it has grown into. The objectives that are set currently are quite ambitious. Features such as a new emitter/detector and a new PIC that required a different code were added during the progress of the project. While these features are a welcomed benefit for the user, they do present considerable design challenges. Also, the op-amp used as a buffer was not part of the primary concept. It was integrated into the system to match the impedance of the sensor with the impedance of the transistor. This is a unique and helpful feature for the system. The portions of the design that we were able to get to work was with the breadboard circuit output going to LEDs and with the breadboard circuit being able to communicate with a PC via RS232 cable.

6.2 EMETCON DLC:-

DLC stands for Distribution Line Carrier, referring to the fact that this power line carrier system can communicate over utility-owned distribution power lines. EMETCON is an acronym for Electronic Metering and Control. The system is two-way, data-on-demand, with the ability to read a remote meter in around six second’s start-to-finish.

6.3 TWACS System:-

TWACS® two-way power line communication technology which provides unique capabilities ideally suited for Automatic Meter Reading (AMR), load control, distribution automation and other value adding services. The TWACS technology delivers over 99% message reliability, which results in highly efficient and dependable AMR demand-side management and distribution automation systems. Unlike conventional power line carrier systems, which superimpose a high frequency on the

power lines, TWACS works by modulating the voltage waveform at the Zero-crossing point.

Conclusion:-

Thus we have studied RF based automatic meter reading used in different places. We got that this technology is very useful in present and future demand. AMR served well for commercial or industrial accounts. What was once a need for monthly data became a need for daily and even hourly readings of the meters. Consequently, the sales of drive-by and telephone AMR has declined in the US, while sales of fixed networks has increased. It is use in remote areas and measuring reading from water meter, energy meter, gas meter etc. It can be modified to control many meter reading by TDM system. It is simple to operate and user friendy.In this project we can control the data which is sending from transmitter to receiver by using microcontroller AT89C2051.

REFERENCES

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