PROJECT REPORT ON
GETTING ENERGY METER DATA THROUGH GSM MOBILE
CONTENTS 1. ABST BSTRAC RACT 2. INTR INTROD ODUC UCTI TION ON 3. DESCRI DESCRIPTI PTION ON OF THE THE PROJEC PROJECT T WORK WORK 4. DETAI DETAILED LED DESCR DESCRIPT IPTION ION OF OF GSM GSM 5. BLOCK BLOCK DIAGRA DIAGRAM M AND ITS DESCRI DESCRIPTI PTION ON 6. CIRCU CIRCUIT IT DESCR DESCRIP IPTI TION ON 7. ELECTRICAL ELECTRICAL METERING METERING INSTRUM INSTRUMENT ENT TECHNOL TECHNOLOGY OGY . DETAILS DETAILS ABOUT ABOUT ELECTR ELECTRONIC ONIC ENERGY ENERGY METERS METERS !. SMART SMART ENERGY ENERGY METE METERS RS " AN O#ER# O#ER#IEW IEW 1$. DETAILED DETAILED DESCRIPTION DESCRIPTION OF !C SERIES SERIES CONTROLLERS CONTROLLERS 11. DETAILED DETAILED DESCRIPTI DESCRIPTION ON ABOUT ABOUT RS232 12. HARDWA HARDWARE RE DETAILS DETAILS 13. SOFTWA SOFTWARE RE DETAILS DETAILS 14. CONCLUSION CONCLUSIONS S AND AND REFERENCE REFERENCES S
GETTING ENERGY METER DATA THROUGH GSM MOBILE ABSTRACT This is innovative project work introduced in the field of wireless communication communications. s. The main aim of the project project work is to collect the energy consumption data of individual house remotely. The advantage of using this system is that the data can be gathered accurately and automatically without going near to the energy meter.
Thes These e day days GSM GSM base based d proj projec ectt works orks are are gain gainin ing g popu popula lari rity ty because of unique facilities provided provided by the GSM network. The term GSM stands for Global System for mobile communications and the network is designed based on European standards. Many concepts from simple to compl comple e sy syst stems ems are are desi design gned ed base based d on this this tech techno nolog logy y for for vari variou ous s applica application tions! s! but here the system system designe designed d with with GSM module is quite quite unique and it is quite useful for state electricity departments.
To prove the concept practically! a real working module is designed with a very high resolution electronic energy meter. This energy meter displ display ays s the the numbe numberr of unit units s cons consume umed d by the the cons consum umer er thro through ugh the the seven segment displays. "hen the consumer wants to know the number units consumed! he#she just needs to send an SMS to the GSM that is interfaced to the energy meter. The energy units$ information in the form of consumable units will be displayed in the digital display and the same will be sent in the form of SMS to the consumer mobile from which the unit$s information is asked. %s the energy is consumed! the display shows in increment mode. These types of systems are very much helpful for the
GETTING ENERGY METER DATA THROUGH GSM MOBILE ABSTRACT This is innovative project work introduced in the field of wireless communication communications. s. The main aim of the project project work is to collect the energy consumption data of individual house remotely. The advantage of using this system is that the data can be gathered accurately and automatically without going near to the energy meter.
Thes These e day days GSM GSM base based d proj projec ectt works orks are are gain gainin ing g popu popula lari rity ty because of unique facilities provided provided by the GSM network. The term GSM stands for Global System for mobile communications and the network is designed based on European standards. Many concepts from simple to compl comple e sy syst stems ems are are desi design gned ed base based d on this this tech techno nolog logy y for for vari variou ous s applica application tions! s! but here the system system designe designed d with with GSM module is quite quite unique and it is quite useful for state electricity departments.
To prove the concept practically! a real working module is designed with a very high resolution electronic energy meter. This energy meter displ display ays s the the numbe numberr of unit units s cons consume umed d by the the cons consum umer er thro through ugh the the seven segment displays. "hen the consumer wants to know the number units consumed! he#she just needs to send an SMS to the GSM that is interfaced to the energy meter. The energy units$ information in the form of consumable units will be displayed in the digital display and the same will be sent in the form of SMS to the consumer mobile from which the unit$s information is asked. %s the energy is consumed! the display shows in increment mode. These types of systems are very much helpful for the
cons consume umers rs to have have vigil vigilan ance ce over over the the ener energy gy cons consum umed ed and and cont contro roll accordingly. The eisting Electronic energy meter can be modified for the purpose& our State Electricity department need not spend much amount for the the chan change ges. s. The The simp simple le modi modifi fica cati tion on to be done done is to tran transm smit it the the cons consum umed ed data data info inform rmat atio ion n by the the ener energy gy mete meterr thro throug ugh h the the GSM GSM technology.
'n this regard the communication link will be formed between the mobile and GSM module! after decoding the secret code passed by the opera operato tor# r#con consu sumer mer!! the the GSM GSM modul module e inte interf rfac aced ed with with micr microc ocon ontr troll oller er transmits the data to the mobile that is displayed in the display. % S'M card is required for the GSM module for the communication with the mobiles.
CHAPTER % 2 INTRODUCTION
The proposed project work is focused about smart energy meters& the subject of smart energy meters is gaining popularity because of wide range features offered by them. The concept implemented here is quite innovative! using GSM technology. There by the consumer will have continuous vigilance over his#her energy consumption wherever he#she may be throughout the "orld.
The present system of energy meter reading and collecting the pending bill amount from the energy consumers involves lot of nuisance& the energy suppliers as well as energy consumers both are facing many problems because of the out dated schemes implemented in energy management system by the state electricity department. The bill collector who is visiting each and every house for collecting the meter reading and raising the bill is holding a hand held equipment! the meter reader enters the data of up to date energy consumption details along with service number (meter number) through a small keypad of billing machine! since this job is done manually human errors will be there and quite often wrong bills are produced. This is quite inconvenient for the energy consumer! either consumer number or energy consumption data printed wrongly! than the consumer may have to roam around the electricity office to rectify the fault. Similarly the department is also responsible for the faults and it is answerable to the customer! in addition to this the electricity department should involve lot of their employees to visit millions of houses. To avoid all these problems this innovative project work is taken up by which lot of man power can be saved and above problems can be abolished.
The main intention of the project work is to design a smart energy meter that can be monitored through GSM modem. 'n this regard! the electronic energy meter is converted as smart meter and the output of energy meter (number of units) is transmitted through GSM modem to the concern mobile phone from which the request is placed. Since GSM modem acts as a transceiver it also receives command signals from another mobile phone. This kind of system is not eisted in our country! it is a first of its kind! the advantages and applications of this system are plenty! and are described in further chapters. *ow coming to the smart energy meters! the potential for smart meters to offer consumers better information about! and control over their energy use! leading to both financial savings and control over the energy consumption! has been discussed for a number of years. %ll state Electricity departments looking for advanced technology to wider their benefits! cost effective solutions are encouraged! therefore as an engineering student! to serve my nation and to emerge an effective solution to the present situation! this new concept is designed to bring to the notice of our state electricity department. The detailed description of the project work is provided in net chapter. The present system of meter reading is having its own draw backs& the electricity board is sending their bill collectors to the consumer house to record and raise the bills of consumed energy. Generally! this collection of data is carried out at a frequency of one month. The electrical charges payable by an individual is then calculated based on the consumption data and the electrical charges (which are usually fied as slabs) per unit of Electricity. The charge per unit of consumption varies from slab to slab. The charges go+up with increase in slabs. Thus this method of data
collection has its own advantages and disadvantages. 'f the data collection is not carried out at a fied interval! there is always a chance that the charges payable by the consumer is erroneous. ,y implementing this kind of system can eliminate bill collectors who is visiting each and every house for taking consumed energy data. *ow the consumer is responsible! such that he will have awareness of the number of units consumed and can use the electricity in a more efficient manner. ,efore getting in to the details! it is necessary to know the importance of Microcontroller! because it is playing major role in this project work. %s the technology advanced particularly in the field of Micro+ controllers! many tedious tasks are left over to these processors& the role of computers to solve such problems is minimi-ed! because it is bulky and costliest affair. Micro controllers are small in si-e and acts as mini computers. These funny devices are playing major function in all the activities! particularly in industries there is no such electronic instrument or machine that functions with out Microcontroller. 'n domestic side also! many house hold electronic gadgets like T and its remote! telephone! microwave oven! /0 player! home security systems! washing machines! etc! can not function without micro controllers! in our day to day living have become a part of information and we find micro+controllers at each and every application. Therefore the trend is directing towards Microcontroller based project works. The 12/34 is having 15b memory power and is aimed to send the information regarding available energy in the form units. 6ere for this chip the program is prepared in Embedded 7/$ which requires more memory when compared with machine language. The output of the chip is fed to
GSM modem through 8S494& the function of 8S 494 is to convert the /M:S logic in to TT; logic which is accepted by the GSM modem. The combination of microcontrollers and GSM modem working together can create tremendous changes in the technology! with the advancement of technology particularly in the field of energy management systems! all the activities right from the basic needs to the compleity can be achieved. ,ased on this technology centrali-ed energy monitoring station can be designed from where all the energy meters of a particular area can be monitored and controlled accordingly. 'f required meter tampering information along with consumer number also can be transmitted through GSM modems and the same can be displayed! if required meter out put can be disconnected remotely through mobile phone. The detailed description of GSM technology is provided in the further chapters.
CHAPTER % 3 DESCRIPTION OF THE PROJECT WORK
Since the concept is practical oriented! it is decided to develop a real working system for the live demonstration. Therefore the process begins with electronic energy meter! here we required very high accuracy energy meter! such that it should able to measure and display the consumed energy perfectly. The energy output of the meter is designed to drive different loads like lamps and heaters! for this purpose! in the demonstration module 9 pins socket is provided. The energy meter is designed to generate pulses according to the load applied to it. The duration between the two pulses vary according to the load! if the load is constant! pulses are produced at stable intervals! and otherwise pulse rate is differed by varying the load current. Since the meter is said to be very accurate! it generates <=>> pulses per unit! means one measuring unit is divided in to <=>> parts. ?inally the energy meter generates only <>> pulses per unit! initially to enhance the accuracy one unit is divided in to <=>> parts so that it can measure very minute loads also accurately. ;ater for the calibration purpose <=>> pulses are converted into <>> pulses! means the meter itself internally! with the help of an encoder <= pulses are converted into one pulse. Generally any energy meter in the world is popularly known as watt hour meter! and it is defined as <>>>" hour! means when <>>> watts load is applied to the meter for one hour! then the meter should display one unit! the unit for consumption of electricity! this is universal standard. %s per the above description! when <>>> watts load is connected! the energy meter should generate <=>> pulses in one hour! when the load is reduced by 3>@! and then
same numbers of pulses are produced in two hours. Therefore the time taken by the energy meter to measure one unit A <>>> # applied load. The energy meter used here offers many latest features like tamper proof! reverse polarity indicator! accurate measurement! high end result! continuous monitoring of phase and neutral currents! etc. The detailed description of this meter is provided in following chapters. The analog pulse produced by the energy meter is converted in to a pure digital pulse. The circuit named as digital pulse generator is designed with ;08! lamp and 333 timer '/. The '/ is configured as monostable mode of operation! triggers at <#9 B 4#9 voltage levels of operating voltage. 'nitially the process begins from pulse output from energy meter! whenever the meter generates a pulse! the lamp glows momentarily and the light intensity will be fallen on ;08 (;ight 0ependant 8esistor)! by which voltage level falls down by less then <#9 cc! which in turn triggers the '/ and generates a perfect square pulse. The detailed description of this digital pulse generator is provided in following chapters. The output of the digital pulse generator circuit is fed to microcontroller unit! depending up on the energy consumption! this circuit generate square pulses and these pulses are stored in microcontroller. This controller can be called as primary unit! and main functions of this unit is as followed. •
To acquire data from energy meter (consumed energy information in the form of pulses).
•
To display the available or consumable energy information in the form of units through a seven segment display connected at the output port of microcontroller.
•
,ased on the pulses produced by energy meter! the micro controller increment the units and the same is displayed in the seven segment display unit (digital display).
•
?inally the GSM unit waits for command signals from the mobile to get the consumed units! based on this command signals received from the mobile phone and decoded by the controller unit! the controller transmits the consumed units data to the same mobile through the GSM modem. The above mentioned are the important functions of the microcontroller
unit and the program is prepared to perform these functions accurately. The display section is designed with four digits! two digits are used after the decimal point! so that one unit is calibrated in to <>> equalent parts and starts counting in increment mode. The microcontroller unit designed with 12/3<#34 chip acquires the data from energy meter and forwarded to the GSM modem through M%C 494. The main function of the GSM modem is to send the available consumed units information of the energy meter to the concern mobile phone! here if required the data can be transmitted to the multiple mobile phones. Since it is a prototype module! here only one mobile number is stored in the system! such that the system sends the information to that particular mobile when requested. The other main function of the GSM modem is to receive the request information from the mobile phone. Generally this mobile phone is under the control of electricity department or the consumer! only authori-ed person should utili-e this phone. To get the energy meter data through this mobile! initially some pass word information has to be generated! if the pass word is correct then only the microcontroller unit accepts the command signals. The secret code is passed along with the command signals& the command signals are
differed based on the energy meter by the energy consumer. The detailed description of the GSM technology is provided in net chapter.
CHAPTER % 4 DETAILED DESCRIPTION OF GSM I&'()*+,'-)& GSM (Global System for Mobile /ommunications ) is a digital cellular communications system. 't was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide. GSM is designed to provide a comprehensive range of services and features to the users not available on analogue cellular networks and in many cases very much in advance of the old public switched telephone network (DST*). 'n addition to digital transmission! GSM incorporates many advanced services and features like worldwide roaming in other GSM networks.
H-/')(0 ) GSM &* ,+( )- R*-) The idea of cell+based mobile radio systems appeared at ,ell ;aboratories (in S%) in the early <2F>s. 6owever! mobile cellular systems were not introduced for commercial use until the <21>s. 0uring the early <21>s! analog cellular telephone systems eperienced a very rapid growth in Europe! particularly in Scandinavia and the nited 5ingdom! but also in ?rance and Germany. Each country developed its own system! which was incompatible with everyone elses in equipment and operation. ,ut in the beginnings of cellular systems! each country developed its own system! which was an undesirable situation for the following reasonsH •
The equipment was limited to operate only within the boundaries of each
country! which in a unified Europe were increasingly unimportant.
•
The market for mobile equipment was limited! so economies of scale!
and the subsequent savings! could not be reali-ed. 'n order to overcome these problems! the /onference of European Dosts and Telecommunications (/EDT) formed! in <214! the Group Special Mobile (GSM) in order to develop a pan+European mobile cellular radio system (the GSM acronym became later the acronym for Global System for Mobile communications ). The standardi-ed system had to meet certain criteria$sH •
Good subjective speech quality
•
Support for international roaming
•
%bility to support handheld terminals
•
Support for range of new services and facilities
•
Spectral efficiency
•
;ow mobile and base stations costs
•
/ompatibility with other systems such as 'ntegrated Services 0igital
*etwork ('S0*) 'n <212 the responsibility for the GSM specifications passed from the /EDT to the European Telecommunications Standards 'nstitute (ETS'). The commercial use of GSM started around mid+<22<. ,y the beginning of <22I! there were <.9 million subscribers worldwide. ,y the beginning of <223! there were => countries with operational or planned GSM networks in Europe! the Middle East! the ?ar East! %ustralia! %frica! and South %merica! with a total of over 3.I million subscribers. %s of the end of <22F! GSM service was available in more than <>> countries and has become the de facto standard in Europe
and %sia. Dresently! GSM networks are operational or planned in over 1> countries around the world.
T,&-, *'-/ GSM is a cellular network! which means that mobile phones connect to it by searching for cells in the immediate vicinity. GSM networks operate in a number of different frequency ranges (separated into GSM frequency ranges for 4G and MTS frequency bands for 9G). Most 4G GSM networks operate in the 2>> M6- or <1>> M6- bands. Some countries in the %mericas (including /anada and the nited States) use the 13> M6- and <2>> M6- bands because the 2>> and <1>> M6- frequency bands were already allocated. Most 9G GSM networks in Europe operate in the 4<>> M6- frequency band The rarer I>> and I3> M6- frequency bands are assigned in some countries where these frequencies were previously used for first+generation systems. GSM+2>> uses 12>J2<3 M6- to send information from the mobile station to the base station (uplink) and 293J2=> M6- for the other direction (downlink)! providing <4I 8? channels (channel numbers < to <4I) spaced at 4>> k6-. 0uple spacing of I3 M6- is used. 'n some countries the GSM+2>> band has been etended to cover a larger frequency range. This etended GSM! E+ GSM! uses 11>J2<3 M6- (uplink) and 243J2=> M6- (downlink)! adding 3> channels (channel numbers 2F3 to <>49 and >) to the original GSM+2>> band. Time division multipleing is used to allow eight full+rate or siteen half+rate speech channels per radio frequency channel. There are eight radio timeslots (giving eight burst periods) grouped into what is called a T0M% frame. 6alf rate channels use alternate frames in the same timeslot. The channel data rate for all 1 channels is 4F>.199 kbit#s! and the frame duration is I.=<3 ms.
The transmission power in the handset is limited to a maimum of 4 watts in GSM13>#2>> and < watt in GSM<1>>#<2>>. GSM has used a variety of voice codes to squee-e 9.< k6- audio into between 3.= and <9 kbit#s. :riginally! two codes! named after the types of data channel they were allocated! were used! called 6alf 8ate (3.= kbit#s) and ?ull 8ate (<9 kbit#s). These used a system based upon linear predictive coding (;D/). 'n addition to being efficient with bitrates! these codes also made it easier to identify more important parts of the audio! allowing the air interface layer to prioriti-e and better protect these parts of the signal. GSM was further enhanced in <22F K<4L with the Enhanced ?ull 8ate (E?8) codec! a <4.4 kbit#s codec that uses a full rate channel. ?inally! with the development of MTS! E?8 was refactored into a variable+rate codec called %M8+*arrowband! which is high quality and robust against interference when used on full rate channels! and less robust but still relatively high quality when used in good radio conditions on half+rate channels. There are five different cell si-es in a GSM network macro! micro! pico! femto and umbrella cells. The coverage area of each cell varies according to the implementation environment. Macro cells can be regarded as cells where the base station antenna is installed on a mast or a building above average roof top level. Micro cells are cells whose antenna height is under average roof top level& they are typically used in urban areas. Dicocells are small cells whose coverage diameter is a few do-en meters& they are mainly used indoors. ?emtocells are cells designed for use in residential or small business environments and connect to the service provider$s network via a broadband internet connection. mbrella cells are used to cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.
/ell hori-ontal radius varies depending on antenna height! antenna gain and propagation conditions from a couple of hundred meters to several tens of kilometres. The longest distance the GSM specification supports in practical use is 93 kilometres (44 mi). There are also several implementations of the concept of an etended cell! where the cell radius could be double or even more! depending on the antenna system! the type of terrain and the timing advance. 'ndoor coverage is also supported by GSM and may be achieved by using an indoor picocell base station! or an indoor repeater with distributed indoor antennas fed through power splitters! to deliver the radio signals from an antenna outdoors to the separate indoor distributed antenna system. These are typically deployed when a lot of call capacity is needed indoors! for eample in shopping centers or airports. 6owever! this is not a prerequisite! since indoor coverage is also provided by in+building penetration of the radio signals from nearby cells. The modulation used in GSM is Gaussian minimum+shift keying (GMS5)! a kind of continuous+phase frequency shift keying. 'n GMS5! the signal to be modulated onto the carrier is first smoothed with a Gaussian low+pass filter prior to being fed to a frequency modulator ! which greatly reduces the interference to neighboring channels (adjacent channel interference).
%rchitecture of the GSM *etworkH The GSM mobile telephony service is based on a series of contiguous radio cells which provide complete coverage of the service area and allow the subscriber operation anywhere within it. Drior to this cellular concept! radiophones were limited to just the one transmitter covering the whole service area. /ellular telephony differs from the radiophone service because instead of
one large transmitter! many small ones are used to cover the same area. The basic problem is to handle the situation where a person using the phone in one cell moves out of range of that cell. 'n the radiophone service there was no solution and the call was lost! which is why the service area was so large. 'n cellular telephony! handing the call over to the net cell solves the problem. This process is totally automatic and requires no special intervention by the user! but it is a comple technical function requiring significant processing power to achieve a quick reaction. The functional architecture of a GSM system can be broadly divided into the Mobile Station! the ,ase Station Subsystem! and the *etwork Subsystem. Each subsystem is comprised of functional entities that communicate through the various interfaces using specified protocols. The subscriber carries the mobile station& the base station subsystem controls the radio link with the Mobile Station. The network subsystem! which is the main part of which is the Mobile services Switching /enter! performs the switching of calls between the mobile and other fied or mobile network users! as well as management of mobile services! such as authentication. •
M)- S''-)& The Mobile Station (MS) represents the only equipment the GSM user
ever sees from the whole system. 't actually consists of two distinct entities. The actual hardware is the Mobile Equipment (ME)! which is anonymous and consists of the physical equipment! such as the radio transceiver! display and digital signal processors. The subscriber information is stored in the Subscriber 'dentity Module (S'M)! implemented as a Smart /ard. The mobile equipment is uniquely identified by the 'nternational Mobile Equipment 'dentity ('ME'). The S'M card contains the 'nternational Mobile Subscriber 'dentity ('MS')! identifying
the subscriber! a secret key for authentication! and other user information. The 'ME' and the 'MS' are independent! thereby providing personal mobility. Thus the S'M provides personal mobility! so that the user can have access to all subscribed services irrespective of both the location of the terminal and the use of a specific terminal. ,y inserting the S'M card into another GSM cellular phone! the user is able to receive calls at that phone! make calls from that phone! or receive other subscribed services. The S'M card may be protected against unauthori-ed use by a password or personal identity number .
The ME provides generic radio and processing functions to access the
network through the radio interface as well as an interface to the user (microphone loudspeaker! display and keyboard) together with an interface to some other terminal equipment (fa machine! D/).
The S'M contain all the subscriber+related information stored on the
users side of the radio interface.
The MS is operational only when a valid S'M is placed in a ME.
B/ S''-)& S+/0/' The ,ase Station Subsystem is composed of two parts! the ,ase Transceiver Station (,TS) and the ,ase Station /ontroller (,S/). The ,TS houses the radio transceivers that define a cell and transmits and receives signals on the cells allocated frequencies with the mobile station. % ,S/ operates with a group of ,TSs and manages the radio resources for one or more of them. The ,S/ is the connection between the MS and the *etwork Subsystem. 't manages the radio channel (setup! tear down! frequency hopping! etc.) as well as handovers and the transmission power levels and
frequency translations of the voice channel used over the radio link to the standard channel used by the Dublic Switched Telephone *etwork or 'S0*.
N'8)(9 S+/0/' The central component of the *etwork Subsystem is the Mobile services Switching /enter (MS/). 't acts like a normal switching node of the normal telephones of the land lines and in addition provides all the functionality needed to handle a mobile subscriber! including registration! authentication! location updating and inter+MS/ handovers. These services are provided in conjunction with several functional entities! which together form the *etwork Subsystem. The MS/ provides the connection to the public fied network (DST* or 'S0*) and is the interface between the GSM and the DST* networks for both telephony and data. Thus the MS/ is primarily responsible forH •
Traffic management
•
/all set+up
•
/all 8outing to a roaming subscriber
•
Termination
•
/harging and accounting information
A::-,'-)&/ ) GSM M)* GSM is world$s most famous Mobile platform. Mobile phones with S'M cards use GSM technology to help you communicate with your family! friends and business associates. GSM systems have following advantages over basic landline telephony systemsH <. Mobility 4. Easy availability 9. 6igh uptime GSM technology is being mostly used for talking to family! friends and business colleagues. "e use communication feature of Telephone landlines for 'nternet! e+mail! data connectivity! remote monitoring! computer+to+computer communication! and security systems. 'n the same way we can use GSM technology and benefit from its advantages.
% GSM modem is a wireless modem that works with a GSM wireless network. % wireless modem behaves like a dial+up modem. The main difference between them is that a dial+up modem sends and receives data through a fied telephone line while a wireless modem sends and receives data through radio waves. % GSM modem can be an eternal device or a D/ /ard # D/M/'% /ard. Typically! an eternal GSM modem is connected to a computer through a serial cable or a S, cable. % GSM modem in the form of a D/ /ard # D/M/'% /ard is designed for use with a laptop computer. 't should be inserted into one of the D/ /ard # D/M/'% /ard slots of a laptop computer. ;ike a GSM mobile phone! a GSM modem requires a S'M card from a wireless carrier in order to operate. %s mentioned in earlier sections of this SMS tutorial! computers use %T commands to control modems. ,oth GSM modems and dial+up modems support a common set of standard %T commands. "e can use a GSM modem just like a dial+up modem. 'n addition to the standard %T commands! GSM modems support an etended set of %T commands. These etended %T commands are defined in the GSM standards. "ith the etended %T commands! we can do things likeH •
8eading! writing and deleting SMS messages.
•
Sending SMS messages.
•
Monitoring the signal strength.
•
Monitoring the charging status and charge level of the battery.
•
8eading! writing and searching phone book entries.
The number of SMS messages that can be processed by a GSM modem per minute is very low ++ only about si to ten SMS messages per minute. GSM FEATURES :ne of the remarkable features is the Subscriber 'dentity Module (S'M). S'M being memory device stores information such as the subscriber$s identification number! list of countries and networks where the subscriber is entitled to service! privacy keys etc. % S'M consists of four+digit personal identification number to activate service from any GSM phone. S'M$s is available as smart cards that may be inserted into GSM phone or plug+in modules! which are portable and removable. The second feature is on+the+air privacy that the GSM system provides. The privacy is maintained by encryption of the digital data according to a specific secret cryptographic key that is known only to the cellular carrier and the key is changed with time.
GSM INTERFACES The different interfaces used in GSM listed as followsH 1. GSM (*-) -( -&'(, This is the interface between MS and ,TSs. 2. A-/ -&'(, The one connecting the ,TS to a ,S/ is known as %bis interface. This is responsible for carrying traffic and maintenance data. 3. A -&'(, This is the interface between a ,S/ and a MS/.
GSM CHANNELS There are two types of GSM logical channelsH
� Traffic /hannelsH These channels carry digitally encoded user speech or data.
� /ontrol /hannelsH Signaling and synchroni-ing commands between ,S and MS are transmitted through these channels.
GSM SER#ICES The GSM services in different spheres are listed as followsH <. 0ata services include computer to computer communication and packet switched traffic. 4. Telephone services which include fa services. ideote and telete are also supported by GSM. 9. Mobile originated traffic and standard mobile telephony are included in teleservices supported by GSM. I. 0ifferent other services includeH
� call diversion � caller line identification � call wait � SMS services
CHAPTER % 5 BLOCK DIAGRAM AND ITS DESCRIPTION The block diagram and its description of the project work is eplained in brief! for better understanding the total block diagram is divided in to various blocks and each block eplanation is provided in this chapter. The complete block diagram of the project work is provided at the end of this chapter. The following are the blocks.
<) Electronic Energy Meter 4) 0igital Dulse Generator 9) Microcontroller I) ;atch
3) 0igital 0isplay =) 8S 494 F) GSM Modem
ELECTRONIC ENERGY METER 'n this block! %0FF3< Energy metering '/ is used. This is a custom built '/ produced by the analog devices! S%. 0etails # 0atasheets of the '/ is collected from 'nternet! world wide website& httpH##""".analog.com (/) %nalog devices! 'nc! 4>>>. This block takes the proportional voltage! proportional current in a fied duration so that the energy consumed! i.e.! Energy A N ' N t.
These two
signals are fed to the metering '/ %0FF3.<@. 'n this dedicated '/! it monitors continuously both the phase and neutral (return) currents. % fault is indicated when these currents differ by more than <4.3@. Then the billing is continued taking the larger of the two currents.
The output of the '/ is taken across Dins 49 and 4I (?< and ?4) is the frequency signal proportional the energy /onsumption. This pulsating frequency is calibrated! i.e.! <=>> pulses per unit of the electric energy consumption.
% facility is provided in this '/ to indicate fault conditions! two logic outputs are provided as 7?%;T$ and 78ED$ (8everse Dolarity)! which can be used as fault condition and reverse polarity indications. These two signals are made used in this project work and two ;E0$S are connected to indicate the above fault conditions.
DIGITAL PULSE GENERATOR The main function of the pulse generator block is to convert the analog signal from the energy meter into digital pulse. The pulse produced by the energy meter is nothing but a peak pulse and this peak pulse is converted into square pulse. 'n this block! a lamp of <4 is arranged parallel to the ;08 (;ight dependent resistor) which glows brightly! whenever there is a pulse from the Energy Meter. This light energy is converted in to discrete electrical pulses with the help of ;08 and '/ 333 timer configured in ,i+stable Multi+vibrator mode. These pulses are treated as a clock pulses for sub+sequent stage for counting #0isplay purpose and monitoring the energy consumption with the help of Microcontroller. To energi-e the lamp source through switching transistor driver stages! the frequency output of the energy metering '/! which is a differential signal is converted in to proportional 0/ signal with the help of a bridge rectifier. This pulsating 0/ signal is fed to the cascaded driving stage transistors and in turn to lamp. The // for the lamp is designed from %/ input through step+down transformer and full wave centre+tapped rectifier. This lamp source is fed near the ;08. The resistance of ;08 varies according to the light source falling on it. This makes the voltage drop across it to vary. This change of voltage is detected with the help of built in comparators provided in '/ 333 timer. This '/ is configured as bistable stage (Schmitt
trigger) so that the output will be either in high state or low state as per light # *o light on ;08 or thresh+hold levels crossing of upper level comparator (4#9 // comparator) and low level comparator (<#9 // comparator). The output of this timer is treated as a clock pulses to the microcontroller and the controller drives the display so that the pulses produced by the energy meter can be displayed.
MICRO"CONTROLLER The complete process of the system is derived with the microcontroller unit! and this unit is playing a major role in this project work! there by the following description mainly focuses about Micro controller and its architecture! because it is treated as heart of the project work. Today! there is no such instrument that can function without Micro controller. Micro controllers have become an integral part of all instruments. Many tedious from simple to dedicated tasks are left over to the controller for solutions. The Micro controller used in this project work is %TME; 12/3< or 12/34! these two '/$s are belongs to 1>3< family. The internal architecture of both the chips is similar ecept the memory power! 12/3< is having I 5b memory power and 12/34 is having 1 5b memory power. 'n<213<. This controller is having <41 bytes of 8%M! I5 bytes of 8:M! two timers! one serial port! and four ports. This '/ is called as 1+ bit Drocessor! means that the /D can work on only 1+ bits of data at a time. The 1>3< is having four ports and each port contain 1 input # output lines. This '/ became very popular after 'ntel allowed other manufacturers to make and market any flavors of the 1>3< they please with the condition that they remain code compatible with the 1>3<. This has led to many versions of the 1>3< with different speeds and amounts of on+chip 8:M marketed by many manufacturers.
%TME; is one of the major manufacturers of these devices and are compatible with the original 1>3< as far as the instructions are concerned. The original 1>3< of 'ntel are having a maimum of =I5 bytes of on+chip 8:M! where as the %TME; 12/3< is having only I5 bytes on the chip. %TME; 12/34 is designed with 15 memory! like wise up to 4>5 bites on the chips are available from %TME; /ompany. The %tmel /orporation has a wide selection of 1>3< chips and out of! the %T 12/3< is a popular and inepensive chip used for many applications. 't has I5 bytes of flash 8:M& 7/$ stands for 7/M:S$! which has low power consumption. The %TME; %T12/3< is a low power! higher performance /M:S 1+bit microcomputer with I5 bytes of flash programmable and erasable read only memory (DE8:M).
'ts high+density non+volatile memory compatible with
standard M/S+3< instruction set makes it a powerful controller that provides highly fleible and cost effective solution to control applications. Micro+controller works according to the program written in it. Most microcontrollers today are based on the 6arvard architecture! which clearly defined the four basic components required for an embedded system. These include a /D core! memory for the program (8:M or ?lash memory)! memory for data (8%M)! one or more timers (customi-able ones and watchdog timers)! as well
as '#:
lines to communicate with
eternal peripherals and
complementary resources all this in a single integrated circuit. % microcontroller differs from a general+purpose /D chip in that the former generally is quite easy to make into a working computer! with a minimum of eternal support chips. The idea is that the microcontroller will be placed in the device to control! hooked up to power and any information it needs! and thats that.
% traditional microprocessor wont allow you to do this. 't requires all of these tasks to be handled by other chips. ?or eample! some number of 8%M memory chips must be added. The amount of memory provided is more fleible in the traditional approach! but at least a few eternal memory chips must be provided! and additionally requires that many connections must be made to pass the data back and forth to them.
?or instance! a typical microcontroller will have a built in clock generator and a small amount of 8%M and 8:M (or ED8:M or EED8:M)! meaning that to make it work! all that is needed is some control software and a timing crystal (though some even have internal 8/ clocks). Microcontrollers will also usually have a variety of input#output devices! such as analog+to+digital converters! timers! %8Ts or speciali-ed serial communications interfaces like 'O/! Serial Deripheral 'nterface and /ontroller %rea *etwork. :ften these integrated devices can be controlled by speciali-ed processor instructions. :riginally! microcontrollers were only programmed in assembly language! or later in / code. 8ecent microcontrollers integrated with on+chip debug circuit accessed by 'n+circuit emulator via PT%G (Point Tet %ction Group) enables a programmer to debug the software of an embedded system with a debugger . More recently! however! some microcontrollers have begun to include a built+in high+level programming language interpreter for greater ease of use. ,%S'/ is a common choice! and is used in the popular ,%S'/ Stamp M/s (Master /ontrol nit). Microcontrollers trade away speed and fleibility to gain ease of equipment design and low cost. Theres only so much room on the chip to include functionality! so for every '#: device or memory increase the microcontroller includes! some other circuitry has to be removed. ?inally! it must be mentioned that some microcontroller architectures are available from many
different vendors in so many varieties that they could rightly belong to a category of their own. /hief among these are the 1>3< family.
LATCH %s per the program prepared for microcontroller! the consumed energy information is to be displayed through F+segment displays! to hold this data latches are used. The display system is interfaced with micro controller through FI;S3F9& one complete port of micro controller is used to drive the display system. 6ere four F+ segment displays are used for displaying the consumed energy. The signal %;E from the processor goes high before a new address is placed on the bus and goes low before it is removed. The action of %;E going low is used to latch the address into a FI;S3F9 1+bit transparent latch. The FI;S3F9 then provides its latched address output to the memories while the /D ,us /arries the data.
The technology selected for this latch is critical to the memory selection. The FI;S3F9 has a worst+case propagation delay from input to output of 2> ns while the FI?9F9s is 1 ns. This results in significantly different memory address access timing requirements depending on the family used. Since it is a prototype module! more ever the function is only to display the consumed energy! too fast acting latches are not required! therefore FI;S3F9 latches selected because of its cost effective. "hile ED8:M devices with access times of 4= ns or less may be available! they are likely to be epensive. % simple and more cost effective approach to solve this timing constraint is to use a faster latch technology! a FI?9F9 for instance.
DIGITAL DISPLAY Seven segment displays commonly contain ;E0 segments arranged as an eight (1)! each display contains seven ;E0$s and these are denoted as a! b! c! d! e! f! and g. /ommon anode means all the seven ;E0$s anodes are shorted
together internally! and one common terminal is brought out from the device. This common terminal is supposed to be connected to the Qcc of the supply through a current limiting resistor! where as all the seven cathodes are controlled independently through control circuit! there by all the numeric numbers from > to 2 will be displayed. This is the general phenomenon of controlling the display independently. %ccording to the requirement! wide varieties of display drive circuits are in use. 6ere all the four displays are connected in parallel and these are driven by the controller through switching transistors and latches. The detailed description of the parallel display driver is provided in circuit analysis chapter. The output port of the first micro+controller unit is used to drive the digital display! for this purpose four F+segment common anode displays are used for displaying the consumed energy information in the form of units! as the energy is consumed the display shows in decrement mode. 'n addition to the digital display! the output of the Microcontroller is also used to drive the relay so that according to the instructions generated by the EED8:M! the Microcontroller energi-es this electro magnetic relay and this relay contact is used to break the supply to the load automatically. RS 232 CON#ERTER ;MA< 232N= The 8S+494 generally used in computers for serial communication is quite popular device. 6ere this chip is used to communicate with the GSM modem! this device is connected between the microcontroller and GSM modem! the main function of this device is to convert the /M:S logic in to TT; logic! because the GSM modem accepts only TT; logic. GSM )* ;!$$>1$$ MH?=
Semen$s GSM#GD8S Smart Modem is a multi+functional! ready to use! rugged unit that can be embedded or plugged into any application. The Smart Modem can be controlled and customi-ed to various levels by using the standard %T commands. The modem is fully type+approved! it can speed up the operational time with full range of oice! 0ata! ?a and Short Messages (Doint to Doint and /ell ,roadcast)! the modem also supports for data transfer. GSM is one of the latest mobile technologies using smart M:0EM! which can easily interfaced to embedded Microcontrollers. *ow everything is going to be automated using this technology! using this technology we can monitor the particular machine parameters. sing GSM and GDS now we can identify the people! vehicles etc in any where of the world
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CHAPTER " 6 CIRCUIT DESCRIPTION The detailed circuit description of the project work is eplained in section wise. ?or better understanding the total circuit diagram is divided into various sections and each section eplanation along with circuit diagram is provided in this chapter.
ELECTRONIC ENERGY METER The energy meter used in this project work is ready made one! made by ;arsen B Toubro! ;BT 6ouse! ,allard Estate! and Mumbai. The energy meter procured from ;BT 6ouse! is a domestic meter. This meter is designed to deliver 4>amps current maimum! because the /T (/urrent Transformer) used in this meter! allows 4>amps maimum through its primary. 'n this meter two /T$s are used! one is connected in series with the phase and the other one is connected in series with the neutral. The output of the /T$s are monitored by the energy metering '/ and energi-es the fault indicator connected at the output of the chip! if the difference is more than <4.3@ at the output of both the /T$s. The detailed description is as followsH The energy consumption measurement is carried out with the help of energy metering '/ %0 FF3.<@. 't also incorporates the fault detection scheme that warns the fault conditions and allows the device to continue accurate billing during a fault event. This does by continuously
monitoring both the phase and neutral (return) currents. % fault is indicated when these currents differ by more than <4.3@. The billing is continued using the larger of the two currents.
The output on the ?< and ?4 is the frequency signal proportional to the energy consumption.
This is calibrated as <=>> pulses per unit of electric
energy consumption. "hen the meter is loaded at the rate of <>>>" for > pulses which are equalent to > pulses are converted into <>> pulses for the easy calibration. To indicate the fault conditions! two logic outputs are also provided as 7?%;T$ and 78ED$ which can be used to indicate a potential mis+wiring or fault condition. 'n this meter four ;E0$S are provided for indication purpose. :ne indicator represents that the main power is present! when the fault occurs the second indicator glows automatically! the third indicator glows when the input wires are reversed and finally the last indicator is nothing but a pulse indicator which glows brightly whenever there is a pulse from the energy meter. The built+in two %0/S digiti-e the voltage signals from the current and voltage transducers. ?or current signal! the current transformers (/TS) are used! two /TS are used for this purpose one is connected in series with the phase and the other one is connected in series with the neutral. ?or voltage signal! the phase voltage is attenuated with the help of potential divider. ?or this! four numbers of <>>5 resistors are connected in series. The built in %0/S are <= bit and are operated with an eternal clock fed by the crystal. The power output is derived from the instantaneous power signal! which is the multiplication of the current and voltage signals. To obtain the eact real power
component! the instantaneous power signal is low pass filtered. %ccumulating the real power information generates the frequency output of the device. This is a low frequency signal! which means a long accumulation time between output pulses. The output frequency is therefore proportional to the average real power. This average real power information can in turn be accumulated to generate real energy consumption. The frequency output in this '/ is generated as shown in the data sheet collected from 'nternet i.e. /hapter + <4.
The voltage signal and current signal are fed to this energy metering '/ along with the sampling clock are shown belowH
'n the above circuit diagram! the ?< and ?4 outputs provide two alternating low going pulses. The device calculates the product of two voltage signals on ' 7%$ and ' 7,$ and then low pass filters this product to etract real power information. This real power information is then converted in to
frequency. The frequency information on ?< and ?4 in the form of active low pulses. The result is an output frequency! which is proportional to the average real power. The average of the real power signal is implicit to the digital to frequency conversion. The output frequency or pulse rate is related to the input voltage as 3.FI '% ', Gain ?
8E?4
This frequency output is fed to pulse shaping circuit for generating the clock pulses for counting and subsequently for displaying the energy consumption in form of seven+segment digital display. DIGITAL PULSE GENERATOR The output of the energy metering circuit! which is calibrated as <=>> pulses per unit of electric energy consumption (thus the display of <=>> pulses is equivalent to one unit of energy consumption) is fed to this pulse shaping circuit. The main function of this circuit is to convert the analog pulse in to digital pulse. The pulse shaping circuit consists of
a) /onversion of pulses into light
pulses b) ;ight to light dependent resistor conversion and converting into clock pulses. The details are as followsH
The output of energy Metering /ircuit (?< and ?4) are fed to full wave bridge rectifier to convert into proportional dc voltage according to the frequency input. This dc voltage is fed to the lamp source through the transistor driver stage. The glowing of lamp depends upon the input signal fed by the Metering circuit. To feed dc voltage to the lamp source! a separate step down transformer is designed! whose output voltage is an ac voltage! rectified into dc with the help of center+tapped full wave rectifier. This dc voltage is a source of
lamp supply and the :* and :?? of the lamp depends upon the ac signal produced by the %0FF3< based metering circuit.
The circuit design of
energi-ation of lamp source is shown belowH
To drive the lamp source! cascaded transistors are used to increase the power handling capacity.
The lamp source energi-ation # de+energi-ation is
converted into clock pulses with the help of '/ 333 timer.
This timer is
configured as Mono+stable Schmitt+trigger. 'n this '/ pin *o.4 (Trigger Din) and Din *o.= (Thresh hold Din) are adjusted for <#9 // and 4#9 //. Thus! the state transitions takes place whenever the voltage at Dins 4 # = is less than <#9 // or more than 4#9 //. This voltage variation takes place due to the resistance variations of the light dependent resistor. This ;08 variation takes place because of the light falling on it. Thereby the output of the timer produces a clock pulses according to the variation of the light#resistance changes. This in turns proportional to the energy consumption. Thus the pulse+shaping block produces the clock pulses required for display according to the energy consumption. The circuit diagram of this clock pulse generation is shown in the net page.
MICRO"CONTROLLER /ircumstances that we find ourselves in today in the field of microcontrollers had their beginnings in the development of technology of integrated circuits. This development has made it possible to store hundreds of thousands of transistors into one chip. That was a prerequisite for production of microprocessors! and the first computers were made by adding eternal peripherals such as memory! input+output lines! timers and other. ?urther increasing of the volume of the package resulted in creation of integrated circuits. These integrated circuits contained both processor and peripherals. That is how the first chip containing a microcomputer! or what would later be known as a microcontroller came about. M)(0 +&-' Memory is part of the microcontroller whose function is to store data. The easiest way to eplain it is to describe it as one big closet with lots of drawers. 'f we suppose that we marked the drawers in such a way that they can not be confused! any of their contents will then be easily accessible. 't is enough to know the designation of the drawer and so its contents will be known to us for sure. Memory components are eactly like that. ?or a certain input we get the contents of a certain addressed memory location and that$s all. Two new concepts are brought to usH addressing and memory location. Memory consists of all memory locations! and addressing is nothing but selecting one of them.
This means that we need to select the desired memory location on one hand! and on the other hand we need to wait for the contents of that location. ,eside reading from a memory location! memory must also provide for writing onto it. This is done by supplying an additional line called control line. "e will designate this line as 8#" (read#write). /ontrol line is used in the following wayH if r#wA
C&'( P(),//-&@ U&-' ;et add 9 more memory locations to a specific block that will have a built in capability to multiply! divide! subtract! and move its contents from one memory location onto another. The part we just added in is called Rcentral processing unit (/D). 'ts memory locations are called registers. 8egisters are therefore memory locations whose role is to help with performing various mathematical operations or any other operations with data wherever data can be found. ;ook at the current situation. "e have two independent entities (memory and /D) which are interconnected! and thus any echange of data is hindered! as well as its functionality. 'f! for eample! we wish to add the contents of two memory locations and return the result again back to memory! we would need a connection between memory and /D. Simply stated! we must have some Rway through data goes from one block to another.
B+/ That Rway is called Rbus. Dhysically! it represents a group of 1! <=! or more wires. There are two types of busesH address and data bus. The first one
consists of as many lines as the amount of memory we wish to address! and the other one is as wide as data! in our case 1 bits or the connection line. ?irst one serves to transmit address from /D memory! and the second to connect all blocks inside the microcontroller.
I&:+' " )+':+' +&-' Those locations we$ve just added are called Rports. There are several types of portsH input! output or bi+directional ports. "hen working with ports! first of all it is necessary to choose which port we need to work with! and then to send data to! or take it from the port. "hen working with it the port acts like a memory location. Something is simply being written into or read from it! and it could be noticed on the pins of the micro+controller. The following is the /ircuit diagram of primary Micro+ controller unit.
DIGITAL DISPLAY The micro+controller is programmed to display the consumed energy information that is acquired from the energy meter. The controller generates ,/0 output which can be used to switch on the elements of a four digit seven+ element display. 6owever! because the controller is getting frequent information from energy meter! it is necessary to use a storage register which can hold data long enough for the display to be read. To hold the data! FI3F9 '/ is used! this is a octal transparent 0+type latches. ?acility is made available that the old data can be retained or new data can be entered while the outputs are in the high+ impedance state.
The display section is designed with four common anode F+Segment displays for displaying the time. The output of the Micro+controller is fed to digital display through the latches. To drive the displays independently 3IF transistors are used. % seven segment ;E0 is a device for display of numbers and letters. 't contains seven ;E0 bars! which can be turned on by placing the appropriate signals on the appropriate pins. 'n order to produce a specific number! we must light the correct segments of the ;E0. ?or eample! to display the number 9! we must light segments a! b! c! d and g. ,y which we understand that the pattern of lit and unlit segments can be formed into a binary number. 6ere all the four displays are connected in parallel! in parallel operation each display is driven through a switching transistor! for this purpose a low power *D* transistor of ,/ 3IF is used. The complete output port is used to drive the seven segments through latch! and to control the four displays independently through transistors! four lines from port 7o$ are used. "hen more than one display is to be used! then they can be time multipleedH the human eye can not detect the blinking if each display is relit every <> milliseconds or so. The ten milliseconds are divided by the number of displays used to find the interval between updating each display. Transistors must be used to handle the currents required by the ;E0$s! typically each ;E0 consumes <> milliamps! therefore each display consumes F> ma. The current is restricted through a current limiting resistor. The following is the /ircuit diagram of 0igital 0isplay 0riven by the micro+controller
POWER SUPPLY The power Supply is a Drimary requirement for the project work. The required 0/ power supply for the base unit as well as for the recharging unit is derived from the mains line. ?or this purpose center tapped secondary of <4+ >+<4 transformers are used. Total two transformers are used to design two different power supply units for the two different units. ?rom each power supply unit two different 0/ voltages of Q<4 and Q3 are derived using rectifiers and fitters. 'n this Q3 output is a regulated output and it is designed using F1>3 positive voltage regulator. This is a 9Din voltage regulator! can deliver current up to 1>> milliamps. 8ectification is a process of rendering an alternating current or voltage into an unidirectional one. The component used for rectification is called 78ectifier$. % rectifier permits current to flow only during the positive half cycles of the applied %/ voltage by eliminating the negative half cycles or alternations of the applied %/ voltage. Thus pulsating 0/ is obtained. To obtain smooth 0/ power! additional filter circuits are required.
% diode can be used as rectifier. There are various types of diodes. ,ut! semiconductor diodes are very popularly used as rectifiers. % semiconductor diode is a solid state device consisting of two elements are being an electron emitter or cathode! the other an electron collector or anode. Since electrons in a semiconductor diode can flow in one direction only+form emitter to collector+ the diode provides the unilateral conduction necessary for rectification.
The rectified :utput is filtered for smoothening the 0/! for this purpose <>>> Micro+farad capacitor is used in the filter circuit. The filter capacitors are usually connected in parallel with the rectifier output and the load. The %/ can pass through a capacitor but 0/ cannot! the ripples are thus limited and the output becomes smoothed. "hen the voltage across the capacitor plates tends to rise! it stores up energy back into voltage and current. Thus the fluctuations in the output voltage are reduced considerable. The following is the circuit diagram of Dower supply.
CHAPTER % 7 ELECTRICAL METERING INSTRUMENT TECHNOLOGY
The Electrical metering instrument technology has come a long way from what it was more than <>> years ago. ?rom the original bulky meters with heavy magnets and coils! there have been many innovations that have resulted in si-e B weight reduction in addition to improvements in features and specifications. 8esolution and accuracy of the meter have seen substantial improvements over the years. 'ntroduction of the digital meter in the later part of last century has completely changed the way Electrical parameters are measured. Starting with oltmeters B %mmeters! the digital meter has conquered the entire spectrum of measuring instruments due to their advantages like ease of reading! better resolution and rugged construction. :f particular significance is the introduction of the Electronic Energy Meter in the mid eighties.
Today the metering instrument technology grown up significantly! such that the consumed energy can be calculated mathematically! displayed! data can be stored! data can be transmitted! etc. Dresently the microcontrollers are playing major role in metering instrument technology. The present project work is designed to collect the consumed energy data of a particular energy consumer through wireless communication system (without going to consumer house)! the system can be called as automatic meter reading (%M8) system. The %utomatic Meter reading system is intended to remotely collect the meter readings of a locality using a communication system! without persons physically going and reading the meters visually.
P+(:)/ Typically! the purpose of %M8 is to eliminate the direct cost of manual meter reading and in addition provide value addition by data analysis. The %M8 system provides the utility with which much more functionality than simply reducing meter reading cost. /urrently! electricity utility deregulation is taking place all over the world and many countries would require for a significant purpose of increasing revenue. 8evenues are increased byH <. 'dentifying Theft of Dower + bypassing meters or physical tampering. 4. 'mproving billing and revenue collection methods. 9. uantifying TB0 ;osses. I. 0emands and 0istribution Management. 3. :utage Management. The %utomatic Meter 8eading System is a host driven! multi+level network system with built+in fleibility and epandability consisting of a 6ost /omputer Station (6/S)! 0ata /oncentrator nits (0/) and Meter 'nterfacing nits (M'). 't is generally located in /entral :ffice where meter+reading data is required to be collected. 6/S is a D/ running a 0atabase with a front end to collect meter reading data and perform elementary analysis. The 6/S calls each of the 0ata /oncentrator located on each of the distribution transformers. Each 6/S! while working dependently! can also be integrated with an eisting corporate information management system through software interface. "ith additional hardware and software support! the 6/S can work as a workstation in an eisting ;ocal %rea *etwork (;%*) and becomes a member of
the entire system or several 6/S can be connected together to form a network of their own. The host /entral Station (6/S) is the control center of the system! where all the function requests onto the 0ata /oncentrator nits (0/) by calling their addresses (or the telephone numbers in case of a public switched network)! and the 0/ will respond accordingly. The address codes (Telephone number) of the 0/$S are stored in 6/S. "ith sufficient mass storage! theoretically all 0/S can be covered with the corporations eisting Meter 8eading Management System. 'n this project work 8adio communication is used between energy consumer and centrali-ed electric sub+station! where the energy consumed by the /onsumer is remotely recorded in the Dersonal /omputer. Since it is a demonstration module! only one energy meter is used at the consumer side! and the received information is directly displayed! for this purpose four+digit display is used.
/omputer is also used for identifying the power theft
information and for storing the consumed energy data. The advantage of using computer is! multiple meters data can be stored separately in different locations. ?or the demonstration purpose only one consumer energy meter is considered! but in practical many consumers energy consumption data can be collected effectively.
*ow a days! the energy consumption and energy distribution has became a big subject for discussion because of huge energy losses. 6ence! the need has come to think on this line and a solution has to be emerged out. Thus this project work has been taken up which serves the purpose of energy monitoring and recording.
The eisting method of power consumption data collection is as followsH
%n energy meter installed in every house records the consumption of electrical energy by an individual. The electricity board employees Dower /onsumption data collectors! who records or note down the consumption data of each household and send the data to 6eadquarters. Generally! this collection of data is carried out at a frequency of one month. The electrical charges payable by an individual is then calculated based on the consumption data and the electrical charges (which are usually fied as slabs) per unit of Electricity. The charge per unit of consumption varies from slab to slab. The charges go+up with increase in slabs. Thus this method of data collection has its own advantages and disadvantages. 'f the data collection is not carried out at a fied interval! there is always a chance that the charges payable by the consumer is erroneous.
?or EH Say if the slabs are fied at <+3> units! 3<+<>> units! <><+4>> units! 4><+9>> units! like wise! and the collection of data is recorded every 9> days (monthly). %ssume a case where data is taken after 93 days. 'n this case the consumer is at loss in that he may fall into net higher category of slabs. 'n case data is taken early! say 43 days! the board will be at a loss as the consumption data may come into a lower category of slabs. Thus this method of recording energy consumption data is not fool+proof.
CHAPTER % DETAILS ABOUT ELECTRONIC ENERGY METERS T ))8-&@ ( ' *&'@/ ) ,'()&-, &(@0 '(/ 1. A,,+(,0 "hile electromechanical meters are normally available with /lass 4 accuracy! electronic meters of /lass < accuracy are very common.
2. L)8 C+((&' P()(&, Most of the electromechanical meters tend to run slow after a few years and stop recording at low loads typically below I>@ of their basic current. This is due to increased friction at their bearings. This results in large losses in revenue since most of the residential consumers will be running at very low loads for almost 4> hours in a day. Electronic meters record consistently and accurately even at 3@ of their basic current. %lso they are guaranteed to start recording energy at >.I@ of their basic current. Their performance does not deteriorate with time since power is measured using electronic techniques.
3. L)8 #)'@ P()(&, Most of the mechanical meters become inaccurate at voltages below F3@ of rated voltage whereas electronic meters record accurately even at 3>@ of rated voltage. This is a major advantage where low voltage problem is very common. 4. I&/''-)& The mechanical meter is very sensitive to the position in which it is installed. 'f it is not mounted vertically! it will run slow! resulting in revenue loss. Electronic meters are not sensitive to their mounting position.
5. T:( The mechanical meters can be tampered very easily even without disturbing the wiring! either by using an eternal magnet or by inserting a thin
film into the meter to touch the rotating disc. 'n addition to these methods! in the case of a single+phase meter! there are more than 4> conditions of eternal wiring that can make the meter record less. 'n the case of 9 Dhase meter! eternal wiring can be manipulated in I ways to make it slow. sing any of these methods cannot tamper electronic meters. Moreover they indicate the presence of tamper by means of ;E0$s. 6. N8 F'+(/ Electronic meters provide many new features like prepaid metering and remote metering that can improve the efficiency of the utility. R)' M'(-&@ ) E&(@0 M'(/ The introduction of electronic energy meters for electrical energy metering has resulted in various improvements in the operations of utilities apart from the increase in revenue due to better recording of energy consumption. :ne such additional benefit is the possibility of reading the meters automatically using meter+reading instruments even without going near the meter. Meter reading instruments (M8') are intelligent devices with built in memory and keyboard. The meter reader can download the energy consumption and related information from the electronic meter into the meter reading instrument either by connecting the M8' physically to the meter using their communication ports or by communicating with the meter from a distance using 8adio ?requency (8?) communication media. 8? communication method is similar to a cordless telephone! which is quite common these days. The meter and the M8' are provided with an antenna. "hen the meter reader presses a button on the M8'! it communicates with the meter through 8? and asks for all the data that are preset. The meter responds with all relevant data like meter identification number! cumulative energy consumed till that time etc. %fter reading many meters like that in one M8'! the
meter reader can go to the office and transfer all these data into a computer! which will have all these data for the previous billing period. sing these two data! the computer calculates the consumption for the current billing period and prepares the bill for each consumer. The use of 8? communication enables the utility to install the meters on top of the electric pole out of reach of the consumers thereby eliminating chances of tamper of the meter. ?requencies in the range of I>> M6- to 2>> M6- are commonly used for this purpose. 6owever other frequencies can also be used. 'f the distance between meter and M8' is of the order of <> or <3 mtrs! this communication can be achieved using low power transmitters at reasonable costs. Dower line carrier communication is another method of remote metering. 'n this method! the meter data is transferred to an M8' or computer by using the power line itself as the medium of transmission. This solution is generally cheaper than 8? but needs good quality power lines to avoid loss of data. This method is more attractive for limited distance communication. Third medium of communication possible is telephone line. This is viable only for industrial meters like the Trivector meter because of the cost of M:0EM$s required and the need for a telephone line! which may not be available in every house. This medium has the advantage of unlimited distance range. P(:-* M'(/ Uet another advantage of the electronic meter is the possibility of introducing prepaid metering system. Drepaid metering system is the one in which the consumer pays money in advance to the utility and then feeds this information into his meter. The meter then updates the credit available to the consumer and starts deducting his consumption from available
credit. :nce the credit reaches a minimum specified value! meter raises an alarm. 'f the credit is completely ehausted! the meter switches off the loads of the consumer. Main advantage of this system is that the utility can eliminate meter readers. %nother benefit is that they get paid in advance. The consumer benefits due to elimination of penalty for late payment. %lso it enables him to plan his electricity bill epenses in a better manner. 0ue to the intelligence built in into the electronic meters! introduction of prepaid metering becomes much easier than in the case of electro+ mechanical meters.
CHAPTER % ! SMART ENERGY METERS " AN O#ER#IEW I&'()*+,'-)& The potential for smart meters to offer consumers better information about! and control over! their energy use! leading to financial savings! has been discussed for a number of years. The other advantage of using smart meter is that the consumer can avoid penalties for late payments. %dvances have been made in developing the design and technology for smart meter systems although! to date! there have been no major pilot schemes to establish the costs and benefits to supply companies! consumers (including the fuel poor)! or to quantify any wider benefits in terms of meeting environmental#security of supply objectives. W' -/ S(' M'( The simplest form of smart metering is a display meter! which allows consumers to monitor consumption in money terms rather than k"h. 't can be combined with a keypad or smart card reader! which could link to prepayment systems thereby potentially reducing costs and the higher tariffs currently offered to prepayment meter customers. %utomated meter reading is an option for some systems! thereby eliminating both manual reading and the need to handle account queries which commonly follow estimated meter readings J the most common cause of complaint to suppliers and energy watch. 'nternet linked systems offer other services! including welfare benefits payments from the 0epartment of "ork and Densions and! as and when Micro /6D and solar roofs are installed! they can
serve as 7net$ meters! tracking the import and eport of electricity to and from the distribution network. F*,9 ') C+/')(/ There is some evidence from the S% and *orway that when households receive feedback on their energy consumption! savings of <>@+<3@ can be achieved. 't may therefore mean a possible contribution to reducing fuel poverty although! clearly! there is limited scope for this in homes where under heating is the major problem. Savings in the 5 may also be lower than in electrically heated homes in colder climates! but even a modest 3@ reduction translates to around V4I off the average domestic energy bill. This figure is suggested in a 0T' working group on smart meters. %lthough technically information on consumption patterns and potential savings could be provided to customers! the format and eact content of the information would depend on the supply company. B((-(/ ') M(9' E&'(0 ,arriers to the introduction of smart meters have beenH the lack of standardi-ed meter types (customers would need to change meters if they changed supplier)& current meter lifespan (although it is estimated that <.3 million meters are replaced each year! these are often refurbished eisting 7dumb$ meters)& and the cost differential + who would pay the additional costs associated with this technologyW These issues have prevented any major trials& although the introduction of new technologies for domestic generation of electricity! Micro /6D and photovoltaic! will mean that more sophisticated metering will be needed.
C(* T,&))@0 P@ M)(0 ,(*/ Memory cards are the simple$s type of smart card. Memory cards only have some amount of memory inside the card and this memory can be normally read and written. There is normally nothing rely intelligent inside those cards. Typically the memory inside this kind of cards is ED8:M! EED8:M or ?;%S6 memory. This card type is very widely used as telephone cards (tele cards). Many countries use a tele+card system! which is very close to the first smart card telephone system in use in ?rance S(' ,(*/ 6ere you can find information on real smart cards! which have a real microprocessor inside the card. There have been many different small microprocessors used inside smart cards including 1>9<#3< variants! D'/ micro+controllers and some special microprocessors just designed for smart card applications. ery many smart cards communicate using the protocols standardi-ed in 'S: F1<= standard. The 'S:F1<= Standard define many physical features! including card si-e! mechanical strength and electrical properties. 'S:F1<=+4 Standard defines card contact type! placement in card and the pin out. The standard pin out isH /< H cc A 3
/3 H Gnd
/4 H 8eset
/= H pp (programming voltage)
/9 H /lock
/F H '#: (data in#out)
/I H 8?
/1 H 8?
Dins marked with 8? are application specific pins defined in application standards. The standard supports two transmission modesH
o
%synchronous transmissionH 'n this type of transmission! characters are transmitted on the '#: line in an asynchronous half duple mode. Each character includes an 1bit byte.
o
Synchronous transmissionH 'n this type of transmission! a series of bits is transmitted on the '#: line in half duple mode in synchroni-ation with the clock signal on /;5. There is a selection of different protocols available for communicating
with the card. There is a method for selecting which communication protocol to use (one card can support one or more protocols). The most commonly used protocol seems to be asynchronous half duple character transmission protocol. 'n contact systems! such as reading the data from a serial EED8:M over a two+wire ('4 /) or three+wire SD' or Micro wire bus! the power! clock! and data lines are connected separately. Some wired smart cards use 8S+494 type asynchronous
communications!
and
in
this
case
supply
power
and
communication through different wires. C)&',' // /(' ,(*/ &* RFID ;R*-) F(+&,0 I*&'--,'-)&= 'n contact systems! such as reading the data from a serial EED8:M over a two+wire ('4 /) or three+wire SD' or Micro wire bus! the power! clock! and data lines are connected separately. Some wired smart cards use 8S+494 type asynchronous
communications!
and
in
this
case
supply
power
and
communication through different wires. 'n contact less smart cards all this communication and usually also the power for the smart card needs to be transferred wirelessly using 8? signals and#or inductive coupling methods. 8adio ?requency 'dentification (8?'0) systems use radio frequency to identify! locate and track people! assets! and animals. /harles "alton pioneered the 8?'0 technology in the <2F>s and <21>s. Dassive 8?'0 systems are composed of three componentsH an interrogator (reader)! a passive tag! and a
host computer. The tag is composed of an antenna coil and a silicon chip that includes basic modulation circuitry and non+volatile memory. The tag is energi-ed by a time+varying electromagnetic radio frequency (8?) wave that is transmitted by the reader. This 8? signal is called a carrier signal. "hen the 8? field passes through an antenna coil! there is an %/ voltage generated across the coil. This voltage is rectified to supply power to the tag. The information stored in the tag is transmitted back to the reader. This is often called backscattering. ,y detecting the backscattering signal! the information stored in the tag can be fully identified. Dassive 8?'0 devices also use a serial bus! but the power! clock! and data are all in the same signal. 'nstead of wires! this signal is carried through wireless means. Typical 8?'0 system use inductive coupling between the card and the reader. ,oth of them have coils! which interact with each other (magnetic coupling). This interaction makes it possible to transfer power to the card (through alternating magnetic field or pulses) and transfer information (modulating the magnetic field). Typical these kind of inductively coupled systems operate at <43+k6- to <9.3=+M6- frequency range. 'S: frequencies of <43 k6- and <9.3= M6- are generally used. <43 k6- and <9.3= M6-! utili-e transformer+type electromagnetic coupling. The typical operating distance is usually few centimeter or tens of centimeters. Sometimes higher frequencies are used for 8?'0 tagging! but the communication methods are somewhat different. 4.I3 G6-! for eample! uses a true 8? link. There are also systems that operate at 6? frequencies (2>4+241 M6- in S% and 1==+ 1=1 M6- in Europe). The radio systems can operate typically from few meters to <> meters. Systems incorporating passive 8?'0 tags operate in ways that may seem unusual to anyone who already understands 8? or microwave systems. There is only one transmitterH the passive tag is not a transmitter or transponder in the purest definition of the term! yet bi+directional communication is taking place. The 8? field generated by a tag reader (the energy transmitter) has three purposesH
o
'nduce enough power into the tag coil to energi-e the tag. Dassive 8?'0 tags utili-e an induced antenna coil voltage for operation. This induced %/ voltage is rectified to provide a voltage source for the device. %s the 0/ voltage reaches a certain level! the device starts operating.
o
Drovide a synchroni-ed clock source to the tag. Many 8?'0 tags divide the carrier frequency down to generate an on+board clock for state machines! counters! etc.! and to derive the data transmission bit rate for data returned to the reader.
o
%ct as a carrier for return data from the tag. ,ackscatter modulation requires the reader to peak+detect the tags modulation of the readers own carrier. ,ackscatter modulation works by repeatedly shunting the tag coil through a transistor& the tag can cause slight fluctuations in the readers 8? carrier amplitude.
o
The 8? link behaves essentially as a transformer& as the secondary winding (tag coil) is momentarily shunted! the primary winding (reader coil) eperiences a momentary voltage drop. This amplitude modulation loading of the reader. Transmitted field provides a communication path back to the reader. 't is important that the device must be equipped with a proper antenna circuit for successful 8?'0 applications. The compleity of 8?'0 tags can vary! typically the '/s are quite simple small memory storage holding for eample <41 bits of memory that can be read! but there are also more complicated devices with similar functionality as normal smart cards.
CHAPTER % 1$ DETAILED DESCRIPTION OF !C SERIES CONTROLLERS
% digital computer typically consists of three major componentsH the /entral Drocessing nit (/D)! program and data memory! and an 'nput#:utput ('#:) system. The /D controls the flow of information among the components of the computer. 't also processes the data by performing digital operations. Most of the processing is done in the %rithmetic+;ogic nit (%;) within the /D. "hen the /D of a computer is built on a single printed circuit board! the computer is called a minicomputer. % microprocessor is a /D that is compacted into a single+chip semiconductor device. Microprocessors are general+purpose devices! suitable for many applications. % computer built around a microprocessor is called a microcomputer. The choice of '#: and memory devices of a microcomputer depends on the specific application. ?or eample! most personal computers contain a keyboard and monitor as standard input and output devices.
% microcontroller is an entire computer manufactured on a single chip. Microcontrollers are usually dedicated devices embedded within an application. ?or eample! microcontrollers are used as engine controllers in automobiles and as eposure and focus controllers in cameras. 'n order to serve these applications! they have a high concentration of on+chip facilities such as serial ports! parallel input output ports! timers! counters& interrupt control! analog+to+ digital converters! random access memory! read only memory! etc. The '#:! memory! and on+chip peripherals of a microcontroller are selected depending on the specifics of the target application. Since microcontrollers are powerful digital processors! the degree of control and programmability they provide significantly enhances the effectiveness of the application.
Embedded control applications also distinguish the microcontroller from its relative! the general+purpose microprocessor. Embedded systems often require real+time operation and multitasking capabilities. 8eal+time operation refers to the fact that the embedded controller must be able to receive and process the signals from its environment as they are received. That is! the environment must not wait for the controller to become available. Similarly! the controller must perform fast enough to output control signals to its environment when they are needed. %gain! the environment must not wait for the controller. 'n other words! the embedded controller should not be a bottleneck in the operation of the system. Multitasking is the capability to perform many functions in a simultaneous or quasi+simultaneous manner.
The embedded controller is often responsible of monitoring several aspects of a system and responding accordingly when the need arises. The 1>3< is the first microcontroller of the M/S+3< family introduced by 'ntel /orporation at the end of the <2F>s. The 1>3< family with its many enhanced members enjoys the largest market share! estimated to be about I>@! among the various microcontroller architectures. The architecture of the 1>3< family of the microcontrollers is presented in this chapter. ?irst! the original 1>3< microcontroller is discussed! followed by the enhanced features of the 1>94! and the 1>/3<3.
T $51 M-,(),)&'()( F-0 A(,-','+( The architecture of the 1>3< family of microcontrollers is referred to as the
M/S+3<
architecture!
or
sometimes
simply
as
M/S+3<.
The
microcontrollers have an 1+bit data bus. They are capable of addressing =I5 of program memory and a separate =I5 of data memory. The 1>3< has I5 of code memory implemented as on+chip Read Only Memory (8:M). The 1>3<
has <41 bytes of internal Random Access Memory (8%M). The 1>3< has two timer#counters! a serial port! I general purpose parallel input#output ports! and interrupt control logic with five sources of interrupts. ,esides internal 8%M! the 1>3< has various Special Fnc!ion Re"is!ers (S?8)! which are the control and data registers for on+chip facilities. The S?8s also include the accumulator! the , register! and the #ro"ram S!a!s $ord (DS")! which contains the /D flags. Drogramming the various internal hardware facilities of the 1>3< is achieved by placing the appropriate control words into the corresponding S?8$s. The 1>9< is similar to the 1>3
%s stated! the 1>3< can address =I5 of eternal data memory and =I5 of eternal program memory. These may be separate blocks of memory! so that up to <415 of memory can be attached to the microcontroller. Separate blocks of code and data memory are referred to as the 6arvard architecture. The 1>3< has two separate read signals! 80X and DSE*X. The first is activated when a byte is to be read from eternal data memory! the other! from eternal program memory. ,oth of these signals are so+called active low signals. That is! they are cleared to logic level > when activated. %ll eternal code is fetched from eternal program memory. 'n addition! bytes from eternal program memory may be read by special read instructions such as the M:/ instruction. There are separate instructions to read from eternal data memory! such as the M:C instruction. That is! the instructions determine which block of memory is addressed! and the corresponding control signal! either 80X or DSE*X is activated during the memory read cycle. % single block of memory may be mapped to act as both data and program memory. This is referred to as the on *eumann< architecture. 'n order to read from the same block using either the 80X signal or the DSE*X signal! the two signals are combined with a logic %*0 operation. This way! the output of the %*0 gate is low when either input is low. The advantage of the 6arvard architecture is not simply doubling the
memory capacity of the microcontroller. Separating program and data increases the reliability of the microcontroller! since there are no instructions to write to the program memory. % 8:M device is ideally suited to serve as program memory. The 6arvard architecture is somewhat awkward in evaluation systems! where code needs to be loaded into program memory. ,y adopting the on *eumann architecture! code may be written to memory as data bytes! and then eecuted as program instructions.
The 1>34 has 43= bytes of internal 8%M and 15 of internal code 8:M. The 1>3< and 1>34 internal 8:M cannot be programmed by the user. The user must supply the program to the manufacturer! and the manufacturer programs the microcontrollers during production. 0ue to the setup costs! the factory masked 8:M option is not economical for small quantity productions. The 1F3< and 1F34 are the Erasa%le #ro"ramma%le Read Only Memory (ED8:M) versions of the 1>3< and 1>34. Many manufacturers offer the ED8:M versions in windowed ceramic and non+windowed plastic packages. These are user programmable. 6owever! the non+windowed versions cannot be erased. These are usually referred to as :ne+Time+ Drogrammable (:TD) microcontrollers! which are more suitable for eperimental work or for small production runs. The 123<
and
1234
contain
?;%S6
EED8:M$s
(Electrically
Erasable
Drogrammable 8ead :nly Memory). These chips can be programmed as the ED8:M versions! using a chip programmer. Moreover! the memory may be erased. Similar to ED8:Ms! Erasing ?;%S6 memory sets all data bits (data bytes become ??h). % bit may be cleared (made >) by programming. 6owever! a -ero bit may not be programmed to a one. This requires erasing the chip. Some larger ?;%S6 memories are organi-ed in banks or sectors. 8ather than erasing the entire chip! you may erase a given sector and keep the remaining sectors unchanged.
0uring the past decade! many manufacturers introduced enhanced members of the 1>3< microcontroller. The enhancements include more memory! more ports! analog J to + digital converters! more timers with compare! reload and capture facilities! more interrupt sources! higher precision multiply and divide units! idle and power down mode support! watchdog timers! and network communication subsystems. %ll microcontroller of the family use the same set of machine instructions! the M/S+3<. The enhanced features are programmed and controlled by additional S?8s. 'n the remainder of this chapter!
the
hardware
architecture
of
the
1>3<
is
presented.
The
enhancements brought by the 1>34 and 1>/3<3 follow. The roll of microcontroller is very important in this project work! 12/3< is used here! this is quit popular '/ generally used for all applications. The prime use of a microcontroller is to function like a minicomputer using a fied program that is stored in 8:M and that does not changeover the lifetime of the system. The microcontroller design uses a much more limited set of instructions that are used to move code and data from internal memory to the %;. Many instructions are coupled with pins on the '/ package. The pins are programmable independently! that is capable of having several different functions depending on the program. The microcontroller is concerned with getting data from and to its own pins& the architecture and instruction set are optimi-ed to handle data in bit! byte! and word si-e. Every application demands a microcontroller! today there is no such electronic instrument or robot that functions with out microcontroller. Generally for any application! often designers chose the 1 J bit controller! because they are most popular microcontrollers in use today! another important aspect is cost effective.
The heart of the chip is the circuitry that generates the clock pulses by which all internal operations are synchroni-ed. Typically a quart- crystal and capacitors are connected to the oscillator pins of microcontroller. The crystal frequency is the final internal clock frequency of the microcontroller. The manufacturers of the 1>3< devices specifies the frequency range! less frequency other then specified may erase the data that is stored in 8:M! there by the frequency must be always be more then the above normal. The oscillator formed by the crystal and capacitors generates a pulse train at the frequency of the crystal. % <4 M6- crystal yields the convenient time of one microsecond per cycle. !C51 MICROCONTROLLER % DESCRIPTION
Intel Corporation introduces 89c51; it is an 8-bit microcontroller. This microcontroller has 128 bytes of RAM, 4K of on-chip ROM, two timers, one serial port, and four ports of 8-bits each all on a single chip. 89c51 is basically Flash ROM version of 8051 families. 89c51 is basically a 40 pin Dual-in-package. Block diagram of 89c51 is as shown in chapter-10, i.e., hardware details. The main features of 89c51 Hardware can be labeled as below:
<. 't has 1+bit /D with registers % (the accumulator) and ,. 4. Siteen+bit program counter (D/) and data pointer (0DT8). 9. Eight+bit program status word (DS"). I. Eight+bit stack pointer (SD). 3. 'nternal 8:M of > to I5. =. 'nternal 8%M of <41 bytes. F. 94 '#> pins arranged as four 1+bit portsH D>+D9 1. Two <=+bit Timer#/ountersH T> and T< 2. ?ull duple serial data receiver#transmitterH S,? <>. /ontrol registersH T/:*! TM:0! S/:*! D/:*! 'D! and 'E.
<<. Two eternal and three internal interrupt sources. <4. :scillator and /lock circuits.
Pin descriptions:
1. VSS (pin-20) Ground= 0 V reference 2. VCC (pin-40) This is the power supply voltage for normal, idle and power-down modes. 3. P.0-P0.7 (pin-39 to pin 32 i.e., port 0) Port 0 is an open-drain, bi-directional I/O port. Pins of Port 0 on which there is a high logic will float and can be used as a high impedance inputs. Port 0 is also the multiplexed low-order address and data bus during accesses to external program and data memory; in this application it uses strong internal pull-ups for emitting 1’s. 4. P1.0 – P1.7 (Pin-1 to Pin 8 i.e., Port 1) Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. Port 1 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 1 pins that are externally pulled low will source current because of the internal pull-ups.
5. P2.0 – P2.7 (Pin-21 to Pin 28 i.e., Port 2) Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. Port 2 pins that have 1s written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 2 pins that are externally being pulled low will source current because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that uses 16-bit addresses (MOVX @DPTR). In this application, it uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8 – bit addresses (MOV @Ri), port 2 emits the contents of the P2 special function register.
6. P3.0 – P3.7 (Pin-10 to Pin 17 i.e., Port )
Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. Port 3 pins that have 1s written to them are pulled high by the internal pull-ups pull-ups and can be used as inputs. As inputs, port 3 pins that are externally externally being pulled low will source current current because of the pull-ups. Port 3 also serves the special features of the 89C51, as listed below: RxD (P3.0): Serial input port. TxD (P3.1): Serial output port. INT0 (P3.2): External interrupt. INT1 (P3.3): External interrupt. T0 (P3.4): Timer 0 external input. T1 (P3.5): Timer 1 external input. WR (P3.6): External data memory write strobe. RD (P3.7): External data memory read strobe. 7. RESET (Pin-9) A high on this pin for two machine cycles while the oscillator is running, resets the device. An internal diffused resistor to VSS permits a power-on reset using only an external capacitor to VCC.
8. ALE (Pin-30) Output pulse for latching the low byte of the address during an Access to external memory. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency, and can be used for external timing or clocking. Note that one ALE pulse is skipped skipped during each access access to external external data memory. memory. Setting Setting SFR auxiliar auxiliary,0 y,0 can disable ALE. With this bit set, ALE will be active only during a MOVX instruction.
9. PSEN (Pin-29) The read strobe to external program memory. When executing code from the external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. PSEN is not activated during fetches from internal program Memory. 10. EA/VPP (Pin-31)
EA must be externally held low to enable the device to fetch code from external program memory locations 0000H to the maximum internal memory boundary. If EA is held high, the device device execute executes s from internal internal program program memory unless the program program counter contains an address greater than 0FFFH for 4 k devices, 1FFFH for 8 k devices, 3FFFH for 16 k devices, and 7FFFH for 32 k devices. The value on the EA pin is latched when RST is released and any subsequent changes have no effect. This pin also receives the 5V/12V programming supply voltage (VPP) during FLASH programming.
11. XTAL1 and XTAL2 (Pin-18 and Pin-19) Crys Crystal tal1: 1: Inp Input ut to the the inver invertin ting g oscill oscillat ator or amp amplif lifier ier an and d input input to the the inter interna nall clock clock generator circuits. Chapter2: Output from the inverting oscillator amplifier
OSCILLATOR CHARACTERISTICS
XTAL XTAL1 1 and XTAL XTAL2 2 are the the input input an and d out output put,, respe respecti ctive vely, ly, of an Invert Inverting ing amplifier. The pins can be configured for use a an On-chip oscillator. To drive the device from from an exte extern rna al cloc clock k sour source ce,, XTAL XTAL1 1 shou should ld be driv driven en wh whil ile e XTAL XTAL2 2 is left left unconnected. There are no requirements on the duty cycle of the external clock signal, because the input to the internal clock circuitry is through a divide-by-two flip-flop. However, minimum and maximum high and low times specified in the data sheet must be observed.
RESET:
A reset is accomplished accomplished by holding the RST pin high for at least two machine cycles (24 oscillator periods), periods), while the oscillator is running. running. To insure a good power-on reset, the RST pin must be high long enough to allow the oscillator time to start up (normally a few milliseconds) plus two machine cycles. At power-on, the voltage on VCC and RST must come up at the same time for a proper start-up. Ports 1, 2, and 3 will asynchronously asynchronously be driven to their reset condition when a voltage above VIH1 (min.)
is applied to RST. The value on the EA pin is latched when RST is disserted and has no further effect.
Accumulator:
The A (Accumulator) (Accumulator) is the versatile of the two CPU registers registers and is used for many man y ope operati rations, ons, includin including g add additio ition, n, subtract subtraction, ion, division division,, integer integer multipli multiplicat cation ion and Boolean bit manipulations. The A register is also used for data transfers between the 8091 and any external memory.
B R@-/'(
The The B regi regist ster er is used used du duri ring ng mu mult ltip iply ly an and d divi divide de op oper erat atio ions ns.. For For othe otherr instructions it can be treated as another scratch pad register.
P()@( S''+/ W)(*
The PSW register register contains contains program status information information as detailed in Table below: The PSW consists of math flags, user program flag F0, and the register bank select bits that identify which of the four general register banks is currently in use by the program.
S',9 P)-&'(
The Stack Pointer register is 8 bits wide. It is incremented before data is stored during PUSH and CALL executions. While the stack may reside anywhere in on-chip RAM, the Stack Pointer is initialized to 07H after a reset. This causes the stack to begin at locations 08H.
D' P)-&'(
The Data Pointer (DPTR) consists of a high byte (DPH) and a low byte (DPL). Its intended function is to hold a 16-bit address. It may be manipulated as a 16bit register or as two independent 8-bit registers.
S(- D' B+(
The Serial Buffer is actually two separate registers, a transmit buffer and a receive buffer. When data is moved to SBUF, it goes to the transmit buffer and is held for serial transmission. (Moving a byte to SBUF is what initiates the transmission.) When data is moved from SBUF, it comes from the receive buffer.
T-( R@-/'(/
Register pairs (TH0, TL0), and (TH1, TL1) are the 16-bit Counting registers for Timer/Counters 0 and 1, respectively.
C)&'() R@-/'(
Special Function Registers IP, IE, TMOD, TCON, SCON, and PCON contain control and status bits for the interrupt system, the Timer/Counters, and the serial port. They are described in later sections. Timers And Counters Timer 0 and Timer 1 The “Timer” or “Counter” function is selected by control bits C/T in the Special Function Register TMOD. These two Timer/Counters have four operating modes, which are selected by bit-pairs (M1, M0). In TMOD. Modes 0, 1, and 2 are the same for both Timers/Counters. Mode 3 is different. The four operating modes are described in the following text:
M)* $
Timer, which is an 8-bit Counter with a divide-by-32 pre scalar. The Mode 0 operation as it applies to Timer 1. In this mode, the Timer register is configured as a 13bit register. As the count rolls over from all 1s to all 0s, it sets the Timer interrupt flag TF1. The counted input is enabled to the Timer when TR1 = 1 and either GATE = 0 or
INT1 = 1. (Setting GATE = 1 allows the Timer to be controlled by Putting either Timer into Mode 0 makes it look like an 8048 external input INT1, to facilitate pulse width measurements). TR1 is a control bit in the Special Function Register TCON (Figure 3).
GATE is in TMOD: The 13-bit register consists of all 8 bits of TH1 and the lower 5 bits of TL1. The upper 3 bits of TL1 are indeterminate and should be ignored. Setting the run flag (TR1) does not clear the registers. Mode 0 operation is the same for the Timer 0 as for Timer 1. Substitute TR0, TF0, and INT0 for the corresponding Timer 1 signals in Figure 2. There are two different GATE bits, one for Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3).
M)* 1
Mode 1 is the same as Mode 0, except that the Timer register is being run with all 16 bits. M)* 2
Mode 2 configures the Timer register as an 8-bit Counter (TL1) with automatic reload, as shown in Figure 4. Overflow from TL1 not only sets TF1, but also reloads TL1 with the contents of TH1, which is preset by software. The reload leaves TH1 unchanged. Mode 2 operations are the same for Timer/Counter 0.
M)* 3
Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1 = 0. Timer 0 in Mode 3 establishes TL0 and TH0 as two separate counters. The logic for Mode 3 on Timer 0 is shown in Figure 5. TL0 uses the Timer 0 control bits: C/T, GATE, TR0, and TF0, as well as the INT0 pin. TH0 is locked into a timer function (counting machine cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0 now controls the “Timer 1” interrupt. Mode 3 is provided for applications requiring an extra 8bit timer on the counter. With Timer 0 in Mode 3, an 80C51 can look like it has three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it out of and into its own Mode 3, or can still be used by the serial port as a baud rate generator, or in fact, in any application not requiring an interrupt.
TCON and TMOD are the two registers used for setting the above modes. The format of these registers is as shown in figure TMOD is dedicated solely to the timers and can be considered to be two duplicate 4-bit registers, each of which controls the action of one of the timers. TCON has control bits and flags for the timers in the upper nibble, and control bits and flags for the external interrupts in the lower nibble. 2.4 Criteria for choosing 89c51Microcontroller 1. The first and foremost criterion in choosing a microcontroller is that it must meet the task at hand efficiently and cost effectively. In our project we have chosen an 8-bit microcontroller, which can handle the computing needs of the task most effectively. 2.
The highest speed this microcontroller can support is 12MHZ
3.
To fulfill our requirements in terms of space, assembling, we have chosen the 40-pin DIP.
4. To support the memory requirement we have chosen it as it includes 4K ROM and 128byte RAM. 5. As there are 32 I/O pins and 2 timers, it supports our input-output requirement greatly. 6. We have used the battery power product like an RTC the power consumption is critical for it. 7. In choosing this controller we have considered the availability of an assembler, debugger, simulator etc. 8. The ready availability in needed quantities both now and in the future. Currently, of the leading 8-bit microcontrollers, the 8051 family has the largest number of diversified suppliers.
CHAPTER % 11 DETAILED DESCRIPTION ABOUT RS 232
This article is intended to help the designer$s sort through the various features available in 8S+494 interface products. The main features described are the regulated charge pump! %uto shutdown! 8S+494 compatible versus compliant operation! ES0 protection! and data rates including Megabaud operation.
W' -/ RS"232 C)+&-,'-)& 8S stands for Rrecommended standard! and 494 is a number assigned to this standard by the Electronics 'ndustry %ssociation (E'%).
'n fact! the
updated name is E'% 4940! but most people still call it 8S+494. The standard defines such things as the type of signal used! timing! the number of bits in a character! which bit goes first! how to separate one character from another! and codes to mark the beginning and the end of the message. ,ecause of these standards! serial communication such as 8S+494 can be used over ordinary telephone lines. RS"232 B,9@()+&* 0espite the development of newer digital interface standards! the humble 8S+494 serial port remains the most widely used means for transferring data. 8obust and easy to use! the 8S+494 port is an attractive alternative to more digitally demanding and temperamental interfaces. Two 8S+494 devices still in use today! the
power supplies because the 8S+494 standard requires each transmitter to provide a Q3 (minimum) signal for a low and a +3 (minimum) signal for a high. These higher voltages ensure greater noise immunity after they travel through lossy cables to 8S+494 receivers. ,ut they require a dual power supply and many D/ boards included a negative power supply solely to power devices such as the and the other inverts the Q<> charge+pump output to +<>. ,ecause these charge pumps are unregulated! the positive and negative output voltages of the transmitters they power often drop well below Q<> and +<>. 6ow far they drop is a function both of the capacitance of the cable driven by the transmitters and the data rate. The M%C494 quickly became an industry standard. Many board designers still use it! despite the fact that single+supply devices have undergone etensive improvements over the years. nderstanding the features of new devices will help the design engineer choose the best parts for the application. RS"232 T(&/,-(/ P)8(* 0 L)8"#)'@ S-&@ S+::-/ %s power+supply voltages dropped from Q3 to Q9.9 and lower! single+ supply 8S+494 transceivers kept pace. Those transceivers that are powered from voltages ranging from 9.> to 3.3 use two regulated charge pumps instead of the unregulated types used in the parts powered by Q3 only. 8ather than double the input voltage! one regulated charge pump boosts the input voltage to about Q3.I& a regulated inverting charge pump supplies an output of
about +3.I. % big power+savings advantage results! as Y3.I driving the capacitive load presented by the cable consumes quite a bit less power than! say! Y2. uestions about noise immunity often arise when design engineers first discover these devices. Their noise immunity! however! is ecellent! as the regulated charge pumps work harder to maintain a Y3.I output as cables get longer and the capacitive load increases. 'n fact! a Y3.I output is maintained with longer cables and higher data rates when using these devices than when using devices with unregulated outputs that are initially of higher output voltage. Maim also offers a series of 8S+494 transceivers that operate from voltages as low as 4.93. Moreover! one 8S+494 transceiver! the M%C94<1! uses an inductor along with capacitors to allow operation with supplies as low as Q<.1. S-&@ S+::0 C+((&' '()+@ A+') /+'*)8& T,&-+/ Many 8S+494 transceivers provide a simple shutdown feature thats activated by applying a logic level to the shutdown pin. :ften this feature saves enough current to allow the battery of a portable piece of equipment to last for a sufficient amount of time. %nother means for shutting down the power of an 8S+ 494 device is available! however& it places the 8S+494 device into shutdown mode whenever it detects that the 8S+494 interface isnt in use. This feature! called %uto shutdown! is useful! because in many applications 8S+494 devices are used for only short periods of time. The %uto shutdown feature monitors whether the 8S+494 interface isnt in use by detecting whether a cable is present. 'f a cable isnt connected to an 8S+ 494 transceiver! theres no reason to power the device. % transceiver equipped with the %uto shutdown feature monitors the 8S+494 signals at its receivers to
determine whether a cable is connected. "hen a cable isnt present! the signals at the 8S+494 receiver inputs hover near >& the transceiver shuts down when all its receiver inputs are at or near >. The part automatically takes itself out of shutdown if any one of the receiver inputs eceeds Q4.F or goes below +4.F (i.e.! whenever the cable is reconnected). %lso! this feature can be overridden with signals that force the device on or off. %uto shutdown Dlus is similar to %uto shutdown in that it is designed to save power by shutting down the 8S+494 device whenever its not in use. The difference! however! is that %uto shutdown Dlus shuts down the transceiver not only when the cable is disconnected! but also when the cable is connected and data edges havent appeared for 9> seconds or more. That way you can get the benefit of an automated shutdown regardless of whether the cable is connected. %uto shutdown+Dlus devices monitor both the 8S+494 receiver inputs and the digital transmitter inputs for signal activity& shutdown ensues if no activity is present on any of these lines. %s with %uto shutdown! you can force on or off the device using pins that override the %uto shutdown plus feature. The %uto shutdown Dlus logic incorporated in an 8S+494 transceiver such as the M%C9491 allows the transceiver to stay powered as long it detects signal transactions at its transmitter or receiver inputs within 9> seconds. :therwise the transceiver is automatically powered down because no signal transactions are present. ;ogic levels applied to the ?:8/E:* and ?:8/E:??+bar pins turn device power on and off independently of whether signal activity is detected. C):'- #(/+/ C):-&' To be compliant with the 8S+494 specification! transmitters are required to provide a Y3 output. ?or 8S+494 receivers to be compliant! their thresholds
must be Y9 maimum. Thus! these devices operate with a healthy Y4 noise margin (and often more! because receiver thresholds are usually lower than Y9). 'ts possible to erode some of that margin and still maintain accurate data transmissions. Margins get reduced when transmitter output voltages span a narrower range. "hen transmitter outputs are a minimum of Y9.F! they are considered to be compatible! instead of compliant! 8S+494 outputs. ?or eample! when you power an 8S+494 device that doesnt contain charge pumps (and hence is cheaper and smaller) with Y3 supplies! its output voltages cannot possibly reach Y3. % device operated under those conditions with transmitter outputs of Y9.F at minimum is said to be 8S+494 compatible instead of compliant. E&&,* ESD P()','-)& %ll 8S+494 devices include ES0+protected structures on their pins to protect against electrostatic discharges encountered during handling and assembly. Some manufacturers offer devices both with standard and enhanced protection. ,ecause both the standard and the enhanced+protection parts almost always come with the same pin out! adding devices with enhanced ES0 protection usually requires no modification to an eisting D/ board. Some applications require Y<3k ES0 protection on both the 8S+494 and the /M:S digital pins. ?or eample! in order to reduce cost and si-e! cell phones do not include the 8S+494 transceiver in the phone itself. 'nstead! they route /M:S+level signals out through the connector at the bottom of the phone. 'f the cell+phone owner wants to connect to the 8S+494 port of a laptop! he or she purchases a Zdata+lumpZ cable! which includes an 8S+494 transceiver. 'n this situation! both sides of the 8S+494 transmitters and receivers are brought out to connectors! eposing them to increased ES0 risk. 'n such cases! it may be desirable to have etended ES0 protection on both the 8S+494 and /M:S
sides of the transmitters and receivers. The M%C991>E and M%C991kbps or below. 0espite this restriction! the data rates of most 8S+494 transceivers far surpass that speed. 'n fact! todays 8S+494 transceivers reach speeds of < Mbps. To reach that speed! those devices violate another 8S+494 specification! the maimum allowed transmitter+output slew rate of 9>#is.
CHAPTER % 12 HARDWARE DETAILS
The '/$s and other important components used in this project work! procured from the 6yderabad Electronics Market. The details or data sheets of the '/$s are down loaded from the 'nternet. The following are the web sites that can be browsed for collecting the data sheets. <. www. Teas 'nstruments.com 4. www. *ational semiconductors.com 9. www. ?airchild semiconductors.com The following are the '/$s and other important components used in this project work (<) %0FF3< J Energy metering '/ (4) M%C 494 (9) 12/3<#34 Microcontroller /hip (I) FI;S3F9 + ;atch (3) oltage 8egulator (=) 333 Timer '/ (F) 8elay
The required D/,$S (Drinted /ircuit boards) for the project work fabricated by S* 8'SE /'8/'TS! 5ushaiguda 'ndustrial Estate! 6yderabad. 5ushaiguda 'ndustrial Estate is very famous for fabricating the 'ndustrial grade D/,$s.
CHAPTER % 14 CONCLUSIONS
The project work RGetting Energy Meter 0ata through GSM Mobile is completed successfully! for the demonstration purpose a prototype module is constructed! which is very near to the real working system! and results are found to be satisfactory. The concept of GSM energy meter is the new trend in technology! wide variety of systems with various features are developed! but here the system offers unique features. The technology implemented here is quite innovative& the benefits of this system are plenty when compared with the eisting system. Since the system utili-es GSM technology! many more features like identifying the tampered energy meter! monitoring the line voltage and load current! etc. can be monitored remotely through the same mobile phone. 'f required the customer can disconnect the supply to the house through his mobile when he is away from the house. ,y implementing this type of system everywhere at domestic and industrial side! using GSM technology! centrali-ed monitoring station can be designed from where all the energy meters are monitored continuously! in this regard a perfect energy auditing system can be designed and accordingly energy pilferage can be minimi-ed. %nother important concept that can be designed based on this GSM technology is! line loss identifier! in this either transmission losses or tapping energy directly from the lines can be detected by sending information to the mobile! to prove this concept! two GSM modems are to be used at both ends of energy transmission lines! and both ends power flow data can be sent to single mobile. ;ike wise the advantages and applications of the GSM technology are plenty.
