Navigation of Robot Vehicle using RF with Landmine Detection

NAVIGATION OF ROBOT USING RF WITH LANDMINE DETECTION

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Navigation of Robot Vehicle using RF

with Landmine Detection


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CHAPTER – 1

SYSTEM CONCEPTS


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1.1 INTRODUCTION:

An embedded system is a special-purpose system in which the computer is

completely encapsulated by or dedicated to the device or system it controls. Unlike a

general-purpose computer, such as a personal computer, an embedded system performs

one or a few predefined tasks, usually with very specific requirements. Since the system

is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost

of the product. Embedded systems are often mass-produced, benefiting from economies

of scale.

Personal digital assistants (PDAs) or handheld computers are generally

considered embedded devices because of the nature of their hardware design, even

though they are more expandable in software terms. This line of definition continues to

blur as devices expand. With the introduction of the OQO Model 2 with the Windows XP

operating system and ports such as a USB port — both features usually belong to

"general purpose computers", — the line of nomenclature blurs even more.

Physically, embedded systems ranges from portable devices such as digital

watches and MP3 players, to large stationary installations like traffic lights, factory

controllers, or the systems controlling nuclear power plants.

In terms of complexity embedded systems can range from very simple with a

single microcontroller chip, to very complex with multiple units, peripherals and

networks mounted inside a large chassis or enclosure.


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1.2 EXAMPLES OF EMBEDDED SYSTEMS:

Avionics, such as inertial guidance systems, flight control hardware/software and

other integrated systems in aircraft and missiles

1. Cellular telephones and telephone switches

2. Engine controllers and antilock brake controllers for automobiles

3. Home automation products, such as thermostats, air conditioners, sprinklers, and

security

Monitoring systems

4. Handheld calculators

5. Handheld computers

6. Household appliances, including microwave ovens, washing machines, television sets,

7.DVD

Players and recorders

8. Medical equipment

9. Personal digital assistant

10. Videogame consoles

11. Computer peripherals such as routers and printers.


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1.3 BLOCK DIAGRAM:

1.3.1 RECEIVER SECTION:

FIG 1: RF TRANSMITTER

1.3.2 TRANSMITTER SECTION:

FIG 2: RF RECIEVER

Buzzer

Dc motor

H_BRIDGE

Dc motor

Landmine Detector

RF Receiver

LPC2148

Power supply LCD

Power supply RF Transmitter with

Keys


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1.3.3BLOCK DIAGRAM EXPLANATION:

In this section we will be discussing about complete block diagram and its

functional description of our project. And also brief description about each block of the

block diagram.

1. 3.4 MICRO CONTROLLER:

In this project work the micro-controller is plays major role. Micro-

controllers were originally used as components in complicated process-control systems.

However, because of their small size and low price, Micro-controllers are now also being

used in regulators for individual control loops. In several areas Micro-controllers are now

outperforming their analog counterparts and are cheaper as well.

1.3.5 POWER SUPPLY:

This section is meant for supplying Power to all the sections mentioned above. It

basically consists of a Transformer to step down the 230V ac to 18V ac followed by

diodes. Here diodes are used to rectify the ac to dc. After rectification the obtained

rippled dc is filtered using a capacitor Filter. A positive voltage regulator is used to

regulate the obtained dc voltage. But here in this project two power supplies are used one

is meant to supply operating voltage for Microcontroller and the other is to supply control

voltage for Relays.

1.3.6 LCD DISPLAY SECTION:

This section is basically meant to show up the status of the project. This project

makes use of Liquid Crystal Display to display / prompt for necessary information.


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1.3.7 MOTORS:

Motor is an output device; its speed will be varied according to the speed set by

the switches. The speed can be varied by varying the voltage given to the PWM converter

(using keypad). The speed of DC motor is directly proportional to armature voltage and

inversely proportional to flux. By maintaining the flux constant, the speed can be varied

by varying the armature voltage.

1.3.8 SCHEMATIC:

FIG 3: PROCESSOR SCHEMATIC


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1.3.9 TRANSMITTER:

FIG 4: TRANSMITTER CHIP

1.3.10 PROXIMITY SENSOR:

FIG 5: METAL DETECTOR SENSOR

A proximity sensor is a sensor able to detect the presence of nearby objects

without any physical contact.

A proximity sensor often emits an electromagnetic field or a beam

of electromagnetic radiation (infrared, for instance), and looks for changes in the field or

return signal. The object being sensed is often referred to as the proximity sensor's target.

Different proximity sensor targets demand different sensors. For example,

https://en.wikipedia.org/wiki/Sensor

https://en.wikipedia.org/wiki/Electromagnetic_field

https://en.wikipedia.org/wiki/Electromagnetic_radiation

https://en.wikipedia.org/wiki/Infrared

https://en.wikipedia.org/wiki/Electric_field


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a capacitive photoelectric sensor might be suitable for a plastic target; an

inductive proximity sensor always requires a metal target.

The maximum distance that this sensor can detect is defined "nominal range".

Some sensors have adjustments of the nominal range or means to report a graduated

detection distance.

Proximity sensors can have a high reliability and long functional life because of

the absence of mechanical parts and lack of physical contact between sensor and the

sensed object.

1.3.11 H- BRIDGE:

An H bridge is an electronic circuit that enables a voltage to be applied across a load in

either direction. These circuits are often used in robotics and other applications to allow

DC motors to run forwards and backwards. H bridges are available as integrated circuits,

or can be built from discrete components.

FIG 6: H-BRIDGE

https://en.wikipedia.org/wiki/Capacitive_proximity_sensor

https://en.wikipedia.org/wiki/Photoelectric_sensor

http://en.wikipedia.org/wiki/Electronic_circuit

http://en.wikipedia.org/wiki/Robotics

http://en.wikipedia.org/wiki/Integrated_circuits

http://en.wikipedia.org/wiki/Discrete_components


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1.3.12 WORKING:

The above block diagram shoes the user section and receiving section. In the both

the user section and robot section. Firstly, the required operating voltage for

Microcontroller 89C51 is 5V. Hence the 5V D.C. power supply is needed by the same.

This regulated 5V is generated by first stepping down the 230V to 9V by the step down

transformer.

The step downed a.c. voltage is being rectified by the Bridge Rectifier. The diodes

used are 1N4007. The rectified a.c voltage is now filtered using a ‗C‘ filter. Now the

rectified, filtered D.C. voltage is fed to the Voltage Regulator. This voltage regulator

allows us to have a Regulated Voltage which is +5V.

The rectified; filtered and regulated voltage is again filtered for ripples using an

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

pin of 89c51

microcontroller to supply operating voltage.

By using transmitting section to control the robot. In the receiving section whenever the

metal sensor detect then robot will stop and information displayed on LCD screen and

give an warning signal through buzzer.

1.4 HARD WARE COMPONENTS:

LPC2148

Landmine Detector

RF Transmitter

RF Receiver

LCD

Buzzer

Power Supply


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1.4.1 ARM PROCESSOR OVERVIEW:

ARM stands for Advanced RISC Machines. It is a 32 bit processor core, used for high end

application.

It is widely used in Advanced Robotic Applications.

FIG 7: ARM PROCESSOR IMAGE

1.4.2 HISTORY AND DEVELOPMENT:

1. ARM was developed at Acron Computers ltd of Cambridge, England between 1983

and

1985.

2. RISC concept was introduced in 1980 at Stanford and Berkley.

3. ARM ltd was found in 1990.

4. ARM cores are licensed to partners so as to develop and fabricate new

microcontrollers

Around same processor cores.


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1.4.3 KEY FEATURES:

1. 16-bit/32-bit ARM7TDMI-S microcontroller in a tiny LQFP64 package.

2. 8 kB to 40 kB of on-chip static RAM and 32 kB to 512 kB of on-chip flash memory.

128-bit wide interface/accelerator enables high-speed 60 MHz operation.

3. In-System Programming/In-Application Programming (ISP/IAP) via on-chip boot

loader

Software. Single flash sector or full chip erase in 400 ms and programming of

256 bytes in 1 ms.

4. Embedded ICE RT and Embedded Trace interfaces offer real-time debugging with

the

On-chipRealMonitor software and high-speed tracing of instruction execution.

5. USB 2.0 Full-speed compliant device controller with 2 kB of endpoint RAM.

In addition, the LPC2146/48 provides 8 kB of on-chip RAM accessible to USB by

DMA.

6. One or two (LPC2141/42 vs. LPC2144/46/48) 10-bit ADCs provide a total of 6/14

Analog inputs, with conversion times as low as 2.44 μs per channel.

7. Single 10-bit DAC provides variable analog output (LPC2142/44/46/48 only).

8. Two 32-bit timers/external event counters (with four capture and four compare

Channels each), PWM unit (six outputs) and watchdog.

9. Low power Real-Time Clock (RTC) with independent power and 32 kHz clock

input.

10. Multiple serial interfaces including two UARTs (16C550), two Fast I2C-bus (400

kbit/s),

SPI and SSP with buffering and variable data length capabilities.

11. Vectored Interrupt Controller (VIC) with configurable priorities and vector

addresses.

12. Up to 45 of 5 V tolerant fast general purpose I/O pins in a tiny LQFP64 package.

13. Up to 21 external interrupt pins available.

14. 60 MHz maximum CPU clock available from programmable on-chip PLL with

settling Time of 100 μs.


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CHAPTER – 2

PROCESSOR DESCRIPTION

LPC-2148


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2.1 PROCESSOR DIAGRAM:

FIG 8: PROCESSOR PIN DESCRIPTION


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2.2 BLOCK DIAGRAM:

FIG 9 : PROCESSOR BLOCK DIAGRAM


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2.3 PIN DESCRIPTION:


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TABLE 1: PIN DESCRIPTION


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2.4 CORE DATA PATH:

1. Architecture is characterized by Data path and control path.

2. Data path is organized in such a way that, operands are not fetched directly from

memory 3. Locations. Data items are placed in register files. No data processing takes

place in

Memory

4. Instructions typically use 3 registers. 2 source registers and 1 destination register.

5. Barrel Shifter preprocesses data, before it enters ALU.

6. Barrel Shifter is basically a combinational logic circuit

2.5 PIPELINE:

1. In ARM 7, a 3 stage pipeline is used. A 3 stage pipeline is the simplest form of

pipeline

That does not suffer from the problems such as read before write.

2. In a pipeline, when one instruction is executed, second instruction is decoded and third

Instruction will be fetched.

This is executed in a single cycle.

2.6 REGISTER BANK:

1. ARM 7 uses load and store Architecture.

2. Data has to be moved from memory location to a central set of registers.

3. Data processing is done and is stored back into memory.

4. Register bank contains, general purpose registers to hold either data or address.

It is a bank of 16 user registers R0-R15 and 2 status registers.

5. Each of these registers is 32 bit wide.


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2.7 DATA REGISTERS- R0-R15:

1. R0-R12 - General Purpose Registers

2. R13-R15 - Special function registers of which,

3. R13 - Stack Pointer, refers to entry pointer of Stack.

4. R14 - Link Register, Return address is put to this whenever a subroutine is called.

5. R15 - Program Counter

Depending upon application R13 and R14 can also be used as GPR. But not

commonly used.

FIG 10: DATA REGISTERS

In addition there are 2 status registers

1. CPSR - Current program status register, status of current execution is stored.

2. SPSR - Saved program Status register, includes status of program as well as processor.

2.8 CPSR:

CPSR contains a number of flags which report and control the operation of ARM7 CPU.

FIG 11: CPSR CONDITIONS


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2.9 CONDITIONAL CODE FLAGS:

N - Negative Result from ALU

Z - Zero result from ALU

C - ALU operation carried out

V - ALU operation overflowed

2.10 INTERRUPT ENABLE BITS:

I - IRQ, Interrupt Disable

F - FIQ, Disable Fast Interrupt

2.11 T- BIT:

If

T=0, Processor in ARM Mode.

T=1, Processor in THUMB Mode

2.12 MODE BITS:

Specifies the processor Modes. Processor Modes will be discussed in the next part of this

tutorial.


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2.13 UNIVERSAL ASYNCHRONOUS RECEIVERTRANSMITTER 0:

2.13.1 FEATURES:

1. Byte Receive and Transmit FIFOs

2. Register locations conform to ‗550 industry standard

3. Receiver FIFO triggers points at 1, 4, 8, and 14 bytes

4. Built-in fractional baud rate generator with autobauding capabilities.

5. Mechanism that enables software and hardware flow control implementation

2.13.2 PIN DESCRIPTION:

TABLE 2: I/O DESCIPTION

2.14 ARCHITECTURE:

The VPB interface provides a communications link between the CPU or host and

the UART0.The UART0 receiver block, U0RX, monitors the serial input line, RXD0, for

valid input. The UART0 RX Shift Register (U0RSR) accepts valid characters via RXD0.

After a valid character is assembled in the U0RSR, it is passed to the UART0 RX Buffer

Register FIFO to await access by the CPU or host via the generic host interface.

The UART0 transmitter block, U0TX, accepts data written by the CPU or host

and buffers the data in the UART0 TX Holding Register FIFO (U0THR). The UART0

TX Shift Register (U0TSR) reads the data stored in the U0THR and assembles the data to

transmit via the serial output pin, TXD0.The UART0 Baud Rate Generator block,

U0BRG, generates the timing enables used by the UART0 TX block. The U0BRG clock

input source is the VPB clock (PCLK). The main clock is divided down per the divisor


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specified in the U0DLL and U0DLM registers. This divided down clock is a 16x

oversample clock, NBAUDOUT

The interrupt interface contains registers U0IER and U0IIR. The interrupt

interface receives several one clock wide enables from the U0TX and U0RX blocks.

Status information from the U0TX and U0RX is stored in the U0LSR. Control

information for the U0TX and U0RX is stored in the U0LCR

TABLE 3: BIT FUNCTION AND ADDRESS


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FIG 12: INTERUPT DISPLAY

2.15 UNIVERSAL ASYNCHRONOUS RECEIVER/TRANSMITTER1:

2.15.1 FEATURES:

1. UART1 is identical to UART0, with the addition of a modem interface.

2.16 byte Receive and Transmit FIFOs

3. Register locations conform to ‗550 industry standard

4. Receiver FIFO triggers points at 1, 4, 8, and 14 bytes

5. Built-in fractional baud rate generator with autobauding capabilities.

6. Mechanism that enables software and hardware flow control implementation

7. Standard modem interface signals included with flow control (auto-CTS/RTS) fully

Supported in hardware (LPC2144/6/8 only).


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TABLE 4: SERIAL PINS

2.15.3 REGISTER DESCRIPTION:

TABLE 5: REGISTER DESCRIPTION


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FIG 13: REGISTER DESCRIPTIONS


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CHAPTER – 3

HARDWARE COMPONENTS


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3.1 RF COMMUNICATION:

RF communication stands for Radio Frequency communication in which

communication is purely based on radio frequency (3 kHz to 300 GHz).we can send and

receive data using Radio frequency.

RF section consists of two units i.e.,

1. TRANSMITTER UNIT

2. RECEIVER UNIT

3.1.1 TRANSMITTER UNIT: In this unit we have RF transmitter with antenna

connected to encoder in order to encode the digital data which is to be transmitted in the

form of radio waves.

3.1.2 RECEIVER UNIT: In this unit we have RF receiver with antenna connected to

decoder in order to decode the digital data which is transmitted by the transmitter unit is

received by this unit using radio waves

3.2 RF LINK TRANSMITTER - 434MHZ:

This is only the 434MHz transmitter. This will work with the RF Links at

434MHz at either baud rate. Only one 434MHz transmitter will work within the same

location. This wireless data is the easiest to use, lowest cost RF link we have ever seen!

Use these components to transmit position data, temperature data, and even current

program register values wirelessly to the receiver. These modules have up to 500 ft.

Range in open space. The transmitter operates from 2-12V. The higher the Voltage, the

greater the range - see range test data in the documents section.

We have used these modules extensively and have been very impressed with their

ease of use and direct interface to an MCU. The theory of operation is very simple. What

the transmitter 'sees' on its data pin is what the receiver outputs on its data pin. If you can

configure the UART module on a PIC, you have an instant wireless data connection. The

typical range is 500ft for open area. This is an ASK transmitter module with an output of


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up to 8mW depending on power supply voltage. The transmitter is based on SAW

resonator and accepts digital inputs, can operate from 2 to 12 Volts-DC, and makes

building RF enabled products very easy.

FIG 14: RF TRANSMITTER

3.3 RF LINK 4800BPS RECEIVER - 434MHZ:

Sold as a receiver only. This receiver type is good for data rates up to 4800bps

and will only work with the 434MHz transmitter. Multiple 434MHz receivers can listen

to one 434MHz transmitter. This wireless data is the easiest to use, lowest cost RF link

we have ever seen! Use these components to transmit position data, temperature data, and

even current program register values wirelessly to the receiver. These modules have up to

500 ft range in open space. The receiver is operated at 5V.

We have used these modules extensively and have been very impressed with their

ease of use and direct interface to an MCU. The theory of operation is very simple. What

the transmitter 'sees' on its data pin is what the receiver outputs on its data pin. If you can

configure the UART module on a PIC, you have an instant wireless data connection. Data

rates are limited to 4800bps. The typical range is 500ft for open area..

1.434 MHz Operation

2.500 Ft. Range - Dependent on Transmitter Power Supply

3.4800 bps transfer rate

4. Low cost

5. Extremely small and light weigh


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FIG 15: RF RECIEVER CHIP

3.4 HT12D:

3.4.1 FEATURES:

18 pin DIP

Operating voltage 2.4V ~ 12V

Low power and high noise immunity CMOS technology

Low standby current

Capable of decoding 12 bits of information

Binary address setting

Received codes are checked 3 times

Address/Data number combination is 8 address bits and 4 data bits

Built in oscillator needs only 5% resistor

Valid transmission indicator

Easy interface with an RF or an infrared transmission medium

Minimal external components

Pair with 212

series of encoders

3.4.2 APPLICATIONS:

Burglar alarm, smoke alarm, fire alarm, car alarm, security system

Garage door and car door controllers


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3.4.3 GENERAL DESCRIPTION:

The 212

decoders are a series of CMOS LSIs for remote control system

applications. They are paired with 212

series of encoder. For proper operation, a pair of

encoder/decoder with the same number of address and data format should be chosen.

The decoders receive serial address and data from a programmed 212

series of

encoders that are transmitted by a carrier using an RF or an IR transmission medium.

They compare the serial input data three times continuously with their local addresses. If

no error or unmatched codes are found, the input data codes are decoded and then

transferred to the output pins. The VT pin also goes high to indicate a valid transmission.

3.4.4BLOCK DIAGRAM:

FIG 16: BLOCK DAIGRAM OF CMOS


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3.4.5 PIN DIAGRAM:

FIG 17: PIN DIAGRAM


A0 - A7: These are the input pins for address A0-A7 setting. These pins can be externally

set to Vss or left open.

D8 – D11: these are the output data pins, power on state is low.

Din: it is a serial data input pin.

VT: Valid transmission, active high pin.

OSC1: oscillator input pin

Osc2: oscillator output pin

Vss: Groung pin

Vdd: Power supply

3.4.7ABSOLUTE MAXIMUM RATINGS:

Supply voltage…….. -0.3V to 13V

Input voltage………. Vss -0.3V to Vdd +0.3V

Storage Temperature……. -500C to 125

0C


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3.5 FUNCTIONAL DESCRIPTION:

3.5.1 OPERATION:

The 212

series of decoders provides various combinations of addresses and data

pins in different packages so as to pair with the 212

series of encoders.

The decoders recevie data that are transmitted by an encoder and inerpret the first

N bits of code period as addresses and the last 12-N bits as data, where N is the address

code number. A signal on the DIN pin actives the oscillator which in turn decodes the

incoming address and data. The decoders will then check the recevied address three times

continuously. If the recevied address codes all match the contents of the decoders local

address, the 12-N bits of data are decoded to activate the output pins and the VT pin is set

high to indicate a valid transmission. This will last unless the address code is incorrect or

no signal is recevied.

3.5.2 OUTPUT TYPE:

Of the 212

series of decoders, the HT12F has no data output pin but its VT pin can

be used as a momentary data output. The HT12D, on the other hand, provides 4 latch

type data pins whose dat remain unchanged until new data are recevied.

Part No. Data pins Address pins Output

Type

Operating

Voltage

HT12D 4 8 Latch 2.4V~12V

HT12F 0 12 --- 2.4V~12V

TABLE 6: OUTPUT TYPE


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3.5.3 FLOWCHART:

The oscillator is disabled in the standby state and activated when a logic ―high‖

signal applies to the DIN pin. That is to say, the DIN should be kept low if there is no

signal input.

FIG 18: FLOW CHART


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3.5.4 DECODER TIMING:

FIG 19: DECODER TIMING

3.6 HT12E:

3.6.1 FEATURES:

18 pin DIP

Operating voltage is 2.4V ~ 12V

Low power and high noise immunity CMOS technology

Low standby current: 0.1µA (typ.) at VDD = 5V

Minimum transmission four words for the HT12E

Built in oscillator needs only 5% resistor

Data code has positive polarity

Minimal external components

3.6.2 APPLICATIONS:

Burglar alarm, smoke alarm, fire alarm, car alarm, security system

Garage door and car door controllers

Cordless telephone


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3.6.3 GENERAL DESCRIPTION:

The 212

encoders are a series of CMOS LSIs for remote control system

applications. They are capable of encoding information which consists of N address bits

and 12-N data bits. Each address / data input can be set to one of the two logic states. The

programmed addresses/data are transmitted together with the header bits via an RF or an

infrared transmission medium upon receipt of a trigger signal. The capability to select a

TE trigger on the HT12E or a DATA trigger on the HT12A further enhances the

application flexibility of the 212

series of encoders. The HT12A additionally provides a

38 kHz carrier for infrared systems.

3.6.4 BLOCK DIAGRAM:

FIG 20: CMOS BLOCK DIAGRAM


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3.6.5 PIN DIAGRAM:

FIG 21: PIN DIAGRAM

A0-A7: These are the input pins for address A0 – A7. These pins can be externally set to

Vss or left open.

Dout: This pin is encoder data serial transmission out pin.

TE: It‘s a transmission enable pin and it‘s a active low pin.

OSC1: Oscillator input pin.

OSC2: Oscillator output pin.

Vss: Ground pin.

Vdd: Power supply pin.

3.6.6 ABSOLUTE MAXIMUM RATINGS:

Supply voltage…………………-0.3V to 13V

Input voltage……………………Vss -0.3V t Vdd +03V

Storage temperature….. -500C to 125

0C

Operating Temperature….. -200C to 75

0C

3.7 FUNCTIONAL DESCRIPTION:

3.7.1 OPERATION:

The 212

series of encoders begin a 4 word transmission cycle upon receipt of a

transmission enable. This cycle will repeat itself as long as the transmission enable is

held low. Once the transmission enables returns high the encoder output completes its

final cycle and then stops as shown below.


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4

FIG 22: TRANSIMMISON TIMING FOR HT12E

34.7.2 ADDRESS/DATA WAVEFORM:

Each programmable address/data pin can be externally set to one the following two logic

states as shown below.

FIG 23: ADDRESS/DATA BIT WAVEFORM FOR THE HT12E

3.7.3 ADDRESS/DATA PROGRAMMING (PRESET):

The status of each address/data pin can be individually pre-set to logic ―high‖ or

―low‖. If a transmission enable signal is applied, the encoder scans and transmits the

status of the 12 bits of address/data serially in the order A0 to AD11 for the HT12E

encoder.

During information transmission these bits are transmitted with a preceding

synchronization bit. If the trigger signal is not applied, the chip enters the standby mode

and consumes a reduced current of less than 1µA for a supply voltage of 5V.


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Usual information preset the address pins with individual security codes using

DIP switches or PCB wiring, while the data is selected by push buttons or electronic

switches.

3.7.4 ADDRESS/DATA SEQUENCE:

The following provides the address/data sequence table for various models of the

212 series of encoders. The correct device should be selected according to the individual

address and data requirements.

HT12E

Address/Data Bits

0 1 2 3 4 5 6 7 8 9 10 11

A0 A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11

TABLE 7: ADDRESS AND DATA BITS

3.8 TRANSMISSION ENABLE:

For the HT12E encoders, transmission is enabled by aplying a low signal to the TE pin.

(16 * 2) ALPHANUMERIC LCD:

3.8.1 DESCRIPTION:

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. A liquid crystal display (LCD)

is a thin, flat electronic visual display that uses the light modulating properties of liquid

crystals (LCs). LCs do not emit light directly. LCDs therefore need a light source and are

classified as "passive" displays. Here the lcd has different memories to display data, those

are discussed below.


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3.8.2 BLOCK DIAGRAM:

FIG 24: LCD BLOCK DIAGRAM

3.8.3 DISPLAY DATA RAM:

Display data RAM (DDRAM) stores display data represented in 8-bit character

codes. Its extended capacity is 80 X 8 bits, or 80 characters. The area in display data

RAM (DDRAM) that is not used for display can be used as general data RAM. So

whatever you send on the DDRAM is actually displayed on the LCD. For LCDs like

1x16, only 16 characters are visible, so whatever you write after 16 chars is written in

DDRAM but is not visible to the user.

Figure below will show you the DDRAM addresses of 2 Line LCD.

FIG 25: DRAM ADDRESS LINE FOR 2 LINE LCD


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3.8.4 CHARACTER GENERATOR ROM:

Now you might be thinking that when you send an ascii value to DDRAM, how

the character is displayed on LCD? So the answer is CGROM. The character generator

ROM generates 5 x 8 dot or 5 x 10 dot character patterns from 8-bit character codes. It

can generate 208 5 x 8 dot character patterns and 32 5 x 10 dot character patterns. User

defined character patterns are also available by mask-programmed ROM.

3.8.5 BUSY FLAG:

Busy Flag is a status indicator flag for LCD. When we send a command or data to

the LCD for processing, this flag is set (i.e BF =1) and as soon as the instruction is

executed successfully this flag is cleared (BF = 0). This is helpful in producing and exact

amount of delay for the LCD processing. To read Busy Flag, the condition RS = 0 and

R/W = 1 must be met and The MSB of the LCD data bus (D7) act as busy flag. When BF

= 1 means LCD is busy and will not accept next command or data and BF = 0 means

LCD is ready for the next command or data to process.

3.8.6 INSTRUCTION REGISTERS (IR) AND DATA REGISTER

(DR):

There are two 8-bit registers in HD44780 controller Instruction and Data register.

Instruction register corresponds to the register where you send commands to LCD e.g

LCD shift command, LCD clear, LCD address etc. and Data register is used for storing

data which is to be displayed on LCD. When send the enable signal of the LCD is

asserted, the data on the pins is latched in to the data register and data is then moved

automatically to the DDRAM and hence is displayed on the LCD.

Data Register is not only used for sending data to DDRAM but also for CGRAM,

the address where you want to send the data, is decided by the instruction you send to

LCD.


DEPT OF ECE 44

3.9 16 X 2 ALPHANUMERIC LCD MODULE FEATURES:

1. Intelligent, with built-in Hitachi HD44780 compatible LCD controller and RAM

2.providing simple interfacing

3.61 x 15.8 mm viewing area

4.5 x 7 dot matrix format for 2.96 x 5.56 mm characters, plus cursor line

5. Can display 224 different symbols

6. Low power consumption (1 mA typical)

7. Powerful command set and user-produced characters

8. TTL and CMOS compatible

9. Connector for standard 0.1-pitch pin headers

3.10 SCHEMATIC:

FIG 26: LCD DISPLAY SCHEMATIC

TABLE 8: CONNECTOR PIN ASSIGNMENT


DEPT OF ECE 45

FIG 27: LCD PIN DISPLAY

3.11 CIRCUIT DESCRIPTION:

Above 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

3.12 PULL UP RESISTORS:

Often we want to connect a digital input line to our microcontroller. Typically this

might be to allow us to monitor the on-off state of a switch.

Eg:

FIG 28: PULL UP RESISTORS

Switch 0 V

(gnd or )

5 V

Microcontroller


DEPT OF ECE 46

At first glance this seems fine. When the switch is closed, the pin on our

microcontroller is tied to 0 volt, i.e. Low. In contrast when the switch is open we would

want the pin to be 5 volts, or high. The input pin would tend to ―float‖ high. This

however isn‘t a true input signal; it is a very weak input and can readily switch from high

to low through the slightest of electrical interference in any of the wiring. A simple

solution might appear to involve simply connecting the other end of the switch to our 5

volt supply

This will give us a 5 volt (high) signal on the input pin when the switch is open.

When the switch is closed however we will get a short between supply and ground =>

zero resistance => infinite current - this is not good news. The problem can be remedied

by simply putting a resistor into the circuit. This is the pull-up resistor.

When the switch is open, the input to the microcontroller is high. There is no direct

connection to the 5v rail, however because the input impedance to the microcontroller is

high, very little of the 5v is dropped over the pull up resistor.

.

FIG 29: CIRCUIT DIAGRAM

Switch

0 V

(gnd or )

5 V

Microcontroller

10 k


DEPT OF ECE 47

3.13 BUZZER:

3.13.1 MAGNETIC TRANSDUCER:

FIG 30: MAGNETIC TRANSDUCER

Magnetic transducers contain a magnetic circuit consisting of a iron core with a wound

coil and a yoke plate, a permanent magnet and a vibrating diaphragm with a movable iron

piece. The diaphragm is slightly pulled towards the top of the core by the magnet's

magnetic field. When a positive AC signal is applied, the current flowing through the

excitation coil produces a fluctuating magnetic field, which causes the diaphragm to

vibrate up and down, thus vibrating air. Resonance amplifies vibration through resonator

consisting of sound hole(s) and cavity and produces a loud sound.

3.13.2 MAGNETIC BUZZER (SOUNDER):

FIG 31: MAGNETIC BUZZER


DEPT OF ECE 48

Buzzers like the TMB-series are magnetic audible signal devices with built-in oscillating

circuits. The construction combines an oscillation circuit unit with a detection coil, a

drive coil and a magnetic transducer. Transistors, resistors, diodes and other small

devices act as circuit devices for driving sound generators. With the application of

voltage, current flows to the drive coil on primary side and to the detection coil on the

secondary side. The amplification circuit, including the transistor and the feedback

circuit, causes vibration. The oscillation current excites the coil and the unit generates an

AC magnetic field corresponding to an oscillation frequency. The oscillation from the

intermittent magnetization prompts the vibration diaphragm to vibrate up and down,

generating buzzer sounds through the resonator.

FIG 32: RECOMMENDED DRIVING CIRCUIT FOR MAGNETIC TRANSDUCER

3.14 INTRODUCTION OF MAGNETIC BUZZER (TRANSDUCER):

FIG 33: AATC STRUCTURE


DEPT OF ECE 49

FIG 34: AATC TESTING CIRCUIT

3.15 SPECIFICATIONS:

RATED VOLTAGE: A magnetic buzzer is driven by 1/2 square waves (V o-p).

OPERATING VOLTAGE: For normal operating. But it is not guaranteed to make the

minimum Sound Pressure Level (SPL) under the rated voltage.

CONSUMPTION CURRENT: The current is stably consumed under the regular

operation

DIRECT CURRENT RESISTANCE: The direct current resistance is measured by

ammeter directly.

SOUND OUTPUT: The sound output is measured by decibel meter. Applying rated

voltage and 1/2 square waves, and the distance of 10 cm.

RATED FREQUENCY: A buzzer can make sound on any frequencies, but we suggest

that the highest and the most stable SPL comes from the rated frequency.

OPERATING TEMPERATURE. : Keep working well between -30℃ and +70℃.

How to choose:

DRIVING METHODS: AX series with built drive circuit will be the best choice when

we cannot provide frequency signal to a buzzer, it only needs direct current.

DIMENSION: Dimension affects frequency, small size result in high frequency.

FIXED METHODS: From the highest cost to the lowest- DIP, wires/ connector, SMD.

SOLDERING METHODS: AS series is soldered by hand, the frequency is lower

because of the holes on the bottom. On the other hand, we suggest AC series for the

reflow soldering, the reliability is better.


DEPT OF ECE 50

3.16 HOW TO CHOOSE A BUZZER:

There are many different kinds of buzzer to choose, first we need to know a few

parameters, such as voltage, current, drive method, dimension, mounting type, and the

most important thing

Is how much SPL and frequency we want.

3.16.1 OPERATING VOLTAGE:

Normally, the operating voltage for a magnetic buzzer is from 1.5V to 24V, for a piezo

buzzer is from 3V to 220V. However, in order to get enough SPL, we suggest giving at

least 9V to drive a piezobuzzer.

3.16. CONSUMPTION CURRENT:

According to the different voltage, the consumption current of a magnetic buzzer is from

dozens to hundreds of mill amperes; oppositely, the piezo type saves much more

electricity, only needs a few mill amperes, and consumes three times current when the

buzzer start to work.

3.16.3 DRIVING METHOD:

Both magnetic and piezo buzzer have self-drive type to choose. Because of the internal

set drive circuit, the self-drive buzzer can emit sound as long as connecting with the

direct current. Due to the different work principle, the magnetic buzzer need to be driven

by 1/2 square waves, and the piezo buzzer need square waves to get better sound output.

3.16.4 DIMENSION:

The dimension of the buzzer affects its SPL and the frequency, the dimension of the

magnetic buzzer is from 7 mm to 25 mm; the piezo buzzer is from 12 mm to 50 mm, or

even bigger.

http://www.buzzer-speaker.com/manufacturer/magnetic%20buzzer.htm

http://www.buzzer-speaker.com/manufacturer/piezo%20buzzer.htm

http://www.buzzer-speaker.com/manufacturer/piezo%20buzzer.htm


DEPT OF ECE 51

3.17 MOTORS:

Motor is a device that creates motion, not an engine; it usually refers to either an

electrical motor or an internal combustion engine.

It may also refer to:

1. Electric motor, a machine that converts electricity into a mechanical motion

AC motor, an electric motor that is driven by alternating current

2. Synchronous motor, an alternating current motor distinguished by a rotor spinning with

coils passing magnets at the same rate as the alternating current and resulting magnetic

field which drives it

3. Induction motor, also called a squirrel-cage motor, a type of asynchronous alternating

current motor where power is supplied to the rotating device by means of electromagnetic

induction

3.18 DC MOTOR, AN ELECTRIC MOTOR THAT RUNS ON DIRECT

CURRENT ELECTRICITY:

1. Brushed DC electric motor, an internally commutated electric motor designed to be run

from a direct current power source

2. Brushless DC motor, a synchronous electric motor which is powered by direct current

electricity and has an electronically controlled commutation system, instead of a

mechanical commutation system based on brushes

3. Electrostatic motor, a type of electric motor based on the attraction and repulsion of

electric charge

4. Servo motor, an electric motor that operates a servo, commonly used in robotics

5. Internal fan-cooled electric motor, an electric motor that is self-cooled by a fan,

typically used for motors with a high energy density

http://en.wikipedia.org/wiki/Engine

http://en.wikipedia.org/wiki/Internal_combustion_engine

http://en.wikipedia.org/wiki/Electric_motor

http://en.wikipedia.org/wiki/AC_motor

http://en.wikipedia.org/wiki/Synchronous_motor

http://en.wikipedia.org/wiki/Induction_motor

http://en.wikipedia.org/wiki/DC_motor

http://en.wikipedia.org/wiki/Brushed_DC_electric_motor

http://en.wikipedia.org/wiki/Brushless_DC_motor

http://en.wikipedia.org/wiki/Electrostatic_motor

http://en.wikipedia.org/wiki/Servo_motor

http://en.wikipedia.org/wiki/Internal_fan-cooled_electric_motor


DEPT OF ECE 52

3.19TYPES OF MOTORS:

Industrial motors come in a variety of basic types. These variations are suitable for many

different applications. Naturally, some types of motors are more suited for certain

applications than other motor types are. This document will hopefully give some

guidance in selecting these motors.

3.20 AC MOTORS:

The most common and simple industrial motor is the three phase AC induction motor,

sometimes known as the "squirrel cage" motor. Substantial information can be found

about any motor by checking its (nameplate).

FIG 35: AC MOTORS

3.21 ADVANTAGES:

1. Simple Design

2. Low Cost

3. Reliable Operation

4. Easily Found Replacements

5. Variety of Mounting Styles

6. Many Different Environmental Enclosures

http://www.oddparts.com/acsi/defines/nameplat.htm

http://www.oddparts.com/acsi/motortut.htm#Simple_Design

http://www.oddparts.com/acsi/motortut.htm#low_cost

http://www.oddparts.com/acsi/motortut.htm#reliable_operation

http://www.oddparts.com/acsi/motortut.htm#Easily_Found_Replacements

http://www.oddparts.com/acsi/motortut.htm#Variety

http://www.oddparts.com/acsi/motortut.htm#Enclosures


DEPT OF ECE 53

3.22 SIMPLE DESIGN:

The simple design of the AC motor -- simply a series of three windings in the exterior

(stator) section with a simple rotating section (rotor). The changing field caused by the 50

or 60 Hertz AC line voltage causes the rotor to rotate around the axis of the motor.

The speed of the AC motor depends only on three variables:

1. The fixed number of winding sets (known as poles) built into the motor, which

determines the motor's base speed.

2. The frequency of the AC line voltage. Variable speed drives change this frequency to

change the speed of the motor.

3. The amount of torque loading on the motor, which causes slip.

3.23 LOW COST:

The AC motor has the advantage of being the lowest cost motor for applications requiring

more than about 1/2 hp (325 watts) of power. This is due to the simple design of the

motor. For this reason, AC motors are overwhelmingly preferred for fixed speed

applications in industrial applications and for commercial and domestic applications

where AC line power can be easily attached. Over 90% of all motors are AC induction

motors. They are found in air conditioners, washers, dryers, industrial machinery, fans,

blowers, vacuum cleaners, and many, many other applications.

3.24 RELIABLE OPERATION:

The simple design of the AC motor results in extremely reliable, low maintenance

operation. Unlike the DC motor, there are no brushes to replace. If run in the appropriate

environment for its enclosure, the AC motor can expect to need new bearings after

several years of operation. If the application is well designed, an AC motor may not need

new bearings for more than a decade.

http://www.oddparts.com/acsi/defines/stator.htm

http://www.oddparts.com/acsi/defines/rotor.htm

http://www.oddparts.com/acsi/defines/hertz.htm

http://www.oddparts.com/acsi/defines/poles.htm

http://www.oddparts.com/acsi/defines/poles.htm

http://www.oddparts.com/acsi/defines/drive.htm

http://www.oddparts.com/acsi/defines/torque.htm

http://www.oddparts.com/acsi/defines/slip.htm

http://www.oddparts.com/acsi/motortut.htm#Simple_Design

http://www.oddparts.com/acsi/motortut.htm#AC_Motors

http://www.oddparts.com/acsi/motortut.htm#Enclosures


DEPT OF ECE 54

3.25 EASILY FOUND REPLACEMENTS:

The wide use of the AC motor has resulted in easily found replacements. Many

manufacturers adhere to either European (metric) or American (NEMA) standards. (For

Replacement Motors)

Variety of Mounting Styles

AC Motors are available in many different mounting styles such as:

1. Foot Mount

2. C-Face

3. Large Flange

4. Vertical

5. Specialty

3.26 DC MOTORS:

The brushed DC motor is one of the earliest motor designs. Today, it is the motor of

choice in the majority of variable speed and torque control applications.

3.27 ADVANTAGES:

1. Easy to understand design

2. Easy to control speed

3. Easy to control torque

4. Simple, cheap drive design

Easy to understand design

http://instantweb.com/o/oddparts/Welcome.html

http://instantweb.com/o/oddparts/Welcome.html

http://www.oddparts.com/acsi/defines/foot.htm

http://www.oddparts.com/acsi/defines/c_face.htm

http://www.oddparts.com/acsi/defines/lflange.htm

http://www.oddparts.com/acsi/defines/vertical.htm

http://www.oddparts.com/acsi/defines/specmout.htm


DEPT OF ECE 55

The design of the brushed DC motor is quite simple. A permanent magnetic field is

created in the stator by either of two means:

1. Permanent magnets

2. Electro-magnetic windings

If the field is created by permanent magnets, the motor is said to be a "permanent magnet

DC motor" (PMDC). If created by electromagnetic windings, the motor is often said to be

a "shunt wound DC motor" (SWDC). Today, because of cost-effectiveness and

reliability, the PMDC motor is the motor of choice for applications involving fractional

horsepower DC motors, as well as most applications up to about three horsepower.

At five horsepower and greater, various forms of the shunt wound DC motor are most

commonly used. This is because the electromagnetic windings are more cost effective

than permanent magnets in this power range.

Caution: If a DC motor suffers a loss of field (if for example, the field power connections

are broken), the DC motor will immediately begin to accelerate to the top speed which

the loading will allow. This can result in the motor flying apart if the motor is lightly

loaded. The possible loss of field must be accounted for, particularly with shunt wound

DC motors.

3.28 EASY TO CONTROL TORQUE:

In a brushed DC motor, torque control is also simple, since output torque is proportional

to current. If you limit the current, you have just limited the torque which the motor can

achieve. This makes this motor ideal for delicate applications such as textile

manufacturing.

3.29 SIMPLE, CHEAP DRIVE DESIGN:

The result of this design is that variable speed or variable torque electronics are easy to

design and manufacture. Varying the speed of a brushed DC motor requires little more

http://www.oddparts.com/acsi/defines/stator.htm


DEPT OF ECE 56

than a large enough potentiometer. In practice, these have been replaced for all but sub-

fractional horsepower applications by the SCR and PWM drives, which offer relatively

precisely control voltage and current. Common DC drives are available at the low end

(up to 2 horsepower) for under US$100 -- and sometimes under US$50 if precision is not

important.

3.30 DISADVANTAGES:

Expensive to produce

Can't reliably control at lowest speeds

Physically larger

High maintenance

Dust

3.31 WORKING OF DC MOTOR:

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.

FIG 36: WORKING OF DC MOTOR

http://www.oddparts.com/acsi/defines/scr.htm

http://www.oddparts.com/acsi/defines/pwm.htm


DEPT OF ECE 57

3.32 PRINCIPLE:

When a rectangular coil carrying current is placed in a magnetic field, a torque acts on

the coil which rotates it continuously.

When the coil rotates, the shaft attached to it also rotates and thus it is able to do

mechanical work.

Every DC motor has six basic parts -- axle, rotor (a.k.a., armature), stator, commutator,

field magnet(s), and brushes. In most common DC motors (and all that Beamers will see),

the external magnetic field is produced by high-strength permanent magnets1. The stator

is the stationary part of the motor -- this includes the motor casing, as well as two or more

permanent magnet pole pieces. The rotors (together with the axle and attached

commutator) rotate with respect to the stator. The rotor consists of windings (generally on

a core), the windings being electrically connected to the commutator. The above diagram

shows a common motor layout -- with the rotor inside the stator (field) magnets.

The geometry of the brushes, commentator contacts, and rotor windings are such that

when power is applied, the polarities of the energized winding and the stator magnet(s)

are misaligned, and the rotor will rotate until it is almost aligned with the stator's field

magnets. As the rotor reaches alignment, the brushes move to the next commentator

contacts, and energize the next winding. Given our example two-pole motor, the rotation

reverses the direction of current through the rotor winding, leading to a "flip" of the

rotor's magnetic field, driving it to continue rotating.

In real life, though, DC motors will always have more than two poles (three is a very

common number). In particular, this avoids "dead spots" in the commutator. You can

imagine how with our example two-pole motor, if the rotor is exactly at the middle of its

rotation (perfectly aligned with the field magnets), it will get "stuck" there. Meanwhile,

with a two-pole motor, there is a moment where the commutator shorts out the power

supply (i.e., both brushes touch both commutator contacts simultaneously). This would

be bad for the power supply, waste energy, and damage motor components as well. Yet

http://encyclobeamia.solarbotics.net/articles/dc.html

http://encyclobeamia.solarbotics.net/articles/current.html

http://encyclobeamia.solarbotics.net/articles/dc.html


DEPT OF ECE 58

another disadvantage of such a simple motor is that it would exhibit a high amount of

torque "ripple" (the amount of torque it could produce is cyclic with the position of the

rotor).

FIG 37: CLOCKWISE ROTATION OF DC MOTOR

3.33 CONSTRUCTION AND WORKING:

FIG 38: CONSTRUCTION AND WORKING OF DC MOTOR

3.34 PARTS OF A DC MOTOR:

3.34.1 ARMATURE:

A D.C. motor consists of a rectangular coil made of insulated copper wire wound on a

soft iron core. This coil wound on the soft iron core forms the armature. The coil is

mounted on an axle and is placed between the cylindrical concave poles of a magnet.

http://encyclobeamia.solarbotics.net/articles/torque.html

http://encyclobeamia.solarbotics.net/articles/torque.html


DEPT OF ECE 59

3.34.2 COMMUTATOR:

A commutator is used to reverse the direction of flow of current. Commutator is a copper

ring split into two parts C1 and C2. The split rings are insulated from each other and

mounted on the axle of the motor. The two ends of the coil are soldered to these rings.

They rotate along with the coil. Commutator rings are connected to a battery. The wires

from the battery are not connected to the rings but to the brushes which are in contact

with the rings.

FIG: 25

FIG 39 : COMMUTATOR BRUSHES AND SINGLE COIL IN A DC MOTOR

3.34.3 BRUSHES:

Two small strips of carbon, known as brushes press slightly against the two split rings,

and the split rings rotate between the brushes.

The carbon brushes are connected to a D.C. source.


DEPT OF ECE 60

3.34.4 WORKING OF A DC MOTOR:

When the coil is powered, a magnetic field is generated around the armature. The left

side of the armature is pushed away from the left magnet and drawn towards the right,

causing rotation.

FIG 40: SIMPLE ELECTRIC MOTOR

When the coil turns through 900, the brushes lose contact with the commutator and the

current stops flowing through the coil.

However the coil keeps turning because of its own momentum.

Now when the coil turns through 1800, the sides get interchanged. As a result the

commutator ring C1 is now in contact with brush B2 and commutator ring C2 is in contact

with brush B1. Therefore, the current continues to flow in the same direction.

FIG 41: ARMATURE CONTROL IN DC MOTORS


DEPT OF ECE 61

3.35 PARAMATERS OF D.C MOTOR:

1. Direction of rotation

2. Motor Speed

3. Motor Torque

4. Motor Start and Stop

3.36 DIRECTION OF ROTATION:

A DC Motor has two wires. We can call them the positive terminal and the negative

terminal, although these are pretty much arbitrary names (unlike a battery where these

polarities are vital and not to be mixed!). On a motor, we say that when the + wire is

connected to + terminal on a power source, and the - wire is connected to the - terminal

source on the same power source, the motor rotates clockwise (if you are looking towards

the motor shaft). If you reverse the wire polarities so that each wire is connected to the

opposing power supply terminal, then the motor rotates counter clockwise. Notice this is

just an arbitrary selection and that some motor manufacturers could easily choose the

opposing convention. As long as you know what rotation you get with one polarity, you

can always connect in such a fashion that you get the direction that you want on a per

polarity basis.

FIG 42 : ROTATION DIRECTIONS IN DC MOTORS


DEPT OF ECE 62

3.37 D.C MOTOR ROTATION V/S POLARITY:

3.37.1 FACTS:

DC Motor rotation has nothing to do with the voltage magnitude or the current

magnitude flowing through the motor.

DC Motor rotation does have to do with the voltage polarity and the direction of

the current flow.

3.38 DC MOTOR SPEED:

Whereas the voltage polarity controls DC motor rotation, voltage magnitude controls

motor speed. Think of the voltage applied as a facilitator for the strengthening of the

magnetic field. In other words, the higher the voltage, the quicker will the magnetic field

become strong. Remember that a DC motor has an electromagnet and a series of

permanent magnets. The applied voltage generates a magnetic field on the electromagnet

portion. This electromagnet field is made to oppose the permanent magnet field. If the

electromagnet field is very strong, then both magnetic entities will try to repel each other

from one side, as well as attract each other from the other side. The stronger the induced

magnetic field, the quicker will this separation/attraction will try to take place. As a

result, motor speed is directly proportional to applied voltage.

FIG 43: DC MOTOR VOLTAGE SPEED GRAPH


DEPT OF ECE 63

3.39 MOTOR SPEED CURVE:

One aspect to have in mind is that the motor speed is not entirely lineal. Each motor will

have their own voltage/speed curve. One thing I can guarantee from each motor is that at

very low voltages, the motor will simply not move. This is because the magnetic field

strength is not enough to overcome friction. Once friction is overcome, motor speed will

start to increase as voltage increase.

The following video shows the concept of speed control and offers some ideas on how

this can be achieved.

3.40 MOTOR TORQUE:

In the previous segment I kind of described speed as having to do with the strength of the

magnetic field, but this is in reality misleading. Speed has to do with how fast the

magnetic field is built and the attraction/repel forces are installed into the two magnetic

structures. Motor strength, on the other hand, has to do with magnetic field strength. The

stronger the electromagnet attracts the permanent magnet, the more force is exerted on

the motor load.

Per example, imagine a motor trying to lift 10 pounds of weight. This is a force that when

multiplied by a distance (how much from the ground we are lifting the load) results in

WORK. This WORK when exerted through a predetermined amount of time (for how

long we are lifting the weight) gives us power. But whatever power came in, must come

out as energy cannot be created or destroyed. So that you know, the power that we are

supplying to the motor is computed by

P = IV

Where P is power, I is motor current and V is motor voltage


DEPT OF ECE 64

Hence, if the voltage (motor speed) is maintained constant, how much load we are

moving must come from the current. As you increase load (or torque requirements)

current must also increase.

3.41 MOTOR LOADING:

One aspect about DC motors which we must not forget is that loading or increase of

torque cannot be infinite as there is a point in which the motor simply cannot move.

When this happens, we call this loading ―Stalling Torque‖. At the same time this is the

maximum amount of current the motor will see, and it is refer to Stalling Current.

Stalling deserves a full chapter as this is a very important scenario that will define a great

deal of the controller to be used. I promise I will later write a post on stalling and its

intricacies.

3.42 MOTOR START AND STOP:

You are already well versed on how to control the motor speed, the motor torque and the

motor direction of rotation. But this is all fine and dandy as long as the motor is actually

moving. How about starting it and stopping it? Are these trivial matters? Can we just

ignore them or should we be careful about these aspects as well? You bet we should!

Starting a motor is a very hazardous moment for the system. Since you have an

inductance whose energy storage capacity is basically empty, the motor will first act as

an inductor. In a sense, it should not worry us too much because current cannot change

abruptly in an inductor, but the truth of the matter is that this is one of the instances in

which you will see the highest currents flowing into the motor. The start is not

necessarily bad for the motor itself as in fact the motor can easily take this Inrush

Current. The power stage, on the other hand and if not properly designed for, may take a

beating.


DEPT OF ECE 65

Once the motor has started, the motor current will go down from inrush levels to

whatever load the motor is at. Per example, if the motor is moving a few gears, current

will be proportional to that load and according to torque/current curves.

3.43 MOTOR DRIVER CIRCUIT:

The name "H-Bridge" is derived from the actual shape of the switching circuit which

control the motion of the motor. It is also known as "Full Bridge". Basically there are

four switching elements in the H-Bridge as shown in the figure below.

FIG 44: MOTOR DRIVER CIRCUIT

As you can see in the figure above there are four switching elements named as "High side

left", "High side right", "Low side right", "Low side left". When these switches are turned

on in pairs motor changes its direction accordingly. Like, if we switch on High side left

and Low side right then motor rotate in forward direction, as current flows from Power

supply through the motor coil goes to ground via switch low side right. This is shown in

the figure below.


DEPT OF ECE 66

FIG 45: H-BRIDGE

Similarly, when you switch on low side left and high side right, the current flows in

opposite direction and motor rotates in backward direction. This is the basic working of

H-Bridge. We can also make a small truth table according to the switching of H-Bridge

explained above.

3.44 TRUTH TABLE:

High Left High Right Low Left Low Right Description

On Off Off On Motor runs clockwise

Off On On Off Motor runs anti-clockwise

On On Off Off Motor stops or decelerates

Off Off On On Motor stops or decelerates

TABLE 9: TRUTH TABLE

As already said, H-bridge can be made with the help of transistors as well as MOSFETs;

the only thing is the power handling capacity of the circuit. If motors are needed to run

with high current then lot of dissipation is there. So head sinks are needed to cool the

circuit.


DEPT OF ECE 67

Now you might be thinking why i did not discuss the cases like High side left on and

Low side left on or high side right on and low side right on. Clearly seen in the diagra,

you don't want to burn your power supply by shorting them. So that is why those

combinations are not discussed in the truth table.

3.45 VARIABLE RESISTORS:

3.45.1 CONSTRUCTION:

FIG 46: VARIABLE RESISTOR

Variable resistors consist of a resistance track with connections at both ends and a wiper

which moves along the track as you turn the spindle. The track may be made from

carbon, cermet (ceramic and metal mixture) or a coil of wire (for low resistances). The

track is usually rotary but straight track versions, usually called sliders, are also

available.

Variable resistors are often called potentiometers in books and catalogues. They are

specified by their maximum resistance, linear or logarithmic track, and their physical

size. The standard spindle diameter is 6mm.

The resistance and type of track are marked on the body:

1. 4K7 LIN means 4.7 k linear track.

2. 1M LOG means 1 M logarithmic track.


DEPT OF ECE 68

Some variable resistors are designed to be mounted directly on the circuit board, but most

are for mounting through a hole drilled in the case containing the circuit with stranded

wire connecting their terminals to the circuit board

LINEAR (LIN) AND LOGARITHMIC (LOG) TRACKS:

3.45.2 LINEAR (LIN): track means that the resistance changes at a constant rate as you

move the wiper. This is the standard arrangement and you should assume this type is

required if a project does not specify the type of track. Presets always have linear tracks.

3.45.2 LOGARITHMIC (LOG): track means that the resistance changes slowly at one

end of the track and rapidly at the other end, so halfway along the track is not half the

total resistance! This arrangement is used for volume (loudness) controls because the

human ear has a logarithmic response to loudness so fine control (slow change) is

required at low volumes and coarser control (rapid change) at high volumes. It is

important to connect the ends of the track the correct way round, if you find that turning

the spindle increases the volume rapidly followed by little further change you should

swap the connections to the ends of the track.

3.46 RHEOSTAT:

FIG 47: RHEOSTAT SYMBOL

This is the simplest way of using a variable resistor. Two terminals are used: one

connected to an end of the track, the other to the moveable wiper. Turning the spindle

changes the resistance between the two terminals from zero up to the maximum

resistance.

Rheostats are often used to vary current, for example to control the brightness of a lamp

or the rate at which a capacitor charges. If the rheostat is mounted on a printed circuit


DEPT OF ECE 69

board you may find that all three terminals are connected! However, one of them will be

linked to the wiper terminal. This improves the mechanical strength of the mounting but

it serves no function electrically.

3.47 POTENTIOMETER:

FIG 48: POTENTIOMETER SYMBOL

Variable resistors used as potentiometers have all three terminals connected.

This arrangement is normally used to vary voltage, for example to set the switching point

of a circuit with a sensor, or control the volume (loudness) in an amplifier circuit. If the

terminals at the ends of the track are connected across the power supply then the wiper

terminal will provide a voltage which can be varied from zero up to the maximum of the

supply.

3.48 PRESETS:

FIG 49: PRESET SYMBOL

These are miniature versions of the standard variable resistor. They are designed to be

mounted directly onto the circuit board and adjusted only when the circuit is built. For

example to set the frequency of an alarm tone or the sensitivity of a light-sensitive circuit.

A small screwdriver or similar tool is required to adjust presets. Presets are much cheaper

than standard variable resistors so they are sometimes used in projects where a standard variable

resistor would normally be used.


DEPT OF ECE 70

CHAPTER – 4

SOFTWARE DESCRIPTION


DEPT OF ECE 71

4.1 ABOUT KEIL SOFTWARE:

It is possible to create the source files in a text editor such as Notepad, run the

Compiler on each C source file, specifying a list of controls, run the Assembler on each

Assembler source file, specifying another list of controls, run either the Library Manager

or Linker (again specifying a list of controls) and finally running the Object-HEX

Converter to convert the Linker output file to an Intel Hex File. Once that has been

completed the Hex File can be downloaded to the target hardware and debugged.

Alternatively KEIL can be used to create source files; automatically compile, link and

covert using options set with an easy to use user interface and finally simulate or perform

debugging on the hardware with access to C variables and memory. Unless you have to

use the tolls on the command line, the choice is clear. KEIL Greatly simplifies the

process of creating and testing an embedded application.

4.2 PROJECTS:

The user of KEIL centers on ―projects‖. A project is a list of all the source files

required to build a single application, all the tool options which specify exactly how to

build the application, and – if required – how the application should be simulated. A

project contains enough information to take a set of source files and generate exactly the

binary code required for the application. Because of the high degree of flexibility

required from the tools, there are many options that can be set to configure the tools to

operate in a specific manner. It would be tedious to have to set these options up every

time the application is being built; therefore they are stored in a project file. Loading the

project file into KEIL informs KEIL which source files are required, where they are, and

how to configure the tools in the correct way. KEIL can then execute each tool with the

correct options. It is also possible to create new projects in KEIL. Source files are added

to the project and the tool options are set as required. The project can then be saved to

preserve the settings. The project is reloaded and the simulator or debugger started, all the

desired windows are opened. KEIL project files have the extension


DEPT OF ECE 72

4.3 SIMULATOR/DEBUGGER:

The simulator/ debugger in KEIL can perform a very detailed simulation of a

micro controller along with external signals. It is possible to view the precise execution

time of a single assembly instruction, or a single line of C code, all the way up to the

entire application, simply by entering the crystal frequency. A window can be opened for

each peripheral on the device, showing the state of the peripheral. This enables quick

trouble shooting of miss-configured peripherals. Breakpoints may be set on either

assembly instructions or lines of C code, and execution may be stepped through one

instruction or C line at a time. The contents of all the memory areas may be viewed along

with ability to find specific variables. In addition the registers may be viewed allowing a

detailed view of what the microcontroller is doing at any point in time.

The Keil Software 8051 development tools listed below are the programs you use to

compile your C code, assemble your assembler source files, link your program together,

create HEX files, and debug your target program. µVision2 for Windows™ Integrated

Development Environment: combines Project Management, Source Code Editing, and

Program Debugging in one powerful environment.

1. C51 ANSI Optimizing C Cross Compiler: creates locatable object modules from your

C source code,

2. A51 Macro Assembler: creates reloadable object modules from your 8051

assembler source code,

3. BL51 Linker/Locator: combines relatable object modules created by the compiler and

assembler into the final absolute object module,

4. LIB51 Library Manager: combines object modules into a library, which may be used

by the linker,

5. OH51 Object-HEX Converter: creates Intel HEX files from absolute object modules.


DEPT OF ECE 73

4.4 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.

4.5 WHAT IS µVISION3?

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

and debug embedded programs. It encapsulates the following components:

1. A project manager.

2. A make facility.

3. Tool configuration.

4. Editor.

5. A powerful debugger.

To help you get started, several example programs (located in the \C51\Examples,

\C251\Examples, \C166\Examples, and \ARM\...\Examples) are provided.

1. HELLO is a simple program that prints the string "Hello World" using the Serial

Interface.

2. MEASURE is a data acquisition system for analog and digital systems.

3. TRAFFIC is a traffic light controller with the RTX Tiny operating system.

4. SIEVE is the SIEVE Benchmark.

5. DHRY is the Dhrystone Benchmark.

6. WHETS is the Single-Precision Whetstone Benchmark.

Additional example programs not listed here are provided for each device architecture.

4.6 BUILDING AN APPLICATION IN µVISION2:

Creating Your Own Application in µVision2To build (compile, assemble, and link) an

application in µVision2, you must:


DEPT OF ECE 74

1. Select Project -(forexample,166\EXAMPLES\HELLO\HELLO.UV2).

2. Select Project - Rebuild all target files or Build target.

µVision2 compiles, assembles, and links the files in your project

4.7 TO CREATE A NEW PROJECT IN µVISION2, YOU MUST:

1. Select Project - New Project.

2. Select a directory and enter the name of the project file.

3. Select Project - Select Device and select an 8051, 251, or C16x/ST10 device from the

Device Database™.

4. Create source files to add to the project.

5. Select Project - Targets, Groups, and Files. Add/Files, select Source Group1, and add

the source files to the project.

6. 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.

7. Select Project - Rebuild all target files or Build target.

4.8 DEBUGGING AN APPLICATION IN µVISION2:

To debug an application created using µVision2, you must:

1. Select Debug - Start/Stop Debug Session.

2. 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.

3. 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.

4.9 STARTING µVISION2 AND CREATING A PROJECT:

µVision2 is a standard Windows application and started by clicking on the program icon.

To create a new project file select from the µVision2 menu


DEPT OF ECE 75

4.9.1 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.

µVision2 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

4.9.2 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 µVision2 device

Database. Just select the micro controller 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

4.9.3 BUILDING PROJECTS AND CREATING A HEX FILES

Typical, 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, µVision2 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 µVision2 editor window.

4.9.4 CPU SIMULATION:

µVision2 simulates up to 16 Mbytes of memory from which areas can be

mapped for read, write, or code execution access. The µVision2 simulator traps

And 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.


DEPT OF ECE 76

4.9.5 DATABASE SELECTION:

You 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.

4.9.6 START DEBUGGING:

You start the debug mode of µVision2 with the Debug – Start/Stop Debug

Session command. Depending on the Options for Target – Debug

Configuration, µVision2 will load the application program and run the startup

code µVision2 saves the editor screen layout and restores the screen layout of the last

debug session. If the program execution stops, µVision2 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 µVision2 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.

4.9.7 DISASSEMBLY WINDOW

The Disassembly window shows your target program as mixed source and assembly

program or just assembly code. A trace history of previously executed instructions may


DEPT OF ECE 77

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.

4.10 SOFTWARE COMPONENTS

4.10.1 ABOUT KEIL:

1. Click on the Keil u Vision Icon on Desktop

2. The following fig will appear

3. Click on the Project menu from the title bar

4. Then Click on New Project


DEPT OF ECE 78

5. Save the Project by typing suitable project name with no extension in u r own

folder sited in either C:\ or D:\

6. Then Click on Save button above.

7. Select the component for u r project. i.e. Atmel……

8. Click on the + Symbol beside of Atmel


DEPT OF ECE 79

9. Select AT89C51 as shown below

10. Then Click on ―OK‖

11. The Following fig will appear


DEPT OF ECE 80

12. Then Click either YES or NO………mostly ―NO‖

13. Now your project is ready to USE

14. Now double click on the Target1, you would get another option ―Source

group 1‖ as shown in next page.

15. Click on the file option from menu bar and select ―new‖


DEPT OF ECE 81

16. The next screen will be as shown in next page, and just maximize it by double

clicking on its blue boarder.

17. Now start writing program in either in ―C‖ or ―ASM‖

18. For a program written in Assembly, then save it with extension ―. asm‖ and

for ―C‖ based program save it with extension ― .C‖


DEPT OF ECE 82

19. Now right click on Source group 1 and click on ―Add files to Group Source‖

20. Now you will get another window, on which by default ―C‖ files will appear.


DEPT OF ECE 83

21. Now select as per your file extension given while saving the file

22. Click only one time on option ―ADD‖

23. Now Press function key F7 to compile. Any error will appear if so happen.

24. If the file contains no error, then press Control+F5 simultaneously.


DEPT OF ECE 84

25. The new window is as follows

26. Then Click ―OK‖

27. Now Click on the Peripherals from menu bar, and check your required port as

shown in fig below

28. Drag the port a side and click in the program file.


DEPT OF ECE 85

RESULT:

The project “NAVIGATION OF ROBOT USING RF WITH LANDMINE

DETECTION” 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.


DEPT OF ECE 86

APPLICATION

1. The main application of this project is based on the fact that it is used to detect

landmines in areas such as forests

2. It is also which used in areas which are in habituated by terrorists and naxalites to

detect landmines.

3. This project also helps in detection of live bombs which are planted by terrorists.

4. It has a small RF camera located along its front along with a metal detector and can

also detect live bombs in cities and public places.

5. It can also be used in areas of Earth quakes and landmines to detect people trapped

inside rubble and sand.

6. It is used to detect faulty cables underground in pipes where a normal human being

cannot travel.


DEPT OF ECE 87

CONCLUSION

Based on the structure of the project it is built for detection of landmines in a specific

area but if a certain features are added to it .this project can have a more wider approach

and applications .Such as a addition of a R/F camera can help this robot detect live

bombs apart for detecting land mines and also it can reach places where it is difficult for

a normal human being to reach such as underground pipes and canals .hence this project

has got a diversified approach and hence it is helping us make our work easier and

protecting us from dangers and unwanted accidents.


DEPT OF ECE 88

FUTURESCOPE

Referring to the futuristic application of this equipment .The main process of this

equipment is going to change but along with the change in its technology. This product is

going to become more advanced it will help in the diffusion of bombs using artificial

limbs and automatic diffusing of landmines using sensors and camera. This technology is

going to help the the government from various threats like terrorism and many other

factors .this device can also be used in war to identify enemy infantry and various other

platforms. Hence this equipment is going to be very useful in its advanced future

prototype designs


DEPT OF ECE 89

BIBLIOGRAPHY

1. http://www.garmin.com/products/gps35

2. http://www.alldatasheet.com

3. http://www.mathworks.com

4. M. A. Mazidi, J. C. Mazidi, R. D. Mckinaly, The 8051 Microcontroller and

Embedded

Systems, Pearson Education, 2006.

5. http://www.national.com/ds/LM/LM35.pdf

6. http://www.nxp.com/documents/user_manual/UM10139.pdf

Navigation of Robot Vehicle using RF with Landmine Detection

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