Major project report

A
Major Project
ON
TV REMOTE AS A CORDLESS MOUSE
Submitted in partial fulfillment of the requirements for the
Degree of
Bachelor of Engineering in Electronics & Communication
Submitted to:
RAJIV GANDHI PROUDYOGIKI VISHWAVIDHYALAYA,
BHOPAL (M.P.)
Submitted by
PRAVEEN SINGH (0191EC101070)
PRASHANT SONI(0191EC101069)
TUSHAR SAHU(0191EC101113)
PRAFUL TAJNE(0191EC101067)
Under the Guidance of
Prof. Archana Sharma Prof. Hema Singh
EC Department Head of EC Department
DEPARTMENT OF ELECTRONICS & COMMUNICATION
TECHNOCRATS INSTITUTE OF TECHNOLOGY (EXCELLENCE),
BHOPAL
SESSION: 2013-2014

TECHNOCRATS INSTITUTE OF TECHNOLOGY
(EXCELLENCE), BHOPAL
CERTIFICATE
This is to certify that the work embodies in this major project work entitled “TV
REMOTE AS A CORDLESS MOUSE” being submitted by PRAVEEN SINGH
(0191EC101070), PRASHANT SONI (0191EC101069), TUSHAR
SAHU(0191EC101113), PRAFUL TAJNE (0191EC101067) in partial fulfillment
of the requirement for the award of Bachelor of Engineering in Electronics &
Communication Engineering to Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal
( M.P.) during the academic year 2013-14 is a record of bonafide piece of work,
carried out by Prof. Archana Sharma under my supervision and guidance in the
Electronics And Communication Engineering, Technocrats Institute of
Technology(Excellence), Bhopal.
Prof. Archana Sharma Prof. Hema Singh
EC Department Head of Department
Electronics & Communication

TECHNOCRATS INSTITUTE OF TECHNOLOGY
(EXCELLENCE), BHOPAL
ELECTRONICS AND COMMUNICATION DEPARTMENT
DECLARATION
We, PRAVEEN SINGH, PRASHANT SONI, TUSHAR SAHU, PRAFUL
TAJNE students of BACHELOR of ENGINEERING in (ELECTRONICS &
COMMUNICATION), Session 2013-14 Technocrats Institute of Technology
(Excellence), Bhopal M.P., here by declare that the work presented in this project
Report entitled “TV REMOTE AS CORDLESS MOUSE” is the outcome of our
own work, is bonafide and correct to the best of our knowledge and this work has
been carried out taking care of Engineering Ethics.
PRASHANT SONI (0191EC101069)
TUSHAR SAHU (0191EC101113)
PRAFUL TAJNE (0191EC101067)
Date :

ACKNOWLEDGEMENT
I deem it’s my privilege to extent my profound gratitude and appreciation towards all
those who have directly or indirectly involved themselves in making this project a
great success, It gives me immense pleasure to express my deepest sense of gratitude
and sincere thanks to my respected guide Prof. Archana Sharma, for their valuable
guidance encouragement and help for this work.
I express my deep sense of gratitude to Prof. Archana Sharma, for his keen intrest,
continued encouragement and support.
I would also like to express my sincere thanks to Dr Asif Ullah Khan Director of
Technocrats Institute of Technology (Excellence),Bhopal, Prof. Hema Singh Head of
Department Electronics & Communication for providing me with all the moral
support and necessary help. My sincere appreciation and thanks to all for keen
interest, continued encouragement and support my family members and friends.
PRASHANT SONI (0191EC101069)
TUSHAR SAHU (0191EC101113)
PRAFUL TAJNE (0191EC101067)

TABLE OF CONTENTS
CONTENTS PAGE NO.
ABSTRACT I
LIST OF FIGURES II
LIST OF TABLES IV
1. INTRODUCTION TO EMBEDDED SYSTEMS
1.1 WHAT IS EMBEDDED SYSTEM ? 1
1.2 SYSTEM DESIGN CALLS 1
1.3 EMBEDDED SYSTEM DESIGN CYCLE 2
1.4 CHARACTERISTICS OF EMBEDDED SYSTEM 2
1.5 APPLICATIONS 3
1.6 CLASSIFICATION 3
1.7 HARD REAL TIME RESPONSE 3
2. BLOCK DIAGRAM EXPLANATION
2.1 EXPLANATION 4
3. HARDWARE REQUIREMENTS
3.1 HARDWARE COMPONENTS 5
3.2 TRANSFORMER 6
3.3 VOLTAGE REGULATOR (LM7805) 8
3.4 FILTER 10
3.5 RECTIFIER 11
3.6 PIC MICROCONTROLLER (16F877A) 12
3.7 TSOP1738 15
3.8 MAX232 17
3.9 DB9 CONNECTOR 19
3.10 LED 21
3.11 IN4007 DIODE 23
3.12 RESISTOR 25
3.13 CAPACITOR 27

4. SOFTWARE REQUIREMENTS
4.1 WHAT IS MPLAB IDE? 35
4.2 DESCRIPTION OF EMBEDDED SYSTEM 35
4.3 COMPONENTS OF MICROCONTROLLER 35
4.4 THE DEVELOPMENT CYCLE 38
4.5 PROJECT MANAGER 38
4.6 DEVICE PROGRAMMING 39
4.7 COMPONENTS OF MPLAB IDE 40
4.8 MPLAB IDE FEATURES AND INSTALLATION 42
4.9 EMBEDDED C 49
5. SCHEMATIC DIAGRAM
5.1 DESCRIPTION 50
5.2 OPERATION 51
6. LAYOUT
6.1 LAYOUT DIAGRAM 53
7. MICROCONTROLLER PROGRAMMING
7.1 CODING 54
8. HARDWARE TESTING
8.1 CONTINUITY TEST 58
8.2 POWER ON TEST 59
9. RESULT AND CONCLUSION
9.1 RESULT 60
9.2 CONCLUSION 60
10. ADVANTAGES AND FUTURE SCOPE
10.1 ADVANTAGES 61
10.2 FUTURE SCOPE 61
REFERENCES 62

ABSTRACT
The project is designed to use a TV remote as a cordless mouse for the computer. A
conventional PC/laptop uses a mouse to operate and control all its applications. As a
PC mouse is wired to the system, one has to sit near the PC to operate it. This
becomes very tedious when the PC is used for presentation purposes (when using a
projector). In this proposed system TV remote can be used as a cordless mouse, and
the user need not operate the PC sitting near it.
A typical TV remote sends coded infrared data that is read by an IR sensor interfaced
to an 8051 family microcontroller. This data so received by the microcontroller sends
it to the COM port of a PC through a level shifter IC. This IR code is traditionally
RC5 code as followed by some manufacturers. Mouse Driver is used on the PC that
recognizes data received from the microcontroller through the COM port and
performs the required operation. Designated numbers on the TV remote are used to
perform up - down, right - left cursor movement. Features like left click and right
click of the mouse can also be performed with of the TV remote.
Further this project can be enhanced using Bluetooth/ RF technology to overcome the
traditional line of sight communication drawbacks of the infrared type.
I

LIST OF FIGURES
CONTENTS PAGE NO.
1. System design calls 1
2. V Diagram 2
3. Block Diagram 4
4. A Typical Transformer 6
5. Ideal Transformer as a Circuit Element 7
6. 7805 Voltage Regulator 8
7. 7805 Internal Block Diagram 9
8. Rectifier Circuit 10
9. Filter Circuit 11
10. PIC16F877A PIN Diagram 12
11. TSOP 15
12. Block Diagram of TSOP 16
13. MAX232 PIN Diagram 18
14. DB9 Connector 19
15. Interfacing Between the Microcontroller and DB9 Connector 21
16. Symbol of LED 22
17. White LED Spectrum 23
18. IN4007 Diodes 24
19. PN Junction Diodes 24
20. Resistors 27
21. Capacitors 28
22. Capacitor - Theory of Operation 29
23. A simple demonstration of a parallel-plate capacitor 31
24. Parallel Plate Model 33
25. Several capacitors in parallel 34
26. Several capacitors in series 34
II

27. PICmicro MCU Data Sheet Instructions 37
28. MPLAB IDE Desktop 42
29. Selecting Device Dialog 43
30. Project Wizard Select Device 44
31. Project Wizard Select Language Tools 45
32. Project Wizard Name 45
33. Project Wizrd Select Template File 46
34. Project Wizard Select Linker Script 46
35. Project Wizard Summary 47
36. Project Window 47
37. Output Window 48
38. Project Context Menu 49
39. Schematic Diagram 50
40. Layout Diagram 53
III

LIST OF TABLES
CONTENTS PAGE NO.
1. Rating of Voltage Regulator 9
2. MAX232 Voltage Levels 17
3. MAX232 PIN Description 18
4. DB9 PIN Description 20
IV

1. INTRODUCTION TO EMBEDDED SYSTEMS
1.1 WHAT IS EMBEDDED SYSTEM ?
An Embedded System is a combination of computer hardware and software, and
perhaps additional mechanical or other parts, designed to perform a specific function.
An embedded system is a microcontroller-based, software driven, reliable, real-time
control system, autonomous, or human or network interactive, operating on diverse
physical variables and in diverse environments and sold into a competitive and cost
conscious market.
An embedded system is not a computer system that is used primarily for processing,
not a software system on PC or UNIX, not a traditional business or scientific
application. High-end embedded & lower end embedded systems. High-end
embedded system - Generally 32, 64 Bit Controllers used with OS. Examples
Personal Digital Assistant and Mobile phones etc . Lower end embedded systems -
Generally 8,16 Bit Controllers used with an minimal operating systems and hardware
layout designed for the specific purpose.
1.2 SYSTEM DESIGN CALLS
Fig. 1.2(a) System design calls
1

1.3 EMBEDDED SYSTEM DESIGN CYCLE
Fig. 1.3(b) V Diagram
1.4 CHARACTERISTICS OF EMBEDDED SYSTEM
 An embedded system is any computer system hidden inside a product other than a
computer.
 They will encounter a number of difficulties when writing embedded system
software in addition to those we encounter when we write applications
– Throughput – Our system may need to handle a lot of data in a short period of
time.
– Response–Our system may need to react to events quickly
– Testability–Setting up equipment to test embedded software can be difficult
– Debugability–Without a screen or a keyboard, finding out what the software is
doing wrong (other than not working) is a troublesome problem
– Reliability – embedded systems must be able to handle any situation without
human intervention
– Memory space – Memory is limited on embedded systems, and you must
make the software and the data fit into whatever memory exists
– Program installation – you will need special tools to get your software into
embedded systems
– Power consumption – Portable systems must run on battery power, and the
software in these systems must conserve power
2

– Processor hogs – computing that requires large amounts of CPU time can
complicate the response problem.
– Cost – Reducing the cost of the hardware is a concern in many embedded
system projects; software often operates on hardware that is barely adequate
for the job.
 Embedded systems have a microprocessor/ microcontroller and a memory. Some
have a serial port or a network connection. They usually do not have keyboards,
screens or disk drives.
1.5 APPLICATIONS
1) Military and aerospace embedded software applications
2) Communication Applications
3) Industrial automation and process control software
4) Mastering the complexity of applications.
5) Reduction of product design time.
6) Real time processing of ever increasing amounts of data.
7) Intelligent, autonomous sensors.
1.6 CLASSIFICATION
 Real Time Systems.
 RTS is one which has to respond to events within a specified deadline.
 A right answer after the dead line is a wrong answer
1.6.1 RTS Classification
 Hard Real Time System
 Soft Real Time System
1.7 HARD REAL TIME SYSTEM
 "Hard" real-time systems have very narrow response time.
 Example: Nuclear power system, Cardiac pacemaker.
3

2. BLOCK DIAGRAM
Fig. 2 Block Diagram
2.1 EXPLANATION
Transformer step down the ac voltage and than passes to the rectifier circuit. Rectifier
Circuit convert ac voltage into dc voltage. 7805 Voltage Regulator provides a
constant dc supply to the IR receiver (TSOP1738), Microcontroller (PC16F877A), PC
Interface, LED. TV remote radiates Infrared signals which are captured by the IR
Receiver.Output of this receiver passes to the microcontroller. Now it provides a
specific instructions to the PC by using PC interface.
4

3. HARDWARE REQUIREMENTS
3.1 HARDWARE COMPONENTS:
1. TRANSFORMER (230 – 12 V AC)
2. VOLTAGE REGULATOR (LM 7805)
3. FILTER
4. RECTIFIER
5. PIC 16F877A
6. TSOP1738
7. MAX232
8. DB9 CONNECTOR
9. LED
10. 1N4007 DIODE
11. RESISTOR
12. CAPACITOR
5

3.2 TRANSFORMER
Transformers convert AC electricity from one voltage to another with a little loss of
power. Step-up transformers increase voltage, step-down transformers reduce voltage.
Most power supplies use a step-down transformer to reduce the dangerously high
voltage to a safer low voltage.
Fig. 3.2(a) A Typical Transformer
The input coil is called the primary and the output coil is called the secondary. There
is no electrical connection between the two coils; instead they are linked by an
alternating magnetic field created in the soft-iron core of the transformer. The two
lines in the middle of the circuit symbol represent the core. Transformers waste very
little power so the power out is (almost) equal to the power in. Note that as voltage is
stepped down and current is stepped up.
The ratio of the number of turns on each coil, called the turn’s ratio, determines the
ratio of the voltages. A step-down transformer has a large number of turns on its
primary (input) coil which is connected to the high voltage mains supply, and a small
number of turns on its secondary (output) coil to give a low output voltage.
Turns Ratio = (Vp / Vs) = ( Np / Ns )
Where,
Vp = primary (input) voltage.
Vs = secondary (output) voltage
Np = number of turns on primary coil
Ns = number of turns on secondary coil
Ip = primary (input) current
6

3.2.1 Ideal power equation :
Fig. 3.2(b) Ideal Transformer as a Circuit Element
If the secondary coil is attached to a load that allows current to flow, electrical power
is transmitted from the primary circuit to the secondary circuit. Ideally, the
transformer is perfectly efficient; all the incoming energy is transformed from the
primary circuit to the magnetic field and into the secondary circuit. If this condition is
met, the incoming electric power must equal the outgoing power:
Giving the ideal transformer equation
Transformers normally have high efficiency, so this formula is a reasonable
approximation.
If the voltage is increased, then the current is decreased by the same factor. The
impedance in one circuit is transformed by the square of the turns ratio. For example,
if an impedance Zs is attached across the terminals of the secondary coil, it appears to
the primary circuit to have an impedance of (Np/Ns)2
Zs. This relationship is reciprocal,
so that the impedance Zp of the primary circuit appears to the secondary to be
(Ns/Np)2
Zp.
7

3.3 VOLTAGE REGULATOR 7805
3.3.1 Features
• Output Current up to 1A.
• Output Voltages of 5, 6, 8, 9, 10, 12, 15, 18, 24V.
• Thermal Overload Protection.
• Short Circuit Protection.
• Output Transistor Safe Operating Area Protection.
Fig. 3.3(a) 7805 Voltage Regulator
3.3.2 Description
The LM78XX/LM78XXA series of three-terminal positive regulators are available in
the TO-220/D-PAK package and with several fixed output voltages, making them
useful in a Wide range of applications. Each type employs internal current limiting,
thermal shutdown and safe operating area protection, making it essentially
indestructible. If adequate heat sinking is provided, they can deliver over 1A output
Current. Although designed primarily as fixed voltage regulators, these devices can be
used with external components to obtain adjustable voltages and currents.
8

3.3.3 Internal Block Diagram
Fig. 3.3(b) 7805 Internal Block Diagram
3.3.4 Absolute Maximum Ratings
Table 3.3(a) Rating of Voltage Regulator
9

3.4 RECTIFIER
A rectifier is an electrical device that converts alternating current (AC), which
periodically reverses direction, to direct current (DC), current that flows in only one
direction, a process known as rectification. Rectifiers have many uses including as
components of power supplies and as detectors of radio signals. Rectifiers may be
made of solid state diodes, vacuum tube diodes, mercury arc valves, and other
components. The output from the transformer is fed to the rectifier. It converts A.C.
into pulsating D.C. The rectifier may be a half wave or a full wave rectifier. In this
project, a bridge rectifier is used because of its merits like good stability and full wave
rectification. In positive half cycle only two diodes( 1 set of parallel diodes) will
conduct, in negative half cycle remaining two diodes will conduct and they will
conduct only in forward bias only.
Fig. 3.4(a) Rectifier Circuit
10

3.5 FILTER
Capacitive filter is used in this project. It removes the ripples from the output of
rectifier and smoothens the D.C. Output received from this filter is constant until the
mains voltage and load is maintained constant. However, if either of the two is varied,
D.C. voltage received at this point changes. Therefore a regulator is applied at the
output stage.
The simple capacitor filter is the most basic type of power supply filter. The use of
this filter is very limited. It is sometimes used on extremely high-voltage, low-current
power supplies for cathode-ray and similar electron tubes that require very little load
current from the supply. This filter is also used in circuits where the power-supply
ripple frequency is not critical and can be relatively high. Below figure can show how
the capacitor charges and discharges.
Fig. 3.5 Filter Circuit
11

3.6 MICRO CONTROLLER PIC16F877
3.6.1 Pin Diagram
Fig.3.6(a) PIC16F877A PIN Diagram
PIC16F873A/876A devices are available only in 28-pin packages, while
PIC16F874A/877A devices are available in 40-pin and 44-pin packages. All
devices in the PIC16F87XA family share common architecture with the following
differences:
 The PIC16F873A and PIC16F874A have one-half of the total on-chip memory of
the PIC16F876A and PIC16F877A.
 The 28-pin devices have three I/O ports, while the 40/44-pin devices have five.
 The 28-pin devices have fourteen interrupts, while the 40/44-pin devices have
fifteen.
 The 28-pin devices have five A/D input channels, while the 40/44-pin devices
have eight.
12

3.6.2 High-Performance RISC CPU:
 Only 35 single-word instructions.
 All single-cycle instructions except for program branches, which are two cycle.
 Operating speed: DC – 20 MHz clock input DC – 200 ns instruction cycle
 Up to 8K x 14 words of Flash Program Memory, Up to 368 x 8 bytes of Data
Memory (RAM), Up to 256 x 8 bytes of EEPROM Data Memory.
 Pin out compatible to other 28-pin or 40/44-pin, PIC16CXXX and PIC16FXXX
microcontrollers.
3.6.3 Special Microcontroller Features:
 100,000 erase/write cycle Enhanced Flash program memory typical.
 1,000,000 erase/write cycle Data EEPROM memory typical.
 Data EEPROM Retention > 40 years.
 Self-reprogrammable under software control.
 In-Circuit Serial Programming™ (ICSP™) via two pins.
 Single-supply 5V In-Circuit Serial Programming.
 Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation.
 Programmable code protection.
 Power saving Sleep mode.
 Selectable oscillator options.
3.6.4 Peripheral Features:
 Timer0: 8-bit timer/counter with 8-bit prescaler.
 Timer1: 16-bit timer/counter with prescaler, can be incremented during Sleep via
external crystal/clock.
 Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler.
 Two Capture, Compare, PWM modules
- Capture is 16-bit, max. resolution is 12.5 ns.
- Compare is 16-bit, max. resolution is 200 ns.
- PWM max resolution is 10-bit.
13

 Synchronous Serial Port (SSP) with SPI™ (Master mode) and I2C (Master/Slave).
 Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI) with 9-
bit address detection.
 Parallel Slave Port (PSP) – 8 bits wide with external RD, WR and CS Controls.
 Brown-out detection circuitry for Brown-out Reset (BOR).
3.6.5 Analog Features:
 10-bit, up to 8-channel Analog-to-Digital Converter (A/D)
 Brown-out Reset (BOR)
 Analog Comparator module with:
1. Two analog comparators.
2. Programmable on-chip voltage reference (VREF) module.
3. Programmable input multiplexing from device inputs and internal
voltage reference.
4. Comparator outputs are externally accessible.
3.6.6 CMOS Technology:
 Low-power, high-speed Flash/EEPROM technology.
 Fully static design.
 Wide operating voltage range (2.0V to 5.5V).
 Commercial and Industrial temperature ranges.
 Low-power consumption.
3.6.7 Memory Organization
There are three memory blocks in each of the PIC16F87XA devices. The
program memory and data memory have separate buses so that concurrent
access can occur and is detailed in this section. The EEPROM data memory block is
detailed in Section 3.0 “Data EEPROM and Flash Program Memory”. Additional
information on device memory may be found in the PIC micro Mid-Range MCU
Family Reference Manual (DS33023).
14

3.6.8 Program Memory Organization
The PIC16F87XA devices have a 13-bit program counter capable of addressing
an 8K word x 14 bit program memory space. The PIC16F876A/877A devices
have 8K words x 14 bits of Flash program memory, while PIC16F873A/874A
devices have 4K words x 14 bits. Accessing a location above the physically
implemented address will cause a wraparound.The Reset vector is at 0000h and the
interrupt vector is at 0004h.
3.7 TSOP1738
3.7.1 Description
The TSOP17 – series are miniaturized receivers for infrared remote control systems.
PIN diode and preamplifier are assembled on lead frame, the epoxy package is
designed as IR filter.
The demodulated output signal can directly be decoded by a microprocessor.
TSOP1738 is the standard IR remote control receiver series, supporting all major
transmission codes.
3.7.2 Features
 Photo detector and preamplifier in one package
 Internal filter for PCM frequency
 Improved shielding against electrical field disturbance
 TTL and CMOS compatibility
 Output active low
 Low power consumption
 High immunity against ambient light Fig.3.7(a) TSOP
1738
 Continuous data transmission possible (up to 2400 bps)
 Suitable burst length >= 10cycles/burst.
15

3.7.3 Block diagram of TSOP:
Fig.3.7(b) Block Diagram of TSOP
The circuit of the TSOP17 is designed in that way that unexpected output pulses due
to noise or disturbance signals are avoided. A band pass filter, an integrator stage and
an automatic gain control are used to suppress such disturbances. The distinguishing
mark between data signal and disturbance signal are carrier frequency, burst length
and duty cycle. The data signal should full fill the following condition:
 Carrier frequency should be close to center frequency of the band pass (e.g.
38kHz).
 Burst length should be 10 cycles/burst or longer.
 After each burst which is between 10 cycles and 70 cycles a gap time of at least
14 cycles is necessary.
 For each burst which is longer than 1.8ms a corresponding gap time is necessary
at some time in the data stream. This gap time should have at least same length as
the burst.
 Up to 1400 short bursts per second can be received continuously. Some examples
for suitable data format are: NEC Code, Toshiba Micom Format, Sharp Code,
RC5 Code, RC6 Code, R–2000 Code, Sony Format (SIRCS). When a disturbance
signal is applied to the TSOP17.It can still receive the data signal. However the
sensitivity is reduced to that level that no unexpected pulses will occur. Some
examples for such disturbance signals which are suppressed by the TSOP17 series
are:
16

– DC light (e.g. from tungsten bulb or sunlight).
– Continuous signal at 38 kHz or at any other frequency.
3.8 MAX232
The MAX232 is an integrated circuit that converts signals from an RS-232 serial port
to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a
dual driver/receiver and typically converts the RX, TX, CTS and RTS signals. The
drivers provide RS-232 voltage level outputs (approx. ± 7.5 V) from a single + 5 V
supply via on-chip charge pumps and external capacitors. This makes it useful for
implementing RS-232 in devices that otherwise do not need any voltages outside the
0 V to + 5 V range, as power supply design does not need to be made more
complicated just for driving the RS-232 in this case. The receivers reduce RS-232
inputs (which may be as high as ± 25 V), to standard 5 V TTL levels. These receivers
have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V.
3.8.1 Voltage levels
It is helpful to understand what occurs to the voltage levels. When a MAX232 IC
receives a TTL level to convert, it changes a TTL Logic 0 to between +3 and +15V,
and changes TTL Logic 1 to between -3 to -15V, and vice versa for converting from
RS232 to TTL.
This can be confusing when you realize that the RS232 Data Transmission voltages at
a certain logic state are opposite from the RS232 Control Line voltages at the same
logic state. To clarify the matter, see the table below. For more information see RS-
232 Voltage Levels.
Table 3.8(a) MAX232 Voltage Levels
17

Fig.3.8(a) MAX232 PIN Diagram
Table 3.8(a) MAX232 PIN Description
18

3.8.2 Application:
The MAX232 has two receivers (converts from RS-232 to TTL voltage levels) and
two drivers (converts from TTL logic to RS-232 voltage levels). This means only two
of the RS-232 signals can be converted in each direction.
Typically a pair of a driver/receiver of the MAX232 is used for
 TX and RX
And the second one for
 CTS and RTS.
There are not enough drivers/receivers in the MAX232 to also connect the DTR,
DSR, and DCD signals. Usually these signals can be omitted when e.g.
communicating with a PC's serial interface. If the DTE really requires these signals
either a second MAX232 is needed, or some other IC from the MAX232 family can
be used.
3.9 DB9 CONNECTOR
The DB9 (originally DE-9) connector is an analog 9-pin plug of the D-Sub miniature
connector family (D-Sub or Sub-D). The DB9 connector is mainly used for serial
connections, allowing for the asynchronous transmission of data as provided for by
standard RS-232 (RS-232C).
Fig 3.9(a) DB9 Connector
19

3.9.1 Pin description:
Table 3.9(a) DB9 PIN Description
This is a common connector used in many computer, audio/video, and data
applications. The official name is D-sub miniature, but many people call it “D-sub” or
just “DB”. The connector gets its name from its trapezoidal shape that resembles the
letter “D”. Most DB connectors have two rows of pins. Common types of D-sub
connectors are DB9 and DB25, used on PCs for serial and parallel ports.
One special type of D-sub connectors is the High-Density DB style, which looks just
like a regular DB connector, only with pins that are slightly smaller and placed closer
together. This is typically referred to as an “HD” connector. HD connectors often
have three rows of pins instead of two. The most common HD connector is the HD15,
which is found on PC video cards and monitors. DB- and HD-connectors use
thumbscrews to secure the connector in place.
Another type of D-sub is the MD, or Micro DB connector. This connector is slimmer
than a standard D-sub, with pins even smaller than the ones used on HD connectors.
The MD is also commonly called a “half-pitch” DB connector. These are often used
in SCSI applications, and the most popular types are the MD50 and MD68
connections.
20

D-sub connectors are usually described by the total number of pins that they can hold.
In some cases, a DB25 connector may only have 4 or 5 pins loaded into it; however, it
is still called a “DB25” connector and not a “DB4” or “DB5”. Another example is the
HD15 connector used by monitors—most monitor cables only are loaded with 14
pins, but it is still called an HD15 connector.
3.9.2 Interfacing Between Microcontroller and DB9 Connector
Fig.3.9(b) Interfacing Between Microcontroller and DB9 Connector
3.10 LED
A light-emitting diode (LED) is a semiconductor light source. LEDs are used as
indicator lamps in many devices, and are increasingly used for lighting. When a light-
emitting diode is forward biased (switched on), electrons are able to recombine with
holes within the device, releasing energy in the form of photons.
This effect is called electroluminescence and the color of the light (corresponding to
the energy of the photon) is determined by the energy gap of the semiconductor. An
LED is often small in area (less than 1 mm2
), and integrated optical components may
be used to shape its radiation pattern.
21

Light-emitting diodes are used in applications as diverse as replacements for aviation
lighting, automotive lighting as well as in traffic signals. The compact size, the
possibility of narrow bandwidth, switching speed, and extreme reliability of LEDs has
allowed new text and video displays and sensors to be developed, while their high
switching rates are also useful in advanced communications technology.
3.10.1 Electronic Symbol:
Fig 3.10(a) Symbol of LED
3.10.2 Colors and materials of LED’S
Conventional LEDs are made from a variety of inorganic semiconductor materials,
the following table shows the available colors with wavelength range, voltage drop
and material.
3.10.3 White LED’S
Light Emitting Diodes (LED) have recently become available that are both white and
bright, so bright that they seriously compete with incandescent lamps in lighting
applications. They are still pretty expensive as compared to a GOW lamp but draw
much less current and project a fairly well focused beam.When run within their
ratings, they are more reliable than lamps as well. Red LEDs are now being used in
automotive and truck tail lights and in red traffic signal lights. You will be able to
detect them because they look like an array of point sources and they go on and off
instantly as compared to conventional incandescent lamps. LEDs are monochromatic
(one color) devices. The color is determined by the band gap of the semiconductor
used to make them. Red, green, yellow and blue LEDs are fairly common. White light
contains all colors and cannot be directly created by a single LED. The most common
form of "white" LED really isn't white. It is a Gallium Nitride blue LED coated with a
phosphor that, when excited by the blue LED light, emits a broad range spectrum that
in addition to the blue emission, makes a fairly white light.
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There is a claim that these white LED's have a limited life. After 1000 hours or so of
operation, they tend to yellow and dim to some extent. Running the LEDs at more
than their rated current will certainly accelerate this process.
There are two primary ways of producing high intensity white-light using LEDs. One
is to use individual LEDs that emit three primary colors—red, green, and blue—and
then mix all the colors to form white light. The other is to use a phosphor material to
convert monochromatic light from a blue or UV LED to broad-spectrum white light,
much in the same way a fluorescent light bulb works. Due to metamerism, it is
possible to have quite different spectra that appear white.
Fig 3.10(b) White LED spectrum
3.11 IN4007 DIODE
Diodes are used to convert AC into DC these are used as half wave rectifier or full
wave rectifier. Three points must he kept in mind while using any type of diode.
 Maximum forward current capacity
 Maximum reverse voltage capacity
 Maximum forward voltage capacity
23

Fig.3.11(a) IN4007 Diodes
The number and voltage capacity of some of the important diodes available in the
market are as follows:
 Diodes of number IN4001, IN4002, IN4003, IN4004, IN4005, IN4006 and
IN4007 have maximum reverse bias voltage capacity of 50V and maximum
forward current capacity of 1 Amp.
 Diode of same capacities can be used in place of one another. Besides this diode
of more capacity can be used in place of diode of low capacity but diode of low
capacity cannot be used in place of diode of high capacity. For example, in place
of IN4002; IN4001 or IN4007 can be used but IN4001 or IN4002 cannot be used
in place of IN4007.The diode BY125made by company BEL is equivalent of
diode from IN4001 to IN4003. BY 126 is equivalent to diodes IN4004 to 4006
and BY 127 is equivalent to diode IN4007.
Fig.3.11(c) PN Junction Diode
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3.11.1 PN Junction Operation
Now that you are familiar with P- and N-type materials, how these materials are
joined together to form a diode, and the function of the diode, let us continue our
discussion with the operation of the PN junction. But before we can understand how
the PN junction works, we must first consider current flow in the materials that make
up the junction and what happens initially within the junction when these two
materials are joined together.
3.12 RESISTOR
A resistor is a two-terminal electronic component designed to oppose an electric
current by producing a voltage drop between its terminals in proportion to the current,
that is, in accordance with Ohm's law:
V = IR
Resistors are used as part of electrical networks and electronic circuits. They are
extremely commonplace in most electronic equipment. Practical resistors can be made
of various compounds and films, as well as resistance wire (wire made of a high-
resistivity alloy, such as nickel/chrome).
The primary characteristics of resistors are their resistance and the power they can
dissipate. Other characteristics include temperature coefficient, noise, and inductance.
Less well-known is critical resistance, the value below which power dissipation limits
the maximum permitted current flow, and above which the limit is applied voltage.
Critical resistance depends upon the materials constituting the resistor as well as its
physical dimensions; it's determined by design.
Resistors can be integrated into hybrid and printed circuits, as well as integrated
circuits. Size, and position of leads (or terminals) are relevant to equipment designers;
resistors must be physically large enough not to overheat when dissipating their
power.
A resistor is a two-terminal passive electronic component which implements electrical
resistance as a circuit element. When a voltage V is applied across the terminals of a
resistor, a current I will flow through the resistor in direct proportion to that voltage.
25

The reciprocal of the constant of proportionality is known as the resistance R, since,
with a given voltage V, a larger value of R further "resists" the flow of current I as
given by Ohm's law:
Resistors are common elements of electrical networks and electronic circuits and are
ubiquitous in most electronic equipment. Practical resistors can be made of various
compounds and films, as well as resistance wire (wire made of a high-resistivity alloy,
such as nickel-chrome). Resistors are also implemented within integrated circuits,
particularly analog devices, and can also be integrated into hybrid and printed circuits.
The electrical functionality of a resistor is specified by its resistance: common
commercial resistors are manufactured over a range of more than 9 orders of
magnitude. When specifying that resistance in an electronic design, the required
precision of the resistance may require attention to the manufacturing tolerance of the
chosen resistor, according to its specific application. The temperature coefficient of
the resistance may also be of concern in some precision applications. Practical
resistors are also specified as having a maximum power rating which must exceed the
anticipated power dissipation of that resistor in a particular circuit: this is mainly of
concern in power electronics applications. Resistors with higher power ratings are
physically larger and may require heat sinking. In a high voltage circuit, attention
must sometimes be paid to the rated maximum working voltage of the resistor.
The series inductance of a practical resistor causes its behavior to depart from ohms
law; this specification can be important in some high-frequency applications for
smaller values of resistance. In a low-noise amplifier or pre-amp the noise
characteristics of a resistor may be an issue. The unwanted inductance, excess noise,
and temperature coefficient are mainly dependent on the technology used in
manufacturing the resistor. They are not normally specified individually for a
particular family of resistors manufactured using a particular technology. A family of
discrete resistors is also characterized according to its form factor, that is, the size of
the device and position of its leads (or terminals) which is relevant in the practical
manufacturing of circuits using them.
26

Fig.3.12(a) Resistors
3.12.1 Units
The ohm (symbol: Ω) is the SI unit of electrical resistance, named after Georg Simon
Ohm. An ohm is equivalent to a volt per ampere. Since resistors are specified and
manufactured over a very large range of values, the derived units of milliohm (1 mΩ
= 10−3
Ω), kilohm (1 kΩ = 103
Ω), and megohm (1 MΩ = 106
Ω) are also in common
usage.
The reciprocal of resistance R is called conductance G = 1/R and is measured in
Siemens (SI unit), sometimes referred to as a mho. Thus a Siemens is the reciprocal of
an ohm: S = Ω − 1
. Although the concept of conductance is often used in circuit
analysis, practical resistors are always specified in terms of their resistance (ohms)
rather than conductance.
3.13 CAPACITOR
A capacitor or condenser is a passive electronic component consisting of a pair of
conductors separated by a dielectric. When a voltage potential difference exists
between the conductors, an electric field is present in the dielectric. This field stores
energy and produces a mechanical force between the plates. The effect is greatest
between wide, flat, parallel, narrowly separated conductors.
An ideal capacitor is characterized by a single constant value, capacitance, which is
measured in farads. This is the ratio of the electric charge on each conductor to the
potential difference between them.
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The conductors and leads introduce an equivalent series resistance and the dielectric
has an electric field strength limit resulting in a breakdown voltage.
Fig. 3.13(a) Capacitors
A capacitor (formerly known as condenser) is a device for storing electric charge. The
forms of practical capacitors vary widely, but all contain at least two conductors
separated by a non-conductor. Capacitors used as parts of electrical systems, for
example, consist of metal foils separated by a layer of insulating film.
Capacitors are widely used in electronic circuits for blocking direct current while
allowing alternating current to pass, in filter networks, for smoothing the output of
power supplies, in the resonant circuits that tune radios to particular frequencies and
for many other purposes.
A capacitor is a passive electronic component consisting of a pair of conductors
separated by a dielectric (insulator). When there is a potential difference (voltage)
across the conductors, a static electric field develops in the dielectric that stores
energy and produces a mechanical force between the conductors. An ideal capacitor is
characterized by a single constant value, capacitance, measured in farads. This is the
ratio of the electric charge on each conductor to the potential difference between
them.The capacitance is greatest when there is a narrow separation between large
areas of conductor.
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In practice the dielectric between the plates passes a small amount of leakage current
and also has an electric field strength limit, resulting in a breakdown voltage, while
the conductors and leads introduce an undesired inductance and resistance.
3.13.1 Theory of operation
Fi.3.13(b) Capacitor - Theory of Operation
Charge separation in a parallel-plate capacitor causes an internal electric field. A
dielectric (orange) reduces the field and increases the capacitance.
Fig.3.13(c) A simple demonstration of a parallel-plate capacitor
A capacitor consists of two conductors separated by a non-conductive region. The
non-conductive region is called the dielectric or sometimes the dielectric medium. In
simpler terms, the dielectric is just an electrical insulator. Examples of dielectric
mediums are glass, air, paper, vacuum, and even a semiconductor depletion region
chemically identical to the conductors.
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A capacitor is assumed to be self-contained and isolated, with no net electric charge
and no influence from any external electric field. The conductors thus hold equal and
opposite charges on their facing surfaces, and the dielectric develops an electric field.
In SI units, a capacitance of one farad means that one coulomb of charge on each
conductor causes a voltage of one volt across the device.
The capacitor is a reasonably general model for electric fields within electric circuits.
An ideal capacitor is wholly characterized by a constant capacitance C, defined as the
ratio of charge ±Q on each conductor to the voltage V between them:
Sometimes charge build-up affects the capacitor mechanically, causing its capacitance
to vary. In this case, capacitance is defined in terms of incremental changes:
3.13.2 Energy storage
Work must be done by an external influence to "move" charge between the
conductors in a capacitor. When the external influence is removed the charge
separation persists in the electric field and energy is stored to be released when the
charge is allowed to return to its equilibrium position. The work done in establishing
the electric field, and hence the amount of energy stored, is given by:
3.13.3 Current-voltage relation
The current i(t) through any component in an electric circuit is defined as the rate of
flow of a charge q(t) passing through it, but actual charges, electrons, cannot pass
through the dielectric layer of a capacitor, rather an electron accumulates on the
negative plate for each one that leaves the positive plate, resulting in an electron
depletion and consequent positive charge on one electrode that is equal and opposite
to the accumulated negative charge on the other.
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As with any antiderivative, a constant of integration is added to represent the initial
voltage v (t0). This is the integral form of the capacitor equation,
.
Taking the derivative of this, and multiplying by C, yields the derivative form,
.
The dual of the capacitor is the inductor, which stores energy in the magnetic field
rather than the electric field. Its current-voltage relation is obtained by exchanging
current and voltage in the capacitor equations and replacing C with the inductance L.’
3.13.4 DC circuits
Fig.3.13(d) RC circuit
A simple resistor-capacitor circuit demonstrates charging of a capacitor.
A series circuit containing only a resistor, a capacitor, a switch and a constant DC
source of voltage V0 is known as a charging circuit. If the capacitor is initially
uncharged while the switch is open, and the switch is closed at t = 0, it follows from
Kirchhoff's voltage law that
Taking the derivative and multiplying by C, gives a first-order differential equation,
At t = 0, the voltage across the capacitor is zero and the voltage across the resistor is
V0. The initial current is then i (0) =V0 /R.
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With this assumption, the differential equation yields
where τ0 = RC is the time constant of the system.
As the capacitor reaches equilibrium with the source voltage, the voltage across the
resistor and the current through the entire circuit decay exponentially. The case of
discharging a charged capacitor likewise demonstrates exponential decay, but with the
initial capacitor voltage replacing V0 and the final voltage being zero.
3.13.5 AC circuits
Impedance, the vector sum of reactance and resistance, describes the phase difference
and the ratio of amplitudes between sinusoidally varying voltage and sinusoidally
varying current at a given frequency. Fourier analysis allows any signal to be
constructed from a spectrum of frequencies, whence the circuit's reaction to the
various frequencies may be found. The reactance and impedance of a capacitor are
respectively
where j is the imaginary unit and ω is the angular velocity of the sinusoidal signal.
The - j phase indicates that the AC voltage V = Z I lags the AC current by 90°: the
positive current phase corresponds to increasing voltage as the capacitor charges; zero
current corresponds to instantaneous constant voltage, etc.
Note that impedance decreases with increasing capacitance and increasing frequency.
This implies that a higher-frequency signal or a larger capacitor results in a lower
voltage amplitude per current amplitude—an AC "short circuit" or AC coupling.
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Conversely, for very low frequencies, the reactance will be high, so that a capacitor is
nearly an open circuit in AC analysis—those frequencies have been "filtered
out".Capacitors are different from resistors and inductors in that the impedance is
inversely proportional to the defining characteristic, i.e. capacitance.
3.13.6 Parallel plate model
Fig.3.13(e) Parallel Plate Model
Dielectric is placed between two conducting plates, each of area A and with a
separation of d.
The simplest capacitor consists of two parallel conductive plates separated by a
dielectric with permittivity ε (such as air). The model may also be used to make
qualitative predictions for other device geometries. The plates are considered to
extend uniformly over an area A and a charge density ±ρ = ±Q/A exists on their
surface. Assuming that the width of the plates is much greater than their separation d,
the electric field near the centre of the device will be uniform with the magnitude E =
ρ/ε. The voltage is defined as the line integral of the electric field between the plates
Solving this for C = Q/V reveals that capacitance increases with area and decreases
with separation
.
The capacitance is therefore greatest in devices made from materials with a high
permittivity.
33

3.13.7 Networks
A. For capacitors in parallel
Fig.3.13(f) Several capacitors in parallel.
Capacitors in a parallel configuration each have the same applied voltage. Their
capacitances add up. Charge is apportioned among them by size. Using the schematic
diagram to visualize parallel plates, it is apparent that each capacitor contributes to the
total surface area.
B. For capacitors in series
Fig.3.13(g) Several capacitors in series.
Connected in series, the schematic diagram reveals that the separation distance, not
the plate area, adds up. The capacitors each store instantaneous charge build-up equal
to that of every other capacitor in the series. The total voltage difference from end to
end is apportioned to each capacitor according to the inverse of its capacitance. The
entire series acts as a capacitor smaller than any of its components.
Capacitors are combined in series to achieve a higher working voltage, for example
for smoothing a high voltage power supply. The voltage ratings, which are based on
plate separation, add up.
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4. SOFTWARE REQUIREMENTS
4.1 WHAT IS MPLAB IDE?
MPLAB IDE is a software program that runs on a PC to develop applications for
Microchip microcontrollers. It is called an Integrated Development Environment, or
IDE, because it provides a single integrated environment to develop code for
embedded microcontrollers.
4.2 DESCRIPTION OF EMBEDDED SYSTEM
An embedded system is typically a design making use of the power of a small
microcontroller, like the Microchip PIC micro MCU or PIC Digital Signal
Controller(DSCs). These microcontrollers combine a microprocessor unit (like the CPU
in a desktop PC) with some additional circuits called peripherals, plus some additional
circuits on the same chip to make a small control module requiring few other external
devices. This single device can then be embedded into other electronic and mechanical
devices for low-cost digital control.
4.3 COMPONENTS OF MICROCONTROLLER
The PIC micro MCU has program memory for the firmware, or coded instructions, to
run a program. It also has file register memory for storage of variables that the
program will need for computation or temporary storage. It also has a number of
peripheral device circuits on the same chip. Some peripheral devices are called I/O
ports. I/O ports are pins on the microcontroller that can be driven high or low to send
signals, blink lights, drive speakers just about anything that can be sent through a wire.
Often these pins are bidirectional and can also be configured as inputs allowing the
program to respond to an external switch, sensor or to communicate with some
external device.
35

Serial communication peripherals allow you to stream communications over a few
wires to another microcontroller, to a local network or to the internet. Peripherals on
the PIC micro MCU called timers accurately measure signal events and generate and
capture communications signals, produce precise waveforms, even automatically
reset the microcontroller if it gets hung or lost due to a power glitch or hardware
malfunction. Other peripherals detect if the external power is dipping below dangerous
levels so the microcontroller can store critical information and safely shut down before
power is completely lost.
The peripherals and the amount of memory an application needs to run a program
largely determines which PIC micro MCU to use. Other factors might include the
power consumed by the microcontroller and its form factor, i.e., the size and
characteristics of the physical package that must reside on the target design.
A development system for embedded controllers is a system of programs running on a
desktop PC to help write, edit, debug and program code ñ the intelligence of embedded
systems applications ñ into a microcontroller. MPLAB IDE runs on a PC and contains
all the components needed to design and deploy embedded systems applications. The
typical tasks for developing an embedded controller application are:
1. Create the high level design. From the features and performance desired, decide
which PIC micro MCU or PIC DSC device is best suited to the application, then design
the associated hardware circuitry. After determining which peripherals and pins
control the hardware, write the firmware ñ the software that will control the hardware
aspects of the embedded application. A language tool such as an assembler, which is
directly translatable into machine code, or a compiler that allows a more natural
language for creating programs, should be used to write and edit code. Assemblers and
compilers help make the code understandable, allowing function labels to identify
code routines with variables that have names associated with their use, and with
constructs that help organize the code in a maintainable structure.
36

Fig 4.3(a) PIC micro MCU Data Sheet Instructions
2. Compile, assemble and link the software using the assembler and/or compiler and
linker to convert your code into ones and zeroes machine code for the PIC micro
MCUs. This machine code will eventually become the firmware (the code
programmed into the microcontroller).
3.Test your code. Usually a complex program does not work exactly the way imagined,
and bugs need to be removed from the design to get proper results. The debugger
allows you to see the ones and zeroes execute, related to the source code you wrote,
with the symbols and function names from your program. Debugging allows you to
experiment with your code to see the value of variable sat various points in the program,
and to do what if check, changing variable values and stepping through routines.
4. Burn the code into a microcontroller and verify that it executes correctly in the
finished application. Of course, each of these steps can be quite complex.
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4.4 THE DEVELOPMENT CYCLE
The process for writing an application is often described as a development cycle, since
it is rare that all the steps from design to implementation can be done flawlessly the first
time. More often code is written, tested and then modified in order to produce an
application that performs correctly. The Integrated Development Environment allows
the embedded systems design engineer to progress through this cycle without the
distraction of switching among an array of tools. By using MPLAB IDE, all the
functions are integrated, allowing the engineer to concentrate on completing the
application without the interruption of separate tools and different modes of operation.
MPLAB IDE is a wrapper that coordinates all the tools from a single graphical user
interface, usually automatically. For instance, once code is written, it can be converted
to executable instructions and downloaded into a microcontroller to see how it works.
In this process multiple tools are needed: an editor to write the code, a project manager
to organize files and settings, a compiler or assembler to convert the source code to
machine code and some sort of hardware or software that either connects to a target
microcontroller or simulates the operation of a microcontroller.
4.5 PROJECT MANAGER
The project manager organizes the files to be edited and other associated files so they
can be sent to the language tools for assembly or compilation, and ultimately to a linker.
The linker has the task of placing the object code fragments from the assembler,
compiler and libraries into the proper memory areas of the embedded controller, and
ensure that the modules function with each other. This entire operation from assembly
and compilation through the link process is called a project build.
From the MPLAB IDE project manager, properties of the language tools can be
invoked differently for each file, if desired, and a build process integrates all of the
language tools operations. The source files are text files that are written conforming to
the rules of the assembler or compiler.
38

The assembler and compiler convert them into intermediate modules of machine code
and placeholders for references to functions and data storage. The linker resolves these
placeholders and combines all the modules into a file of executable machine code. The
linker also produces a debug file which allows MPLAB IDE to relate the executing
machine codes back to the source files. A text editor is used to write the code. It is not a
normal text editor, but an editor specifically designed for writing code for Microchip
MCUs. It recognizes the constructs in the text and uses color coding to identify various
elements, such as instruction mnemonics, C language constructs and comments. The
editor supports operations commonly used in writing source code, such as finding
matching braces in C, commenting and un-commenting out blocks of code, finding text
in multiple files and adding special bookmarks. After the code is written, the editor
works with the other tools to display code execution in the debugger. Breakpoints can
be set in the editor, and the values of variables can be inspected by hovering the mouse
pointer over the variable name. Names of variables can be dragged from source text
windows and then dropped into a Watch window.
4.6 DEVICE PROGRAMMING
After the application has been debugged and is running in the development
environment, it needs to be tested on its own. A device can be programmed with the in-
circuit debugger or a device programmer. MPLAB IDE can be set to the programmer
function, and the part can be burned. The target application can now be observed in its
nearly final state. Engineering prototype programmers allow quick prototypes to be
made and evaluated. Some applications can be programmed after the device is
soldered on the target PC board. Using In-Circuit Serial Programming(ICSP)
programming capability, the firmware can be programmed into the application at the
time of manufacture, allowing updated revisions to be programmed into an embedded
application later in its life cycle. Devices that support in-circuit debugging can even be
plugged back into the MPLAB ICD 2 after manufacturing for quality tests and
development of next generation firmware.
39

4.7 COMPONENTS OF MPLAB IDE
The MPLAB IDE has both built-in components and plug-in modules to configure the
system for a variety of software and hardware tools.
4.7.1 MPLAB IDE Built-In Components
The built-in components consist of:
Project Manager
The project manager provides integration and communication between the IDE and the
language tools.
Editor
The editor is a full-featured programmer's text editor that also serves as a window into
the debugger.
Assembler/Linker and Language Tools
The assembler can be used stand-alone to assemble a single file, or can be used with the
linker to build a project from separate source files, libraries and recompiled objects. The
linker is responsible for positioning the compiled code into memory areas of the target
microcontroller.
Debugger
The Microchip debugger allows breakpoints, single stepping, watch windows and all
the features of a modern debugger for the MPLAB IDE. It works in conjunction with the
editor to reference information from the target being debugged back to the source code.
Execution Engines
There are software simulators in MPLAB IDE for all PIC micro MCU and dsPIC DSC
devices. These simulators use the PC to simulate the instructions and some peripheral
functions of the PIC micro MCU and PIC DSC devices.
40

Optional in-circuit emulators and in-circuit debuggers are also available to test code as
it runs in the applications hardware.
4.7.2 Additional Optional Components for MPLAB IDE
Optional components can be purchased and added to the MPLAB IDE:
Compiler Language Tools
MPLAB C18 and MPLAB C30 C compilers from Microchip provide fully integrated,
optimized code. Along with compilers from HI-TECH, IAR, micro Engineering Labs,
CCS and Byte Craft, they are invoked by the MPLAB IDE project manager to compile
code that is automatically loaded into the target debugger for instant testing and
verification.
Programmers
PICSTART Plus, PIC kit 1 and 2, PRO MATE II, MPLAB PM3 as well as MPLAB
ICD 2 can program code into target devices. MPLAB IDE offers full control over
programming both code and data, as well as the Configuration bits to set the various
operating modes of the target microcontrollers or digital signal controllers.
In-Circuit Emulators
MPLAB ICE 2000 and MPLAB ICE 4000 are full-featured emulators for the PIC
micro MCU and dsPIC DSC devices. They connect to the PC via I/O ports and allow
full control over the operation of microcontroller in the target applications.
In-Circuit Debugger
MPLAB ICD 2 provides an economic alternative to an emulator. By using some of the
on-chip resources, MPLAB ICD 2 can download code into a target microcontroller
inserted in the application, set breakpoints, single step and monitor registers and
variables.
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4.8 MPLAB IDE FEATURES AND INSTALLATION
MPLAB IDE is a Windows Operating System (OS) based Integrated Development
Environment for the PIC micro MCU families and the dsPIC Digital Signal
Controllers. The MPLAB IDE provides the ability to:
 Create and edit source code using the built-in editor.
 Assemble, compile and link source code.
 Debug the executable logic by watching program flow with the built-in simulator or
in real time with in-circuit emulators or in-circuit debuggers.
 Make timing measurements with the simulator or emulator.
 View variables in Watch windows.
4.8.1 Running MPLAB IDE
To start MPLAB IDE, double click on the icon installed on the desktop after installation
or select Start>Programs>Microchip>MPLAB IDE vx.xx>MPLAB IDE. A screen will
display the MPLAB IDE logo followed by the MPLAB IDE desktop.
Fig. 4.8(a) MPLAB IDE Desktop
4.8.2 SELECTING THE DEVICE
To show menu selections in this document, the menu item from the top row in
MPLAB IDE will be shown after the menu name like this MenuName>MenuItem.
42

To choose the Select Device entry in the Configure menu, it would be written as
Configure>Select Device. Choose Configure>Select Device. In the Device dialog,
select the PIC18F8722 from the list if itís not already selected.
Fig.4.8(b) Selecting Device Dialog
The lights indicate which MPLAB IDE components support this device.
 A green light indicates full support.
 A yellow light indicates preliminary support for an upcoming part by the particular
MPLAB IDE tool component. Components with a yellow light instead of a green
light are often intended for early adopters of new parts who need quick support and
understand that some operations or functions may not be available.
 A red light indicates no support for this device. Support may be forthcoming or
inappropriate for the tool, e.g., PIC DSC devices cannot be supported on MPLAB
ICE 2000.
4.8.3 CREATING THE PROJECT
The next step is to create a project using the Project Wizard. A project is the way the
files are organized to be compiled and assembled.
We will use a single assembly file for this project and a linker script. Choose
Project>Project Wizard. From the Welcome dialog, click on Next> to advance.
43

The next dialog (Step One) allows you to select the device, which we have already
done. Make sure that it says PIC18F8722. If it does not, select the PIC18F8722 from the
drop down menu. Click Next>.
Fig.5.9(c) Project Wizard Select Device
4.8.4 SETTING UP LANGUAGE TOOLS
Step Two of the Project Wizard sets up the language tools that are used with this
project. Select Microchip MPASM Toolsuite in the Active Toolsuite list box. Then
MPASM and MPLINK should be visible in the Toolsuite Contents box. Click on each
one to see its location. If MPLAB IDE was installed into the default directory, the
MPASM assembler executable will be:
C:Program FilesMicrochipMPASM Suitempasmwin.exe
the MPLINK linker executable will be:
C:Program FilesMicrochipMPASM Suitemplink.exe
and the MPLIB librarian executable will be:
C:Program FilesMicrochipMPASM Suitemplib.exe
If these do not show up correctly, use the browse button to set them to the proper files in
the MPLAB IDE subfolders.
44

Fig.4.8(d) Project Wizard Select Language Tools
4.8.5 NAMING THE PROJECT
Step Three of the wizard allows you to name the project and put it into a folder. This
sample project will be called MyProject. Using the Browse button, place the project in
a folder named Projects32.
Fig.4.8(e) Project Wizard Name
4.8.6 ADDING FILES TO THE PROJECT
Step Four of the Project Wizard allows file selection for the project. A source file has
not yet been selected, so we will use an MPLAB IDE template file. The template files
are simple files that can be used to start a project.
45

They have the essential sections for any source file, and contain information that will
help you write and organize your code.There is one template file for each Microchip
PIC micro MCU and PIC DSC device. Choose the file named 8722tmpo.asm. If
MPLAB IDE is installed in the default location, the full path to the file will be:
C:ProgramFilesMicrochipMPASM SuiteTemplateObject8722tmpo.asm
Fig.4.8(f) Project Wizard Select Template File
Press Add>> to move the file name to the right panel, and click on the checkbox at the
start of the line with the file name to enable this file to be copied to our project directory.
Next, add the second file for our project, the linker script. There is a linker script for each
device.
Fig.4.8(g) Project Wizard Select Linker Script
46

These files define the memory configuration and register names for the various parts. Use
the file named 18F8722.lkr. The full path is:
C:Program FilesMicrochipMPASM SuiteLKR18F8722.lkr
Make sure that your dialog looks like the picture above, with both checkboxes checked,
then press Next> to finish the Project Wizard. The final screen of the Project Wizard is
a summary showing the selected device, the tool suite and the new project file name.
Fig.4.8(h) Project Wizard Summary
After pressing the Finish button, review the Project Window on the MPLAB IDE
desktop. If the Project Window is not open, select View>Project.
Fig.4.8(i) Project Window
47

4.8.7 BUILDING THE PROJECT
From the Project menu, we can assemble and link the current files. They donít have
any of our code in them yet, but this ensures that the project is set up correctly.
To build the project, select either:
 Project>Build All
 Right click on the project name in the project window and select Build All
 Click the Build All icon on the Project toolbar. Hover the mouse over icons to see
pop-up text of what they represent.
 The Output window shows the result of the build process. There should be no
errors on any step. The warnings listed in Figure will not interfere with
theoperation of the tutorial program. They are merely identifying a directive that
has been deprecated, i.e., is being discontinued in favor of another. To turn off
thedisplay of warnings, do the following:
 Select Project>Build Options>Project and click on the MPASM Assembler tab.
 Select Output from the Categories drop-down list.
 Select Errors onlyî from the Diagnostic level drop-down list.
 Click OK.
Fig.4.9(a) Output Window
48

4.8.8 CREATING CODE
Open the template file in the project by double clicking on its name in the Project
Window, or by selecting it with the cursor and using the right mouse button to bring up
the context menu:
Fig.4.9(b) Project Context Menu
4.9 EMBEDDED C
Use of embedded processors in passenger cars, mobile phones, medical equipment,
aerospace systems and defense systems is widespread, and even everyday domestic
appliances such as dish washers, televisions, washing machines and video recorders
now include at least one such device.
Because most embedded projects have severe cost constraints, they tend to use low-
cost processors like the 8051 family of devices considered in this book. These popular
chips have very limited resources available most such devices have around 256 bytes
(not megabytes) of RAM, and the available processor power is around 1000 times less
than that of a desktop processor. As a result, developing embedded software presents
significant new challenges, even for experienced desktop programmers.
49

5. SCHEMATIC DIAGRAM
Fig.5 Schematic Diagram
5.1 DESCRIPTION
5.1.1 POWER SUPPLY
The circuit uses standard power supply comprising of a step-down transformer from
230Vto 12V and 4 diodes forming a Bridge Rectifier that delivers pulsating dc which
is then filtered by an electrolytic capacitor of about 470µF to 1000µF. The filtered dc
being unregulated, IC LM7805 is used to get 5V DC constant at its pin no 3
irrespective of input DC varying from 9V to 14V. The input dc shall be varying in the
event of input ac at 230volts section varies in the ratio of V1/V2=N1/N2.
The regulated 5V DC is further filtered by a small electrolytic capacitor of 10µF for
any noise so generated by the circuit. One LED is connected of this 5V point in series
with a resistor of 330Ω to the ground i.e., negative voltage to indicate 5V power
supply availability. The 12V point is used for other applications as on when required.
50

5.1.2 MAX232
The MAX232 used in the project is an integrated circuit that converts signals from an
RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits
like microcontroller. The MAX232 is a dual driver/receiver and typically converts the
RX, TX, CTS and RTS signals
5.1.3 BRIEF EXPLANATION OF TSOP 1738
The TSOP 1738 is a member of IR remote control receiver series. This IR sensor
module consists of a PIN diode and a pre amplifier which are embedded into a single
package. The output of TSOP is active low and it gives +5V in off state. When IR
waves, from a source, with a centre frequency of 38 kHz incident on it, its output goes
low.
TSOP module has an inbuilt control circuit for amplifying the coded pulses from the
IR transmitter. A signal is generated when PIN photodiode receives the signals. This
input signal is received by an automatic gain control (AGC). For a range of inputs, the
output is fed back to AGC in order to adjust the gain to a suitable level. The signal
from AGC is passed to a band pass filter to filter undesired frequencies. After this, the
signal goes to a demodulator and this demodulated output drives an npn transistor.
The collector output of the transistor is obtained at pin 3 of TSOP module.
5.2 OPERATION
5.2.1 Connections
The output of power supply which is 5v is connected to the 11&32 pin of pic
microcontroller & Gnd is connected to 12&31 pin of pic microcontroller. Pins 25, 26
of pic microcontroller are connected to pins 11 & 12 of Max232.
Pins 13 and 14 of Max232 are given to pins 2 and 3 of DB9 connector. Pin 33 of pic
microcontroller are given to 3rd
pin of TSOP1738.
51

5.2.2 Working
The project uses an IR receiver such as TSOP1738 that responds to only specific
frequency of 38 kHz, in order to avoid receiving false signal from normal
environmental infrared sources. The output of this receiver is interfaced to interrupt 1
i.e., pin 33 of the pic microcontroller. A standard TV remote that delivers infrared
codes at 38 kHz is thus received by the TSOP receiver feeding a 14 bit data so emitted
from the remote to the controller through receiver. The program is so returned that it
recognizes the 14 bit data relating to a particular number being pressed at the
remote.Here the channel ON & OFF buttons and volume low to volume high buttons
of the TV remote buttons are used for sending specific 14 bit data to pin – 33 of PIC
MC. Software used at the PC receives these commands the serial port being connected
to the MC through MAX232, RS232 interface. Thus the TV remote works like a
mouse from a distance.
52

6. LAYOUT DIAGRAM
6.1 LAYOUT DIAGRAM
Fig.6.1 Layout Diagram
53

7. MICROCONTROLLER PROGRAMMING
7.1 CODING
54

8. HARDWARE TESTING
8.1 CONTINUITY TEST
In electronics, a continuity test is the checking of an electric circuit to see if current
flows (that it is in fact a complete circuit). A continuity test is performed by placing a
small voltage (wired in series with an LED or noise-producing component such as a
piezoelectric speaker) across the chosen path. If electron flow is inhibited by broken
conductors, damaged components, or excessive resistance, the circuit is "open".
Devices that can be used to perform continuity tests include multi meters which
measure current and specialized continuity testers which are cheaper, more basic
devices, generally with a simple light bulb that lights up when current flows.
An important application is the continuity test of a bundle of wires so as to find the
two ends belonging to a particular one of these wires; there will be a negligible
resistance between the "right" ends, and only between the "right" ends.
This test is the performed just after the hardware soldering and configuration has been
completed. This test aims at finding any electrical open paths in the circuit after the
soldering. Many a times, the electrical continuity in the circuit is lost due to improper
soldering, wrong and rough handling of the PCB, improper usage of the soldering
iron, component failures and presence of bugs in the circuit diagram. We use a multi
meter to perform this test. We keep the multi meter in buzzer mode and connect the
ground terminal of the multi meter to the ground. We connect both the terminals
across the path that needs to be checked. If there is continuation then you will hear the
beep sound.
58

8.2 POWER ON TEST
This test is performed to check whether the voltage at different terminals is according
to the requirement or not. We take a multi meter and put it in voltage mode.
Remember that this test is performed without microcontroller. Firstly, we check the
output of the transformer, whether we get the required 12 V AC voltage.
Then we apply this voltage to the power supply circuit. Note that we do this test
without microcontroller because if there is any excessive voltage, this may lead to
damaging the controller.
We check for the input to the voltage regulator i.e., are we getting an input of 12v and
an output of 5v. This 5v output is given to the microcontrollers’ 40th
pin. Hence we
check for the voltage level at 40th
pin. Similarly, we check for the other terminals for
the required voltage. In this way we can assure that the voltage at all the terminals is
as per the requirement.
59

9. RESULT AND CONCLUSION
9.1 RESULT
TV remote works like a mouse i.e. by pressing its button following operations are
performed :
 2 = up arrow
 5 = down arrow
 4 = left arrow
 6 = right arrow
 1 = left click
 3 = right click
 Volume+ = to increase cursor speed
 Volume- = to decrease cursor speed
9.2 CONCLUSION
Mouse Driver is used on the PC that recognizes data received from the
microcontroller through the COM port and performs the required operation.
Designated numbers on the TV remote are used to perform up - down, right - left
cursor movement. Features like left click and right click of the mouse can also be
performed with the TV remote. Further this project can be enhanced using Bluetooth/
RF technology to overcome the traditional line of sight communication drawbacks of
the infrared type.
60

10. ADVANTAGES AND FUTURE SCOPE
10.1 ADVANTAGES
 Physically Being in Front of Computer.
 Reduced Productivity Cost.
 BT Connectivity.
 Not Required Mouse Pad
 Absence of BT Dongle
10.2 FUTURE SCOPE
 Elimination of Specific Remote
 Contolling Various Applications Viz
o For entertainment purpose,
o Browsers,
o Players like i-Tunes, etc.
61

REFERENCES
DATA SHEETS
 PIC16F877A
 7805 Regulator
 IN4007 Diode (Bridge Rectifier)
 LEDs
 Philips TV Remote
 RS232 DB9 Connector
 TSOP 1738
WEBSITES
 www.atmel.com
 www.beyondlogic.org
 www.wikipedia.org
 www.howstuffworks.com
 www.alldatasheets.com
62

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