CHAPTER 1INTRODUCTIONGSM controlled robot or SMS controlled robot is a wireless robot which performs the necessary actions by receiving a set of instructions in the form a Short Message Service (SMS). In this project we can control the robot directions like forward, backward, left and right by sending SMS from the mobile. Earlier, we have already seen the working of a DTMF Controlled Robot without using Microcontroller.This project mainly consists of 2 sections, one is mobile unit and the other one is robot unit. The GSM modem which is fixed at the robot receives the messages sent by the obstacle sensor and gives the instructions to the microcontroller to control the robot directions. In this project, we interface LPC2148 microcontroller with GSM SIM 900. The protocol used for the communication between controller and GSM modem is UART (Universal Asynchronous Receiver-Transmitter). This system continuously checks for message to take the decision for controlling the robot.SMSControlled Robot Circuit Design:The major components used in the above circuit are microcontroller, motor driver, level converter, GSM module and robot. Here LPC2148 microcontroller is used and it requires a power supply of positive 12V DC. In order to provide regulated 12V DC voltage to the controller, use 7812 power supply circuit. Here one 12V batteries are used, it is for giving the supply to the circuit and to run the DC motors.GSM modem Tx and Rx pins are connected to the 13 and 14 pins of max232. Microcontroller TXD and RXD pins are connected to the 11 and 12 pins of level converter. Here max232 is a mediator between controller and GSM module and it is used to convert the voltage levels. To know more details about max232 referMax232 Datasheet.GSM module requires 5V power supply. In order to communicate with this GSM we need to send AT commands using serial communication (UART protocol). Use a baud rate of 9600 to communicate with GSM.P2.0, P2.1, P2.2 and P2.3 pins of controller are connected to the l293d input pins and these pins are used to control the two DC motors. The operating voltage of this IC is 5V. Using this IC we can operate the 2 DC motors with a voltage ranging from 4.5 to 36V. We need to apply the motors supply at 8th pin of l293d.

CHAPTER 2EMBEDDED SYSTEMS 2.1 Description of embedded systems:Embedded computers or embedded systems, and actually account for more than 90% of all the worlds manufactured processors. In general, users of embedded systems see a specialized function (such as a High-Definition TV) and do not directly think of the computer embedded within the system. Such embedded computers are gaining importance as an increasing number of systems use embedded processors, RAM, disk drives, and networks. Embedded systems range in size from simple toasters and mini-robots to large-scale systems deployed in process control, manufacturing, power generation, defense systems, telecommunication systems, automotive systems, air traffic control, avionics, video-on-demand and video-conferencing systems. Embedded systems also differ from their conventional PC or workstation cousins in several ways. Embedded systems are typically used over long periods of time, will not (or cannot) be programmed or maintained by its end-users, and often face significantly different design constraints such as limited memory, low cost, strict performance guarantees, fail-safe operation, low power, reliability and guaranteed real-time behavior. These embedded systems often use simple executives (OS kernels) or real-time operating systems with typically small footprints, support for real-time scheduling and no hard drives. Many embedded systems also interact with their physical environment using a variety of sensors and/or actuators.An embedded system is a special computer system designed to perform one or a few dedicated functions often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer (PC), is designed to be flexible and to meet a wide range of end-user needs. Embedded systems control many devices in common use today.Embedded systems are controlled by one or more main processing cores that are typically either microcontrollers or digital signal processors (DSP). The key characteristic, however, is being dedicated to handle a particular task, which may require very powerful processors. For example, air traffic control systems may usefully be viewed as embedded, even though they involve mainframe computers and dedicated regional and national networks between airports and radar sites. Since the embedded system is dedicated to specific tasks, design engineers can optimize it to reduce the size and cost of the product and increase the reliability and performance. Some embedded systems are mass-produced, benefiting from economies of scale.In general, "embedded system" is not a strictly definable term, as most systems have some element of extensibility or programmability. For example, handheld computers share some elements with embedded systems such as the operating systems and microprocessors which power them, but they allow different applications to be loaded and peripherals to be connected. Moreover, even systems which don't expose programmability as a primary feature generally need to support software updates. On a continuum from "general purpose" to "embedded", large application systems will have subcomponents at most points even if the system as a whole is "designed to perform one or a few dedicated functions", and is thus appropriate to call "embedded".Embedded systems programming is not like normal PC programming. In many ways, programming for an embedded system is like programming PC 15 years ago. The hardware for the system is usually chosen to make the device as cheap as possible. Spending an extra dollar a unit in order to make things easier to program can cost millions. Hiring a programmer for an extra month is cheap in comparison. This means the programmer must make do with slow processors and low memory, while at the same time battling a need for efficiency not seen in most PC applications. Below is a list of issues specific to the embedded field.2.1.1 Tools:Embedded development makes up a small fraction of total programming. There's also a large number of embedded architectures, unlike the PC world where 1 instruction set rules, and the UNIX world where there's only 3 or 4 major ones. This means that the tools are more expensive. It also means that they're lower featured, and less developed. On a major embedded project, at some point you will almost always find a compiler bug of some sort.2.1.2 Resources:To save costs, embedded systems frequently have the cheapest processors that can do the job. This means your programs need to be written as efficiently as possible. When dealing with large data sets, issues like memory cache misses that never matter in PC programming can hurt you. Luckily, this won't happen too often- use reasonably efficient algorithms to start, and optimize only when necessary. Of course, normal profilers won't work well, due to the same reason debuggers don't work well. So more intuition and an understanding of your software and hardware architecture is necessary to optimize effectively.2.2 Need for embedded systems:The uses of embedded systems are virtually limitless, because every day new products are introduced to the market that utilizes embedded computers in novel ways. In recent years, hardware such as microprocessors, microcontrollers, and FPGA chips have become much cheaper. So when implementing a new form of control, it's wiser to just buy the generic chip and write your own custom software for it. Producing a custom-made chip to handle a particular task or set of tasks costs far more time and money. Many embedded computers even come with extensive libraries, so that "writing your own software" becomes a very trivial task indeed. From an implementation viewpoint, there is a major difference between a computer and an embedded system. Embedded systems are often required to provide Real-Time response.2.2.1 Reliability:Embedded systems often reside in machines that are expected to run continuously for years without errors and in some cases recover by them if an error occurs. Therefore the software is usually developed and tested more carefully than that for personal computers, and unreliable mechanical moving parts such as disk drives, switches or buttons are avoided.2.3Operating System:They often have no operating system, or a specialized embedded operating system (often a real-time operating system), or the programmer is assigned to port one of these to the new system.2.4Debugging:Debugging is usually performed with an in-circuit emulator, or some type of debugger that can interrupt the micro controllers internal microcode. The microcode interrupt lets the debugger operate in hardware in which only the CPU works. The CPU-based debugger can be used to test and debug the electronics of the computer from the viewpoint of the CPU. Developers should insist on debugging which shows the high-level language, with breakpoints and single stepping, because these features are widely available. Also, developers should write and use simple logging facilities to debug sequences of real-time events. PC or mainframe programmers first encountering this sort of programming often become confused about design priorities and acceptable methods. Mentoring, code-reviews and ego less programming are recommended.2.5Design of Embedded Systems:The electronics usually uses either a microprocessor or a microcontroller. Some large or old systems use general-purpose mainframes computers or minicomputers.2.6 Applications of embedded systems:Embedded systems span all aspects of modern life.

2.7 Telecommunication systems:It employs numerous embedded systems from telephone switches for the network to mobile phones at the end-user. Computer networking uses dedicated routers and network bridges to route data.2.7.1 Consumer electronics:It includes personal digital assistants (PDAs), embedded systems which include microwave oven, remote control, VCD players, DVD players, digital camera, mp3 players, videogame consoles, GPS receivers and printers etc.2.7.2 Household appliances: Home appliances as microwave ovens, washing machines and dishwashers, are including embedded systems to provide flexibility, efficiency and features. Advanced HVAC systems use networked thermostats to more accurately and efficiently control temperature that can change by time of day and season.2.7.3 Office/home automation system:It uses wired- and wireless-networking that can be used to control lights, climate, security, audio/visual, surveillance, etc., all of which use embedded devices for sensing and controlling.

CHAPTER-3HARDWARE DESCRIPTION3.1 Introduction:In this chapter the block diagram of the project and design aspect of independent modules are described. The block diagram is as shown below in fig 3.1.Block diagram:

Micro controllerMicro controllerObstacle sensorGSM ModemMotor DriverLeftMotorRightMotor

Figure 3.1: Block diagram

The main components of this project are: LPC2148 Microcontroller GSM Motor Driver Motors IP Camera Obstacle sensor

3.1.1. LPC2148FEATURES: High-performance, Low-power Consumption 32-bit Microcontroller RISC Architecture 64-pin High-Performance ARM Microcontroller Flash Program Memory: 512 K Bytes SRAM Data Memory: 32 K Bytes I/O Pins: 45 Timers: Two 32-bit A/D Converter: 10-bit Fourteen Channels DAC: 10-bit Real-Time Clock (RTC): Independent Power and Dedicated 32kHz Input IC: Two Modules with Master or Slave Operation SPI: Full Duplex Serial Operation UART: Two Modules USB: 2.0B Fully Compliant Controller with RAM External Oscillator: up to 25MHz with integrated PLL for 60MHz OperationPin Configurations:

Figure 3.1.1: LPC2148 CHIP

Figure 3.1.1.2: LPC2148 PIN CONFIGURATIONOVERVIEW:The LPC2148 is a general purpose 32-bit microprocessor, which offers high performance and very low power consumption. The architecture is based on RISCPrinciples, and the instruction set and related decode mechanism are much simpler than those of micro programmed CISC. This simplicity results in a high instruction throughput and impressive real-time interrupt response from a small and cost-effective processor core.Pipeline techniques are employed so that all parts of the processing and memory systems can operate continuously. Typically, while one instruction is being executed, its successor is being decoded, and a third instruction is being fetched from memory.The key idea behind Thumb is that of a super-reduced instruction set. Essentially, the LPC2148 processor has two instruction sets: The standard 32-bit ARM set.LPC2148 combines microcontroller with embedded high speed flash memory ranging from 32 kb to 512 kb. A 128-bit wide memory interface and a unique accelerator architecture enable 32-bit code execution at the maximum clock rate. For critical code size applications, the alternative 16-bit Thumb mode reduces code by more than 30 % with minimal performance penalty.Due to its tiny size and low power consumption, LPC2148 is ideal for applications where miniaturization is a key requirement. Serial communications interfaces ranging from a USB 2.0 Full-speed device, multiple UARTs, SPI, SSP to I2C-bus and on-chip SRAM of 8 KB up to 40 KB, make these devices very well suited for communication gateways and protocol converters, providing both large buffer size and high processing power.Block diagram of LPC2148:

Figure: 3.1.2 Block diagram of LPC2148PIN DESCRIPTION:LPC2148 has two I/0 ports namely PORT0 and PORT1. Each PORT has 32 IO pins. In PORT0 pins P0.24, P0.26 and P0.27 are not available. In PORT1 pins 0 to 15 are not available. Each port pin has multiple functions. These functions can be selected by using pin Connect Block. Pin Connect Block contains three 32-bit registers namely PINSEL0, PINSEL1 and PINSEL2.IOPIN (IOPIN0 for PORT0 and IOPIN0 for PORT1):GPIO Port pin value register. The current state of the GPIO configured port pins can always be read from this register, regardless of pin direction. This register has the current status of the corresponding port.IODIR (IODIR0 for PORT0 and IODIR0 for PORT1):GPIO Port Direction control register. This register individually controls the direction of each port pin. This register is used to set each port pin as either input or output. If 0, the port pin is considered as input and if 1, then the port pin is considered as output.IOSET (IOSET0 for PORT0 and IOSET0 for PORT1):GPIO Port Output Set register. This register controls the state of output pins in conjunction with the IOCLR register. Writing ones produces highs at the corresponding port pins. Writing zeroes has no effect.IOCLR (IOCLR0 for PORT0 and IOCLR0 for PORT1):GPIO Port Output Set register. This register controls the state of output pins in conjunction with the IOSET register. Writing ones produces lows at the corresponding port pins. Writing zeroes has no effect.PINSEL0 Register:PINSEL0 register serves to select any function from the pins P0.0 to P0.15

PINSEL1 Register:PINSEL1 register serves to select any function from the pins P0.16 to P0.31

The PINSEL0 and PINSEL1 register control the function of device pins as show below. Pairs of bits in these registers correspond to specific device pins.

Value Function 00 Primary (default) function, typically GPIO port01 First alternate function10Second alternative function11Reserved

PINSEL2 Register:

Bit Symbol Function0,1 If 0 then pins P1.36-26 are used as GPIO 2 GPIO/DEBUG pins if 1 then, PinsP1.36-26 are used as DEBUG Port3 GPIO/TRACE if 0 then pins p1.25-16 are used as GPIO pins if 1 then, pins P1.25-16 are used as a Trace port.4to31 - ReservedPINSEL2 register serves to select any function from the pins P1.16 to P1.31.

3.1.2. UARTs (Universal Asynchronous Receiver and Transmitter):

Figure: 3.1.3 UART pinsThe LPC2148 contains two UARTs, UART0 and UART1. In addition to standard transmit and receive data lines, the LPC2148 UART1 also provide a full modem control handshake interface. Compared to previous LPC2000 microcontrollers, Arts in LPC2148 introduce a fractional baud rate generator for both UARTs, enabling these microcontrollers to achieve standard baud rates such as 115200 with any crystal frequency above 2 MHz 16 byte Receive and Transmit FIFOs (First In First Out). Register locations conform to 550 industry standard. Receiver FIFO trigger points at 1, 4, 8, and 14 bytes Built-in fractional baud rate generator covering wide range of baud rates without a need for external crystals of particular values. Transmission FIFO control enables implementation of software (ON/OFF) flow control on both UARTs. LPC2148 UART1 equipped with standard modem interface signals. This module also provides full support for hardware flow control3.1.3. I2C-Bus serial I/O Controller:The LPC2148 contains two I2C-bus controllers. The I2C-bus is bidirectional, for inter-IC control using only two wires: A serial clock line (SCL), A serial data line (SDL).Each device is recognized by a unique address and can operate as either a receiver-only device. Transmitters and/or receivers can operate in either master or slave mode, depending on whether the chip has to initiate a data transfer or is only addressed. The I2C-bus is a multi-master bus, it can be controlled by more than one bus master connected to it. The I2C-bus implemented in LP2148 supports bit rates up to 400 Kbit/s (Fast I2C-bus). Compliant with standard I2C-bus interface. Easy to configure as master, slave, or master/slave. Programmable clocks allow versatile rate control. Bidirectional data transfer between masters and slaves. Multi-master bus (no central master). Arbitration between simultaneously transmitting masters without corruption of serial data on the bus. Serial clock synchronization allows devices with different bit rates to communicate via one serial bus. Serial clock synchronization can be used as a handshake mechanism to suspend and resume serial transfer. The I2C-bus can be used for test and diagnostic purposes.3.1.4.SPI (Serial Peripheral Interface) I/O Controller:The LPC2148 contains one SPI controller. The SPI is a full duplex serial interface, designed to handle multiple masters and slaves connected to a given bus. Only a single master and a single slave can communicate on the interface during a given data transfer. During a data transfer the master always sends a byte of data to the slave, and the slave always sends a byte of data to the master. Compliant with Serial Peripheral Interface (SPI) specification. Synchronous, Serial, Full Duplex, Communication. Combined SPI master and slave. Maximum data bit rate of one eighth of the input clock rate. Synchronous serial communication. Master or slave operation. 8-frame FIFOs for both transmit and receive.3.1.5.Crystal Oscillator:On-chip integrated oscillator operates with external crystal in range of 1 MHz to 25 MHz The oscillator output frequency, fosc and the ARM processor clock frequency is referred to as CCLK for purposes of rate equations, etc. fosc and CCLK are the same value unless the PLL (Phase Locked Loop) is running and connected.Power Control:The LPC2148 supports two reduced power modes: Idle mode Power down mode. In Idle mode, execution of instructions is suspended until either a reset or interrupt occurs. Peripheral functions continue operation during idle mode and may generate interrupts to cause the processor to resume execution. Idle mode eliminates power used by the processor itself, memory systems and related controllers, and internal buses.In Power-down mode, the oscillator is shut down and the chip receives no internal clocks. The processor state and registers, peripheral registers, and internal SRAM values are preserved throughout Power-down mode and the logic levels of chip output pins remain static. The Power-down mode can be terminated and normal operation resumed by either a reset or certain specific interrupts that are able to function without clocks. Since all dynamic operation of the chip is suspended, Power-down mode reduces chip power consumption to nearly zero.Reset Circuit:Reset button is essential in a system to avoid programming pitfalls and sometimes to manually bring back the system to the initialization mode.

3.2 GLOBAL SYSTEM FOR MOBILE (GSM)Introduction:GSM (Global System for Mobile) is SIM900 Quad-band GSM / GPRS device, works on frequencies 850 MHZ, 900 MHZ, 1800 MHZ and 1900 MHZ. It is very compact in size and easy to use as plug in GSM Modem. The Modem is designed with 3V3 and 5V DC TTL interfacing circuitry, which allows User to directly interface with 5V Microcontrollers (PIC, AVR, Arduino, 8051, etc.) as well as 3V3 Microcontrollers (ARM, ARM Cortex XX, etc.). The baud rate can be configurable from 9600- 115200 bps through AT (Attention) commands. This GSM/GPRS TTL Modem has internal TCP/IP stack to enable User to connect with internet through GPRS feature. It is suitable for SMS as well as DATA transfer application in mobile phone to mobile phone interface. The modem can be interfaced with a Microcontroller using USART (Universal Synchronous Asynchronous Receiver and Transmitter) feature (serial communication).Features: Quad Band GSM: 850 / 900 / 1800 / 1900 MHz Built in RS232 to TTL or vice versa Logic Converter (MAX232) Configurable Baud Rate SMA (Sub Miniature version A) connector with GSM L Type Antenna Built in SIM (Subscriber Identity Module) Card holder Built in Network Status LED Inbuilt Powerful TCP / IP (Transfer Control Protocol / Internet Protocol) stac for internet data transfer through GPRS (General Packet Radio Service) Audio Interface Connectors (Audio in and Audio out) Most Status and Controlling pins are available Normal Operation Temperature : -20 C to +55 C Input Voltage : 5V to 12V DC LDB9 connector (Serial Port) provided for easy interfacingHardware Description: Figure 3.2: GSM moduleSIMCom SIM900A GSM Module:This is actual SIM900 GSM module which is manufactured by SIMCom. Designed for global market, SIM900 is a quad-band GSM/GPRS engine that works on frequencies GSM 850MHz, EGSM 900MHz, DCS 1800MHz and PCS 1900MHz. SIM900 features GPRS multislot class 10/ class 8 (optional) and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. With a tiny configuration of 24mm x 24mm x 3mm, SIM900 can meet almost all the space requirements in Users applications, such as M2M, smart phone, PDA and other mobile devices.

Figure 3.2.1: GSM SIM900 chipMAX232 IC:The MAX232 is an integrated circuit that converts signals from an RS-232 serialport to signals suitable for use in TTL compatible digital logic circuits, so that devices works on TTL logic can share the data with devices connected through Serial port (DB9 Connector).Serial port / DB9 connector:User just needs to attach RS232 cable here so that it can be connected to devices which has Serial port / DB9 Connector.

Figure 3.2.2: Serial port

3.3 MAX232:The MAX232 device is a dual driver/receiver that includes a capacitive voltage generator to supply TIA/EIA-232-232-F voltage levels from a single 5-V supply. Each receiver converts TIA/EIA-232-F inputs to 5-V TTL/CMOS levels. These receivers have a typical threshold of 1.3 V, a typical hysteresis of 0.5 V, and can accept 30-V inputs. Each driver converts TTL/CMOS input levels into TIA/EIA-232-F levels. The driver, receiver, and voltageThe drivers provide RS-232 voltage level outputs (approx. 7.5V) from a single +5V supply via on-chipcharge pumpsand external capacitors. This makes it useful for implementing RS-232 in devices that otherwise do not need any voltages outside the 0V to +5V range, aspower supplydesign 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 25V), to standard 5VTTLlevels. These receivers have a typical threshold of 1.3V, and a typicalhysteresisof 0.5V.Pin diagram of MAX232:

Figure 3.3: Pin diagram of MAX232The MAX232 (A) has two receivers (converts from RS-232 to TTL voltage levels), and two drivers (converts from TTL logic to RS-232 voltage levels). This means only two of the RS-232 signals can be converted in each direction. Typically, a pair of a driver/receiver of the MAX232 is used for TX and RX signals, and the second one for CTS and RTS signals.There are not enough drivers/receivers in the MAX232 to also connect the DTR, DSR, and DCD signals. Usually these signals can be omitted when e.g. communicating with a PC's serial interface. If the DTE really requires these signals, either a second MAX232 is needed, or some other IC from the MAX232 family can be used. Also, it is possible to directly wire DTR (DB9 pin #4) to DSR (DB9 pin #6) without going through any circuitry. This gives automatic (brain dead) DSR acknowledgment of an incoming DTR signal.Features of MAX232: Meet or Exceed Operates From a Single 5-V Power Supply With 1.0-F Charge-Pump Capacitors Operate Up To 120 kilobytes Two Drivers and Two Receivers Recommended V.28 Battery powered systems Terminals Modems Computers Package options include plastic Small-outline(D,DW)Packages Standard Plastic(N) DIPs ESD Protection Exceeds 2000 V per MIL-STD-883, Method 3015 Maxim MAX232

3.4 DB9 CONNECTORS:

Figure 3.4.1: DB9-RS232-USB

Figure 3.4.2: Male DB9-RS232 Figure 3.4.3: Female DB9-RS232DISCRIPTION: The DB9-USB-RS232 connectors can be used to upgrade an RS232 port to an active USB port without the need to redesign the PCB These active connectors contain all the USB to RS232 (and vice-versa) conversion electronics and are designed to fit directly into the same PCB footprint as a PC compatible RS232DB9 connector. This DB9 consist of 9 pins in it. DB9 consist of RS232 male and female connectors In this MAX232 is connected to DB9 for receiving and transmitting the data This is accomplished by incorporating the industry standard FTDIFT232R USB-Serial Bridge IC plus the required level shifters inside the module.Power Supply Socket:This power supply socket which actually named as AC/DC Socket provides the functionality to user to connect external power supply from Transformer, Battery or Adapter through DC jack. User can provide maximum of 12V AC/DC power supply through AC/DC socket. This is power supply designed into maximum protection consideration so that it can even prevent reverse polarity DC power supply as well as DC conversion from AC power Supply. It also includes LM317 Voltage Regulator which provides an output voltage adjustable over a1.2Vto 37V.

Figure 3.4.4: GSM power supplyPower On/Off and GSM On Switch:Power On/Off switch is type of push-on push-off DPDT switch which is used for only make power supply on/off provided through AC/DC Socket indicated by Power LED. GSM On Switch is type of Push on DPST tactile switch which is used for only to make GSM module On indicated by Module On/Off LED while initiating with Network indicated by Network.

SIM (Subscriber Identity Module) Card Slot:This onboard SIM card slot provide User functionality of insert a SIM (GSM only) card of any service provider. Process of inserting and locking SIM card into SIM card slot is given in this manual. While inserting in and removing out SIM card from SIM card slot, User needs to take precaution that power supply should be OFF so that after making Power supply ON it will be easy to reinitialize with SIM for this module.

Figure 3.4.5: SIM card slotIndicator LEDs:Indicator LEDs just used to indicate status accordingly. These are three LEDs represents Power On/Off Status, Network Status and Module On/Off Status respectively. Power LED will keep on until the power supply is enable to this board by using push-on push off switch. Network Status LED will show whether inserted SIM card successfully connected to service providers Network or not, in short signal strength. Module On/Off indicator LED will show status of GSM modules power on/off.

Figure 3.4.6: GSM Signal Indicator LEDsInserting SIM card into SIM card Slot/Holder:Here is the process how to insert SIM card into SIM card slot. User just need to unlock SIM card cover by sliding back. Then user need to open this cover and insert SIM card according to slot. Put down cover on SIM card and then lock by sliding forward.

Figure 3.4.7: Inserting SIM card into SIM card SlotConnecting GSM module with RS232 (SB9-DB9) Serial Cable:User can connect GSM interfacing board either through Serial port or through Serial to USB converter. Here is process to connect RS232 cable to GSM interfacing board.

Figure 3.4.8: Connecting GSM module with RS232 (SB9-DB9) Serial CableAT Commands for GSM:CommandsDescription

ATCheck if serial interface and GSM is working.

ATE0Turn echo off, less traffic on serial line.

AT+CPMSSelection of SMS memory.

AT+CMGFSMS string format, how they are compressed.

AT+CMGRRead new message from a given memory location.

AT+CMGSSend message to a given recipient.

AT+CMGDDelete message.

AT+CNMIDisplay of new incoming SMS.

3.5. OBSTACLE DETECTING SENSORObstacle Detecting Sensor is used to detect objects and obstacles in front of sensor in a narrow angle useful in robotics applications. Sensor keeps transmitting modulated infrared light and when any object comes near, it is detected by the sensor by monitoring the reflected light from the object. It can be used in robots for obstacle avoidance, for automatic doors, for parking aid devices or for security alarm systems, or contact less tachometer by measuring RPM of rotation objects like fan blades.

Figure 3.5: Obstacle sensorFeatures 1 Khz Modulated IR transmitter LEDs Ambient light protected IR receiver 3 pin easy interface connector Indicator LED Up to 20cm range for white object Can differentiate between dark and light colors Active Low on object detection

Applications Proximity Sensor Object Near detection Tachometer (Measure Fan Speed) Obstacle Detector Sensor Line/Wall Follower Sensor

3.6. DC MOTORADC motoris any of a class of electrical machines that converts direct current electrical power into mechanical power. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current flow in part of the motor. Most types produce rotary motion; a linear motor directly produces force and motion in a straight line.DC motors were the first type widely used, since they could be powered from existing direct-current lighting power distribution systems. A DC motor's speed can be controlled over a wide range, using either a variable supply voltage or by changing the strength of current in its field windings. Small DC motors are used in tools, toys, and appliances. Theuniversal motorcan operate on direct current but is a lightweight motor used for portable power tools and appliances. Larger DC motors are used in propulsion of electric vehicles, elevator and hoists, or in drives for steel rolling mills. The advent of power electronics has made replacement of DC motors with AC motors possible in many applications.

Figure 3.6: DC motor

Figure 3.6.1: Working of DC motorWorkings of a brushed electric motor with a two-pole rotor (armature) and permanent magnet stator. "N" and "S" designate polarities on the inside face of the magnets the outside faces have opposite polarities. The+and-signs show where the DC current is applied to thecommutatorwhich supplies current to thearmature coilsA simple DC motor has a stationary set of magnets in thestatorand anarmaturewith one more windings of insulated wire wrapped around a soft iron core that concentrates the magnetic field. The windings usually have multiple turns around the core, and in large motors there can be several parallel current paths. The ends of the wire winding are connected to acommutator. The commutator allows each armature coil to be energized in turn and connects the rotating coils with the external power supply through brushes. (Brushless DC motors have electronics that switch the DC current to each coil on and off and have no brushes.)The total amount of current sent to the coil, the coil's size and what it's wrapped around dictate the strength of the electromagnetic field created.The sequence of turning a particular coil on or off dictates what direction the effective electromagnetic fields are pointed. By turning on and off coils in sequence a rotating magnetic field can be created. These rotating magnetic fields interact with the magnetic fields of the magnets (permanent orelectromagnets) in the stationary part of the motor (stator) to create a force on the armature which causes it to rotate. In some DC motor designs the stator fields use electromagnets to create their magnetic fields which allow greater control over the motor.Controlling DC MotorsMotor gives power to your MCU. Ya power to do physical works, for example to move your robot. So it is essential to know how to control a DC motor effectively with a MCU. We can control a DC motor easily with microcontrollers. We can start it, stop it or make it go either in clockwise or anti clock wise direction. We can also control its speed but it will be covered in latter tutorials.

Figure 3.6.2: MCUsControl with MCUsAs the MCUs PORT are not powerful enough to drive DC motors directly so we need some kind of drivers. A very easy and safe is to use popular L293D chips. It is a 16 PIN chip. The pin configuration is as follows.

Figure 3.6.3: L293D Dual DC Motor Controller

PIN DISCRIPTION:

Pin NoFunctionName

1Enable pin for Motor 1; active highEnable 1,2

2Input 1 for Motor 1Input 1

3Output 1 for Motor 1Output 1

4Ground (0V)Ground

5Ground (0V)Ground

6Output 2 for Motor 1Output 2

7Input 2 for Motor 1Input 2

8Supply voltage for Motors; 9-12V (up to 36V)Vcc2

9Enable pin for Motor 2; active highEnable 3,4

10Input 1 for Motor 1Input 3

11Output 1 for Motor 1Output 3

12Ground (0V)Ground

13Ground (0V)Ground

14Output 2 for Motor 1Output 4

15Input2 for Motor 1Input 4

16Supply voltage; 5V (up to 36V)Vcc1

MOTOR CONTROLLER:This chip is designed to control 2 DC motors. There are 2 INPUT and 2 OUTPUT PINs for each motors. The connections are as follows. Figure 3.6.4: Motor Controller Using L293d chip DC Motors cannot be interfaced directly to microcontrollers since these do not support logic states. Since if sudden high state is applied to motor gets struck so the motor is interfaced to controller for smooth direction changing the name of that IC is L293D (line driver). To this single IC two DC motor can be connected. Totally four pins of processor is used to connect to this IC. By giving different logic values to these the motor directions can be change as shown above. Hence the direction of robot is changes by using mobile through messages.

3.7. IP CAMERAAnInternet protocol camera, or IP camera, is a type of digital video camera commonly employed forsurveillance, and which, unlike analogclosed circuit television(CCTV) cameras, can send and receive data via a computer network and the Internet. Although most cameras that do this arewebcams, the term "IP camera" or "netcam" is usually applied only to those used for surveillance. The first centralized IP camera was Axis Neteye 200, released in 1996 by Axis Communications.There are two kinds of IP cameras: Centralized IP cameras, which require a centralNetwork Video Recorder (NVR) to handle the recording, video and alarm management. Decentralized IP cameras, which do not require a centralNetwork Video Recorder(NVR), as the cameras have recording function built-in and can thus record directly to any standard storage media, such as SD cards, NAS (network attached storage) or a PC/Server.Using the Android smartphone camera to capture imagesIn our technological world, almost any Smartphone is equipped with powerful cameras able to capture vivid images. In this case, for real-life applications you need two smart phones with the Android OS and a live streaming application installed on both devices. One Smartphone should be attached to the robot, and the other will stay in your hands to see therobot in action. Both Android devices require Internet connectivity.

Figure 3.7: IP cam video recorderApplications:Below are available two Android applications designed for live streaming between Android devices. Camera Wi-Fi Live Stream a simple and powerful application for Android devices that allow users to view real-time video images captured with an Android device camera. The application is designed to work in a web browser or on other Android device; IP Webcam an application that allows you to view Android camera in a web browser or VLC player. This application can be used without internet access, it could be used in your Wi-Fi network. Also, the IP Webcam is used for real-time video streaming from Smartphone to Smartphone

CHAPTER-4 POWER SUPPLY4.1 Block diagram of Power supply:LPC2148 works on 3.3 V power supply. LM 117 can be used for generating 3.3 V supply. However, basic peripherals like LCD, ULN 2003 (Motor Driver IC) etc. works on 5V. So AC mains supply is converted into 5V using below mentioned circuit and after that LM 117 is used to convert 5V into 3.3V.

Step down T/FBridge RectifierFilter CircuitRegulatorI/O 230V/50HZPower supply to all sections

Fig.4.1 Block Diagram of Power SupplyThe power supply from socket is connected to the step down transformer in order to step down the voltage from 230v to 12v and the output of step down transformer is 12v ac is connected to rectifier to convert it to pulsating dc from rectifier we will get 12v pulsating dc. Here this circuit diagram is for+12V regulated DC power supply. Thesepower supply circuit diagramis ideal for an average current requirement of 1Amp. It is a 3-terminal voltage regulator IC. It has short circuitprotection, thermal overload protection.4.2 Transformer A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core, and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is called mutual induction. If a load is connected to the secondary, current will flow in the secondary winding, and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (VP) and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows. By appropriate selection of the ratio of turns, a transformer thus enables an alternating current (AC) voltage to be "stepped up" by making Ns greater than Np, or "stepped down" by making Ns less than Np. While new technologies have eliminated the need for transformers in some electronic circuits, transformers are still found in nearly all electronic devices designed for household ("mains") voltage. Transformers are essential for high-voltage electric power transmission, which makes long-distance transmission economically practical.

Fig.4.2 Transformer4.3 Bridge Rectifier The purpose of a rectifier is to convert an AC waveform into a DC waveform (OR) Rectifier converts AC current or voltages into DC current or voltage. There are two different rectification circuits, known as 'half-wave' and 'full-wave' rectifiers. Both use components called diodes to convert AC into DC.

Figure 4.3: Bridge rectifierFig4.3 Bridge rectifierFor the positive half cycle of the input ac voltage, diodes D1 and D3 conduct, whereas diodes D2 and D4 remain in the OFF state. The conducting diodes will be in series with the load resistance RLand hence the load current flows through RL.For the negative half cycle of the input ac voltage, diodes D2 and D4 conduct whereas, D1 and D3 remain OFF. The conducting diodes D2 and D4 will be in series with the load resistance RLand hence the current flows through RLin the same direction as in the previous half cycle. Thus a bi-directional wave is converted into a unidirectional wave.When four diodes are connected as shown in figure, the circuit is called as bridge rectifier. The input to the circuit is applied to the diagonally opposite corners of the network, and the output is taken from the remaining two corners. Let us assume that the transformer is working properly and there is a positive potential, at point A and a negative potential at point B. the positive potential at point A will forward bias D3 and reverse bias D4. The negative potential at point B will forward bias D1 and reverse D2. At this time D3 and D1 are forward biased and will allow current flow to pass through them; D4 and D2 are reverse biased and will block current flow. The path for current flow is from point B through D1, up through RL, through D3, through the secondary of the transformer back to point B. this path is indicated by the solid arrows. Waveforms (1) and (2) can be observed across D1 and D3.One-half cycle later the polarity across the secondary of the transformer reverse, forward biasing D2 and D4 and reverse biasing D1 and D3. Current flow will now be from point A through D4, up through RL, through D2, through the secondary of T1, and back to point A. This path is indicated by the broken arrows. Waveforms (3) and (4) can be observed across D2 and D4. The current flow through RL is always in the same direction. In flowing through RL this current develops a voltage corresponding to that. Since current flows through the load (RL) during both half cycles of the applied voltage, this bridge rectifier is a full-wave rectifier.One advantage of a bridge rectifier over a conventional full-wave rectifier is that with a given transformer the bridge rectifier produces a voltage output that is nearly twice that of the conventional full-wave circuit. This may be shown by assigning values to some of the components shown in views A and B. assume that the same transformer is used in both circuits. The peak voltage developed between points X and y is 1000 volts in both circuits. In the conventional full-wave circuit shown in view A, the peak voltage from the center tap to either X or Y is 500 volts. Since only one diode can conduct at any instant, the maximum voltage that can be rectified at any instant is 500 volts. The maximum voltage that appears across the load resistor is nearly-but never exceeds-500 v0lts, as result of the small voltage drop across the diode. In the bridge rectifier shown in view B, the maximum voltage that can be rectified is the full secondary voltage, which is 1000 volts. Therefore, the peak output voltage across the load resistor is nearly 1000 volts. With both circuits using the same transformer, the bridge rectifier circuit produces a higher output voltage than the conventional full-wave rectifier circuit.4.4 filterAfter rectification we obtain dc supply from ac but it is not pure dc it may have some ac ripples .To reduce these ripples we use filters. It comprises of two filters low frequency ripple filter and high frequency ripple filter. To reduce low frequency ripples we use electrolytic capacitor. The voltage rating of capacitor must be double from incoming dc supply. It blocks dc and passes ripples to ground.4.5 ResistorResistors "Resist" the flow of electrical current. The higher the value of resistance (measured inohms) the lower the current will be.Resistance is the property of a component whichrestricts the flow of electric current. Energy is used up as the voltage across the component drives the current through it and this energy appears as heat in the component.

Figure 4.5: Resistor4.6 Capacitor:Capacitors store electric charge. They are used with resistors intimingcircuitsbecause it takes time for a capacitor to fill with charge. They are used tosmoothvarying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC (changing) signals but they block DC (constant) signals.

Fig: 4.6 circuit symbolElectrolytic capacitors are polarized andthey must be connected the correct way round, at least one of their leads will be marked + or -.

4.7 IC Voltage regulatorElectronic voltage regulators are found in devices such as computerpower supplieswhere they stabilize the DC voltages used by the processor and other elements. In automobilealternatorsand centralpower stationgenerator plants, voltage regulators control the output of the plant. In anelectric power distributionsystem, voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.

Fig: 4.7 7805 regulatorThere are two types of regulator are they.1. Positive Voltage Series (78xx) and2. Negative Voltage Series (79xx)78xx:78 indicate the positive series and xx indicates the voltage rating. Suppose 7805 produces the maximum 5V.05indicates the regulator output is 5V.79xx:78 indicate the negative series and xx indicates the voltage rating. Suppose 7905 produces the maximum -5V.05indicates the regulator output is -5V.These regulators consists the three pins there arePin1: It is used for input pin.Pin2: This is ground pin for regulatorPin3: It is used for output pin. Through this pin we get the output.4.7.1 Three-Terminal Voltage Regulators:Fig shows the basic connection of a three-terminal voltage regulator IC to a load. The fixed voltage regulator has an unregulated dc input voltage, Vi, applied to one input terminal, a regulated output dc voltage, Vo, from a second terminal, with the third terminal connected to ground. For a selected regulator, IC device specifications list a voltage range over which the input voltage can vary to maintain a regulated output voltage over a range of load current. The specifications also list the amount of output voltage change resulting from a change in load current (load regulation) or in input voltage (line regulation).

Fig. 4.7.1 Fixed Positive Voltage RegulatorsThe series 78 regulators provide fixed regulated voltages from 5 to 24 V, 7812 is connected to provide voltage regulation with output from this unit of +12V dc. An unregulated input voltage is filtered by capacitor C1 and connected to the ICs IN terminal. The ICs OUT terminal provides a regulated + 12V which is filtered by capacitor C2 (mostly for any high-frequency noise). The third IC terminal is connected to ground.

CHAPTER 5SOFTWARE KEIL VISIONKeil compiler is software used where the machine language code is written and compiled. After compilation, the machine source code is converted into hex code which is to be dumped into the microcontroller for further processing. Keil compiler also supports C language code.STEPS TO WRITE AN ASSEMBLY LANGUAGE PROGRAM IN KEIL AND HOW TO COMPILE IT: Install the Keil Software in the PC in any of the drives. After installation, an icon will be created with the name Keil uVision3. Just drag this icon onto the desktop so that it becomes easy whenever you try to write programs in keil. Double click on this icon to start the keil compiler. A page opens with different options in it showing the project workspace at the leftmost corner side, output window in the bottom and an ash coloured space for the program to be written. Now to start using the keil, click on the option project. A small window opens showing the options like new project, import project, open project etc. Click on New project. A small window with the title bar Create new project opens. The window asks the user to give the project name with which it should be created and the destination location. The project can be created in any of the drives available. You can create a new folder and then a new file or can create directly a new file. After the file is saved in the given destination location, a window opens where a list of vendors will be displayed and you have to select the device for the target you have created. A small window opens asking whether to copy the startup code into the file you have created just now. Just click on No to proceed further. Now you can see the TARGET and SOURCE GROUP created in the project workspace. Now click on File and in that New. A new page opens and you can start writing program in it. After the program is completed, save it with any name but with the .asm extension. Save the program in the file you have created earlier. You can notice that after you save the program, the pre defined keywords will be highlighted in bold letters. Now add this file to the target by giving a right click on the source group. A list of options open and in that select Add files to the source group. Check for this file where you have saved and add it. Right click on the target and select the first option Options for target. A window opens with different options like device, target, output etc. First click on target. Now click the option Output and give any name to the hex file to be created in the Name of executable text area and put a tick to the Create HEX file option present in the same window. The hex file can be created in any of the drives. You can change the folder by clicking on Select folder for Objects. To check for the output, there are several windows like serial window, memory window, project window etc. Depending on the program you have written, select the appropriate window to see the output by entering into debug mode. The icon with the letter d indicates the debug mode. Click on this icon and now click on the option View and select the appropriate window to check for the output. After this is done, click the icon debug again to come out of the debug mode.

PROTEUS 8 PROFESSIONALProteus 8 is a single application with many service modules offering different functionality (schematic capture, PCB layout, etc.). The wrapper that enables all of the various tools to communicate with each other consists of three main parts.Proteus PCB design combines the ISIS schematic capture and ARES PCB layout programs to provide a powerful, integrated and easy to use suite of tools for professional PCB Design. All Proteus PCB design products include an integrated shape based auto router and a basic SPICE simulation capability as standard. More advanced routing modes are included in Proteus PCB Design Level 2 and higher whilst simulation capabilities can be enhanced by purchasing the Advanced Simulation option and/or micro-controller simulation capabilities.Application FrameworkProteus 8 consists of a single application (PDS.EXE). This is the framework or container which hosts all of the functionality of Proteus. ISIS, ARES, 3DV all open as tabbed windows within this framework and therefore all have access to the common database.Common Database The common database contains information about parts used in the project. A part can contain both a schematic component and a PCB footprint as well both user and system properties. Shared access to this database by all application modules makes possible a huge number of new features, many of which will evolve over the course of the Version 8 lifecycle.Live Net listTogether with the common database the maintenance of a live net list allows all open modules to automatically reflect changes. The most obvious example of this is wiring in ISIS producing rats nest connections in ARES but it goes much further than that. The new Bill of Materials module contains a live viewer and the 3D Viewer and Design Explorer are also linked into the live net list.This document covers the Proteus 8 application frame work and other functionality related to the software suite as a whole. The various application modules (e.g. ISIS, ARES) each have their own reference manuals and tutorial documentation.

CHAPTER 6SCHEMATIC DIAGRAMThe following figure shows the schematic diagram of our project

Working:In this project we are going to control the ROBOT by using GSM SMS from the remote location. Commands send by from the users mobile. These commands are receives by the GSM system present on the robot. The commands the fed to the microcontroller which process on the commands the according to that robot will work. The system uses a compact circuitry built around LPC2148 (ARM7) microcontroller. Programs are developed in Embedded C. Flash magic is used for loading programs into Microcontroller.The power supply from socket is connected to the step down transformer in order to step down the voltage from 230v to 12v and the output of step down transformer is 12v ac is connected to rectifier to convert it to pulsating dc from rectifier we will get 12v pulsating dc. Here this circuit diagram is for+12V regulated DC power supply. Thesepower supply circuit diagramis ideal for an average current requirement of 1Amp. It is a 3-terminal voltage regulator IC. It has short circuitprotection, thermal overload protection.LPC2148is the widely used IC from ARM-7 family. It has 8 to 40 KB of on-chip static RAM and 32 to 512 KB of on-chip flash program memory.128 bit wide interface/accelerator enables high speed 60 MHz operation. Low power real-time clock with independent power and dedicated 32 kHz clock input.System designers wishing to upgrade from ARM7 benefit from a robust ARM processor roadmap providing multiple upgrade options, including the latest Cortex processors. Due to its tiny size and low power consumption, LPC2148 is ideal for applications where miniaturization is a key requirement. Serial communications interfaces ranging from a USB 2.0 Full-speed device, multiple UARTs, SPI, SSP to I2C-bus and on-chipObstacle Detecting Sensor is used to detect objects and obstacles in front of sensor in a narrow angle useful in robotics applications. Sensor keeps transmitting modulated infrared light and when any object comes near, it is detected by the sensor by monitoring the reflected light from the object. It can be used in robots for obstacle avoidance, for automatic doors, for parking aid devices or for security alarm systems, or contact less tachometer by measuring RPM of rotation objects like fan blades.The proposed robot can be operated by send some SMS to the GSM modem which is placed at the robot side. Depending upon the message received through GSM modem, the motors which are connected to the robot drives the robot in forward, reverse, right or left direction. The IP CAM which is fixed at the robot captures the surrounding images and sends to the owner mobile phone. A user can monitor the surroundings at the remote area. All these operations can be controlled by the host microcontroller placed at the robot.

CHAPTER-7ADVANTAGES & APPLIATIONSADVANTAGES Spying on people in ways people can't move and from views humans can't reach Giving us information that humans can't get Working at places 24/7 without any salary and food. Plus they don't get bored They can perform tasks faster than humans and much more consistently and accuratelyAPPLIATIONS Scientific use Military and law enforcement use Search and rescue Forest conservation

SNAP SHOTThe following figure shows the kit of our project GSM BASED REMOTE SENSING AND TELE-OPERATION OF A MOBILE ROBOT

Figure 8.1: SNAP SHOT OF GSM ROBOT

CONCLUSIONThe project GSM based remote sensing and Tele operation of mobile robot has been successfully designed and tested. It has been developed by integrating features of all the hardware components used. By developing this robotic vehicle with its multi-tasking feature, we have overcome the drawbacks of RF communication which have a limited range whereas this robot can be controlled from anywhere just using this GSM technology. The main advantage of this robot is by using obstacle sensor, it is detected by the sensor by monitoring the reflected light from the object. It also have IP CAM which is fixed at the robot captures the surrounding images and sends to the owner mobile phone. A user can monitor the surroundings at the remote area. All these operations can be controlled by the host microcontroller placed at the robot.Today we find most robots working for people in industries, factories, warehouses, and laboratories. Robots are useful in many ways. For instance, it boosts economy because businesses need to be efficient to keep up with the industry competition. Therefore, having robots helps business owners to be competitive, because robots can do jobs better and faster than humans can, e.g. robot can built, assemble a car. Yet robots cannot perform every job; today robots roles include assisting research and industry. Finally, as the technology improves, there will be new ways to use robots which will bring new hopes and new potentials.

FUTURE SCOPE Robot can be controlled through voice recognition mechanism We can make this robot to move automatically We can add different sensors We can add camera also to record Military use: Military usage of remotely controlled military vehicles dates back the first half of 20th century. This can be a great asset to save lives of both people along with soldiers in case of terrorist attacks like the one happened in 26 Nov, 2008 in Mumbai, India. Search and Rescue: It will likely play an increased role in search and rescue in the United States. Slowly other European countries (even some developing nations) are thinking about making use of these vehicles in case of natural calamities &emergencies. Scientific Use: Remote control vehicles have various scientific uses including hazardous environments. Majority of the probes to the other planets in our solar system have been remote control vehicles, although some of the more recent ones were partially autonomous. The sophistication of these devices has fueled greater debate on the need for manned spaceflight and exploration. The Voyager I spacecraft is the first craft of any kind to leave the solar system. The Martian explorers Spirit and Forest Conservation: In the recent times, there has been a serious endangerment to the wildlife population. A lot of animals are on the verge of becoming extinct, including the tiger. The spy robotic car can aid us in this purpose. Since it is a live streaming device and also mobile, it can keep the forest guards constantly updated about the status of different areas which are prone to attack. As a result, it can help to prevent further destruction of the forest resources by enabling correct prohibitory action at the appropriate time.

REFERENCES1. David Tenenbaum,University of WisconsinMadison News, December 26, 20122. Papailiou, D.D.Frontiers in PropulsionResearch, JPLTech. Memo 33-722.Jet PropulsionLaboratory. 19753. Forward, R.L.J. Brit. Interplanet. Soc.35, 391 (1982).4. Vaughan, R. N. Sumpter, A. Frost, and S. Cameron. "Experiments in Automatic Flock Control." Edinburgh, UK, 1998.5. Wilson, J. S. (2005).Sensor technology handbook Amsterdam: IEEE Elsevier.6. Yacoub, M. D. (2002). Wireless technology: protocols, standards, and techniques Boca Raton: CRC Press. 7. Control engineering control system power and grounding better practice Amsterdam: Newnes. Petruzzellis, T. (1994). 8. The alarm, sensor & security circuit cookbook .IEEE Blue Ridge Summit, PA: TAB Books. www.pirsensor.com9. Barrett, S. F. (2012). Arduino microcontroller processing for everyone! (2nd ed.). San Rafael, Calif. (1537 Fourth Street, IEEE San Rafael, CA 94901 USA): Morgan & Claypool. www.microcontroller.com.10. The8051MicrocontrollerPage61Kenneth J. Ayala- 2004

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