gsm base industrial control

GSM Based Industrial automation

1. INTRODUCTION1.1 Introduction to Project:Wireless communication has announced its arrival on big stage and the world is going mobile. We want to control everything and without moving an inch. This remote control of appliances is possible through Embedded Systems. The use of Embedded System in Communication has given rise to many interesting applications that ensures comfort and safety to human life. GSM (Global System for Mobile communications) is an open, digital cellular technology used for transmitting mobile voice and data services. Here we are using it only for transmitting and receiving the messages. GSM wireless data module is used for remote wireless applications, machine to machine or user to machine and remote data communications in many applications. The communication used in this project is the mobile communication. GSM (GLOBAL SYSTEM FOR MOBILE COMMUNICATION) modem is connected to the microcontroller through a MAX232 which is a TTL level converter. GSM based Industrial automation implements the emerging applications of the GSM technology. Using GSM networks, a control system has been proposed that will act as an embedded system which can monitor and control appliances and other devices locally using built-in input and output peripherals. Remotely the system allows the user to effectively monitor and control the house/office appliances and equipments via the mobile phone set by sending commands in the form of SMS messages and receiving the appliances status.

ECE Department, RVRIET

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The objective of this project is to develop a device that allows for a user to remotely control and monitor multiple home/office appliances using a cellular phone. This system will be a powerful and flexible tool that will offer this service at any time, and from anywhere with the constraints of the technologies being applied. Possible target appliances include (but are not limited to) climate control system, security systems, lights; anything with an electrical interface. The proposed approach for designing this system is to implement a microcontroller-based control module that receives its instructions and command from a cellular phone over the GSM network. The microcontroller then will carry out the issued commands and then communicate the status of a given appliance or device back to the cellular phone.

1.2 Background:The new age of technology has redefined communication. Most people nowadays have access to mobile phones and thus the world indeed has become a global village. At any given moment, any particular individual can be contacted with the mobile phone. But the application of mobile phone can not just be restricted to sending SMS or starting conversations. New innovations and ideas can be generated from it that can further enhance its capabilities. Technologies such as Infra-red, Bluetooth, etc which has developed in recent years goes to show the very fact that improvements are in fact possible and these improvements have eased our life and the way we live. Remote management of several home and office appliances is a subject of growing interest and in recent years we have seen many systems providing such controls.


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These days, apart from supporting voice calls a mobile phone can be used to send text messages as well as multimedia messages (that may contain pictures, graphics, animations, etc.). Sending written text messages is very popular among mobile phone users. Instant messaging, as it is also known, allows quick transmission of short messages that allow an individual to share ideas, opinions and other relevant information. We have used the very concept to design a system that acts a platform to receive messages which in fact are commands sent to control different appliances and devices connected to the platform. We have designed a control system which is based on the GSM technology that effectively allows control from a remote area to the desired location. The application of our suggested system is immense in the ever changing technological world. It allows a greater degree of freedom to an individual whether it is controlling the household appliances or office equipments. The need to be physically present in order to control appliances of a certain location is eliminated with the use of our system. With the advancement and breakthroughs in technology over the years, the lives of people have become more complicated and thus they have become busier than before. With the adoption of our system, we can gain control over certain things that required constant attention. The application of our system comes in handy when people who forget to do simple things such as turn ON or OFF devices at their home or in their office, they can now do so without their presence by the transmission of a simple text message from their mobile phone. This development, we believe, will ultimately save a lot of time especially when people dont have to come back for simple things such as to turn ON/OFF switches at their home or at their office once they set out for their respective work.

1.3 History of Embedded Systems:-

In the earliest years of computers in the 1930-40s, computers were sometimes dedicated to a single task, but were far too large and expensive for most kinds of tasks performed by embedded computers of today. Over time however, the concept of


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programmable controllers evolved from traditional electromechanical sequencers, via solid state devices, to the use of computer technology. Since these early applications in the 1960s, embedded systems have come down in price and there has been a dramatic rise in processing power and functionality. The first microprocessor for example, the Intel 4004, was designed for calculators and other small systems but still required many external memory and support chips. In 1978 National Engineering Manufacturers Association released a standard" for programmable microcontrollers, including almost any computer-based controllers, such as single board computers, numerical, and event-based controllers. The integration of microcontrollers has further increased the applications for which embedded systems are used into areas where traditionally a computer would not have been considered. A general purpose and comparatively low-cost microcontroller may often be programmed to fulfill the same role as a large number of separate components. Although in this context an embedded system is usually more complex than a traditional solution, most of the complexity is contained within the microcontroller itself. The intangible nature of software makes it much easier to prototype and test new revisions compared with the design and construction of a new circuit not using an embedded processor.


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Figure 1.1: Blocks of an Embedded System Embedded Device Technology is a transformational technology a technology that is revolutionizing the way we function. Embedded Systems can be seen everywhere from Wrist Watches, Washing Machines, Microwave Ovens and Mobile Telephones to Automobiles, Aircrafts and Nuclear Power Plants. Embedded Systems are the brains behind 90% of all electronic devices worldwide. The explosion of Embedded System Technology is expected to happen across product categories like office products, consumer products, products, automobiles, medical instrumentation, vending machines, communications infrastructure, etc. An Embedded System is a combination of hardware and software designed to control the additional hardware attached to the system. The software system is completely encapsulated by the hardware that it controls. Embedded system means the processor is embedded into that application or it is meant for that specific application. Thus printer, keyboard, and video game player etc. are all examples of devices performing specific application.


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In an Embedded System, there is only one application software that is typically burned into ROM. An Embedded System is time-constrained and often resourceconstrained. The brain of an Embedded System is the processor. It may be generalpurpose microprocessor like Intel x86 families or a microcontroller like 8051 family. An embedded product uses a microprocessor or microcontroller to do one specific task only.

A microcontroller is a specific kind of microprocessor whose primary job is to control the hardware it is attached to. A microcontroller has more pins dedicated to carrying I/O signals as compared to microprocessor. A Microcontroller has built-in memory and peripherals (single-chip computer). Whereas a microprocessor has memory and supporting peripherals externally connected.

1.4 Examples of embedded systems:1. Cellular telephones and telephone switches 2. Engine controllers and antilock brake controllers for automobiles 3. Household appliances, including microwave ovens, DVD players 4. Automatic teller machines (ATMs) 5. Home appliances such as fan, refrigerator and tube light etc. 6. Hand held calculators. An embedded system typically has a specialized function with programs stored on ROM. Examples of embedded systems are chips that monitor automobile functions, including engine controls, antilock brakes, air bags, active suspension systems, environmental systems, security systems, and entertainment systems. Everything needed for those functions is custom designed into specific chips. No external operating system is required.


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Figure 1.2: Examples of Embedded Systems An embedded system is a special-purpose computer system designed to perform a dedicated function. Unlike a general-purpose computer, such as a personal computer, an embedded system performs one or a few pre-defined tasks, usually with very specific requirements, and often includes task-specific hardware and mechanical parts not usually found in a general-purpose computer. Since the system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product. Embedded systems are often mass-produced, benefiting from economies of scale. Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. In terms of complexity embedded systems run from simple, with a single microcontroller chip, to very complex with multiple units, peripherals and networks mounted inside a large chassis or enclosure.


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Mobile phones or handheld computers share some elements with embedded systems, such as the operating systems and microprocessors which power them, but are not truly embedded systems themselves because they tend to be more general purpose, allowing different applications to be loaded and peripherals to be connected. Network managers will need to manage more and more embedded systems devices, ranging from printers to scanners, to handheld computing devices, to cell phones. All of these have a need to connect with other devices, either directly or through a wireless or direct-connect network. Most will have custom operating systems or variations of existing operating systems (e.g., Microsoft Windows CE). It's easy to picture nearly every electronic device as having an embedded system. For example, refrigerators, washing machines, and even coffee brewers will benefit in some way from embedded systems. A critical feature of an embedded system is its ability to communicate, so embedded systems support Ethernet, Bluetooth (wireless), infrared, or other technologies. A weather station on top of a building may employ an embedded system that gathers information from external sensors. This information can be pushed or pulled. In the push scenario, the data is automatically sent to devices that have requested it. In the pull scenario, users or network devices access the weather station to read the latest information.


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1.5 Organization of Thesis: Chapter 2 deals with the block diagram of the project, and the Peripherals of the

project. Chapter 3 provides information on hardware design Chapter 4 deals with software design Chapter 5 is all about testing methodology Chapter 6 is about source code Chapter 7 is all about project results

Chapter 8 provides the details conclusion and future scope chapter 9 is about microcontroller

Chapter 10 is L293D Chapter 11 is about LM324 and IR Sensors Chapter 12 is about index Chapter 13 is References


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2. PLAN OF IMPLEMENTATION2.1 Block Diagram:-

Figure 2.1: Block Diagram

2.2 Micro Controller:A microcontroller is a small computer on a single integrated circuit containing a processor core, memory and programmable input/output peripherals. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers. Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, and remote


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controls, office machines, appliances, power tools, and toys. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes. Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems.

2.3 DC Motor:A direct current (DC) motor is a fairly simple electric motor that uses electricity and a magnetic field to produce torque, which turns the motor. At its most simple, a DC motor requires two magnets of opposite polarity and an electric coil, which acts as an electromagnet. The repellent and attractive electromagnetic forces of the magnets provide the torque that causes the DC motor to turn. A DC motor requires at least one electromagnet. This electromagnet switches the current flow as the motor turns, changing its polarity to keep the motor running. The other magnet or magnets can either be permanent magnets or other electromagnets. Often, the electromagnet is located in the center of the motor and turns within the permanent magnets, but this arrangement is not necessary.

2.4 Liquid Crystal Display:A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals (LCs). LCs does not emit light directly. LCDs are more energy efficient and offer safer disposal than CRTs. Its low electrical power consumption enables it to be used in battery-powered electronic equipment. It is an electronically-modulated optical device made up of any number of pixels filled with Liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in colour or monochrome.


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2.5 Power Supply:A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy (e.g., mechanical, chemical, solar) to electrical energy. A power supply is one that controls the output voltage or current to a specific value; the controlled value is held nearly constant despite variations in either load current or the voltage supplied by the power supply's energy source.

2.6 L293D Motor driver:Large amount of current is required to run a motor. The microcontroller can drive only smaller currents. So a motor driver is interfaced with the microcontroller to which provides necessary current to drive the motors. It also acts as an isolator in between the microcontroller and motors to protect the microcontroller from the back e.m.f produced by the motors.

2.7 IR Tran receivers (TCRT5000):TheTCRT5000 is reflective sensors which include an infrared emitter and phototransistor in a leaded package which blocks visible light. We used two pairs of sensors in our project one is for sensing minimum level and other is for maximum level of water.

2.8 Relay:A relay is an electrically controllable switch widely used in industrial controls, automobiles and appliances.


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The relay allows the isolation of two separate sections of a system with two different voltage sources i.e., a small amount of voltage/current on one side can handle a large amount of voltage/current on the other side but there is no chance that these two voltages mix up. When current flows through the coil, a magnetic field are created around the coil i.e., the coil is energized. This causes the armature to be attracted to the coil. The armatures contact acts like a switch and closes or opens the circuit. When the coil is not energized, a spring pulls the armature to its normal state of open or closed. There are all types of relays for all kinds of applications.

2.9 LDR:LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000,000 ohms, but when they are illuminated with light resistance drops dramatically. LDR is light dependent resistor; its resistance in complete dark is around 100 Kilo ohms that drops to few ohms depending upon intensity of light. This sensor is quite frequently used by students and hobbyists.

2.10 MAX232:The MAX232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signals. The drivers provide RS-232 voltage level outputs (approx. 7.5 V) from a single + 5 V supply via on-chip charge pumps and external capacitors. This makes it useful for implementing RS-232 in devices that otherwise do not need any voltages outside the 0 V to + 5 V range, as power supply design does not need to be made more complicated just for driving the RS-232 in this case. The receivers reduce RS-232 inputs (which may be as high as 25 V), to standard 5 V TTL levels.


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2.11 4X4 Matrix Keypad:A keypad is a set of buttons arranged in a block or "pad" which usually bear digits and other symbols and usually a complete set of alphabetical letters. If it mostly contains numbers then it can also be called a numeric keypad. Keypads are found on many alphanumeric keyboards and on other devices such as calculators, push-button telephones, combination locks, and digital door locks, which require mainly numeric input. In order to detect which key is pressed from the matrix, we make row lines low one by one and read the columns. Lets say we first make Row1 low, and then read the columns. If any one of the key in row1 is pressed it will make the corresponding column as low i.e. if second key is pressed in Row1, then the column2 will be low. So we come to know that key 2 of Row1 is pressed. This is how scanning is done.

2.12 GSM Module:Sim300 GSM 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 customized to various levels by using the standard AT commands. The modem is fully type-approved, it can speed up the operational time with full range of Voice, Data, Fax and Short Messages (Point to Point and Cell Broadcast).


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3. HARDWARE DESIGN3.1 Design and interface of JHD162A with AT89S52:Liquid Crystal Display also called as LCD is very helpful in providing user interface as well as for debugging purpose. The most common type of LCD controller is HITACHI 44780 which provides a simple interface between the controller & an LCD. These LCD's are very simple to interface with the controller as well as are cost effective. The most commonly used ALPHANUMERIC displays are:A. 1x16 (Single Line & 16 characters), B. 2x16 (Double Line & 16 character per line), C. 4x20 (four lines & Twenty characters per line).

The LCD requires 3 control lines (RS, R/W & EN) & 8 (or 4) data lines. The number on data lines depends on the mode of operation. If operated in 8-bit mode then 8 data lines + 3 control lines i.e. total 11 lines are required. And if operated in 4bit mode then 4 data lines + 3 control lines i.e. 7 lines are required. How do we decide which mode to use? Its simple if you have sufficient data lines you can go for 8 bit mode & if there is a time constrain i.e. display should be faster than we have to use 8bit mode because basically 4-bit mode takes twice as more time as compared to 8-bit mode. 3.1.1 Connections:The LCD has 3control pins: a) RS: Register[To select command(RS=0) or data register(RS=1)] b) R/W: Read/Write[To send read(R/W=1) or write command (R/W=0)] c) E: Enable [To latch the data and command to LCD(high to low transition)]. The LCD has 8 data pins [DB0 TO DB7]: Pins on LCD are Pin-7 to Pin-14


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3.1.2 Other Connections: The LED+ and LED- pins of LCD are used for the Backlight of LCD. Vcc, Vee and Vss of LCD are used for powering the LCD and controlling the contrast of LCD. When RS is low (0), the data is to be treated as a command. When RS is high (1), the data being sent is considered as text data which should be displayed on the screen. When R/W is low (0), the information on the data bus is being written to the LCD. When RW is high (1), the program is effectively reading from the LCD. Most of the times there is no need to read from the LCD so this line can directly be connected to Ground thus saving one controller line. The ENABLE pin is used to latch the data present on the data pins. A HIGH LOW signal is required to latch the data. The LCD interprets and executes our command at the instant the EN line is brought low. If you never bring EN low, your instruction will never be executed. PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 SYMBOL VSS VCC VEE RS R/W EN DB0 DB1 DB2 DB3 DB4 DB5 DB6 DB7 I/O ---I I I/O I/O I/O I/O I/O I/O I/O I/O I/O DESCRIPTION Ground +5V power supply Power supply to control contrast RS=0 to select command register RS=1 to select data register R/W=0 for write, R/W=1 for read Enable The 8-bit data bus The 8-bit data bus The 8-bit data bus The 8-bit data bus The 8-bit data bus The 8-bit data bus The 8-bit data bus The 8-bit data bus

Table 3.1: LCD Pin Description

3.2 LCD Interfacing to micro controller:ECE Department, RVRIET 16


Figure 3.1: LCD Interfacing To Micro Controller For Contrast setting a 10K pot should be used as shown in the figure, Display Data Ram (DDRAM) stores the display data. So when we have to display a character on LCD we basically write it into DDRAM. For a 2x16 LCD the DDRAM address for first line is from 80h to 8fh & for second line is 0c0h to 0cfh. So if we want to display

Table 3.2: LCD Commands to pins

3.3 Interfacing the Keypad to the Microcontroller:At the lowest level, keyboards are organized in a matrix of rows and columns. The CPU accesses both rows and columns through ports; therefore, with two 8-bit ports, an 8x8 matrix of keys can be connected to a microprocessor. When a key is pressed, a row and a column make a contact; otherwise, there is no connection between


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rows and columns. In IBM PC keyboards, a single microcontroller (consisting of a microprocessor, RAM and EPROM, and several PORTS all on a single chip) takes care of hardware and software interfacing of the keyboard, in such systems, it is the function of programs stored in the EPROM of the microcontroller to scan the keys continuously, identify which one has been activated, and present it to the motherboard. In this section we look at the mechanism by which the microcontroller scans and identifies the key. 3.3.1 Scanning and Identifying the Key:-

Figure 3.2: 4X4 Matrix Keypad Fig shows a 4x4 matrix connected to two ports. The rows are connected to an output port and the columns are connected to an input port. If no key has been pressed, reading the input port will yield 1s for all columns since they are all connected to high (Vcc). If all the rows are grounded and a key is pressed, one of the columns will have 0 since the pressed provides the path to ground. It is the function of the microcontroller to scan the keyboard continuously to detect and identify the key pressed. How it is done is explained next. 3.3.2 Grounding Rows and Reading the Columns:To detect a pressed key, the microcontroller grounds all rows by providing 0 to the output latch, and then it reads the columns. If the data read from the columns is D3ECE Department, RVRIET 18


D0=1111, no key has been pressed and the process continues until a key press is detected. However, if one of the column bits has a 0, this means that a key press has occurred. For Example, if D3-D0=1101, this means that a key in the D1 column has been pressed. After a key press is detected the microcontroller will go through the process of identifying the key. Starting with the top row, the microcontroller grounds it by providing a low to row D0 only; then it reads the columns. If the data reads is all 1s, no key in that row is activated and the process is moved to the next row. It grounds the next row, reads the columns, and checks for any 0. This process continues until the row is identified. After identification of the row in which the key has been pressed, the next task is to find out which column the pressed key belongs to. This should be easy since the microcontroller knows at any time which row and column are being accessed. 3.3.3 The Process of Scanning a Key goes through the following 4 Steps:1. To make sense that the preceding key has been released, 0s are output to all rows at

once and the columns are read and checked repeatedly until all the columns are high. When all columns are found to be high, the program waits for a short amount of time before it goes to the next stage of waiting for a key to be pressed.

2. To see if any key is pressed, the columns scanned over and over in an infinite loop until one of them has a zero (0) on it. Remember that the output latches connected to rows still have their initial zeros making them grounded. After the key press detection it waits 20ms for bounce and then scans the columns again. This serves two functions It ensures that the first key detection was not an erroneous one due to a spike noise and The 20ms delay prevents the same key press from being interpreted as a multiple key press .If after 20 ms delay the key is still pressed, it goes to the


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next stage to detect which row it belongs to ;otherwise it goes back in to the loop to detect a read key press. 3. To detect which row the key press belongs to, it grounds one row at a time reading the column search time .If it finds that all columns are high this means that the key press does not belongs to the row, therefore it grounds the next row and continues until it finds the row key press belongs to, it sets up the starting address for the look up table holding the scan codes for that row and goes to The next stage to identify the key. 4. To identify the key press, it rotates the column bits one bit at a time in to the carry flag and check to see if it is low. Upon finding the zero, it pulls out the (ASCII code) character for that key from the look up table. Otherwise it increments the pointer to point to the next element of the look up table.

3.4 Interfacing L293 Driver to the Microcontroller:L293D is a dual H-Bridge motor driver, So with one IC we can interface two DC motors which can be controlled in both clockwise and counter clockwise direction and if you have motor with fix direction of motion the you can make use of all the four I/Os to connect up to four DC motors. L293D has output current of 600mA and peak output current of 1.2A per channel. Moreover for protection of circuit from back

EMF ouput diodes are included within the IC. The output supply (VCC2) has a wide range from 4.5V to 36V, which has made L293D a best choice for DC motor driver.A simple schematic for interfacing a DC motor using L293D is shown below.


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Figure 3.3: interfacing of L293 As in the above figure, three pins are needed for interfacing a DC motor (A, B, Enable). If you want the o/p to be enabled completely then you can connect Enable to VCC and only 2 pins needed from controller to make the motor work. As per the truth mentioned in the image above its fairly simple to program the microcontroller. Its also clear from the truth table of BJT circuit and L293D the programming will be same for both of them, just keeping in mind the allowed combinations of A and B. We will discuss about programming in C as well as assembly for running motor with the help of a microcontroller.

3.5 GSM modem:3.5.1 Introduction:-


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Sim300 GSM 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 customized to various levels by using the standard AT commands. The modem is fully type-approved, it can speed up the operational time with full range of Voice, Data, Fax and Short Messages (Point to Point and Cell Broadcast). 3.5.2 Description of the interfaces:The modem comprises several interfaces: LED Function including operating Status External antenna Serial and control link Power Supply SIM card holder

3.5.3 LED Status Indicator:The LED will indicate different status of the modem: OFF ON Flashing Slowly Flashing rapidly Modem Switched off Modem is connecting to the network Modem is in idle mode Modem is in transmission/communication (GSM only)

GSM is one of the latest mobile technologies using smart MODEM, which can easily interfaced to embedded microcontrollers. Now everything is going to be automated using this technology, using this technology we can access the devices remotely. Using GSM and GPS now we can identify the people, vehicles etc in anywhere of the world.

MODEM is communicating with the microcontroller using AT commands, for example if we want to send an SMS to number 98xxxxxxxxx,the commands we have to send is AT+CMGS=, , , .


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Figure 3.4 GSM checking HyperTerminal snapshot In this project it is used to send SMS to the mobile In this project MODEM is communication with the microcontroller through serial port, the microcontroller will send the commands to the modem through RS 232.and the data is read through serial port therefore to make compatible computer serial port with microcontroller serial port we are using the RS 232 converter. The GSM module has GSM modem, DB9 connector, MAX 232 line driver for its communication with the microcontroller. Since the operating voltage different for the microcontroller and the modem, the MAX 232 is used which provides the electrical interface between an asynchronous communication controller and the serial port connector .The serial port connector here is DB9 connecter. The microcontroller has TTL logic levels for TXD, RXD pins and for RS232 different voltage levels logics. So for proper communications MAX232 is used to convert RS 232 voltages to TTL logic voltage levels. The baud rate is set to 9,600 bits/s. GSM modems in use has baud rate of 9600 bits/sec. It enables us to send and receive 30 messages at a time. With GSM modems, you must insert a valid SIM card into the slot on the front of the modem. Once the modem has been prepared for use, connect it to a serial port on your PC using the data cable that is included with the modem.


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Figure 3.5 GSM module interface with AT89S52

3.6 Reset Circuit:High logical state on this input halts the MCU and clears all the registers. Bringing this pin back to logical state zero starts the program a new as if the power had just been turned on. In another words, positive voltage impulse on this pin resets the MCU. Depending on the device's purpose and environs, this pin is usually connected to the push-button, reset-upon-start circuit or a brown out reset circuit. The image shows one simple circuit for safe reset upon starting the controller. It is utilized in situations when power fails to reach its optimal voltage. 3.7. Crystal Oscillator Circuit:Input(X1) and output(X2) of internal oscillator. Quartz crystal controlling the frequency commonly connects to these pins. Capacitances within the oscillator mechanism are not critical and are normally about 30pF. Instead of a quartz crystal, miniature ceramic resonators can be used for dictating the pace.


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3.8 Schematic diagram:-

Figure 3.6: Schematic diagram

4. SOFTWARE DESIGN4.1 Cross Complier:-


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A cross

compiler is

a compiler capable

of

creating executable code

for

a platform other than the one on which the compiler is run. Cross compiler tools are used to generate executable for embedded system or multiple platforms. It is used to compile for a platform upon which it is not feasible to do the compiling, like microcontrollers that don't support an operating system. It has become more common to use this tool for Para virtualization where a system may have one or more platforms in use. Not targeted by this definition are source to source translators, which are often mistakenly called cross compilers.

4.1.1 Uses of Cross Compliers:The fundamental use of a cross compiler is to separate the build environment from target environment. This is useful in a number of situations: Embedded computers where a device has extremely limited resources. For example, a microwave oven will have an extremely small computer to read its touchpad and door sensor, provide output to a digital display and speaker, and to control the machinery for cooking food. This computer will not be powerful enough to run a compiler, a file system, or a development environment. Since debugging and testing may also require more resources than are available on an embedded system, crosscompilation can be less involved and less prone to errors than native compilation. Compiling for multiple machines. For example, a company may wish to support several different versions of an operating system or to support several different operating systems. By using a cross compiler, a single build environment can be set up to compile for each of these targets. Compiling on a server farm. Similar to compiling for multiple machines, a complicated build that involves many compile operations can be executed across any machine that is free, regardless of its underlying hardware or the operating system version that it is running.

Boot strapping to a new platform. When developing software for a new platform, or the emulator of a future platform, one uses a cross compiler to compile


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necessary tools such as the operating system and a native compiler. Compiling native code for emulators for older now-obsolete platforms like the Commodore 64 or Apple II by enthusiasts who use cross compilers that run on a current platform (such as Aztec C's MS DOS 6502 cross compilers running under Windows XP).

4.2 Embedded driver code for LCD:Before starting to display on LCD we need to initialize it. Firstly we must tell the LCD whether we'll be using 8-bit or 4-bit mode. Also we will be telling the LCD that we need 5x8 character font. Both these options are selected using a single command i.e. 38h. So to activate both these options we must execute following instructions.

4.3 Basic Commands of LCD:When LCD is powered up the display should show a series of dark squares, possibly only on part of display. These characters are actually in their off state, so the contrast control should be adjusted anti-clockwise until the squares are just visible. The display module resets itself to an initial state when power is applied, which curiously the display has blanked off so that even if characters are entered, they cannot be seen. It is therefore necessary to issue a command at this point, to switch the display on.

4.3.1 Circuit Description of LCD Experiment:The circuit can be wired up on a plug-in-style prototyping board, using dual-inline switches for the data lines (S1-S8). A toggle switch for the RS input (S10) and a momentary action switch (or macro switch) for usage.

Most of the LCD modules conform to a standard interface specification. A 14pin access is provided having eight data lines, three control lines and three power


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lines. The connections are laid out in one of the two common configurations, either two rows of seven pins, or a single row of 14 pins. One of the, pins are numbered on the LCDs print circuit board (PCB), but if not, it is quite easy to locate pin1. Since this pin is connected to ground, it often has a thicker PCB track, connected to it, and it is generally connected to metalwork at same point. The LCD requires either 8 or 11 I/O lines to communicate with. For the sake of this tutorial, e going to use an 8-bit data bus--so we'll be using 11 of the 8051's I/O pins to interface with the LCD. A 1-to-1 relation is established between a pin on the 8051 and a line on the 44780 LCD. Thus write assembly program to access the LCD, and equate constants to the 8051 ports so that refer to the lines by their 44780 name as opposed to P0.1, P0.2, etc. DB0 EQU P1.0 DB1 EQU P1.1 DB2 EQU P1.2 DB3 EQU P1.3 DB4 EQU P1.4 DB5 EQU P1.5 DB6 EQU P1.6 DB7 EQU P1.7 EN EQU P3.7 RS EQU P3.6 RW EQU P3.5 DATA EQU P1 Having established the above equates, we may now refer to our I/O lines by their 44780 name. For example, to set the RW line high (1), we can execute the following instruction: SETB RW

4.3.2 Handling the EN Control Line:-


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As mentioned above, the EN line is used to tell the LCD that you are ready for it to execute an instruction that you've prepared on the data bus and on the other control lines. Note that the EN line must be raised/lowered before/after each instruction sent to the LCD regardless of whether that instruction is read or write text or instruction. In short, you must always manipulate EN when communicating with the LCD. EN is the LCD's way of knowing that you are talking to it. If you don't raise/lower EN, the LCD doesn't know you're talking to it on the other lines. Thus, before we interact in any way with the LCD we will always bring the EN line low with the following instruction: CLR EN And once finished setting up instruction with the other control lines and data bus lines, we'll always bring this line high: SETB EN The line must be left high for the amount of time required by the LCD as specified in its datasheet. This is normally on the order of about 250 nanoseconds, but checks the datasheet. In the case of a typical 8051 running at 12 MHz, an instruction requires 1.08 microseconds to execute so the EN line can be brought low the very next instruction. However, faster microcontrollers (such as the DS89C420 which executes an instruction in 90 nanoseconds given an 11.0592 Mhz crystal) will require a number of NOPs to create a delay while EN is held high. The number of NOPs that must be inserted depends on the microcontroller you are using and the crystal you have selected.The instruction is executed by the LCD at the moment the EN line is brought low with a final CLR EN instruction. Programming Tip: The LCD interprets and executes our command at the instant the EN line is brought low. If you never bring EN low, your instruction will never be executed. Additionally, when you bring EN low and the LCD executes your instruction, it requires a certain amount of time to execute the command. The time it requires to execute an instruction depends on the instruction and the speed of the crystal which is attached to the 44780's oscillator input. 4.3.3 Checking the Busy Status of the LCD:-


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As previously mentioned, it takes a certain amount of time for each instruction to be executed by the LCD. The delay varies depending on the frequency of the crystal attached to the oscillator input of the 44780 as well as the instruction which is being executed. While it is possible to write code that waits for a specific amount of time to allow the LCD to execute instructions, this method of "waiting" is not very flexible. If the crystal frequency is changed, the software will need to be modified. Additionally, if the LCD itself is changed for another LCD which, although 44780 compatible, requires more time to perform its operations, the program will not work until it is properly modified. A more robust method of programming is to use the "Get LCD Status" command to determine whether the LCD is still busy executing the last instruction received. The "Get LCD Status" command will return to us two tit-bits of information; the information that is useful to us right now is found in DB7. In summary, when we issue the "Get LCD Status" command the LCD will immediately raise DB7 if it's still busy executing a command or lower DB7 to indicate that the LCD is no longer occupied. Thus our program can query the LCD until DB7 goes low, indicating the LCD is no longer busy. Since programmer use this code every time we send an instruction to the LCD, it is useful to make it a subroutine. Let's write the code: WAIT_LCD: CLR RS ;It's a command SETB RW ;It's a read command MOV DATA,#0FFh ;Set all pins to FF initially SETB EN ;Clock out command to LCD MOV A,DATA ;Read the return value JB ACC.7,WAIT_LCD ;If bit 7 high, LCD still busy CLR EN ;Finish the command CLR RW ;Turn off RW for future commands Thus, standard practice will be to send an instruction to the LCD and then call our WAIT_LCD routine to wait until the instruction is completely executed by the


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LCD. This will assure that our program gives the LCD the time it needs to execute instructions and also makes our program compatible with any LCD, regardless of how fast or slow it is. Programming Tip: The above routine does the job of waiting for the LCD, but was it to be used in a real application a very definite improvement would need to be made: as written, if the LCD never becomes "not busy" the program will effectively "hang," waiting for DB7 to go low. If this never happens, the program will freeze. Of course, this should never happen and won't happen when the hardware is working properly. But in a real application it would be wise to put some kind of time limit on the delay--for example, a maximum of 256 attempts to wait for the busy signal to go low. This would guarantee that even if the LCD hardware fails, the program would not lock up. 4.3.4 Initializing the LCD:Before using the LCD, it must initialize and configure it. This is accomplished by sending a number of initialization instructions to the LCD. The first instruction send must tell the LCD whether be communicating with it with an 8-bit or 4-bit data bus. Also select a 5x8 dot character font. These two options are selected by sending the command 38h to the LCD as a command. Thus, to send this 38h command to the LCD must execute the following 8051 instructions: CLR RS MOV DATA,#38h SETB EN CLR EN LCALL WAIT_LCD Programming Tip: The command 06h is really the instruction 04h plus 02h to configure the LCD such that every time we send it a character, the cursor position automatically moves to the right So, in all, initialization code is as follows: INIT_LCD:


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CLR RS MOV DATA,#38h SETB EN CLR EN LCALL WAIT_LCD CLR RS MOV DATA,#0Eh SETB EN CLR EN LCALL WAIT_LCD CLR RS MOV DATA,#06h SETB EN CLR EN LCALL WAIT_LCD RET Having executed this code the LCD will be fully initialized and ready to send display data to it. 4.3.5 Clearing the Display:When the LCD is first initialized, the screen should automatically be cleared by the 44780 controller. An LCD command exists to accomplish this function. Not surprisingly, it is the command 01h. Since clearing the screen is a function very likely will wish to call more than once, it's a good idea to make it a subroutine: CLEAR_LCD: CLR RS MOV DATA, #01h SETB EN


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CLR EN LCALL WAIT_LCD RET How that we've written a "Clear Screen" routine, may clear the LCD at any time by simply executing an LCALL CLEAR_LCD. Programming Tip: Executing the "Clear Screen" instruction on the LCD also positions the cursor in the upper left-hand corner 4.3.6 Writing Text to the LCD:Writing text to the LCD is something we'll almost certainly want to do over and over--so let's make it a subroutine. WRITE_TEXT: SETB RS MOV DATA, A SETB EN CLR EN LCALL WAIT_LCD RET The WRITE_TEXT routine that wrote will send the character in the accumulator to the LCD which will, in turn, display it. Thus to display text on the LCD all need to do is load the accumulator with the byte to display and make a call to this routine. A "HELLO WORLD" Program Now that we have all the component subroutines written, writing the classic "Hello World" program--which displays the text "Hello World" on the LCD is a relatively trivial matter. Consider: LCALL INIT_LCD LCALL CLEAR_LCD MOV A,#'H' LCALL WRITE_TEXT


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MOV A,#'E' LCALL WRITE_TEXT MOV A,#'L' LCALL WRITE_TEXT MOV A,#'L' LCALL WRITE_TEXT MOV A,#'O' LCALL WRITE_TEXT MOV A,#' ' LCALL WRITE_TEXT MOV A,#'W' LCALL WRITE_TEXT MOV A,#'O' LCALL WRITE_TEXT MOV A,#'R' LCALL WRITE_TEXT MOV A,#'L' LCALL WRITE_TEXT MOV A,#'D' LCALL WRITE_TEXT The above "Hello World" program should, when executed, initialize the LCD, clear the LCD screen, and display "Hello World" in the upper left-hand corner of the display. 4.3.7 Cursor Positioning:The above "Hello World" program is simplistic in the sense that it prints its text in the upper left-hand corner of the screen. However, what if we wanted to display the word "Hello" in the upper left-hand corner but wanted to display the word "World" on the second line at the tenth character? This sounds simple--and actually, it is simple. However, it requires a little more understanding of the design of the


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LCD.The 44780 contains a certain amount of memory which is assigned to the display. All the text we write to the 44780 is stored in this memory, and the 44780 subsequently reads this memory to display the text on the LCD itself. This memory can be represented with the following "memory map": In the above memory map, the area shaded in blue is the visible display. As you can see, it measures 16 characters per line by 2 lines. The numbers in each box is the memory address that corresponds to that screen position. Thus, the first character in the upper left-hand corner is at address 00h. The following character position (character #2 on the first line) is address 01h, etc. This continues until we reach the 16th character of the first line which is at address 0Fh. However, the first character of line 2, as shown in the memory map, is at address 40h. This means if we write a character to the last position of the first line and then write a second character, the second character will not appear on the second line. That is because the second character will effectively be written to address 10h--but the second line begins at address 40h. Thus we need to send a command to the LCD that tells it to position the cursor on the second line. The "Set Cursor Position" instruction is 80h. To this we must add the address of the location where we wish to position the cursor. In our example, we said we wanted to display "World" on the second line on the tenth character position. Referring again to the memory map, we see that the tenth character position of the second line is address 4Ah. Thus, before writing the word "World" to the LCD, we must send a "Set Cursor Position" instruction--the value of this command will be 80h (the instruction code to position the cursor) plus the address 4Ah. 80h + 4Ah = CAh. Thus sending the command CAh to the LCD will position the cursor on the second line at the tenth character position: CLR RS MOV DATA,#0CAh SETB EN


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CLR EN LCALL WAIT_LCD The above code will position the cursor on line 2, character 10. To display "Hello" in the upper left-hand corner with the word "World" on the second line at character position 10 just requires us to insert the above code into our existing "Hello World" program. This results in the following: CALL lcd_command Now that we have to Turn On the display & set the cursor option i.e. cursor ON/OFF & Cursor blinking ON/OFF for that we will use the command 0Eh i.e. Display On , Cursor ON but Cursor blinking OFF. MOV A,#0Eh CALL lcd_command And the last command we require is to configure the LCD in such a way that everytime we send a character to it the cursor position automatically increments by one & moves to right i.e. 06h. MOV A,#06h CALL lcd_command The lcd_initialize contains the following instructions lcd_initialize: MOV A,#38h CALL lcd_command MOV A, #38h CALL lcd_command MOV A,#38h CALL lcd_command Ret


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4.4 Flow Chart for displaying data on screen:-

Fig Flowchart for LCD

4.5 LCD Test Code to Display a Message on Screen:#include sbit r0=P1^0; sbit r1=P1^1; sbit r2=P1^2;


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sbit r3=P1^3; sbit c0=P1^4; sbit c1=P1^5; sbit c2=P1^6; sbit c3=P1^7; sfr ldata=0x80; sbit rs=P2^7; sbit rw=P2^6; sbit en=P2^5; sbit busy=P0^7; void lcdcmd(unsigned char); void lcddata(unsigned char); void lcdready(void); void MSDelay(unsigned int); void WriteString(unsigned char,unsigned char *); unsigned char KeyTest(void); void Start(void); void LCDClear(void); void lcdcmd (unsigned char value) { lcdready(); ldata=value; rs=0; rw=0; en=1; MSDelay(1); en=0; } void lcddata (unsigned char value) { lcdready();


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ldata=value; rs=1; rw=0; en=1; MSDelay(1); en=0; } void lcdready(void) { busy=1; rs=0; rw=1; while(busy==1) { en=0; MSDelay(1); en=1; } } void MSDelay(unsigned int Iter) { unsigned int i, j; for(i=0;iI/O Ports=>Port N from the pulldown menus, where is the port number. A checked box in the port window indicates a high (1) pin, and an empty box indicates a low (0) pin. Both the I/O port data and the data at the left side of the screen are updated whenever the program is paused. The debugger will help eliminate many programming errors, however the simulation is not perfect and code that executes properly in simulation may not always work on the actual microcontroller.


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5.3 Device Database:A unique feature of the Keil Vision3 IDE is the Device Database, which contains information about more than 400 supported micro controllers. When you create a new n e w Vision3 project and select the target chip from the database, Vision3 sets all assembler, compiler, linker, and debugger options for you. The only option you must configure is the memory map.

5.4 Peripheral Simulation:The Vision3 Debugger provides complete simulation for the CPU and on-chip peripherals of most embedded devices. To discover which peripherals of a device are supported, in Vision3 select the Simulated Peripherals item from the Help menu. You may also use the web-based Device Database. We are constantly adding new devices and simulation support for on-chip peripherals so be sure to check Device Database often.

5.5 Programmer:The programmer used is a powerful programmer for the Atmel 89 series of microcontrollers that includes 89C51/52/55, 89S51/52/55 and many more. It is simple to use & low cost, yet powerful flash microcontroller programmer for the Atmel 89 series. It will Program, Read and Verify Code Data, Write Lock Bits, Erase and Blank Check. All fuse and lock bits are programmable. This programmer has intelligent onboard firmware and connects to the serial port. It can be used with any type of computer and requires no special hardware. All that is needed is a serial communication port which all computers have. All devices also have a number of lock bits to provide various levels of software and programming protection. These lock bits are fully programmable using this programmer. Lock bits are useful to protect the program to be read back from micro controller only allowing erase to reprogram the micro controller. Major parts of this programmer are Serial Port, Power


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Supply and Firm ware microcontroller. Serial data is sent and received from 9 pin connector by MAX232 chip. A Male to Female serial port cable, connects to the 9 pin connector of hardware and another side connects to back of computer. All the programming intelligence is built into the programmer so you do not need any special hardware to run it. Programmer comes with window based software for easy programming of the devices.

5.6 Pro Load Programming Software:Pro Load is a software working as a user friendly interface for programmer boards from Sun ROM Technologies. Pro Load gets its name from Program Loader term, because that is what it is supposed to do. It takes in compiled HEX file and loads it to the hardware. Any compiler can be used with it, Assembly or C, as all of them generate compiled HEX files. Pro Load accepts the Intel HEX format file generated from compiler to be sent to target microcontroller. It auto detects the hardware connected to the serial port. It also auto detects the chip inserted and bytes used. The software is developed in Delhi and requires no overhead of any external DLL. The programmer connects to the computers serial port (Comm 1, 2, 3 or 4) with a standard DB9 Male to DB9 Female cable. Baud Rate - 57600, COMx Automatically selected by window software. No PC Card Required. After making the necessary selections, the Auto Program button is clicked as shown in the figure below which burns the selected hex file onto the microcontroller.


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Figure: 5.7 Programming window


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6. SOURCE CODE

#include sbit r0=P1^0; //keypad rows sbit r1=P1^1; sbit r2=P1^2; sbit r3=P1^3; sbit c0=P1^4; //keypad columns sbit c1=P1^5; sbit c2=P1^6; sbit c3=P1^7; sfr ldata=0x80; // PORT0 for SFR address(LCD data pins) sbit rs=P2^7; sbit rw=P2^6; sbit en=P2^5; sbit busy=P0^7; //RS set for Giving the Command or Data // Read/write command for the data in the LCD RAM // Enable Bit of the LCD //busy pin of the controller

sbit Motor_In1=P2^0; sbit Motor_In2=P2^3; sbit en1=P2^1; sbit sense1=P3^2; sbit sense2=P3^3; void lcdcmd (unsigned char); void lcddata (unsigned char); void lcdready(void); void MSDelay(unsigned int); void WriteString(unsigned char,unsigned char *); unsigned char KeyTest(void); void Start(void); void LCDClear(void); void MainMenu(void);


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void UpdateService(void); unsigned char MY_PWD[4]={'1','2','3','4'};

void lcdcmd (unsigned char value) { lcdready(); ldata=value; rs=0; rw=0; en=1; MSDelay(1); en=0; } void lcddata (unsigned char value) { lcdready(); ldata=value; rs=1; rw=0; en=1; MSDelay(1); en=0; } void lcdready(void) { busy=1; rs=0; rw=1; while(busy==1) { en=0; MSDelay(1);ECE Department, RVRIET 52


en=1;

} } void MSDelay(unsigned int Iter) { unsigned int i, j; for(i=0;i

gsm base industrial control

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include sbit

sbit c0p14

sbit c3p17

sbit r2p12

sbit r3p13

sbit c2p16

sbit enp25

sbit rwp26