FIRE SENSING ROBOT

INDEX

CONTENTS

1. Abbreviations

2. Introduction

3. Block Diagram

4. Block Diagram Description

5. Schematic

6. Schematic Description

7. Hardware Components

Microcontroller

H-BRIDGE

Smoke sensor

POWER SUPPLY

Buzzer

8. Circuit Description

9. software

10.Conclusion (or) Synopsis

11. Future Aspects

12. Bibliography

ABBREVIATIONS

SYMBOL NAME

ACC Accumulator

B B register

PSW Program status word

SP Stack pointer

DPTR Data pointer 2 bytes

DPL Low byte

DPH High byte

P0 Port0

P1 Port1

P2 Port2

P3 Port3

IP Interrupt priority control

IE Interrupt enable control

TMOD Timer/counter mode control

TCON Timer/counter control

T2CON Timer/counter 2 control

T2MOD Timer/counter mode2 control

TH0 Timer/counter 0high byte

TL0 Timer/counter 0 low byte

TH1 Timer/counter 1 high byte

TL1 Timer/counter 1 low byte

TH2 Timer/counter 2 high byte

TL2 Timer/counter 2 low byte

SCON Serial control

SBUF Serial data buffer

PCON Power control

INTRODUCTION

A robot is officially defined by as an automatically controlled, reprogrammable,

multipurpose manipulator programmable in three or more axes. The field of robotics

may be more practically defined as the study, design and use of robot systems for

manufacturing (a top-level definition relying on the prior definition of robot).

Typical applications of robots include welding, painting, ironing, assembly, pick and

place, packaging and palletizing, product inspection, and testing, all accomplished with

high endurance, speed, and precision.

Robot types, features

The most commonly used robot configurations are articulated robots, SCARA robots and

gantry robots (aka Cartesian Coordinate robots, or x-y-z robots). In the context of general

robotics, most types of robots would fall into the category of robot arms (inherent in the

use of the word manipulator in the above-mentioned ISO standard). Robots exhibit

varying degrees of autonomy:

Some robots are programmed to faithfully carry out specific actions over and over

again (repetitive actions) without variation and with a high degree of accuracy.

These actions are determined by programmed routines that specify the direction,

acceleration, velocity, deceleration, and distance of a series of coordinated

motions.

Other robots are much more flexible as to the orientation of the object on which

they are operating or even the task that has to be performed on the object itself,

which the robot may even need to identify. For example, for more precise

guidance, robots often contain machine vision sub-systems acting as their "eyes",

linked to powerful computers or controllers. Artificial intelligence, or what passes

for it, is becoming an increasingly important factor in the modern industrial robot.

History

George Devol applied for the first robotics patents in 1954 (granted in 1961). The first

company to produce a robot was Unimation, founded by George Devol and Joseph F.

Engel berger in 1956, and was based on Devol's original patents. Unimation robots were

also called programmable transfer machines since their main use at first was to transfer

objects from one point to another, less than a dozen feet or so apart. They used hydraulic

actuators and were programmed in joint coordinates, i.e. the angles of the various joints

were stored during a teaching phase and replayed in operation. They were accurate to

within 1/10,000 of an inch. Unimation later licensed their technology to Kawasaki Heavy

Industries and Guest-Nettlefolds, manufacturing Unimates in Japan and England

respectively. For some time Unimation's only competitor was Cincinnati Milacron Inc. of

Ohio. This changed radically in the late 1970s when several big Japanese conglomerates

began producing similar industrial robots.

In 1969 Victor Scheinman at Stanford University invented the Stanford arm, an all-

electric, 6-axis articulated robot designed to permit an arm solution. This allowed it to

accurately follow arbitrary paths in space and widened the potential use of the robot to

more sophisticated applications such as assembly and arc welding. Scheinman then

designed a second arm for the MIT AI Lab, called the "MIT arm." Scheinman, after

receiving a fellowship from Unimation to develop his designs, sold those designs to

Unimation who further developed them with support from General Motors and later

marketed it as the Programmable Universal Machine for Assembly (PUMA).

In 1973 KUKA Robotics built its first robot, known as FAMULUS, this is the first

articulated robot to have six electromechanically driven axes.

Interest in robotics swelled in the late 1970s and many companies entered the field,

including large firms like General Electric, and General Motors (which formed joint

venture FANUC Robotics with FANUC LTD of Japan). US start-ups included Automatix

and Adept Technology, Inc. At the height of the robot boom in 1984, Unimation was

acquired by Westinghouse Electric Corporation for 107 million US dollars.

Westinghouse sold Unimation to Stäubli Faverges SCA of France in 1988. Stäubli was

still making articulated robots for general industrial and clean room applications as of

2004 and even bought the robotic division of Bosch in late 2004.

Eventually the myopic vision of American industry was superseded by the financial

resources and strong domestic market enjoyed by the Japanese manufacturers. Only a few

non-Japanese companies managed to survive in this market, including Adept Technology,

Stäubli-Unimation, the Swedish-Swiss company ABB (ASEA Brown-Boveri), the

Austrian manufacturer igm Robotersysteme AG and the German company KUKA

Robotics.

Now a day's every system is automated in order to face new challenges. In the

present days Automated systems have less manual operations, flexibility, reliability

and accurate. Due to this demand every field prefers automated control systems.

Especially in the field of electronics automated systems are giving good performance.

In the present scenario of war situations, unmanned systems plays very important role

to minimize human losses. So this robot is very useful to do operations like detecting

fire.

Here is an automated unmanned system being designed around a

microcontroller which serves for detecting hazardous parameters such as smoke.

According to this project, a robot is designed which is made to move all the

time. Apart from this, the system also detects the presence of smoke with the help of a

smoke sensor. All the devices such as smoke sensor, motor by which robot is made to

move, buzzer are being interfaced to microcontroller which forms the control unit of

the project.

In the standby mode the robot is moved here and there. Whenever any

smoke is detected by the smoke sensor, the same is sensed and is intimated to the user

by the microcontroller using buzzer.

This project finds its place in places where one wants to make the unmanned

system to sense some hazardous condition.

BLOCK DIAGRAM:

MICRO CONTROLLER UNIT

FIRE SENSOR

BUZZER

BatteryMotorsDrivers

Block Diagram Explanation:

This Project mainly consists of Power Supply section, Microcontroller section, Motor

Driver section and a smoke sensor.

Power Supply Section: This section is meant for supplying Power to all the sections

mentioned above. It basically consists of a 9V DC battery followed by a positive voltage

regulator is used to regulate the required dc voltage for the Microcontroller circuit

operation. There is another power supply which is a 6V DC (four 1.5V batteries) is

required for the operation of the motor driver circuitry.

Microcontroller Section: This section forms the control unit of the whole project. This

section basically consists of a Microcontroller with its associated circuitry like Crystal

with capacitors, Reset circuitry, Pull up resistors (if needed) and so on. The

Microcontroller forms the heart of the project because it controls the devices being

interfaced and communicates with the devices according to the program being written.

Motor Driver Section: This section basically consists of the required circuitry to drive

the motors. This is nothing but an H-Bridge circuitry to drive the motors which controls

direction of the robot.

Smoke Sensor: smoke sensoris used in this project. Whenever the sensor finds smoke

at particular region in the robot’s path. Then the sensor gives the signal to

Microcontroller. The smoke sensor acts as a input source in this project.

Buzzer: The buzzer is an output source for the project. The buzzer is used as an

indication purpose for the occurrence of the high temperatures.

Schematic Explanation:

Firstly, the required operating voltage for Microcontroller 89s51 is 5V. Hence the

5V D.C. power supply is needed by the same. So in this project we are using +9V DC

battery for providing the required voltage for the circuit operation.

The 9V DC battery is connected to the LM7805 regulator so that it allows us to

have a Regulated Voltage which is +5V. This regulated voltage is filtered for ripples

using an electrolytic capacitor 100μF. Now the output from this section is fed to 40th pin

of 89s51 microcontroller to supply operating voltage. In this project, there is another

power supply which is 6V (four- 1.5V battery) supply. This is required for the operation

of the motor driver circuitry to drive the motors.

The microcontroller 89c51 with Pull up resistors at Port0 and crystal oscillator of

11.0592 MHz crystal in conjunction with couple of capacitors of is placed at 18th & 19th

pins of 89c51 to make it work (execute) properly.

The motor driver is nothing but a H-bridge circuitry for controlling motors. That

is for the controlling of the robot direction. The motor driver circuitry includes the two

H-Bridges. Each H-bridge will take care of controlling motor. Each H-bridge having

two inputs. That is, four inputs of two H-bridges are connected to the port pins P1.0,

P1.0, P1.2, P1.3 of the Microcontroller. According the logic values applied at the input

of the H-bridge circuitry the direction of the robot will be controlled. That will be done

through the software. Buzzer is connected to the port P2.0.smoke is connected to the port

P3.2.

HARDWARE USED:

MICROCONTROLLER

SMOKE SENSOR

MOTOR DRIVER

MOTOR

BUZZER

BATTERY

MICRO CONTROLLER (AT89S51)

Introduction:

A Micro controller consists of a powerful CPU tightly coupled with memory,

various I/O interfaces such as serial port, parallel port timer or counter, interrupt

controller, data acquisition interfaces-Analog to Digital converter, Digital to Analog

converter, integrated on to a single silicon chip.

If a system is developed with a microprocessor, the designer has to go for external

memory such as RAM, ROM, EPROM and peripherals. But controller is provided all

these facilities on a single chip. Development of a Micro controller reduces PCB size and

cost of design.

One of the major differences between a Microprocessor and a Micro controller is

that a controller often deals with bits not bytes as in the real world application.

Intel has introduced a family of Micro controllers called the MCS-51.

Figure: micro controller

Features:

• Compatible with MCS-51® Products

• 4K Bytes of In-System Programmable (ISP) Flash Memory

– Endurance: 1000 Write/Erase Cycles

• 4.0V to 5.5V Operating Range

• Fully Static Operation: 0 Hz to 33 MHz

• Three-level Program Memory Lock

• 128 x 8-bit Internal RAM

• 32 Programmable I/O Lines

• Two 16-bit Timer/Counters

• Six Interrupt Sources

• Full Duplex UART Serial Channel

• Low-power Idle and Power-down Modes

Description

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K

bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s

high-density nonvolatile memory technology and is compatible with the industry- standard

80C51 instruction set and pinout. The on-chip Flash allows the program memory to be

reprogrammed in-system or by a conventional nonvolatile memory programmer. By

combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip,

the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and

cost-effective solution to many embedded control applications.

Block diagram:

Figure: Block diagram

Pin diagram:

Figure: pin diagram of micro controller

Pin 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. Port 1

also receives the low-order address bytes during Flash programming and verification.

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

also receives the high-order address bits and some control signals during Flash

programming and verification.

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. Port 3

receives some control signals for Flash programming and verification. Port 3 also serves the

functions of various special features of the AT89S51, as shown in the following table.

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.

If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit

set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly

pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external

execution mode.

PSEN:

Program Store Enable (PSEN) is the read strobe to external program memory. When

the AT89S51 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 Figs

6.2.3. Either a quartz crystal or ceramic resonator may be used. To drive the device from

an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as

shown in Figure 6.2.4.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.

Fig 6.2.3 Oscillator Connections Fig 6.2.4 External Clock Drive Configuration

H-Bridge:

Fig: shows the H-Bridge operation. The H-Bridge consists of a four PNP

transistors such as Q1, Q2, Q3 and Q4. These transistors are arranged in a way that a DC

motor M can rotate. A and B are represented as two inputs for operating a motor through

the transistors. For the circuit operation, we are providing +12V DC as a VCC. The

operation will be explained as follows:

The inputs A and B can be applied as a either logic ‘0’ or logic ‘1’ ie., may be

either 5V DC voltage or Ground. If the input A =logic ‘0’ and B=logic’1’ then

transistors Q1 and Q4 will be ‘ON’ state and Q2 and Q3 will be ‘OFF’ state. The current

flows from Q1 to Q4 so that the motor M can rotate in clockwise direction.

If the input A =logic ‘1’ and B=logic’0’ then transistors Q1 and Q4 will be ‘OFF’

state and Q2 and Q3 will be ‘ON’ state. The current flows from Q1 to Q4 so that the

motor M can rotate in Anti-clockwise direction.

If the input A =logic ‘1’ and B=logic’1’ then transistors Q1 and Q4 will be ‘OFF’

state and Q2 and Q3 will be ‘OFF’ state. No current flows from in the circuit. The circuit

will be in hold condition. The motor will not rotate any direction. So, there is no wastage

of power will occur. Otherwise, if both inputs are low that is all transistors are come

under working and more current will flows in the circuit. But the motor will be at hold

condition. More power is wasted.

DC Motor

DC motors are configured in many types and sizes, including brush less, servo, and gear

motor types. A motor consists of a rotor and a permanent magnetic field stator. The magnetic

field is maintained using either permanent magnets or electromagnetic windings. DC motors are

most commonly used in variable speed and torque.

Motion and controls cover a wide range of components that in some way are used to

generate and/or control motion. Areas within this category include bearings and bushings,

clutches and brakes, controls and drives, drive components, encoders and resolves, Integrated

motion control, limit switches, linear actuators, linear and rotary motion components, linear

position sensing, motors (both AC and DC motors), orientation position sensing, pneumatics and

pneumatic components, positioning stages, slides and guides, power transmission (mechanical),

seals, slip rings, solenoids, springs.

Motors are the devices that provide the actual speed and torque in a drive system. This

family includes AC motor types (single and multiphase motors, universal, servo motors,

induction, synchronous, and gear motor) and DC motors (brush less, servo motor, and gear

motor) as well as linear, stepper and air motors, and motor contactors and starters.

In any electric motor, operation is based on simple electromagnetism. A current-carrying

conductor generates a magnetic field; when this is then placed in an external magnetic field, it

will experience a force proportional to the current in the conductor, and to the strength of the

external magnetic field. As you are well aware of from playing with magnets as a kid, opposite

(North and South) polarities attract, while like polarities (North and North, South and South)

repel. The internal configuration of a DC motor is designed to harness the magnetic interaction

between a current-carrying conductor and an external magnetic field to generate rotational

motion.

Buzzer

A buzzer or beeper is a signalling device, usually electronic, typically used in

automobiles, household appliances such as a microwave oven, or game shows. It most

commonly consists of a number of switches or sensors connected to a control unit that

determines if and which button was pushed or a preset time has lapsed, and usually

illuminates a light on the appropriate button or control panel, and sounds a warning in the

form of a continuous or intermittent buzzing or beeping sound.

Initially this device was based on an electromechanical system which was

identical to an electric bell without the metal gong (which makes the ringing noise).

Often these units were anchored to a wall or ceiling and used the ceiling or wall as a

sounding board. Another implementation with some AC-connected devices was to

implement a circuit to make the AC current into a noise loud enough to drive a

loudspeaker and hook this circuit up to a cheap 8-ohm speaker. Nowadays, it is more

popular to use a ceramic-based piezoelectric sounder like a Sonalert which makes a high-

pitched tone. Usually these were hooked up to "driver" circuits, which varied the pitch of

the sound or pulsed the sound, on and off.

Electronic symbol for a buzzer.

Metal disk with piezoelectric disk attached, as found in a buzzer

In game shows it is also known as a "lockout system," because when one person

signals ("buzzes in"), all others are locked out from signalling.Several game shows have

large buzzer buttons which are identified as "plungers".

The word "buzzer" comes from the rasping noise that buzzers made when they

were electromechanical devices, operated from stepped-down AC line voltage at 50 or 60

cycles. Other sounds commonly used to indicate that a button has been pressed are a ring

or a beep.

FIRE SENSOR:

The semiconductor (or IC for integrated circuit) temperature sensor is an electronic device fabricated in a similar way to other modern electronic semiconductor components such as microprocessors. Typically hundreds or thousands of devices are formed on thin silicon wafers. Before the wafer is scribed and cut into individual chips, they are usually laser trimmed.

Semiconductor temperature sensors are available from a number of manufacturers. There are no generic types as with thermocouple and RTDs, although a number of devices are made by more than one manufacturer. The AD590 and the LM35 have traditionally been the most popular devices, but over the last few years better alternatives have become available.

These sensors share a number of characteristics - linear outputs, relatively small size, limited temperature range (-40 to +120°C typical), low cost, good accuracy if calibrated but also poor interchangeability. Often the semiconductor temperature sensors are not well designed thermally, with the semiconductor chip not always in good thermal contact with an outside surface. Some devices are inclined to oscillate unless precautions are taken. Provided the limitations of the semiconductor temperature sensors are understood, they can be used effectively in many applications.

The most popular semiconductor temperature sensors are based on the fundamental temperature and current characteristics of the transistor. If two identical transistors are operated at different but constant collector current densities, then the difference in their base-emitter voltages is proportional to the absolute temperature of the transistors. This voltage difference is then converted to a single ended voltage or a current. An offset may be applied to convert the signal from absolute temperature to Celsius or Fahrenheit.

In general, the semiconductor temperature sensor is best suited for embedded applications - that is, for use within equipment. This is because they tend to be electrically and mechanically more delicate than most other temperature sensor types. However they do have legitimate application in many areas, hence their inclusion.

Types of semiconductor sensors

A summary of available semiconductor temperatures sensors is presented below, followed by more detail on some of the more popular devices. The sensors can be grouped into five broad categories: voltage output, current output, resistance output, digital output and simple diode types.

1. Voltage Output Temperature Sensors

The following sensors provide a voltage outputs signal with relatively low output impedance. All require an excitation power source and all are essentially linear.

Sensor Manuf. Output Tolerance

(range) Package Comments

AD22100 Analog Devices

22.5mV/°C at 5V

250mV offset

±2°C & ±4°C(-50 to +150°C)

TO-92SO-8

Output ratiometric with supply voltage - good with ratiometric ADC's

AD22103 Analog Devices

28mV/°C (at 3.3V),

250mV offset

±2.5°C(0°C to +100°C)

TO-92SO-8

Output ratiometric with supply voltage

LM135LM235LM335

National Semi, Linear

Tech

10mV/°K or10mV/°C

±2.7°C to ±9°C(-55°C to 150°C-40°C to 100°C)

TO-92TO-46

Zener like operation with scale trim pin, 400µA

LM34 National Semi 10mV/°F ±3°F & ±4°F

(-20°C to 120°C)

TO-46TO-92SO-8

Needs a negative supply for temperatures < -5°C

LM35 National Semi 10mV/°C ±1°C & ±1.5°C

(-20°C to 120°C)

TO-46TO-92SO-8

Needs a negative supply for temperatures < 10°C

LM45 National Semi 10mV/°C

500mV offset ±1°C & ±1.5°C

(-20°C to 120°C)

TO-46TO-9SO-8

LM35 with 500mV output offset

LM50 National Semi 10mV/°C

500mV offset ±3°C & ±4°C

(-40°C to 125°C)

TO-46TO-92SO-8

Low cost part, 500mV off set, easy to use

LM60 National Semi 6.24 mV

offset ±3°C & ±4°C

(-40°C to 125°C) SOT-23

Supply voltage down to 2.7V

S-8110S-8120

Seiko Instruments

-8.5 mV/°C(note neg. TC)

±2.5°C & ±5°C(-40°C to 100°C)

SOT-23SC-82AB

Very low 10µA operating current

TC102TC103TC1132TC1133

Telcom Semi 10 mV/°C ±8°C

(-20°C to 125°C) SOT-23TO-92

.

TMP35 Analog Devices

10 mV/°C ±3°C ±4°C

(10°C to 125°C)

TO-92SO-8

SOT-23

Similar to LM35 plus shutdown for power saving (not in TO-92)

TMP36 Analog Devices

10 mV/°C500 mV offset

±3°C ±4°C(-40°C to 125°C)

TO-92SO-8

SOT-23

Similar to LM50 plus shutdown (not in TO-92)

TMP37 Analog Devices

20 mV/°C ±3°C ±4°C

(5°C to 100°C)

TO-92SO-8

SOT-23 High sensitivity

LM94021LM94022

National Semi programmable±2.5°C

(-50°C to 150°C) SC80

Low power, easy to use

FM20 Fairchild -11.77 mV/°C±5°C

-55°C to 130°C SOT23 Low power

FM50 Fairchild 10 mV/°C ±3°C

-40°C to 125°C SOT23 Similar to LM50

The LM34 and LM35 parts are prone to oscillation if sensor cable capacitively loads their output. The symptom is an offset in the sensors output - something which is not always obvious. It is wise to always include the manufacturer's recommended resistor - capacitor network close to the sensor.

2. Current Output Temperature Sensors

The current output sensors acts as a high-impedance, constant current regulator typically passing 1 micro-amp per degree Kelvin and require a supply voltage of between 4 and 30 V.

Sensor Manuf. Output Tolerance

(range) Package Comments

AD590 Analog Devices

1µA/°K ±5.5°C & ±10°C

(-55°C to +150°C)

TO-52 An old favorite, but need to watch cable leakage currents

AD592 Analog Devices

1µA/°K ±1°C & ±3.5°C

(-25°C to +105°C)

TO-92 A more precise AD590

TMP17 Analog Devices

1µA/°K ±4°C

(-40°C to +105°C)

SO-8 Thermally faster AD590

LM134 National Programmable ±3°C & ±20°C TO-46 Not well specified, but

LM234LM334

Semi 0.1µA/°K to

4µA/°K (-25°C to +100°C)

TO-92 with calibration can be effective.

3. Digital Output Temperature Sensors

The digital temperature sensor is the first sensor to integrate a sensor and an analog to digital converter (ADC) on to a single silicon chip. In general, these sensors do not lend themselves for use with standard measuring devices because of their non standard digital interfaces. Many are designed specifically for the thermal management of microprocessor chips. A selection of representative devices is presented below:

Sensor Manuf. Output Tolerance

(range) Package Comments

LM95071 National Semi 14 bit SPI ±2°C

(-45°C to 150°C) SOT-5

High resolution(0.03°C)2.4-5.5V operation

LM56 National Semi 2 comparators with setable thresholds

±3°C & ±4°C(-40°C to 125°C)

SOP-8MSOP-8

Thermostat with two outputs with hysteresis

LM75 National Semi I2C Serial,

9 bit or 0.5°C resolution

±3°C(-55°C to +125°C)

SOP-8MSOP-8

Addressable, multi drop connection. Better suited to embedded systems

TMP03TMP04

Analog Devices

Pulse width modulation(mark-space

ratio)

±4°C(-25°C to 100°C)

TO-92SO-8

TSSOP-8

Nominal 35 Hz output with 1:1 mark-space ratio at 25°C

DS1620DS1621

National Semi 2 or 3 wire

serial, 0.5°C resolution

±0.5°C(0°C to 70°C)

±5°C(-55°C to 125°C)

SOP-8DIP-8

Also has digitally programmed thermostat output. ±0.03°C resolution possible

DS1624 Dallas 2 wire serial0.3°C

resolution

±5°C(-55°C to 125°C)

SOP-8DIP-8

Addressable, multi drop connection.

Also has 256 bits of EEPROM

DS1820 Dallas 1 wire serial

0.5°C resolution

±0.5°C(0°C to 70°C)

±5°C(-55°C to 125°C)

ModifiedTO-92

SSOP-16

Good un-calibrated tolerance over 0-70°C range.

DS1821 Dallas 1 wire serial

1°C resolution

±1°C(0°C to 70°C)

±2°C(-55°C to 125°C)

Modified TO-92TO-220

SO-8

Has a thermostat mode.

DS2435 Dallas 1 wire serial0.5°C or 1°C

resolution

±4°C(0°C to 127.5°C-40°C to 85°C)

TO-92modified

Also builds a time / temperature histogram

TCN75 Telcom Semi I2C Serial,

9 bit or 0.5°C resolution

±3°C(-55°C to +125°C)

DIP-8SOP-8

TSSOP-8

Second source for LM75

FM75 Fairchild

SMBus12 bit / 0.07°C

resolution

±4°C-40°C to 125°C

MSOP8

Variable resolution, threshold output

The Analog Devices parts are interesting. They employ a sigma-delta ADC that produces continuous pulse stream output with a mark-space ratio, which is proportional to the temperature. This makes for easy interfacing to a microprocessor and also for isolating by optical or other means. The same signal could also be passed through a low pass filter to generate an analog voltage.

The Dallas DS2435 goes beyond that of a sensor plus ADC by providing simple data reduction using an eight bin time / temperature histogram with definable bin boundaries. It appears to have been specifically designed for battery management, but other application could include food transport monitoring, machine use monitoring. This sensor demonstrated the way of the future in sensor technology where sensor, ADC, memory and microcontroller are integrated to form an application specific task very cost effectively.

4. Resistance Output Silicon Temperature Sensors

The temperature - versus - bulk resistance characteristics of semiconductor materials allow the manufacture of simple temperature sensors using standard silicon semiconductor fabrication equipment. This construction can be more stable than other semiconductor sensor, due to the greater tolerance to ion migration. However other characteristics (see below) require that care be taken in using these sensors.

Sensor Manuf. Output Tolerance

(range) Package Comments

KTY81KTY82KTY83KTY84KTY85

Phillips

1K or 2K at 25°C,

+0.8%/°CSee below

±1°C to ±12°C(-55°C to +150°Csome to 300°C)

SOD-70,SOT-23SOD-68SOD-80

Bulk resistance of silicon. Keep excitation current >0.1mA and < 1mA

KYY10KTY11KTY13

Siemens

1K or 2K at 25°C,

+0.8%/°CSee below

±1°C & ±3.5°C(-50°C to +150°C)

TO-92modified

Bulk resistance of silicon.

The silicon temperature sensor's resistance is given by the equation:

R = Rr ( 1 + a.( T - Tr ) + b.( T - Tr )2- c.(T - Ti)d )

where Rr is the resistance at temperature Tr and a, b, c and d are constants. Ti is an inflection point temperature such that c = 0 for T < Ti.

The resistance of some of these semiconductor sensors is dependent on the excitation current (due to current density effects in the semiconductor) and the polarity of the applied voltage. As with other non-passive temperature sensors, self-heating can induce errors.

There are a number of specialist cryogenic temperature sensors that use resistive semiconductor sensor elements made from silicon and germanium.

5. Diode Temperature Sensors

The ordinary semiconductor diode may be used as a temperature sensor. Cheap and nasty! The diode is the lowest cost temperature sensor and can produce more than satisfactory results if you are prepared to undertake a two point calibration and provide a stable excitation current.   Almost any silicon diode is ok. The forward biased voltage across a diode has a temperature coefficient of about 2.3mV/°C and is reasonably linear. The measuring circuit is simple as shown to the right.

The bias current should be held as constant as possible - using constant current source, or a resistor from a stable voltage source.

Without calibration the initial error is likely to be too large - in the order of ±30°C - the largest of all the contact type temperature sensors. This initial error is greatly reduced if sensor grade parts are used.

One advantage of the diode as a temperature sensor is that it can be electrically robust - tolerant to voltage spikes induced by lightning strike. This is particularly true if power diodes (e.g. the common 1N4004) are used and a second back to back diode is used to limit power dissipation during high peak currents.

The transistor sensor is used in diode mode by connecting the base and collector together. If this is not done, the sensor is wired between base and emitter and the excitation current reduced by a factor of about 100. The result is a very low power, sensitive and linear sensor. The simplicity and performance of the sensor is under valued.

To improve the performance of the diode as a temperature sensor, two diode voltages (V1 and V2) can be measured at different currents (I1 and I2), typically selected to be about 1:10 ratio. The absolute temperature can be calculated from the equation:

T = (V1 - V2) / (8.7248x10-5 ln( I1 / I2))

The result is in Kelvins (K). This is the method employed by most integrated circuit temperatures sensors and explains why some output a signal proportional to absolute temperature.

Accuracy of semiconductor sensors

As can be seen from the above information, the "out of the box" or interchangeability accuracy of most semiconductor temperature sensors is not particularly good. In addition the raw sensing element is generally packaged in a standard case for electronic devices, which is less than ideal for precision temperature measurement. However, despite these shortcomings, the sensors are sensitive, reasonably linear and very usable.

If individual sensors are calibrated, significantly better measurement accuracy is possible. Typically, a two point calibration will yield a five-fold better accuracy and a three point calibration will yield a ten-fold improvement over the full temperature range. If the temperature range is limited, even better accuracies are possible. Due to the sensitivity of some sensors, they can be very good in measuring small temperature changes (as opposed to absolute measurement).

Power supply

The power supplies are designed to convert high voltage AC mains electricity to a

suitable low voltage supply for electronics circuits and other devices. A power supply can

by broken down into a series of blocks, each of which performs a particular function. A

d.c power supply which maintains the output voltage constant irrespective of a.c mains

fluctuations or load variations is known as “Regulated D.C Power Supply”

For example a 5V regulated power supply system as shown below:

Transformer:

A transformer is an electrical device which is used to convert electrical power

from one

Electrical circuit to another without change in frequency.

Transformers convert AC electricity from one voltage to another with little loss of

power. Transformers work only with AC and this is one of the reasons why mains

electricity is AC. Step-up transformers increase in output voltage, step-down

transformers decrease in output voltage. Most power supplies use a step-down

transformer to reduce the dangerously high mains voltage to a safer low voltage. The

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 current

is stepped up. The ratio of the number of turns on each coil, called the turn’s 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.

An Electrical Transformer

Turns ratio = Vp/ VS = Np/NS

Power Out= Power In

VS X IS=VP X IP

Vp = primary (input) voltage

Np = number of turns on primary coil

Ip  = primary (input) current    

RECTIFIER:

A circuit which is used to convert a.c to dc is known as RECTIFIER. The process

of conversion a.c to d.c is called “rectification”

TYPES OF RECTIFIERS:

Half wave Rectifier

Full wave rectifier

1. Centre tap full wave rectifier.

2. Bridge type full bridge rectifier.

Comparison of rectifier circuits:

Parameter

Type of Rectifier

Half wave Full wave Bridge

Number of diodes

1

2

4

PIV of diodes

Vm

2Vm

Vm

D.C output voltage

Vm/

2Vm/

2Vm/

Vdc,at

no-load

0.318Vm

0.636Vm 0.636Vm

Ripple factor

1.21

0.482

0.482

Ripple

frequency

f

2f

2f

Rectification

efficiency

0.406

0.812

0.812

Transformer

Utilization

Factor(TUF)

0.287 0.693 0.812

RMS voltage Vrms Vm/2 Vm/√2 Vm/√2

Full-wave Rectifier:

From the above comparison we came to know that full wave bridge rectifier as more

advantages than the other two rectifiers. So, in our project we are using full wave bridge

rectifier circuit.

Bridge Rectifier: A bridge rectifier makes use of four diodes in a bridge arrangement to

achieve full-wave rectification. This is a widely used configuration, both with individual

diodes wired as shown and with single component bridges where the diode bridge is

wired internally.

A bridge rectifier makes use of four diodes in a bridge arrangement as shown in

fig(a) to achieve full-wave rectification. This is a widely used configuration, both with

individual diodes wired as shown and with single component bridges where the diode

bridge is wired internally.

Fig(A)

Operation:

During positive half cycle of secondary, the diodes D2 and D3 are in forward biased

while D1 and D4 are in reverse biased as shown in the fig(b). The current flow direction

is shown in the fig (b) with dotted arrows.

Fig(B)

During negative half cycle of secondary voltage, the diodes D1 and D4 are in forward

biased while D2 and D3 are in reverse biased as shown in the fig(c). The current flow

direction is shown in the fig (c) with dotted arrows.

Fig(C)

Filter:

A Filter is a device which removes the a.c component of rectifier output

but allows the d.c component to reach the load

Capacitor Filter:

We have seen that the ripple content in the rectified output of half wave rectifier is

121% or that of full-wave or bridge rectifier or bridge rectifier is 48% such high

percentages of ripples is not acceptable for most of the applications. Ripples can be

removed by one of the following methods of filtering.

(a) A capacitor, in parallel to the load, provides an easier by –pass for the ripples voltage

though it due to low impedance. At ripple frequency and leave the d.c.to appears the load.

(b) An inductor, in series with the load, prevents the passage of the ripple current (due to

high impedance at ripple frequency) while allowing the d.c (due to low resistance to d.c)

(c) Various combinations of capacitor and inductor, such as L-section filter section

filter, multiple section filter etc. which make use of both the properties mentioned in (a)

and (b) above. Two cases of capacitor filter, one applied on half wave rectifier and

another with full wave rectifier.

Filtering is performed by a large value electrolytic capacitor connected across the

DC supply to act as a reservoir, supplying current to the output when the varying DC

voltage from the rectifier is falling. The capacitor charges quickly near the peak of the

varying DC, and then discharges as it supplies current to the output. Filtering

significantly increases the average DC voltage to almost the peak value (1.4 × RMS

value).

To calculate the value of capacitor(C),

C = ¼*√3*f*r*Rl

Where,

f = supply frequency,

r = ripple factor,

Rl = load resistance

Note: In our circuit we are using 1000µF. Hence large value of capacitor is placed

to reduce ripples and to improve the DC component.

Regulator:

Voltage regulator ICs is available with fixed (typically 5, 12 and 15V) or variable

output voltages. The maximum current they can pass also rates them. Negative voltage

regulators are available, mainly for use in dual supplies. Most regulators include some

automatic protection from excessive current ('overload protection') and overheating

('thermal protection'). Many of the fixed voltage regulator ICs have 3 leads and look like

power transistors, such as the 7805 +5V 1A regulator shown on the right. 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.

Fig 6.1.6 A Three Terminal Voltage Regulator

78XX:

The Bay Linear LM78XX is integrated linear positive regulator with three

terminals. The LM78XX offer several fixed output voltages making them useful in wide

range of applications. When used as a zener diode/resistor combination replacement, the

LM78XX usually results in an effective output impedance improvement of two orders of

magnitude, lower quiescent current. The LM78XX is available in the TO-252, TO-220 &

TO-263packages,

Features:

• Output Current of 1.5A

• Output Voltage Tolerance of 5%

• Internal thermal overload protection

• Internal Short-Circuit Limited

• No External Component

• Output Voltage 5.0V, 6V, 8V, 9V, 10V,12V, 15V, 18V, 24V

• Offer in plastic TO-252, TO-220 & TO-263

• Direct Replacement for LM78XX

Circuit Description

The robot direction is controlled through the motor driver circuitry. There

are two motors are present which controls the direction the robot. The motor driver

circuitry is designed with two H-bridges as shown in the Motor driver section. Basically

the H-bridge is constructed with the help of four PNP transistors. These transistors are

connected in such a manner to run the motor in both clockwise and anticlockwise

directions based on the input logics applied at the inputs of the H-bridge. So that

depending on the logics applied for the inputs of the two H-bridges the direction of the

robot will be controlled.

According to this project, a robot is designed which is made to move

all the time. Apart from this, the system also detects the presence of smoke with the

help of a smoke sensor. All the devices such as smoke sensor, motor by which robot is

made to move, buzzer are being interfaced to microcontroller which forms the control

unit of the project.

In the standby mode the robot is moved here and there. Whenever any

smoke is detected by the smoke sensor, the same is sensed and is intimated to the user

by the microcontroller using buzzer.

SOFTWARE Components

ABOUT SOFTWARE

Software used is:

*Keil software for C programming

*Express PCB for lay out design

*Express SCH for schematic design

KEIL µVision3

What's New in µVision3?

µVision3 adds many new features to the Editor like Text Templates, Quick Function

Navigation, and Syntax Coloring with brace high lighting Configuration Wizard for

dialog based startup and debugger setup. µVision3 is fully compatible to µVision2 and

can be used in parallel with µVision2.

What is µVision3?

µVision3 is an IDE (Integrated Development Environment) that helps you write, compile,

and debug embedded programs. It encapsulates the following components:

A project manager.

A make facility.

Tool configuration.

Editor.

A powerful debugger.

Express PCB

Express PCB is a Circuit Design Software and PCB manufacturing

service. One can learn almost everything you need to know about Express PCB from the

help topics included with the programs given.

Details:

Express PCB, Version 5.6.0

Express SCH

The Express SCH schematic design program is very easy to use. This software

enables the user to draw the Schematics with drag and drop options.

A Quick Start Guide is provided by which the user can learn how to use it.

Details:

Express SCH, Version 5.6.0

EMBEDDED C:

The programming Language used here in this project is an Embedded C

Language. This Embedded C Language is different from the generic C language in few

things like

a) Data types

b) Access over the architecture addresses.

The Embedded C Programming Language forms the user friendly language with access

over Port addresses, SFR Register addresses etc.

Embedded C Data types:

Data Types Size in Bits Data Range/Usage

unsigned char 8-bit 0-255

signed char 8-bit -128 to +127

unsigned int 16-bit 0 to 65535

signed int 16-bit -32,768 to +32,767

sbit 1-bit SFR bit addressable only

bit 1-bit RAM bit addressable only

sfr 8-bit RAM addresses 80-FFH

only

Unsigned char:

The unsigned char is an 8-bit data type that takes a value in the range of 0-

255(00-FFH). It is used in many situations, such as setting a counter value, where there is

no need for signed data we should use the unsigned char instead of the signed char.

Remember that C compilers use the signed char as the default if we do not put the key

word

Signed char:

The signed char is an 8-bit data type that uses the most significant bit (D7 of

D7-D0) to represent the – or + values. As a result, we have only 7 bits for the magnitude

of the signed number, giving us values from -128 to +127. In situations where + and – are

needed to represent a given quantity such as temperature, the use of the signed char data

type is a must.

Unsigned int:

The unsigned int is a 16-bit data type that takes a value in the range of 0 to

65535 (0000-FFFFH).It is also used to set counter values of more than 256. We must use

the int data type unless we have to. Since registers and memory are in 8-bit chunks, the

misuse of int variables will result in a larger hex file. To overcome this we can use the

unsigned char in place of unsigned int.

Signed int:

Signed int is a 16-bit data type that uses the most significant bit (D15 of D15-

D0) to represent the – or + value. As a result we have only 15 bits for the magnitude of

the number or values from -32,768 to +32,767.

Sbit (single bit):

The sbit data type is widely used and designed specifically to access single bit

addressable registers. It allows access to the single bits of the SFR registers.

Accessing SFR addresses 80-FFH

Another way to access the SFR RAM space 80-FFH is to use the sfr data type.

This is shown in the below example .Both the bit and byte addresses for the P0-P3 ports

are given in the table. Notice in the given example that there is no #include<reg51.h>

statement which allows us to access any byte of the SFR RAM space 80-FFH.

Single Bit Addresses of Ports

P0 Addr P1 Addr P2 Addr P3 Addr Ports Bit

P0.0 80H P1.0 90H P2.0 A0H P3.0 B0H D0

P0.1 81H P1.1 91H P2.1 A1H P3.1 B1H D1

P0.2 82H P1.2 92H P2.2 A2H P3.2 B2H D2

P0.3 83H P1.3 93H P2.3 A3H P3.3 B3H D3

P0.4 84H P1.4 94H P2.4 A4H P3.4 B4H D4

P0.5 85H P1.5 95H P2.5 A5H P3.5 B5H D5

P0.6 86H P1.6 96H P2.6 A6H P3.6 B6H D6

P0.7 87H P1.7 97H P2.7 A7H P3.7 B7H D7

DATA CONVERTION PROGRAMS IN EMBEDDED C

Many micro-controllers have a real time clock (RTC) where the time and date

are kept even when the power is off. These time and date are often in packed BCD by

RTC. To display them they must be converted to ASCII. So, in this topic we are showing

application of logic and instructions in the conversion of BCD and ASCII.

ASCII numbers

On ASCII key boards, when the key “0” is activated, “0110000” (30h)

is provided to the system. Similarly 31h (0110001) is provided for the key “1”, and so on

as shown in the table

Packed BCD to ASCII conversion

The RTC provides the time of day (hour, minutes, seconds) and the date (year,

month, day) continuously, regardless of whether the power is ON or OFF. In the

conversion procedure the packed BCD is first converted to unpacked BCD. Then it is

tagged with 0110000 (30h).

ASCII code for Digits 0-9

Key ASCII (hex) Binary BCD (unpacked)

0 30 011 0000 0000 0000

1 31 011 0001 0000 0001

2 32 011 0010 0000 0010

3 33 011 0011 0000 0011

4 34 011 0100 0000 0100

5 35 011 0101 0000 0101

6 36 011 0110 0000 0110

7 37 011 0111 0000 0111

8 38 011 1000 0000 1000

9 39 011 1001 0000 1001

ASCII to packed BCD conversion

To convert ASCII to packed BCD it is first converted to unpacked and then

combined to make packed BCD. For example 4 and 7 on the keyboard give 34h and 37h

respectively the goal is to produce 47h or “0100 0111” which is packed BCD.

Key ASCII unpacked BCD packed BCD

4 34 00000100

7 37 00000111

01000111 or 47h

Checksum byte in ROM

To ensure the integrity of ROM contents, every system must perform the

checksum calculation. The process of checksum will detect any corruption of the contents

of ROM. One of the cause of the ROM corruption is current surge either when the system

is turned on or during operation. To ensure data integrity in ROM the checksum process

uses, what is a checksum byte. The is an extra byte that is tagged to the end of the series

of the of data.

To calculate the checksum byte of a series of bytes of data, the following steps can be

used

1) Add the bytes together and drop the carries.

2) Take the 2’s complement of the total sum. This is the checksum byte , which

becomes the last byte of the series

Binary (hex) to decimal and ASCII conversion in embedded C

In C-language we use a function call “printf” which is standard IO library

function doing the conversions of data from binary to decimal, or vice versa. But here we

are using our own functions for conversions because it occupies much of memory.

One of the most commonly used is binary to decimal conversion. In devices

such as ADC chips the data is provided to the controller in binary. In order to display

binary data we need to convert it to decimal and then to ASCII. Since the hexadecimal

format is a convenient way of representing binary data we refer to binary data as hex. The

binary data 00-FFH converted to decimal will give us 000 to 255.

One way to do this is to divide it by 10 and keep the remainder, for example

11111101 or FDH is 253 in decimal. The following is one version of the algorithm for

conversion of hex (binary) to decimal.

Quotient Remainder

FD/0A 19 3(low digit) LSD

19/0A 2 5(middle digit)

2(high digit) (MSD)

CONCLUSION

The project “SMOKE SENSING AND ALERTING SYSTEM WITH

ANDROID” has been successfully designed and tested. Integrating features of all the

hardware components used have developed it. Presence of every module has been reasoned

out and placed carefully thus contributing to the best working of the unit. Secondly, using

highly advanced IC’s and with the help of growing technology the project has been

successfully implemented.

BIBLIOGRAPHY

NAME OF THE SITES:

1. WWW.MITEL.DATABOOK.COM

2. WWW.ATMEL.DATABOOK.COM

3. WWW.FRANKLIN.COM

4. WWW.KEIL.COM

REFERENCES

1. 8051-MICROCONTROLLER AND EMBEDDED SYSTEM.

Mohd. Mazidi.