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,

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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

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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……. -500
C to 1250
C

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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….. -500
C to 1250
C
Operating Temperature….. -200
C to 750
C
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.

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

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

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.

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

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

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

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

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.

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 C51Examples,
C251Examples, C166Examples, 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,166EXAMPLESHELLOHELLO.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

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