1. INTRODUCTION

1.1 ObjectiveThe main objective of this project is to develop a fire detector which can sense the formation of smoke and temperature then actuate the control system to extinguish the fire. Here the system has to detect smoke so that we can detect the fire accidents quickly and avoid the major damage.The environmental conditions that exist in industrial facilities can present huge challenges. High levels of dust and dirt can cause malfunctions and nuisance alarms, smoke dilution in large volumetric enclosures influenced by air movement and stratification make it difficult to detect the early signs of fire. Normally occurring background levels of smoke cannot easily be distinguished from real fire conditions. Unheated or un-cooled spaces cause temperature extremes outside of the operating range of some smoke detectors.To provide the best possible fire protection for an industrial application or environment means selecting the correct technology and the most appropriate product in the first instance. The detector must maintain its sensitivity over the life of the detector and provide a low total cost of ownership.1.2 High Level DesignIn any closed area if any fire accidents occur then the damage will be more sometimes even the loss of life. To avoid this we have to detect them as early as possible and take any preventive measures. Sometimes it is not possible for a human being to react quickly. In such cases the automated systems are very useful. In this system we are using a smoke sensor which can detect the smoke and send a signal as input to the micro controller. The micro controller will be continuously checking the respective pin. When it gets a high signal at that pin it means that smoke has been detected. At that time it first gives siren to alert any humans in that premises to vacate and then it actuates the extinguishers. They may be the water sprinklers or the CO2 containers. At the same time control appliances based on the light sensor.

1.3 Block Diagram

Fig 1: Block Diagram

The smoke sensor senses the environmental conditions. While sensing if there is any bad condition in a particular zone i.e, fire hazards, then it gives the commands the sensor for its operation. At the same time, the measured physical quantity will be displayed on the LCD. The output of LCD is given to 8051 micro controller. Micro controller gives commands to operate Buzzer and sprinkler instantaneously. To operate sprinkler, we require very less voltage. This voltage is obtained with the help of opto coupler and TRIAC, such that fire is extinguished.Light sensor senses the environmental condition. If it is dark, the output of LDR will be high, such that the bulb glows up, else off.

2. EMBEDDED SYSTEM

2.1 INTRODUCTIONComputers have evolved from few, huge mainframes shared by many people, and mini computers that were smaller but still shared to todays PCsmillions in number, miniscule in size compared to the mainframes, and used by only one person at a time. The next generation could be invisible, with billions being around and each of us using more than one at a time. Welcome to the world of embedded systems, of computers that will not look like computers and wont function like anything were familiar with.2.2 What is embedded system?An Embedded System is a combination of computer hardware and software, and perhaps additional mechanical or other parts, designed to perform a specific function. An embedded system is a microcontroller-based, software driven, reliable, real-time control system, autonomous, or human or network interactive, operating on diverse physical variables and in diverse environments and sold into a competitive and cost conscious market.

Fig 2.1: Embedded system design callsAn embedded system is not a computer system that is used primarily for processing, not a software system on PC or UNIX, not a traditional business or scientific application. High-end embedded & lower end embedded systems. High-end embedded system - Generally 32, 64 Bit Controllers used with OS. Examples Personal Digital Assistant and Mobile phones etc .Lower end embedded systems - Generally 8,16 Bit Controllers used with an minimal operating systems and hardware layout designed for the specific purpose.

Fig 2.2: Embedded system design cycle v diagram

2.3 Characteristics of Embedded System:1. An embedded system is any computer system hidden inside a product other than a computer.1. They will encounter a number of difficulties when writing embedded system software in addition to those we encounter when we write applications.1. Throughput Our system may need to handle a lot of data in a short period of time.1. ResponseOur system may need to react to events quickly.1. TestabilitySetting up equipment to test embedded software can be difficult.1. DebugabilityWithout a screen or a keyboard, finding out what the software is doing wrong (other than not working) is a troublesome problem. Reliability embedded systems must be able to handle any situation without human intervention. Memory space Memory is limited on embedded systems, and you must make the software and the data fit into whatever memory exists. Program installation you will need special tools to get your software into embedded systems. Power consumption Portable systems must run on battery power, and the software in these systems must conserve power. Processor hogs computing that requires large amounts of CPU time can complicate the response problem. Cost Reducing the cost of the hardware is a concern in many embedded system projects; software often operates on hardware that is barely adequate for the job. Embedded systems have a microprocessor/ microcontroller and a memory. Some have a serial port or a network connection. They usually do not have keyboards, screens or disk drives.

APPLICATIONS1) Military and aerospace embedded software applications2) Communication Applications3) Industrial automation and process control software4) Mastering the complexity of applications.5) Reduction of product design time.6) Real time processing of ever increasing amounts of data.7) Intelligent, autonomous sensors.

CLASSIFICATION1. Real Time Systems.1. RTS is one which has to respond to events within a specified deadline.1. A right answer after the dead line is a wrong answer.

RTS CLASSIFICATION1. Hard Real Time Systems1. Soft Real Time System

HARD REAL TIME SYSTEM "Hard" real-time systems have very narrow response time. Example: Nuclear power system, Cardiac pacemaker. SOFT REAL TIME SYSTEM "Soft" real-time systems have reduced constrains on "lateness" but still must operate very quickly and repeatable. Example: Railway reservation system takes a few extra seconds the data remains valid.

3. HARDWARE REQUIREMENTS

3.1 POWER SUPPLY BLOCKThe input to the circuit is applied from the regulated power supply. The a.c. input i.e., 230V from the mains supply is step down by the transformer to 12V and is fed to a rectifier. The output obtained from the rectifier is a pulsating d.c voltage. So in order to get a pure d.c voltage, the output voltage from the rectifier is fed to a filter to remove any a.c components present even after rectification. Now, this voltage is given to a voltage regulator to obtain a pure constant dc voltage.

Fig 3.1: Power supply circuit diagram3.1.1 TransformerTransformers convert AC electricity from one voltage to another with a little loss of power. Step-up transformers increase voltage, step-down transformers reduce voltage. Most power supplies use a step-down transformer to reduce the dangerously high voltage to a safer low voltage.

Fig 3.1.1: A Typical TransformerThe input coil is called the primary and the output coil is called the secondary. There is no electrical connection between the two coils; instead they are linked by an alternating magnetic field created in the soft-iron core of the transformer. The two lines in the middle of the circuit symbol represent the core. Transformers waste very little power so the power out is (almost) equal to the power in. Note that as voltage is stepped down and current is stepped up. The ratio of the number of turns on each coil, called the turns ratio, determines the ratio of the voltages. A step-down transformer has a large number of turns on its primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on its secondary (output) coil to give a low output voltage. TURNS RATIO :

Where,

Vp = primary (input) voltage, Vs = secondary (output) voltageNp = number of turns on primary coilNs = number of turns on secondary coil Ip = primary (input) current Is= secondary (output) current.

3.1.2 Rectifier:The output from the transformer is fed to the rectifier. It converts A.C. into pulsating D.C. The rectifier may be a half wave or a full wave rectifier. In this project, a bridge rectifier is used because of its merits like good stability and full wave rectification.

Fig 3.1.2: Full Bridge Rectifier3.1.3 Filter:Capacitive filter is used in this project. It removes the ripples from the output of rectifier and smoothens the D.C. Output received from this filter is constant until the mains voltage and load is maintained constant. However, if either of the two is varied, D.C. voltage received at this point changes. Therefore a regulator is applied at the output stage.

Fig 3.1.3: Capacitive Filter3.1.4 Voltage regulatorAs the name itself implies, it regulates the input applied to it. A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. In this project, power supply of 5V and 12V are required. In order to obtain these voltage levels, 7805 and 7812 voltage regulators are to be used. The first number 78 represents positive supply and the numbers 05, 12 represent the required output voltage levels. Features Output Current up to 1A. Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V. Thermal Overload Protection. Short Circuit Protection. Output Transistor Safe Operating Area Protection.

Fig 3.1.4: LM7805 Voltage regulator

The LM7805 is simple to use. You simply connect the positive lead of your unregulated DC power supply (anything from 9VDC to 24VDC) to the Input pin, connect the negative lead to the Common pin and then when you turn on the power, you get a 5 volt supply from the Output pin.

3.2 Microcontroller AT89S52The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmels high-density non volatile memory technology and is compatible with the industry standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional non volatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.

Block Diagram of AT89S52:

Fig 3.2: Block diagram of AT89S52Features Compatible with MCS-51 Products 8K Bytes of In-System Programmable (ISP) Flash Memory Endurance: 10,000 Write/Erase Cycles 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz Three-level Program Memory Lock 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel Low-power Idle and Power-down Modes Interrupt Recovery from Power-down Mode Watchdog Timer Dual Data Pointer Power-off Flag Fast Programming Time Flexible ISP Programming (Byte and Page Mode) Green (Pb/Halide-free) Packaging Option

Pin Configurations of AT89S52

Fig 3.3: Pin diagram of AT89S52Pin Description:VCC: Supply voltage.GND: Ground

Port 0:Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required during program verification.

Port 1:Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX).

Port 2:Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that uses 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register.

Port 3:Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups.

RST:Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives high for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.

ALE/PROG:Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory.

PSEN:Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.

EA/VPP:External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enable voltage (VPP) during Flash programming.

XTAL1:Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2:Output from the inverting oscillator amplifier.

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

Idle ModeIn idle mode, the CPU puts itself to sleep while all the on chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset.

Power down Mode In the power down mode the oscillator is stopped, and the instruction that invokes power down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power down mode is terminated. The only exit from power down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.

3.3 LDR (Light Dependent Resistor)A photo resistor or light dependent resistor (LDR) is a resistor whose resistance decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photo resistor is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance. A photoelectric device can be either intrinsic or extrinsic. An intrinsic semiconductor has its own charge carriers and is not an efficient semiconductor, for example, silicon. In intrinsic devices the only available electrons are in the valence band, and hence the photon must have enough energy to excite the electron across the entire band gap.Fig 3.4: LDR Extrinsic devices have impurities, also called do pants, added whose ground state energy is closer to the conduction band; since the electrons do not have as far to jump, lower energy photons (that is, longer wavelengths and lower frequencies) are sufficient to trigger the device. If a sample of silicon has some of its atoms replaced by phosphorus atoms (impurities), there will be extra electrons available for conduction. This is an example of an extrinsic semiconductor. Photo resistors are basically photocells.

Key Specifications/Special Features: Specifications: Maximum power consumption: 500V DC Maximum peak value: 500mW Spectrum peak value: 540nm Light resistance: 5 to 10k Dark resistance: 0.6M

Performances and features: Coated with epoxy Good reliability Small volume High sensitivity Fast response Good spectrum characteristic Typical applications: Camera automatic photometry Photoelectric controls Indoor ray controls Annunciation Industrial controls Light control switches Light control lamps Electronic toys Measuring conditions: Light resistance: measured at 10 lux with standard light A (2854K color temperature) and 2hrs illumination at 400 to 600 lux prior to testing. Dark resistance: measured 10 seconds after closed 10 lux. Gamma characteristic: between 10 lux and 100 lux and given by = lg (R10/R100) R10, R100 Cell resistance at 10 lux and 100 lux The error of is 0.1. Pmax: maximum power dissipation at ambient temperature of 25 C. Vmax: maximum voltage in darkness that may be applied to the cell continuously.

3.4 LM35The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of 14C at room temperature and 34C over a full 55 to +150C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35s low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 A from its supply, it has very low self-heating, less than 0.1C in still air. The LM35 is rated to operate over a 55 to +150C temperature range.

Features:1. Calibrated directly in Celsius (Centigrade)1. Linear + 10.0 mV/C scale factor1. 0.5C accuracy guarantee able (at +25C)1. Rated for full 55 to +150C range1. Suitable for remote applications1. Low cost due to wafer-level trimming1. Operates from 4 to 30 volts1. Less than 60 A current drain1. Low self-heating, 0.08C in still air1. Nonlinearity only 14C typical1. Low impedance output, 0.1 W for 1 mA load

Typical Applications

Fig 3.5: Basic Centigrade Temperature Sensor3.4.1 MQ-2 GAS SENSORIt can detect: LPG, i-butane, propane, methane, alcohol, Hydrogen, smoke

Fig 3.6: MQ-2 Gas SensorDescription:MQ-2Semiconductor Sensor for Combustible Gas Sensitive material of MQ-2 gas sensor is SnO2, which with lower conductivity in clean air. When the target combustible gas exist, the sensors conductivity is more high along with the gas concentration rising. Please use simple electro circuit, Convert change of conductivity to correspond output signal of gas concentration. MQ-2 gas sensor has high sensitivity to LPG, Propane and Hydrogen, also could be used to Methane and other combustible steam, it is with low cost and suitable for different application.

Characteristics:1. High sensitivity to Combustible gas in wide range2. High sensitivity to LPG, Propane & Hydrogen3. Fast response4. Wide detection range5. Stable performance long life low cost6. Simple drive circuit

Applications: 1. Domestic gas leakage detector2. Industrial Combustible gas detector3. Portable gas detector4. They are used in gas leakage detecting equipments in family and industry, are suitable for detecting of LPG, i-butane, propane, methane, alcohol, Hydrogen, smoke.

3.5 ADC0808/09The ADC0808, ADC0809 data acquisition component is a monolithic CMOS device with an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible control logic. The 8-bit A/D converter uses successive approximation as the conversion technique. The converter features a high impedance chopper stabilized comparator, a 256R voltage divider with analog switch tree and a successive approximation register. The 8-channel multiplexer can directly access any of 8-single-ended analog signals.

Fig 3.7: Pin diagram

FUNCTIONAL DESCRIPTIONMultiplexer:The device contains an 8-channel single-ended analog signal multiplexer. A particular input channel is selected by using the address decoder. The below table shows the input states for the address lines to select any channel. The address is latched into the decoder on the low-to-high transition of the address latch enable signal.

CONVERTER CHARACTERISTICSThe ConverterThe heart of this single chip data acquisition system is its 8-bit analog-to-digital converter. The converter is designed to give fast, accurate, and repeatable conversions over a wide range of temperatures. The converter is partitioned into 3 major sections: the 256R ladder network, the successive approximation register, and the comparator. The converters digital outputs are positive true. The 256R ladder network approach (Figure 1) was chosen over the conventional R/2R ladder because of its inherent monotonicity, which guarantees no missing digital codes. Monotonicity is particularly important in closed loop feedback control systems. A non-monotonic relationship can cause oscillations that will be catastrophic for the system. Additionally, the 256R network does not cause load variations on the reference voltage.The A/D converters successive approximation register (SAR) is reset on the positive edge of the start conversion (SC) pulse. The conversion is begun on the falling edge of the start conversion pulse. A conversion in process will be interrupted by receipt of a new start conversion pulse. Continuous conversion may be accomplished by tying the end of conversion (EOC) output to the SC input. If used in this mode, an external start conversion pulse should be applied after power up. End-of-conversion will go low between 0 and 8 clock pulses after the rising edge of start conversion. The most important section of the A/D converter is the comparator. It is this section which is responsible for the ultimate accuracy of the entire converter. It is also the comparator drift which has the greatest influence on the repeatability of the device. A chopper-stabilized comparator provides the most effective method of satisfying all the converter requirements.

I/O Pins

ADDRESS LINE A, B, CThe device contains 8-channels. A particular channel is selected by using the address decoder line. The above table shows the input states for address lines to select any channel. Address Latch Enable ALEThe address is latched on the Low High transition of ALE.

STARTThe ADCs Successive Approximation Register (SAR) is reset on the positive edge i.e. Low- High of the Start Conversion pulse. Whereas the conversion is begun on the falling edge i.e. high Low of the pulse. Output EnableWhenever data has to be read from the ADC, Output Enable pin has to be pulled high thus enabling the TRI-STATE outputs, allowing data to be read from the data pins D0-D7. End of Conversion (EOC)This Pin becomes high when the conversion has ended, so the controller comes to know that the data can now be read from the data pins. ClockExternal clock pulses are to be given to the ADC; this can be given either from LM 555 in Astable mode or the controller can also be used to give the pulses. ALGORITHM1. Start.2. Select the channel.3. A Low High transition on ALE to latch in the address.4. A Low High transition on Start to reset the ADCs SAR.5. A High Low transition on ALE.6. A High Low transition on start to start the conversion.7. Wait for End of cycle (EOC) pin to become high.8. Make Output Enable pin High.9. Take Data from the ADCs output 10. Make Output Enable pin Low.11. StopThe clock can also be provided through the controller thus eliminating the need of external circuit for clock. Calculating Step SizeADC 0808 is an 8 bit ADC i.e. it divides the voltage applied at Vref+ & Vref- into 28 i.e. 256 steps. Step Size = (Vref+ - Vref-)/256Suppose Vref+ is connected to Vcc i.e. 5V & Vref- is connected to the ground, then the step size will beStep size= (5 - 0)/256= 19.53 mv.Calculating DoutThe data we get at the D0 - D7 depends upon the step size & the Input voltage i.e. Vin.Dout = Vin /step Size.

ADC INTERFACING WITH MICROCONTROLLER

Fig 3.8: ADC interfacing with microcontroller

The address and data pins of ADC can be connected to any of the ports of 8051.

3.6 TRIAC (Triode for Alternating Current)The triac is a three terminal semiconductor device for controlling current. It is effectively a development of the SCR or thyristor, but unlike the thyristor which is only able to conduct in one direction, the triac is a bidirectional device. As such the triac is an ideal device to use for AC switching applications because it can control the current flow over both halves of an alternating cycle. A thyristor is only able to control them over one half of a cycle. During the remaining half no conduction occurs and accordingly only half the waveform can be utilized. TRIAC BasicsThere are three terminal on a triac. These are the Gate and two other terminals. These other triac terminals are often referred to as an "Anode" or "Main Terminal"

Fig 3.9: TRIAC circuit symbolThe gate, that acts as the trigger to turn the device ON. The current then flows between the two anodes or main terminals. These are usually designated Anode 1 and Anode 2 or Main Terminal 1 and Main Terminal 2 (MT1 and MT2).It can be imagined from the circuit symbol that the triac consists of two thyristors back to back. The operation of the triac can be looked on in this fashion, although the actual operation at the semiconductor level is rather complicated. When the voltage on the MT1 is positive with regard to MT2 and a positive gate voltage is applied, one of the SCRs conducts. When the voltage is reversed and a negative voltage is applied to the gate, the other SCR conducts. This is provided that there is sufficient voltage across the device to enable a minimum holding current to flow. TRIAC OperationThe structure of a triac may be considered as a p-n-p-n structure and the triac may be considered to consist of two conventional SCRs fabricated in an inverse parallel configuration.In operation, when terminal A2 is positive with respect to A1, then a positive gate voltage will give rise to a current that will trigger the part of the triac consisting of p1 n1 p2 n2 and it will have an identical characteristic to an SCR. When terminal A2 is negative with respect to A1 a negative current will trigger the part of the triac consisting of p2 n1 p1 n3. In this way conduction on the triac occurs over both halves an alternating cycle.

Fig 3.10: TRIAC

TRIAC StructureTriac do not fire symmetrically as a result of slight differences between the two halves of the device. This results in harmonics being generated and the less symmetrical the triac fires, the greater the level of harmonics produced. It is generally undesirable to have high levels of harmonics in a power system and as a result triacs are not favoured for high power systems. Instead two thyristors may be used as it is easier to control their firing.To help in overcoming this problem, a device known as a diac (diode AC switch) is often placed in series with the gate. This device helps make the switching more even for both halves of the cycle. This results from the fact that the diac switching characteristic is far more even than that of the triac. Since the diac prevents any gate current flowing until the trigger voltage has reached a certain voltage in either direction, this makes the firing point of the triac more even in both directions.

3.7 Crystal Oscillator (11.0592MHz)It provide clock pulses of 11.0592 Mhz frequency. It can be used as UARTclock (61.8432MHz). It allows integer division to common baud rates (96115200 baud or 96961,200baud). It is acommon clock forIntel 8051microprocessors.Ituses the mechanicalresonanceof a vibratingcrystalofpiezoelectric materialto create an electrical signal with a very precisefrequency.This frequency is commonly used to keep track of time, to provide a stableclock signalfordigitalintegrated circuits, and to stabilize frequencies forradio transmittersandreceivers.The most common type of piezoelectric resonator used is thequartzcrystal, so oscillator circuits incorporating them became known as crystal oscillators.

Fig 3.11: Crystal oscillator

Thecrystal oscillator circuitsustains oscillation by taking a voltage signal from the quartzresonator, amplifying it, and feeding it back to the resonator. The rate of expansion and contraction of the quartz is theresonantfrequency, and is determined by the cut and size of the crystal. When the energy of the generated output frequencies matches the losses in the circuit, an oscillation can be sustained.One of the most important traits of the crystal oscillatoris that it exhibits very lowphase noise.In the crystal oscillator, the crystal mostly vibrates in one axis, therefore only one phase is dominant. This property of lowphase noisemakes them particularly useful in telecommunications where stable signals are needed and in scientific equipment where very precise time references are needed.The result is that a quartz crystal behaves like a circuit composed of aninductor, capacitorandresistor with a precise resonant frequency.

FEATURES:- The crystaloscillator circuitsustains oscillation by taking a voltage signal from the quartz resonator, amplifying it, and feeding it back to the resonator- It provides clock pulses of 11.0592 MHz frequency.- The popularity of the crystals is due tolow cost.3.8 OPTO CouplerAn optical coupler, also called opto-isolator, opto coupler, opto coupler, photo coupler or optical isolator, is a passive optical component that can combine or split transmission data (optical power) from optical fibers. It is an electronic device which is designed to transfer electrical signals by using light waves in order to provide coupling with electrical isolation between its input and output. The main purpose of an opto coupler is to prevent rapidly changing voltages or high voltages on one side of a circuit from distorting transmissions or damaging components on the other side of the circuit. An opto coupler contains a light source often near an LED which converts electrical input signal into light, a closed optical channel and a photo sensor, which detects incoming light and either modulates electric current flowing from an external power supply or generates electric energy directly. The sensor can either be a photo resistor, a silicon-controlled rectifier, a photodiode, a phototransistor or a triac.

Fig 3.12: OptocouplerThe opto coupler applicationor function in the circuit is to: Monitor high voltage Output voltage sampling for regulation System control micro for power on/off Ground isolation

3.9 Electronic BuzzerA buzzer is a mechanical, electromechanical, magnetic, electromagnetic, electro-acoustic or piezoelectric audio signalling device. A piezo electric buzzer can be driven by an oscillating electronic circuit or other audio signal source. A click, beep or ring can indicate that a button has been pressed.

Fig 3.13: Buzzer

FEATURES

The PS series are high-performance buzzers that employ uni morph piezoelectric elements and are designed for easy incorporation into various circuits.They feature extremely low power consumption in comparison to electromagnetic units. Because these buzzers are designed for external excitation, the same part can serve as both a musical tone oscillator and a buzzer. They can be used with automated inserters. Moisture-resistant models are also available. The lead wire type(PS1550L40N) with both-sided adhesive tape installed easily is prepared.

APPLICATIONSElectric ranges, washing machines, computer terminals, various devices that require speech synthesis output.

3.10 LIQUID CRYSTAL DISPLAY (LCD)Liquid crystal display (LCD) has material which combines the properties of both liquid and crystals. They have a temperature range within which the molecules are almost as mobile as they would be in a liquid, but are grouped together in an order form similar to a crystal. Fig 3.14: LCD Display

FEATURES* HIGH CONTRAST LCD SUPERTWIST DISPLAY* EA DIP162-DNLED: YELLOW/GREEN WITH LED BACKLIGHT* EA DIP162-DN3LW AND DIP162J-DN3LW WITH WHITE LED B/L., LOPOWER* INCL. HD 44780 OR COMPATIBLE CONTROLLER* INTERFACE FOR 4- AND 8-BIT DATA BUS* POWER SUPPLY +5V OR 2.7V OR 3.3V* OPERATING TEMPERATURE 0~+50C (-DN3LW, -DHNLED: -20~+70C)* LED BACKLIGHT Y/G max. 150mA@+25C* LED BACKLIGHT WHITE max. 45mA@+25C* SOME MORE MODULES WITH SAME MECHANIC AND SAME PINOUT:-DOTMATRIX 1x8, 4x20-GRAPHIC 122x32* NO SCREWS REQUIRED: SOLDER ON IN PCB ONLY* DETACHABLE VIA 9-PIN SOCKET EA B200-9 (2 PCS. REQUIRED)Liquid crystal display is very important device in embedded system. It offers high flexibility to user as he can display the required data on it. But due to lack of proper approach to LCD interfacing many of them fail. Many people consider LCD interfacing a complex job but according to me LCD interfacing is very easy task, you just need to have a logical approach. This page is to help the enthusiast who wants to interface LCD with through understanding. Copy and Paste technique may not work when an embedded system engineer wants to apply LCD interfacing in real world projects.You will be known about the booster rockets on space shuttle. Without these booster rockets the space shuttle would not launch in geosynchronous orbit. Similarly to understand LCD interfacing you need to have booster rockets attached! To get it done right you must have general idea how to approach any given LCD. This page will help you develop logical approach towards LCD interfacing.Major task in LCD interfacing is the initialization sequence. In LCD initialization you have to send command bytes to LCD. Here you set the interface mode, display mode, address counter increment direction, set contrast of LCD, horizontal or vertical addressing mode, color format. This sequence is given in respective LCD driver datasheet. Studying the function set of LCD lets you know the definition of command bytes. It varies from one LCD to another. If you are able to initialize the LCD properly 90% of your job is done.Next step after initialization is to send data bytes to required display data RAM memory location. Firstly set the address location using address set command byte and than send data bytes using the DDRAM write command. To address specific location in display data RAM one must have the knowledge of how the address counter is incremented.No. Instruction Hex Decimal1 Function Set: 8-bit, 1 Line, 5x7 Dots 0x30 482 Function Set: 8-bit, 2 Line, 5x7 Dots 0x38 563 Function Set: 4-bit, 1 Line, 5x7 Dots 0x20 324 Function Set: 4-bit, 2 Line, 5x7 Dots 0x28 405 Entry Mode 0x06 66Display off Cursor off(clearing display without clearing DDRAM content)0x0887 Display on Cursor on 0x0E 148 Display on Cursor off 0x0C 129 Display on Cursor blinking 0x0F 1510 Shift entire display left 0x18 2412 Shift entire display right 0x1C 3013 Move cursor left by one character 0x10 1614 Move cursor right by one character 0x14 2015 Clear Display (also clear DDRAM content) 0x01 116 Set DDRAM address or coursor position on display 0x80+add* 128+add*17 Set CGRAM address or set pointer toCGRAM location 0x40+add** 64+add LCD pin diagram A liquid crystal display (LCD) is an electronically-modulated optical device shaped into a thin, flat panel made up of any number of color or monochrome pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector. It is often used in battery-powered electronic devices because it requires very small amounts of electric power.

Fig 3.15: LCD Panel pin diagramAbove is the quite simple schematic. The LCD panel's Enable and Register Select is connected to the Control Port. The Control Port is an open collector / open drain output. While most Parallel Ports have internal pull-up resistors, there are a few which don't. Therefore by incorporating the two 10K external pull up resistors, the circuit is more portable for a wider range of computers, some of which may have no internal pull up resistors. We make no effort to place the Data bus into reverse direction. Therefore we hard wire the R/W line of the LCD panel, into write mode. This will cause no bus conflicts on the data lines. As a result we cannot read back the LCD's internal Busy Flag which tells us if the LCD has accepted and finished processing the last instruction. This problem is overcome by inserting known delays into our program. The 10k Potentiometer controls the contrast of the LCD panel. Nothing fancy here. As with all the examples, I've left the power supply out. You can use a bench power supply set to 5v or use a onboard +5 regulator. Remember a few de-coupling capacitors, especially if you have trouble with the circuit working properly. The 2 line x 16 character LCD modules are available from a wide range of manufacturers and should all be compatible with the HD44780. The one I used to test this circuit was a Power tip PC-1602F and an old Philips LTN211F-10 which was extracted from a Poker Machine! The diagram to the right shows the pin numbers for these devices. When viewed from the front, the left pin is pin 14 and the right pin is pin 1.

3.11 LEDA light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lighting. When a light-emitting diode is forward biased (switched on), electrons are able to recombine with holes within the device, releasing energy in the form of photons.

Fig 3.16: symbol of LED

This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is often small in area (less than 1mm2), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability.Light-emitting diodes are used in applications as diverse as replacements for aviation lighting, automotive lighting as well as in traffic signals. The compact size, the possibility of narrow bandwidth, switching speed, and extreme reliability of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are also useful in advanced communications technology.

3.12 1N4007Diodes are used to convert AC into DC these are used as half wave rectifier or full wave rectifier. Three points must he kept in mind while using any type of diode. 1. Maximum forward current capacity 2. Maximum reverse voltage capacity 3. Maximum forward voltage capacity

Fig 3.17: 1N4007 diodesThe number and voltage capacity of some of the important diodes available in the market are as follows: Diodes of number IN4001, IN4002, IN4003, IN4004, IN4005, IN4006 and IN4007 have maximum reverse bias voltage capacity of 50V and maximum forward current capacity of 1 Amp. Diode of same capacities can be used in place of one another. Besides this diode of more capacity can be used in place of diode of low capacity but diode of low capacity cannot be used in place of diode of high capacity. For example, in place of IN4002; IN4001 or IN4007 can be used but IN4001 or IN4002 cannot be used in place of IN4007.The diode BY125made by company BEL is equivalent of diode from IN4001 to IN4003. BY 126 is equivalent to diodes IN4004 to 4006 and BY 127 is equivalent to diode IN4007.

PN JUNCTION OPERATION Now that you are familiar with P- and N-type materials, how these materials are joined together to form a diode, and the function of the diode, let us continue our discussion with the operation of the PN junction. But before we can understand how the PN junction works, we must first consider current flow in the materials that make up the junction and what happens initially within the junction when these two materials are joined together. Current Flow in the N-Type Material Conduction in the N-type semiconductor, or crystal, is similar to conduction in a copper wire. That is, with voltage applied across the material, electrons will move through the crystal just as current would flow in a copper wire. This is shown in figure 1-15. The positive potential of the battery will attract the free electrons in the crystal. These electrons will leave the crystal and flow into the positive terminal of the battery. As an electron leaves the crystal, an electron from the negative terminal of the battery will enter the crystal, thus completing the current path. Therefore, the majority current carriers in the N-type material (electrons) are repelled by the negative side of the battery and move through the crystal toward the positive side of the battery.

Current Flow in the P-Type Material Current flow through the P-type material is illustrated. Conduction in the P material is by positive holes, instead of negative electrons. A hole moves from the positive terminal of the P material to the negative terminal. Electrons from the external circuit enter the negative terminal of the material and fill holes in the vicinity of this terminal. At the positive terminal, electrons are removed from the covalent bonds, thus creating new holes. This process continues as the steady stream of holes (hole current) moves toward the negative terminal.3.13 RESISTORA resistor is a two-terminal electronic component designed to oppose an electric current by producing a voltage drop between its terminals in proportion to the current, that is, in accordance with Ohm's law:V = IRResistors are used as part of electrical networks and electronic circuits. They are extremely commonplace in most electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel/chrome).

Fig 3.18: Resistor

The primary characteristics of resistors are their resistance and the power they can dissipate. Other characteristics include temperature coefficient, noise, and inductance. Less well-known is critical resistance, the value below which power dissipation limits the maximum permitted current flow, and above which the limit is applied voltage. Critical resistance depends upon the materials constituting the resistor as well as its physical dimensions; it's determined by design. Resistors can be integrated into hybrid and printed circuits, as well as integrated circuits. Size, and position of leads (or terminals) are relevant to equipment designers; resistors must be physically large enough not to overheat when dissipating their power.

A resistor is a two-terminal passive electronic component which implements electrical resistance as a circuit element. When a voltage V is applied across the terminals of a resistor, a current I will flow through the resistor in direct proportion to that voltage. The reciprocal of the constant of proportionality is known as the resistance R, since, with a given voltage V, a larger value of R further "resists" the flow of current I as given by Ohm's law:

Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in most electronic equipment. Practical resistors can be made of various compounds and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-chrome). Resistors are also implemented within integrated circuits, particularly analog devices, and can also be integrated into hybrid and printed circuits.The electrical functionality of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than 9 orders of magnitude. When specifying that resistance in an electronic design, the required precision of the resistance may require attention to the manufacturing tolerance of the chosen resistor, according to its specific application. The temperature coefficient of the resistance may also be of concern in some precision applications. Practical resistors are also specified as having a maximum power rating which must exceed the anticipated power dissipation of that resistor in a particular circuit: this is mainly of concern in power electronics applications. Resistors with higher power ratings are physically larger and may require heat sinking. In a high voltage circuit, attention must sometimes be paid to the rated maximum working voltage of the resistor.The series inductance of a practical resistor causes its behaviour to depart from ohms law; this specification can be important in some high-frequency applications for smaller values of resistance. In a low-noise amplifier or pre-amp the noise characteristics of a resistor may be an issue. The unwanted inductance, excess noise, and temperature coefficient are mainly dependent on the technology used in manufacturing the resistor. They are not normally specified individually for a particular family of resistors manufactured using a particular technology. A family of discrete resistors is also characterized according to its form factor, that is, the size of the device and position of its leads (or terminals) which is relevant in the practical manufacturing of circuits using them.

UnitsThe ohm (symbol: ) is the SI unit of electrical resistance, named after Georg Simon Ohm. An ohm is equivalent to a volt per ampere. Since resistors are specified and manufactured over a very large range of values, the derived units of milliohm (1 m = 103 ), kilohm (1 k = 103 ), and megohm (1 M = 106 ) are also in common usage.The reciprocal of resistance R is called conductance G = 1/R and is measured in Siemens (SI unit), sometimes referred to as a mho. Thus a Siemens is the reciprocal of an ohm: S = 1. Although the concept of conductance is often used in circuit analysis, practical resistors are always specified in terms of their resistance (ohms) rather than conductance.

3.14 CAPACITORA capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated conductors.An ideal capacitor is characterized by a single constant value, capacitance, which is measured in farads. This is the ratio of the electric charge on each conductor to the potential difference between them. In practice, the dielectric between the plates passes a small amount of leakage current. The conductors and leads introduce an equivalent series resistance and the dielectric has an electric field strength limit resulting in a breakdown voltage.The properties of capacitors in a circuit may determine the resonant frequency and quality factor of a resonant circuit, power dissipation and operating frequency in a digital logic circuit, energy capacity in a high-power system, and many other important aspects.

Fig 3.19: capacitorA capacitor (formerly known as condenser) is a device for storing electric charge. The forms of practical capacitors vary widely, but all contain at least two conductors separated by a non-conductor. Capacitors used as parts of electrical systems, for example, consist of metal foils separated by a layer of insulating film.Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuits that tune radios to particular frequencies and for many other purposes.A capacitor is a passive electronic component consisting of a pair of conductors separated by a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a static electric field develops in the dielectric that stores energy and produces a mechanical force between the conductors. An ideal capacitor is characterized by a single constant value, capacitance, measured in farads.

4. SOFTWARE REQUIREMENTS

4.1 Introduction to Keil micro vision (IDE) Keil an ARM Company makes C compilers, macro assemblers, real-time kernels, debuggers, simulators, integrated environments, evaluation boards, and emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families. Keil development tools for the 8051 Microcontroller Architecture support every level of software developer from the professional applications engineer to the student just learning about embedded software development. When starting a new project, simply select the microcontroller you use from the Device Database and the Vision IDE sets all compiler, assembler, linker, and memory options for you.Keil is a cross compiler. So first we have to understand the concept of compilers and cross compilers. After then we shall learn how to work with keil.

4.2 CONCEPT OF COMPILERCompilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors. I.E the programs written in one of the HLL like Cwill compile the code to run on the system for a particular processor like x86 (underlying microprocessor in the computer). For example compilers for Dos platform is different from the Compilers for Unix platformSo if one wants to define a compiler then compiler is a program that translates source code into object code. The compiler derives its name from the way it works, looking at the entire piece of source code and collecting and reorganizing the instruction. See there is a bit little difference between compiler and an interpreter. Interpreter just interprets whole program at a time while compiler analyses and execute each line of source code in succession, without looking at the entire program.The advantage of interpreters is that they can execute a program immediately. Secondly programs produced by compilers run much faster than the same programs executed by an interpreter. However compilers require some time before an executable program emerges. Now as compilers translate source code into object code, which is unique for each type of computer, many compilers are available for the same language.

4.3 CONCEPT OF CROSS COMPILERA cross compiler is similar to the compilers but we write a program for the target processor (like 8051 and its derivatives) on the host processors (like computer of x86). It means being in one environment you are writing a code for another environment is called cross development. And the compiler used for cross development is called cross compiler.So the definition of cross compiler is a compiler that runs on one computer but produces object code for a different type of computer.

4.4 KEIL C CROSS COMPILERKeil is a German based Software development company. It provides several development tools like IDE (Integrated Development environment) Project Manager Simulator Debugger C Cross Compiler, Cross Assembler, Locator/LinkerThe Keil ARM tool kit includes three main tools, assembler, compiler and linker. An assembler is used to assemble the ARM assembly program. A compiler is used to compile the C source code into an object file. A linker is used to create an absolute object module suitable for our in-circuit emulator.4.5 Building an Application in Vision2To build (compile, assemble, and link) an application in Vision2, you must:1. Select Project -(forexample,166\EXAMPLES\HELLO\HELLO.UV2).1. Select Project - Rebuild all target files or Build target.Vision2 compiles, assembles, and links the files in your project.4.6 Creating Your Own Application in Vision2 To create a new project in Vision2, you must:1. Select Project - New Project.1. Select a directory and enter the name of the project file.1. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device from the Device Database.1. Create source files to add to the project.1. Select Project - Targets, Groups, Files. Add/Files, select Source Group1, and add the source files to the project.1. Select Project - Options and set the tool options. Note when you select the target device from the Device Database all special options are set automatically. You typically only need to configure the memory map of your target hardware. Default memory model settings are optimal for most applications.1. Select Project - Rebuild all target files or Build target.

4.7 Debugging an Application in Vision2To debug an application created using Vision2, you must:1. Select Debug - Start/Stop Debug Session.1. Use the Step toolbar buttons to single-step through your program. You may enter G, main in the Output Window to execute to the main C function.1. Open the Serial Window using the Serial #1 button on the toolbar.Debug your program using standard options like Step, Go, Break, and so on.

4.8 Starting Vision2 and Creating a ProjectVision2 is a standard Windows application and started by clicking on the program icon. To create a new project file select from the Vision2 menu Project New Project. This opens a standard Windows dialog that asks you for the new project file name. We suggest that you use a separate folder for each project. You can simply use the icon Create New Folder in this dialog to get a new empty folder. Then select this folder and enter the file name for the new project, i.e. Project1. Vision2 creates a new project file with the name PROJECT1.UV2 which contains a default target and file group name. You can see these names in the Project.

4.9 Window Files.Now use from the menu Project Select Device for Target and select a CPU for your project. The Select Device dialog box shows the Vision2 device data base. Just select the microcontroller you use. We are using for our examples the Philips 80C51RD+ CPU. This selection sets necessary tool Options for the 80C51RD+ device and simplifies in this way the tool Configuration.

4.10 Building Projects and Creating a HEX FilesTypical, the tool settings under Options Target are all you need to start a new application. You may translate all source files and line the application with a click on the Build Target toolbar icon. When you build an application with syntax errors, Vision2 will display errors and warning messages in the Output Window Build page. A double click on a message line opens the source file on the correct location in a Vision2 editor window. Once you have successfully generated your application you can start debugging.

After you have tested your application, it is required to create an Intel HEX file to download the software into an EPROM programmer or simulator. Vision2 creates HEX files with each build process when Create HEX files under Options for Target Output is enabled. You may start your PROM programming utility after the make process when you specify the program under the option Run User Program #1.

4.11 CPU SimulationVision2 simulates up to 16 Mbytes of memory from which areas can be mapped for read, write, or code execution access. The Vision2 simulator trapsand reports illegal memory accesses. In addition to memory mapping, the simulator also provides support for the integrated peripherals of the various 8051 derivatives. The on-chip peripherals of the CPU you have selected are configured from the Device.

4.12 Database selectionYou have made when you create your project target. Refer to page 58 for more Information about selecting a device. You may select and display the on-chip peripheral components using the Debug menu. You can also change the aspects of each peripheral using the controls in the dialog boxes.

4.13 Start DebuggingYou start the debug mode of Vision2 with the Debug Start/Stop Debug Session Command. Depending on the Options for Target Debug Configuration, Vision2 will load the application program and run the startup code Vision2 saves the editor screen layout and restores the screen layout of the last debug session. If the program execution stops, Vision2 opens an editor window with the source text or shows CPU instructions in the disassembly window. The next executable statement is marked with a yellow arrow. During debugging, most editor features are still available. For example, you can use the find command or correct program errors. Program source text of your application is shown in the same windows. The Vision2 debug mode differs from the edit mode in the following aspects:_ The Debug Menu and Debug Commands described on page 28 are available. The additional debug windows are discussed in the following._ The project structure or tool parameters cannot be modified. All build commands are disabled.

4.14 Disassembly WindowThe Disassembly window shows your target program as mixed source and assembly program or just assembly code. A trace history of previously executed instructions may be displayed with Debug View Trace Records. To enable the trace history, set Debug Enable/Disable Trace Recording. If you select the Disassembly Window as the active window all program step commands work on CPU instruction level rather than program source lines. You can select a text line and set or modify code breakpoints using toolbar buttons or the context menu commands.You may use the dialog Debug Inline Assembly to modify the CPU instructions. That allows you to correct mistakes or to make temporary changes to the target program you are debugging. Numerous example programs are included to help you get started with the most popular embedded 8051 devices.The Keil Vision Debugger accurately simulates on-chip peripherals (IC, CAN, UART, SPI, Interrupts, I/O Ports, A/D Converter, D/A Converter, and PWM Modules) of your 8051 device. Simulation helps you understand hardware configurations and avoids time wasted on setup problems. Additionally, with simulation, you can write and test applications before target hardware is available.

4.15 EMBEDDED C Use of embedded processors in passenger cars, mobile phones, medical equipment, aerospace systems and defense systems is widespread, and even everyday domestic appliances such as dish washers, televisions, washing machines and video recorders now include at least one such device. Because most embedded projects have severe cost constraints, they tend to use low-cost processors like the 8051 family of devices considered in this book. These popular chips have very limited resources available most such devices have around 256 bytes (not megabytes!) of RAM, and the available processor power is around 1000 times less than that of a desktop processor. As a result, developing embedded software presents significant new challenges, even for experienced desktop programmers. If you have some programming experience - in C, C++ or Java - then this book and its accompanying CD will help make your move to the embedded world as quick and painless as possible.

5. CODING

5.1 Program Code #include#include#include#include"adc0808.h"sbit ldr=P3^7;sbit pump=P3^6;sbit light=P3^5;sbit buzz=P3^4;void main(){lcd_init();lcd_init();message(0x80,"Industrial Protection");delay(500);while(1){adcdata();delay(500);if(C1>50){init(0x01);message(0x80,"High temparature");buzz=0;pump=0; delay(300);}if(C2>4000){init(0x01);message(0x80,"High Smoke");buzz=0;pump=0; delay(300);}if(C1