4 channel rf remote control device
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CONTENTS PAGE NO.s
Abstract I List of Figures IISymbols & Abbreviations III
Chapter 1. Introduction 1.1 Overview 1 1.2 Classification of digital Watermarking 71.3 Applications of Wavelet Transformations 81.4 Attacks 101.5 Image Performance Measures 14
Chapter 2. Discrete Wavelet Transform1.6 Functions of Discrete Wavelet Transforms 201.7 The Continuous Wavelet Transforms and Wavelet Series 211.8 Discrete Wavelet Transformations 221.9 DWT and Filter Banks 23 1.10 Wavelet Families 26
Chapter 3. Proposed Algorithm1.11 Watermark Embedding 281.12 Watermark Extraction 31
1.13 Program Code 32
Chapter 4. Results1.14 PSNR and NCC 46 1.15 Results for Attacks 49
Chapter 5. GUI
1.16 Embedding 531.17 Attacks 541.18 Extracting 55
Chapter 6. Conclusion 56Chapter 7. References 57
Abbreviations
Symbol Name
ACC Accumulator
B B register
PSW Program status word
SP Stack pointer
DPTR Data pointer 2 bytes
DPL Low byte
DPH High byte
P0 Port0
P1 Port1
P2 Port2
P3 Port3
IP Interrupt priority control
IE Interrupt enable control
TMOD Timer/counter mode control
TCON Timer/counter control
T2CON Timer/counter 2 control
T2MOD Timer/counter mode2 control
TH0 Timer/counter 0high byte
TL0 Timer/counter 0 low byte
TH1 Timer/counter 1 high byte
TL1 Timer/counter 1 low byte
TH2 Timer/counter 2 high byte
TL2 Timer/counter 2 low byte
SCON Serial control
SBUF Serial data buffer
MAX MAXIM (IC manufacturer )
TTL Transistor to Transistor Logic
ATM Automatic Teller Machine
RS 232 Recommended Standard
AC Alternating Current
DC Direct Current
LCD Liquid Crystal Display
PC Personal Computer
RPS Regulated Power Supply
RMS Root Mean Square
EEPROM Electrically Erasable Programmable ROM
ROM Read Only Memory
RAM Random Access Memory
BIOS Basic Input Output System
SRAM Static RAM
EPROM Erasable Programmable ROM
DRAM Dynamic Random Access Memory
ISR Interrupt Service Routine
ICCIntegrated Circuit Chip
CAD Card Acceptance Device
IFD Interface Device
IDE Integrated Development Environment
ABSTRACT
Electricity plays an important role in our everyday life. A lot of emphasis is placed on power save
as the demand is high and the production is low for it.
We use electricity at our homes and offices for several purposes including lighting, fans, and
electrical appliances so on. If we consider an example at our homes, for lighting, we turn the
switches on at dusk at several places. Some of the lights are intended to be switched off after
some time, for instance veranda. But due to laziness, we ignore it and switch them off only at late
night. We would like to design and develop a system so that the electrical switches work
remotely. A person doesn’t need to reach the physical location of the switch; they can accomplish
the task remotely. i.e. a light switch in veranda can be controlled from the bed room itself. The
application for this type of system is numerous and is limited to only one’s imagination. Upon
completion of this project we expect to get good knowledge on circuit design, development and
troubleshooting techniques. We intend to use micro controller and RF modules in the system so
that we gain knowledge on building a system around these core components. Finally, we will get
good embedded system knowledge as well.
The block diagram for 4 channel RF controlled remote operated device is shown in the above
figure, in system level. The 230V ac is rectified, the regulator provides a constant 5V DC which
is required for the Micro controller and control circuit.
Based on the input from the switch the micro controller transmits and receives the data through
RF modules and controls the switch operation accordingly
1.INTRODUCTION
1.1EMBEDDED SYSTEM:
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 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.
1.2Wireless communication:
Going wireless always starts with a basic RF communication, using serial encoders and decoders.
This process and methodology is easily understandable if you are new to this subject. Wireless
communication is the transfer of information between two or more points that are not connected
FIG :- EMBEDDED SYSTEM
by an electrical conductor. The most common wireless technologies use electromagnetic
wireless telecommunications, such as radio. With radio waves distances can be short, such as a
few meters for television remote control, or as far as thousands or even millions of kilometers for
deep-space radio communications. It encompasses various types of fixed, mobile, and portable
applications, including two-way radios, cellular telephones, personal digital assistants (PDAs),
and wireless networking. Other examples of applications of radio wireless
technology include GPS units, garage door openers, wireless computer
mice, keyboards and headsets, headphones, radio receivers, satellite, broadcast
television and cordless telephones.
Wireless operations permit services, such as long-range communications, that are impossible or
impractical to implement with the use of wires. The term is commonly used in the
telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and
receivers, remote controls etc.) which use some form of energy (e.g. radio waves, acoustic
energy, etc.) to transfer information without the use of wires. Information is transferred in this
manner over both short and long distances
One of the best-known examples of wireless technology is the mobile phone, also known as a
cellular phone, with more than 4.6 billion mobile cellular subscriptions worldwide as of the end
of 2010.These wireless phones use radio waves to enable their users to make phone calls from
many locations worldwide. They can be used within range of the mobile telephone site used to
house the equipment required to transmit and receive the radio signals from these instruments.
2. BLOCK DIAGRAM
1.3Block diagram description:
A general RF communication block diagram is shown above. Since most of the
encoders/decoders/microcontrollers are TTL compatible, most of the inputs by the user will be
given in TTL logic level. Thus, this TTL input is to be converted into serial data input using an
encoder or a microcontroller. This serial data can be directly read using the RF Transmitter,
which then performs ASK (in some cases FSK) modulation on it and transmit the data through
the antenna. In the receiver side, the RF Receiver receives the modulated signal through the
antenna, performs all kinds of processing, filtering, demodulation, etc and gives out a serial data.
This serial data is then converted to a TTL level logic data, which is the same data that the user
has input. So now, let’s look into the hardware that are required.
FIG: - RF COMMUNICATION BLOCK DIAGRAM
3. SCHEMATICS
1.4 Transmitter Section:
Make the following circuit on a breadboard. You are requested to implement the following circuit
at your own risk! We will NOT be responsible for any damages caused due to implementation of
the circuit, physically, mentally or financially.
Schematic explanation:-
Here, we have used four switches S1, S2, S3 and S4 to give 4-bit parallel data (D0-D3). Since the
switches are in active low state (i.e. low signal is sent when the switch is pressed), we need to add
external pull-up resistors as shown, so as to provide a high signal by default. A resistance as high
as 1Mohm is required in between OSC1 and OSC2 pins. The Transmitter Enable (TE, pin 14) pin
is an active low pin. Thus, it is permanently grounded, so as to enable the transistor always. The
output serial data DOUT is fed to the RF Transmitter Module directly.
The most important thing lies in the address pins (A0-A7, pin1-8). Suppose you have two
wireless devices (A and B) in your house, both have different remote controls (AA and BB) and
both implement the same type of RF module (say 433 MHz). AA is the remote control of A and
Fig: - Transmitter interfacing
BB is of B. Now, you obviously wouldn’t want AA to control B (which is the most probable case
since both the devices use same kind of RF module, having same frequency!). This is where
address pins come into play. There are 8 address pins, thus giving you an opportunity to have 8!
(8 factorial) different and independent ways to connect to a device, so that there is no
interference. The address pins must have the same address in both transmitter and receiver, or
else the data won’t be transferred.
1.5 Receiver section
Schematic explanation:-
The circuit of the receiver is also quite simple. Capacitor C1 is used between Vcc and GND for
noise filtering. Apart from that, all the address pins (A0-A7, pin 1-8) are grounded, just as in
transmitter. This is to ensure that the transmitted data is being received. Both the transmitter and
the receiver MUST have the same address pins configuration. Pin 17 (VT) is enabled whenever
the receiver receives any data. The serial data received by the RF Receiver module is directly fed
Fig: - Receiver interfacing
to pin 14 (DIN), which is then converted into 4-bit parallel data (D0-D3). A 33 ohm resistor is
connected in between OSC1 and OSC2.When the switch is connected to the battery and when
Hardware Components
The Hardware components used in this project are
1.6 Regulated Power Supply
1.7 Microcontroller
1.8 RF transmitter
1.9 RF receiver
1.20 Encoder
1.21 Decoder
1.22 Relays
1.23 Frequency matcher
1.24 LED
1.6 REGULATED POWER SUPPLY:-
The power supplies are designed to convert high voltage AC mains electricity to a
suitable low voltage supply for electronics circuits and other devices. A RPS (Regulated Power
Supply) is the Power Supply with Rectification, Filtering and Regulation being done on the AC
mains to get a Regulated power supply for Microcontroller and for the other devices being
interfaced to it.
A power supply can by broken down into a series of blocks, each of which performs a
particular function. A d.c power supply which maintains the output voltage constant irrespective
of a.c mains fluctuations or load variations is known as “Regulated D.C Power Supply”
For example a 5V regulated power supply system as shown below:
1.61 Transformer:
A transformer is an electrical device which is used to convert electrical power from
one Electrical circuit to another without change in frequency.
Transformers convert AC electricity from one voltage to another with little loss of power.
Transformers work only with AC and this is one of the reasons why mains electricity is AC. Step-up
transformers increase in output voltage, step-down transformers decrease in output voltage. Most power
supplies use a step-down transformer to reduce the dangerously high mains voltage to a safer low voltage.
The input coil is called the primary and the output coil is called the secondary. There is no electrical
connection between the two coils; instead they are linked by an alternating magnetic field created in the
soft-iron core of the transformer. The two lines in the middle of the circuit symbol represent the core.
Transformers waste very little power so the power out is (almost) equal to the power in. Note that as
voltage is stepped down current is stepped up. The ratio of the number of turns on each coil, called the
turn’s ratio, determines the ratio of the voltages. A step-down transformer has a large number of turns on its
primary (input) coil which is connected to the high voltage mains supply, and a small number of turns on
its secondary (output) coil to give a low output voltage.
Fig 1 Components of linear power
supply
Fig 2 : An Electrical Transformer
Turns ratio = Vp/ VS = Np/NS
Power Out= Power In
VS X IS=VP X IP
Vp = primary (input) voltage
Np = number of turns on primary coil
Ip = primary (input) current
1.62 RECTIFIER:
A circuit which is used to convert a.c to dc is known as RECTIFIER. The process of
conversion a.c to d.c is called “rectification”
TYPES OF RECTIFIERS:
Half wave Rectifier
Full wave rectifier
1. Centre tap full wave rectifier.
2. Bridge type full bridge rectifier.
Comparison of rectifier circuits:
Parameter
Type of Rectifier
Half wave Full wave Bridge
Number of diodes 1 2 4
PIV of diodes Vm 2Vm Vm
D.C output voltage Vm/ 2Vm/ 2Vm/
Vdc,at no-load 0.318Vm 0.636Vm 0.636Vm
Ripple factor 1.21 0.482 0.482
Ripple frequency f 2f 2f
Rectification efficiency 0.406 0.812 0.812
Transformer
UtilizationFactor(TUF)
0.287 0.693 0.812
RMS voltage Vrms Vm/2 Vm/√2 Vm/√2
1.621 Full-wave Rectifier:
From the above comparison we came to know that full wave bridge rectifier as more
advantages than the other two rectifiers. So, in our project we are using full wave bridge rectifier
circuit.
1.622 Bridge Rectifier:
A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-
wave rectification. This is a widely used configuration, both with individual diodes wired as
shown and with single component bridges where the diode bridge is wired internally.
A bridge rectifier makes use of four diodes in a bridge arrangement as shown in fig
(3) to achieve full-wave rectification. This is a widely used configuration, both with individual
diodes wired as shown and with single component bridges where the diode bridge is wired
internally.
Fig 3 : Bridge rectifier
Operation:
During positive half cycle of secondary, the diodes D2 and D3 are in forward biased while D1
and D4 are in reverse biased as shown in the fig(4). The current flow direction is shown in the fig
(4) with dotted arrows.
Fig (4): Bridge Rectifier Positive Cycle
During negative half cycle of secondary voltage, the diodes D1 and D4 are in forward biased
while D2 and D3 are in reverse biased as shown in the fig(5). The current flow direction is shown
in the fig (5) with dotted arrows.
Fig(5) : Bridge Rectifier Negative Cycle
1.63 Filter:
A Filter is a device which removes the a.c component of rectifier output but allows
the d.c component to reach the load
1.631 Capacitor Filter:
We have seen that the ripple content in the rectified output of half wave rectifier is 121% or
that of full-wave or bridge rectifier or bridge rectifier is 48% such high percentages of ripples is
not acceptable for most of the applications. Ripples can be removed by one of the following
methods of filtering.
(a) A capacitor, in parallel to the load, provides an easier by –pass for the ripples voltage though
it due to low impedance. At ripple frequency and leave the D.C. to appear at the load.
(b) An inductor, in series with the load, prevents the passage of the ripple current (due to high
impedance at ripple frequency) while allowing the d.c (due to low resistance to d.c)
(c) Various combinations of capacitor and inductor, such as L-section filter section filter, multiple
section filter etc. Which make use of both the properties mentioned in (a) and (b) above. Two cases of
capacitor filter, one applied on half wave rectifier and another with full wave rectifier.
Filtering is performed by a large value electrolytic capacitor connected across the DC supply to
act as a reservoir, supplying current to the output when the varying DC voltage from the rectifier is falling.
The capacitor charges quickly near the peak of the varying DC, and then discharges as it supplies current to
the output. Filtering significantly increases the average DC voltage to almost the peak value (1.4 × RMS
value).
To calculate the value of capacitor(C),
C = ¼*√3*f*r*Rl
Where,
f = supply frequency,
r = ripple factor,
Rl = load resistance
Note: In our circuit we are using 1000µF hence large value of capacitor is placed to reduce ripples
and to improve the DC component.
1.64 Regulator:
Voltage regulator Ics is available with fixed (typically 5, 12 and 15V) or variable
output voltages. The maximum current they can pass also rates them. Negative voltage regulators
are available, mainly for use in dual supplies. Most regulators include some automatic protection
from excessive current (‘overload protection’) and overheating (‘thermal protection’). Many of
the fixed voltage regulators Ics have 3 leads and look like power transistors, such as the 7805
+5V 1A regulator shown on the right. The LM7805 is simple to use. You simply connect the
positive lead of your unregulated DC power supply (anything from 9VDC to 24VDC) to the Input
pin, connect the negative lead to the Common pin and then when you turn on the power, you get a
5 volt supply from the output pin.
Fig 6: A Three Terminal Voltage Regulator
78XX:
The Bay Linear LM78XX is integrated linear positive regulator with three terminals. The
LM78XX offer several fixed output voltages making them useful in wide range of applications.
When used as a zener diode/resistor combination replacement, the LM78XX usually results in an
effective output impedance improvement of two orders of magnitude, lower quiescent current.
The LM78XX is available in the TO-252, TO-220 & TO-263packages,
Features:
• Output Current of 1.5A
• Output Voltage Tolerance of 5%
• Internal thermal overload protection
• Internal Short-Circuit Limited
• Output Voltage 5.0V, 6V, 8V, 9V, 10V, 12V, 15V, 18V, 24V
1.7 Micro controller
1.7.1 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 pre-defined
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
1.7.11 Atmel
Atmel® microcontrollers deliver a rich blend of highly efficient, integrated designs, proven
technology, and groundbreaking innovation that is ideal for today's smart, connected products. In
this era of The Internet of Things, microcontrollers are a key technology fueling machine-to-
machine (M2M) communications. Building on decades of experience and industry leadership,
Atmel has proven architectures that are optimized for low power, high-speed connectivity,
optimal data bandwidth, and rich interface support. A wide variety of configuration options
enables developers to devise complete system solutions for all kinds of applications. Atmel
microcontrollers can also support seamless integration of capacitive touch technology, to
implement buttons, sliders, and wheels. No matter what your market or device, Atmel offers a
compelling solution that is tailored to your needs—today and tomorrow.
Atmel AVR 8- and 32-bit microcontroller — Atmel AVR 8- and 32-bit
microcontrollers deliver a unique combination of performance, power efficiency, and
design flexibility. Optimized to speed time to market, and easily adapt to new ones,
they are based on the industry’s most code-efficient architecture for C and assembly
programming. The extensive AVR portfolio makes it easy to reuse knowledge when
improving your products and expanding to new markets.
ARM Processor-Based Microcontrollers — Atmel offers a wide range of industry-
leading AT91SAM ARM-based Flash MCUs and eMPU solutions. This broad
portfolio of 32-bit ARM® solutions can meet the needs of virtually any device or
marketplace. Flexible and highly integrated, Atmel ARM-based solutions are
designed to optimize system control, wired and wireless connectivity, user interface
management, low power, and ease of use.
MCU Wireless — To support today's increasingly connected applications, Atmel
offers a complete line of IEEE 802.15.4-compliant and ZigBee certified wireless
solutions. They are based on the Atmel rich family of RF transceivers, AVR and
ARM microcontrollers, as well as single chip wireless microcontrollers.
8051 Architecture Microcontroller — Atmel has a rich portfolio of microcontrollers
based on the 8051 instruction set combines proven technology with the latest features
and functionality. Developers can choose from 8-bit microcontrollers based on the
powerful, low-power Single-Cycle AT89LP core, as well as MCS-51® industry
standard socket drop-in devices—all featuring advanced Flash technologies.
Convenience, security, reliability and power efficiency drive low-frequency RF application
requirements. You can rely on Atmel® to help you design cost-effective, highly reliable RF
products. Atmel wireless technologies enable innovative, scalable and dedicated designs that fit
small footprints, consume very little power, and operate in rugged environments—indoors or
outdoors.
Atmel wireless technologies span these in-demand wireless areas:
MCU Wireless — To support today's increasingly connected applications, Atmel
offers a complete line of IEEE 802.15.4-compliant and ZigBee Certified wireless
solutions. These are based on the rich family of Atmel RF transceivers, as well as
Atmel AVR®, ARM®-based and single-chip wireless microcontrollers.
RF Identification — Address the needs of contactless identification products
operating at 125 kHz, 134.2 kHz and 13.56 MHz bandwidth ranges and support the
ISO 14443-B standard.
Smart RF — Target proprietary (non-standards based) wireless industrial and
consumer applications such as automatic metering, alarm systems and home control,
as well as toys and gaming.
Wi-Fi — Address the needs for Wi-Fi capability in embedded systems. Atmel low-
power Wi-Fi solutions cover a wide range of applications requiring support for legacy
Wi-Fi, as well as Wi-Fi Direct. Wi-Fi Direct is a software-based extension of standard
Wi-Fi that allows devices to communicate directly without the data passing through a
wireless access point (Wi-Fi Router or Gateway).
For the user, touch technology is all about sensitivity, speed, and accuracy—in other words, an
interface that senses and responds to their touches precisely and reliably, in the blink of an eye.
As a global leader in capacitive touch technology, with more than 15 years of experience, Atmel
can be your partner in delivering transformative touch innovations to the market, quickly and cost
effectively. Our robust, noise-resistant integrated circuits (ICs) are designed to provide superior
performance and response times while conserving power and saving space. For enhanced
functionality and design ease, you can also integrate our touch technology with leading-edge
Atmel AT91SAM and AVR® microcontrollers.
1.7.12 Atmel mega8 microcontroller:-
Features
• High-performance, Low-power Atmel®AVR® 8-bit Microcontroller
• Advanced RISC Architecture
– 130 Powerful Instructions – Most Single-clock Cycle Execution
– 32 × 8 General Purpose Working Registers
– Fully Static Operation
– Up to 16MIPS Throughput at 16MHz
– On-chip 2-cycle Multiplier
• High Endurance Non-volatile Memory segments
Fig: -Atmel micro controller
– 8Kbytes of In-System Self-programmable Flash program memory
– 512Bytes EEPROM
– 1Kbyte Internal SRAM
– Write/Erase Cycles: 10,000 Flash/100,000 EEPROM
– Data retention: 20 years at 85°C/100 years at 25°C(1)
– Optional Boot Code Section with Independent Lock Bits
In-System Programming by On-chip Boot Program
True Read-While-Write Operation
– Programming Lock for Software Security
• Peripheral Features
– Two 8-bit Timer/Counters with Separate Prescalar, one Compare Mode
– One 16-bit Timer/Counter with Separate Prescalar, Compare Mode, and Capture
Mode
– Real Time Counter with Separate Oscillator
– Three PWM Channels
– 8-channel ADC in TQFP and QFN/MLF package
Eight Channels 10-bit Accuracy
– 6-channel ADC in PDIP package
Six Channels 10-bit Accuracy
– Byte-oriented Two-wire Serial Interface
– Programmable Serial USART
– Master/Slave SPI Serial Interface
– Programmable Watchdog Timer with Separate On-chip Oscillator
– On-chip Analog Comparator
• Special Microcontroller Features
– Power-on Reset and Programmable Brown-out Detection
– Internal Calibrated RC Oscillator
– External and Internal Interrupt Sources
– Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and
Standby
• I/O and Packages
– 23 Programmable I/O Lines
– 28-lead PDIP, 32-lead TQFP, and 32-pad QFN/MLF
• Operating Voltages
– 2.7V - 5.5V (ATmega8L)
– 4.5V - 5.5V (ATmega8)
• Speed Grades
– 0 - 8MHz (ATmega8L)
– 0 - 16MHz (ATmega8)
• Power Consumption at 4 MHz, 3V, 25°C
– Idle Mode: 1.0mA
– Power-down Mode: 0.5µA
FIG : - ATMEL MEGA 8 IC
1.7.13 Pin diagram: -
Features:
Pin Number Description
1 (RESET) PC6
2 (RXD) PD0
3 (TXD) PD1
4 (INT0) PD2
5 (INT1) PD3
6 (XCK/T0) PD4
7 VCC
8 GND
9 (XTAL1/TOSC1) PB6
10 (XTAL2/TOSC2) PB7
11 (T1)PD5
12 (AIN0) PD6
13 (AIN1) PD7
14 (ICP1) PB0
15 (OC1A) PB1
16 (SS/OC1B) PB2
17 (MOSI/OC2) PB3
18 (MISO) PB4
19 (SCK) PB5
20 AVCC
21 AREF
22 GND
23 (ADC0) PC0
24 (ADC1) PC1
25 (ADC2) PC2
26 (ADC3) PC3
27 (ADC4/SDA) PC4
28 (ADC5/SCL) PC5
Architecture explanation: -
The Atmel AVR core combines a rich instruction set with 32 general purpose working registers.
All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two
independent registers to be accessed in one single instruction executed in one clock cycle.
The resulting architecture is more code efficient while achieving throughputs up to ten times
faster than conventional CISC microcontrollers.
The ATmega8 provides the following features: 8 Kbytes of In-System Programmable Flash
with Read-While-Write capabilities, 512 bytes of EEPROM, 1 Kbyte of SRAM, 23 general
purpose I/O lines, 32 general purpose working registers, three flexible Timer/Counters with
compare modes, internal and external interrupts, a serial programmable USART, a byte
oriented Two- wire Serial Interface, a 6-channel ADC (eight channels in TQFP and QFN/MLF
packages) with 10-bit accuracy, a programmable Watchdog Timer with Internal Oscillator, an
SPI serial port, and five software selectable power saving modes. The Idle mode stops the CPU
while allowing the SRAM; Timer/Counters, SPI port, and interrupt system to continue
functioning. The Power- down mode saves the register contents but freezes the Oscillator,
disabling all other chip functions until the next Interrupt or Hardware Reset. In Power-save
mode, the asynchronous timer continues to run, allowing the user to maintain a timer base while
the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O
modules except asynchronous timer and ADC, to minimize switching noise during ADC
conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest of the
device is sleeping. This allows very fast start-up combined with low-power consumption.
The device is manufactured using Atmel’s high density non-volatile memory technology. The
Flash Program memory can be reprogrammed In-System through an SPI serial interface, by a
conventional non-volatile memory programmer, or by an On-chip boot program running on the
AVR core. The boot program can use any interface to download the application program in the
Application Flash memory. Software in the Boot Flash Section will continue to run while the
Application Flash Section is updated, providing true Read-While-Write operation. By
combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic
chip, the Atmel ATmega8 is a powerful microcontroller that provides a highly-flexible and
cost-effective solution to many embedded control applications.
The ATmega8 is supported with a full suite of program and system development tools,
including C compilers, macro assemblers, program debugger/simulators, In-Circuit Emulators,
and evaluation kits.
Block Description:
VCC- Digital supply voltage.
GND - Ground.
Port B (PB7..PB0) XTAL1/XTAL2/TOSC1/ TOSC2
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit).
The Port B output buffers have symmetrical drive characteristics with both high sink and
source capability. As inputs, Port B pins that are externally pulled low will source current if
the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition
becomes active, even if the clock is not running.
Depending on the clock selection fuse settings, PB6 can be used as input to the inverting
Oscil- lator amplifier and input to the internal clock operating circuit.
Depending on the clock selection fuse settings, PB7 can be used as output from the
inverting
Oscillator
amplifier.
If the Internal Calibrated RC Oscillator is used as chip clock source, PB7..6 is used as
TOSC2..1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.
Port C (PC5..PC0) Port C is an 7-bit bi-directional I/O port with internal pull-up
resistors (selected for each bit). The Port C output buffers have symmetrical drive
characteristics with both high sink and source capability. As inputs, Port C pins that are
externally pulled low will source current if the pull-up resistors are activated. The Port C pins
are tri-stated when a reset condition becomes active, even if the clock is not running.
PC6/RESET If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin.
Note that the electrical char- acteristics of PC6 differ from those of the other pins of Port C.
If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset
input. A low level on this pin for longer than the minimum pulse
length will generate a Reset, even if the clock is not running..
Shorter pulses are not guaranteed to generate a Reset.
Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up
resistors (selected for each bit). The Port D output buffers have symmetrical drive
characteristics with both high sink and source capability. As inputs, Port D pins that are
externally pulled low will source current if the pull-up resistors are activated. The Port D
pins are tri-stated when a reset condition becomes active, even if the clock is not running.
.
RESET Reset input. A low level on this pin for longer than the minimum
pulse length will generate a reset, even if the clock is not running.. Shorter pulses are not
guaranteed to generate a reset.
Types of memory:
The 89C51 have three general types of memory. They are on-chip memory, external
Code memory and external Ram. On-Chip memory refers to physically existing memory on the
micro controller itself. External code memory is the code memory that resides off chip. This is
often in the form of an external EPROM. External RAM is the Ram that resides off chip. This
often is in the form of standard static RAM or flash RAM.
a) Code memory
Code memory is the memory that holds the actual 89C51 programs that is to be run. This
memory is limited to 64K. Code memory may be found on-chip or off-chip. It is possible to have
4K of code memory on-chip and 60K off chip memory simultaneously. If only off-chip memory
is available then there can be 64K of off chip ROM. This is controlled by pin provided as EA
b) Internal RAM
The 89C51 have a bank of 128 of internal RAM. The internal RAM is found on-chip. So
it is the fastest Ram available. And also it is most flexible in terms of reading and writing.
Internal Ram is volatile, so when 89C51 is reset, this memory is cleared. 128 bytes of internal
memory are subdivided. The first 32 bytes are divided into 4 register banks. Each bank contains 8
registers. Internal RAM also contains 128 bits, which are addressed from 20h to 2Fh. These bits
are bit addressed i.e. each individual bit of a byte can be addressed by the user. They are
numbered 00h to 7Fh. The user may make use of these variables with commands such as SETB
and CLR.
FLASH MEMORY:
Flash memory (sometimes called “flash RAM”) is a type of constantly-powered non
volatile that can be erased and reprogrammed in units of memory called blocks. It is a variation of
electrically erasable programmable read-only memory (EEPROM) which, unlike flash memory,
is erased and rewritten at the byte level, which is slower than flash memory updating. Flash
memory is often used to hold control code such as the basic input/output system (BIOS) in a
personal computer. When BIOS needs to be changed (rewritten), the flash memory can be written
to in block (rather than byte) sizes, making it easy to update. On the other hand, flash memory is
not useful as random access memory (RAM) because RAM needs to be addressable at the byte
(not the block) level.
Flash memory gets its name because the microchip is organized so that a section of
memory cells are erased in a single action or “flash.” The erasure is caused by Fowler-Nordheim
tunneling in which electrons pierce through a thin dielectric material to remove an electronic
charge from a floating gate associated with each memory cell. Intel offers a form of flash
memory that holds two bits (rather than one) in each memory cell, thus doubling the capacity of
memory without a corresponding increase in price.
.
Memory Type Features
FLASH Low-cost, high-density, high-speed
architecture; low power; high reliability
ROM
Read-Only Memory
Mature, high-density, reliable, low cost;
time-consuming mask required, suitable for
high production with stable code
SRAM
Static Random-Access Memory
Highest speed, high-power, low-density
memory; limited density drives up cost
EPROM
Electrically Programmable Read-Only
Memory
High-density memory; must be exposed to
ultraviolet light for erasure
EEPROMorE2PROM
Electrically Erasable Programmable Read-
Only Memory
Electrically byte-erasable; lower reliability,
higher cost, lowest density
DRAM
Dynamic Random Access Memory
High-density, low-cost, high-speed, high-
power
Technical Overview of Flash Memory
Flash memory is a nonvolatile memory using NOR technology, which allows the user to
electrically program and erase information. Intel® Flash memory uses memory cells similar to an
EPROM, but with a much thinner, precisely grown oxide between the floating gate and the source
. Flash programming occurs when electrons are placed on the floating gate. The charge is stored
on the floating gate, with the oxide layer allowing the cell to be electrically erased through the
source. Intel Flash memory is an extremely reliable nonvolatile memory architecture.
REGISTERS:
32
In the CPU, registers are used to store information temporarily. That information could
be a byte of data to be processed, or an address pointing to the data to be fetched. The vast
majority of 8051 registers are 8–bit registers. In the 8051 there is only one data type: 8bits. The
8bits of a register are shown in the diagram from the MSB (most significant bit) D7 to the LSB
(least significant bit) D0. With an 8-bit data type, any data larger than 8bits must be broken into
8-bit chunks before it is processed. Since there are a large number of registers in the 8051, we
will concentrate on some of the widely used general-purpose registers and cover special registers
in future chapters.
D7 D6 D5 D4 D3 D2 D1 D0
The most widely used registers of the 8051 are A (accumulator), B, R0, R1, R2, R3, R4,
R5, R6, R7, DPTR (data pointer), and PC (program counter). All of the above registers are 8-
bits, except DPTR and the program counter. The accumulator, register A, is used for all
arithmetic and logic instructions.
SFRs (Special Function Registers)
Among the registers R0-R7 is part of the 128 bytes of RAM memory. What about
registers A, B, PSW, and DPTR? Do they also have addresses? The answer is yes. In the 8051,
registers A, B, PSW and DPTR are part of the group of registers commonly referred to as SFR
(special function registers). There are many special function registers and they are widely used.
The SFR can be accessed by the names (which is much easier) or by their addresses. For
example, register A has address E0h, and register B has been ignited the address F0H, as shown
in table.
The following two points should noted about the SFR addresses.
1. The Special function registers have addresses between 80H and FFH. These
addresses are above 80H, since the addresses 00 to 7FH are addresses of RAM
memory inside the 8051.
2. Not all the address space of 80H to FFH is used by the SFR. The unused locations
80H to FFH are reserved and must not be used by the 8051 programmer.
33
Regarding direct addressing mode, notice the following two points: (a) the address value
is limited to one byte, 00-FFH, which means this addressing mode is limited to accessing RAM
locations and registers located inside the 8051. (b) If you examine the l st file for an assembly
language program, you will see that the SFR registers names are replaced with their addresses as
listed in table.
Symbol Name Address
ACC Accumulator 0E0H
B B register 0F0H
PSW Program status word 0D0H
SP Stack pointer 81H
DPTR Data pointer 2 bytes
DPL Low byte 82H
DPH High byte 83H
P0 Port0 80H
P1 Port1 90H
P2 Port2 0A0H
P3 Port3 0B0H
IP Interrupt priority control 0B8H
IE Interrupt enable control 0A8H
TMOD Timer/counter mode control 89H
TCON Timer/counter control 88H
T2CON Timer/counter 2 control 0C8H
T2MOD Timer/counter mode2 control 0C9H
34
TH0 Timer/counter 0high byte 8CH
TL0 Timer/counter 0 low byte 8AH
TH1 Timer/counter 1 high byte 8DH
TL1 Timer/counter 1 low byte 8BH
TH2 Timer/counter 2 high byte 0CDH
TL2 Timer/counter 2 low byte 0CCH
RCAP2H T/C 2 capture register high
byte
0CBH
RCAP2L T/C 2 capture register low byte 0CAH
SCON Serial control 98H
SBUF Serial data buffer 99H
PCON Power control 87H
Table: 8051 Special function register Address
A Register (Accumulator)
35
Fig : Accumulator register
This is a general-purpose register which serves for storing intermediate results during operating.
A number (an operand) should be added to the accumulator prior to execute an instruction upon
it. Once an arithmetical operation is preformed by the ALU, the result is placed into the
accumulator. If a data should be transferred from one register to another, it must go through
accumulator. For such universal purpose, this is the most commonly used register that none
microcontroller can be imagined without (more than a half 8051 microcontroller’s instructions
used use the accumulator in some way).
B Register
B register is used during multiply and divide operations which can be performed only upon
numbers stored in the A and B registers. All other instructions in the program can use this register
as a spare accumulator (A).
Fig : B register
During programming, each of registers is called by name so that their exact address is not
so important for the user. During compiling into machine code (series of hexadecimal numbers
recognized as instructions by the microcontroller), PC will automatically, instead of registers’
name, write necessary addresses into the microcontroller.
R Registers (R0-R7)
36
Fig : RAM
This is a common name for the total 8 general purpose registers (R0, R1, and R2 ...R7).
Even they are not true SFRs, they deserve to be discussed here because of their purpose. The
bank is active when the R registers it includes are in use. Similar to the accumulator, they are
used for temporary storing variables and intermediate results. Which of the banks will be active
depends on two bits included in the PSW Register. These registers are stored in four banks in the
scope of RAM.
The following example best illustrates the useful purpose of these registers. Suppose that
mathematical operations on numbers previously stored in the R registers should be performed:
(R1+R2) – (R3+R4). Obviously, a register for temporary storing results of addition is needed.
Everything is quite simple and the program is as follows:
MOV A, R3; Means: move number from R3 into accumulator
ADD A, R4; Means: add number from R4 to accumulator (result remains in accumulator)
MOV R5, A; Means: temporarily moves the result from accumulator into R5
MOV A, R1; Means: move number from R1 into accumulator
ADD A, R2; Means: add number from R2 to accumulator
SUBB A, R5; Means: subtract number from R5 (there are R3+R4)
37
8051 Register Banks and Stack
RAM memory space allocation in the 8051
There are 128 bytes of RAM in the 8051. The 128 bytes of RAM inside the 8051 are
assigned addresses 00 to7FH. These 128 bytes are divided into three different groups as follows:
1. A total of 32 bytes from locations 00 to 1FH hex are set aside for register banks and
the stack.
2. A total of 16 bytes from locations 20 to 2FH hex are set aside for bit-addressable
read/write memory.
3. A total of 80 bytes from locations 30H to 7FH are used for read and write storage, or
what is normally called Scratch pad. These 80 locations of RAM are widely used for
the purpose of storing data and parameters nu 8051 programmers.
Register banks in the 8051
A total of 32bytes of RAM are set aside for the register banks and stack. These 32
bytes are divided into 4 banks of registers in which each bank has registers, R0-R7. RAM
locations 0 to 7 are set aside for bank 0 of R0-R7 where R0 is RAM location 0, R1 is RAM
location 1, and R2 is location 2, and so on, until memory location7, which belongs to R7 of
bank0. The second bank of registers R0-R7 starts at RAM location 08 and goes to location 0FH.
The third bank of R0-R7 starts at memory location 10H and goes to location 17H. Finally, RAM
locations 18H to 1FH are set aside for the fourth bank of R0-R7. Fig shows how the 32 bytes are
allocated into 4 banks.
As we can see from fig 1, the bank 1 uses the same RAM space as the stack. This is a
major problem in programming the 8051. We must either not use register bank1, or allocate
another area of RAM for the stack.
Default register bank
If RAM locations 00-1F are set aside for the four register banks, which register bank of
R0-R7 do we have access to when the 8051 is powered up? The answer is register bank 0; that is ,
RAM locations 0, 1,2,3,4,5,6, and 7 are accessed with the names R0, R1, R2, R3, R4, R5, R6, and
R7 when programming the 8051. It is much easier to refer to these RAM locations with names
such as R0, R1 and so on, than by their memory locations as shown in fig 2.The register banks are
38
switched by using the D3 & D4 bits of register PSW
Fig : 8051 Register Banks and their RAM Addresses
PSW Register (Program Status Word)
39
Fig 16: PSW register
This is one of the most important SFRs. The Program Status Word (PSW) contains
several status bits that reflect the current state of the CPU. This register contains: Carry bit,
Auxiliary Carry, two register bank select bits, Overflow flag, parity bit, and user-definable status
flag. The ALU automatically changes some of register’s bits, which is usually used in regulation
of the program performing.
P – Parity bit If a number in accumulator is even then this bit will be automatically set (1),
otherwise it will be cleared (0). It is mainly used during data transmission and receiving via serial
communication.
- Bit 1. This bit is intended for the future versions of the microcontrollers, so it is not supposed to
be here.
OV Overflow occurs when the result of arithmetical operation is greater than 255 (decimal), so
that it can not be stored in one register. In that case, this bit will be set (1). If there is no overflow,
this bit will be cleared (0).
RS0, RS1 – Register bank selects bits. These two bits are used to select one of the four register
banks in RAM. By writing zeroes and ones to these bits, a group of registers R0-R7 is stored in
one of four banks in RAM.
RS1 RS2 Space in RAM
0 0 Bank0 00h-07h
0 1 Bank1 08h-0Fh
1 0 Bank2 10h-17h
1 1 Bank3 18h-1Fh
40
F0 – Flag 0. This is a general-purpose bit available to the user.
AC – Auxiliary Carry Flag is used for BCD operations only.
CY – Carry Flag is the (ninth) auxiliary bit used for all arithmetical operations and shift
instructions.
DPTR Register (Data Pointer)
These registers are not true ones because they do not physically exist. They consist of
two separate registers: DPH (Data Pointer High) and (Data Pointer Low). Their 16 bits are used
for external memory addressing. They may be handled as a 16-bit register or as two independent
8-bit registers. Besides, the DPTR Register is usually used for storing data and intermediate
results which have nothing to do with memory locations.
Fig : DPTR register
SP Register (Stack Pointer)
41
Fig : SP register
The stack is a section of RAM used by the CPU to store information temporarily. This
information could be data or an address. The CPU needs this storage area since there are only a
limited number of registers.
Program counter:
The important register in the 8051 is the PC (Program counter). The program counter
points to the address of the next instruction to be executed. As the CPU fetches the OPCODE
from the program ROM, the program counter is incremented to point to the next instruction. The
program counter in the 8051 is 16bits wide. This means that the 8051 can access program
addresses 0000 to FFFFH, a total of 64k bytes of code. However, not all members of the 8051
have the entire 64K bytes of on-chip ROM installed, as we will see soon.
Types of instructions
Depending on operation they perform, all instructions are divided in several groups:
Arithmetic Instructions
Branch Instructions
Data Transfer Instructions
Logical Instructions
Logical Instructions with bits
The first part of each instruction, called MNEMONIC refers to the operation an instruction
performs (copying, addition, logical operation etc.). Mnemonics commonly are shortened form of
name of operation being executed. For example:
INC R1; Increment R1 (increment register R1)
42
LJMP LAB5 ; Long Jump LAB5 (long jump to address specified as LAB5)
JNZ LOOP: Jump if Not Zero LOOP (if the number in the accumulator is not 0, jump to address
specified as LOOP)
Another part of instruction, called OPERAND is separated from mnemonic at least by
one empty space and defines data being processed by instructions. Some instructions have no
operand; some have one, two or three. If there is more than one operand in instruction, they are
separated by comma. For example:
RET – (return from sub-routine)
JZ TEMP – (if the number in the accumulator is not 0, jump to address specified as TEMP)
ADD A,R3 – (add R3 and accumulator)
CJNE A,#20,LOOP – (compare accumulator with 20. If they are not equal, jump to address
specified as LOOP)
Arithmetic instructions
These instructions perform several basic operations (addition, subtraction, division,
multiplication etc.) After execution, the result is stored in the first operand. For example:
ADD A, R1 – The result of addition (A+R1) will be stored in the accumulator.
Arithmetical Instructions
Mnemonic Description Byte NumberOscillator
Period
ADD A,Rn Add R Register to accumulator 1 1
ADD A,Rx Add directly addressed Rx Register to accumulator 2 2
43
ADD A,@Ri Add indirectly addressed Register to accumulator 1 1
ADD A,#X Add number X to accumulator 2 2
ADDC A,Rn Add R Register with Carry bit to accumulator 1 1
Branch Instructions
There are two kinds of these instructions:
Unconditional jump instructions:
After their execution a jump to a new location from where the program continues
execution is executed.
Conditional jump instructions:
If some condition is met – a jump is executed. Otherwise, the program normally
proceeds with the next instruction.
Branch Instruction
Mnemonic DescriptionByte
Number
Oscillator
Period
ACALL adr11Call subroutine located at address within 2 K byte
Program Memory space2 3
LCALL adr16 Call subroutine located at any address within 64 K 3 4
44
byte Program Memory space
RET Return from subroutine 1 4
RETI Return from interrupt routine 1 4
AJMP adr11Jump to address located within 2 K byte Program
Memory space2 3
LJMP adr16Jump to any address located within 64 K byte
Program Memory space3 4
Data Transfer Instructions
These instructions move the content of one register to another one. The register which
content is moved remains unchanged. If they have the suffix “X” (MOVX), the data is exchanged
with external memory.
Data Transfer Instruction
Mnemonic Description Byte NumberCycle
Number
MOV A,Rn Move R register to accumulator 1 1
MOV A,Rx Move directly addressed Rx register to accumulator 2 2
MOV A,@Ri Move indirectly addressed register to accumulator 1 1
MOV A,#X Move number X to accumulator 2 2
Logical Instructions
45
These instructions perform logical operations between corresponding bits of two
registers. After execution, the result is stored in the first operand.
Logical Instructions
Mnemonic Description Byte NumberCycle
Number
ANL A,Rn Logical AND between accumulator and R register 1 1
ANL A,RxLogical AND between accumulator and directly addressed
register Rx2 2
ANL A,@RiLogical AND between accumulator and indirectly
addressed register1 1
ANL A,#X Logical AND between accumulator and number X 2 2
Logical Operations on Bits
Similar to logical instructions, these instructions perform logical operations. The
difference is that these operations are performed on single bits.
Logical operations on bits
Mnemonic Description Byte NumberCycle
Number
CLR C Clear Carry bit 1 1
CLR bit Clear directly addressed bit 2 2
SETB C Set Carry bit 1 1
46
SETB bit Set directly addressed bit 2 2
CPL C Complement Carry bit 1 1
CPL bit Complement directly addressed bit 2 2
TIMERS
On-chip timing/counting facility has proved the capabilities of the microcontroller for
implementing the real time application. These includes pulse counting, frequency measurement,
pulse width measurement, baud rate generation, etc,. Having sufficient number of timer/counters
may be a need in a certain design application. The 8051 has two timers/counters. They can be
used either as timers to generate a time delay or as counters to count events happening outside the
microcontroller. Let discuss how these timers are used to generate time delays and we will also
discuss how they are been used as event counters.
PROGRAMMING 8051 TIMERS
The 8051 has timers: Timer 0 and Timer1.they can be used either as timers or as event
counters. Let us first discuss about the timers’ registers and how to program the timers to generate
time delays.
BASIC RIGISTERS OF THE TIMER
Both Timer 0 and Timer 1 are 16 bits wide. Since the 8051 has an 8-bit architecture, each
16-bit timer is accessed as two separate registers of low byte and high byte.
TIMER 0 REGISTERS
The 16-bit register of Timer 0 is accessed as low byte and high byte. The low byte
register is called TL0(Timer 0 low byte)and the high byte register is referred to as TH0(Timer 0
high byte).These register can be accessed like any other register, such as A,B,R0,R1,R2,etc.for
example, the instruction ”MOV TL0, #4F”moves the value 4FH into TL0,the low byte of Timer
0.These registers can also be read like any other register.
47
Fig 20:Timer 0(TH0 and TL0 ) registers
TIMER 1 REGISTERS
Timer 1 is also 16-bit register is split into two bytes, referred to as TL1 (Timer 1 low
byte) and TH1 (Timer 1 high byte).these registers are accessible n the same way as the register of
Timer 0.
TMOD (timer mode) REGISTER
Both timers TIMER 0 and TIMER 1 use the same register, called TMOD, to set the
various timer operation modes. TMOD is an 8-bit register in which the lower 4 bits are set aside
for Timer 0 and the upper 4 bits for Timer 1.in each case; the lower 2 bits are used to set the timer
mode and the upper 2 bits to specify the operation.
MODES:
M1, M0:
M0 and M1 are used to select the timer mode. There are three modes: 0, 1, 2.Mode 0 is
a 13-bit timer, mode 1 is a 16-bit timer, and mode 2 is an 8-bit timer. We will concentrate on
48
modes 1 and 2 since they are the ones used most widely. We will soon describe the characteristics
of these modes, after describing the reset of the TMOD register.
GATE: Gate control when set. The timer/counter is enabled only
While the INTx pin is high and the TRx control pin is.
Set. When cleared, the timer is enabled.
C/T Timer or counter selected cleared for timer operation
(Input from internal system clock).set for counter
Operation (input TX input pin).
M 1 Mode bit 1
M0 Mode bit 0
M1 M0 MODE Operating Mode
0 0 0 13-bit timer mode
8-bit timer/counter THx with
TLx as 5 – Bit pre-scaler.
0 1 1 16-bit timer mode
16-bit timer/counters THx with
TLx are Cascaded; there is no
prescaler
1 0 2 8-bit auto reload
8-bit auto reload
timer/counter;THx Holds a
value that is to be reloaded into
TLx each time it overflows.
1 1 3 Split timer mode.
49
C/T (clock/timer)
This bit in the TMOD register is used to decide whether the timer is used as a delay
generator or an event counter. If C/T=0, it is used as a timer for time delay generation. The clock
source for the time delay is the crystal frequency of the 8051.this section is concerned with this
choice. The timer’s use as an event counter is discussed in the next section
Serial Communication:
Computers can transfer data in two ways: parallel and serial. In parallel data transfers,
often 8 or more lines (wire conductors) are used to transfer data to a device that is only a few feet
away. Examples of parallel data transfer are printers and hard disks; each uses cables with many
wire strips. Although in such cases a lot of data can be transferred in a short amount of time by
using many wires in parallel, the distance cannot be great. To transfer to a device located many
meters away, the serial method is used. In serial communication, the data is sent one bit at a time,
in contrast to parallel communication, in which the data is sent a byte or more at a time. Serial
communication of the 8051 is the topic of this chapter. The 8051 has serial communication
capability built into it, there by making possible fast data transfer using only a few wires.
If data is to be transferred on the telephone line, it must be converted from 0s and 1s to
audio tones, which are sinusoidal-shaped signals. A peripheral device called a modem, which
stands for “modulator/demodulator”, performs this conversion.
Serial data communication uses two methods, asynchronous and synchronous. The
synchronous method transfers a block of data at a time, while the asynchronous method transfers
a single byte at a time.
In data transmission if the data can be transmitted and received, it is a duplex
transmission. This is in contrast to simplex transmissions such as with printers, in which the
computer only sends data. Duplex transmissions can be half or full duplex, depending on
whether or not the data transfer can be simultaneous. If data is transmitted one way at a time, it is
referred to as half duplex. If the data can go both ways at the same time, it is full duplex. Of
50
course, full duplex requires two wire conductors for the data lines, one for transmission and one
for reception, in order to transfer and receive data simultaneously.
Asynchronous serial communication and data framing
The data coming in at the receiving end of the data line in a serial data transfer is all 0s
and 1s; it is difficult to make sense of the data unless the sender and receiver agree on a set of
rules, a protocol, on how the data is packed, how many bits constitute a character, and when the
data begins and ends.
Start and stop bits
Asynchronous serial data communication is widely used for character-oriented
transmissions, while block-oriented data transfers use the synchronous method. In the
asynchronous method, each character is placed between start and stop bits. This is called framing.
In the data framing for asynchronous communications, the data, such as ASCII characters, are
packed between a start bit and a stop bit. The start bit is always one bit, but the stop bit can be
one or two bits. The start bit is always a 0 (low) and the stop bit (s) is 1 (high).
Data transfer rate
The rate of data transfer in serial data communication is stated in bps (bits per second).
Another widely used terminology for bps is baud rate. However, the baud and bps rates are not
necessarily equal. This is due to the fact that baud rate is the modem terminology and is defined
as the number of signal changes per second. In modems a single change of signal, sometimes
transfers several bits of data. As far as the conductor wire is concerned, the baud rate and bps are
the same, and for this reason we use the bps and baud interchangeably.
The data transfer rate of given computer system depends on communication ports
incorporated into that system. For example, the early IBMPC/XT could transfer data at the rate
of 100 to 9600 bps. In recent years, however, Pentium based PCS transfer data at rates as high as
56K bps. It must be noted that in asynchronous serial data communication, the baud rate is
generally limited to 100,000bps.
RS232 Standards
To allow compatibility among data communication equipment made by various
manufacturers, an interfacing standard called RS232 was set by the Electronics Industries
51
Association (EIA) in 1960. In 1963 it was modified and called RS232A. RS232B AND RS232C
were issued in 1965 and 1969, respectively. Today, RS232 is the most widely used serial I/O
interfacing standard. This standard is used in PCs and numerous types of equipment. However,
since the standard was set long before the advert of the TTL logic family, its input and output
voltage levels are not TTL compatible. In RS232, a 1 is represented by -3 to -25V, while a 0 bit
is +3 to +25V, making -3 to +3 undefined. For this reason, to connect any RS232 to a
microcontroller system we must use voltage converters such as MAX232 to convert the TTL
logic levels to the RS232 voltage levels, and vice versa. MAX232 IC chips are commonly
referred to as line drivers.
RS232 pins
RS232 cable is commonly referred to as the DB-25 connector. In labeling, DB-25P
refers to the plug connector (male) and DB-25S is for the socket connector (female). Since not
all the pins are used in PC cables, IBM introduced the DB-9 Version of the serial I/O standard,
which uses 9 pins only, as shown in table.
1 2 3 4 5
6 7 8 9
(Out of computer and exposed end of cable)
Fig 21: DB-9 pin connector
Pin Functions:
Pin Description
1 Data carrier detect (DCD)
2 Received data (RXD)
3 Transmitted data (TXD)
4 Data terminal ready(DTR)
5 Signal ground (GND)
6 Data set ready (DSR)
7 Request to send (RTS)
8 Clear to send (CTS)
52
9 Ring indicator (RI)
Note: DCD, DSR, RTS and CTS are active low pins.
The method used by RS-232 for communication allows for a simple connection of three lines:
Tx, Rx, and Ground. The three essential signals for 2-way RS-232
Communications are these:
TXD: carries data from DTE to the DCE.
RXD: carries data from DCE to the DTE
SG: signal ground
1.8 RF transmitter section
RF transmitters are electronic devices that create continuously varying electric current,
encode sine waves, and broadcast radio waves. RF transmitters use oscillators to create sine
waves, the simplest and smoothest form of continuously varying waves, which contain
information such as audio and video. Modulators encode these sign wives and antennas broadcast
them as radio signals. There are several ways to encode or modulate this information, including
amplitude modulation (AM) and frequency modulation (FM). Radio techniques limit localized
interference and noise. With direct sequence spread spectrum, signals are spread over a large
band by multiplexing the signal with a code or signature that modulates each bit. With frequency
hopping spread spectrum, signals move through a narrow set of channels in a sequential, cyclical,
and predetermined pattern.
Selecting RF transmitters requires an understanding of modulation methods such as AM
and FM. On-off key (OOK), the simplest form of modulation, consists of turning the signal on or
off. Amplitude modulation (AM) causes the base band signal to vary the amplitude or height of
the carrier wave to create the desired information content. Frequency modulation (FM) causes the
instantaneous frequency of a sine wave carrier to depart from the center frequency by an amount
proportional to the instantaneous value of the modulating signal. Amplitude shift key (ASK)
transmits data by varying the amplitude of the transmitted signal. Frequency shift key (FSK) is a
digital modulation scheme using two or more output frequencies. Phase shift key (PSK) is a
53
digital modulation scheme in which the phase of the transmitted signal is varied in accordance
with the base band data signal.
Additional considerations when selecting RF transmitters include supply voltage, supply
current, RF connectors, special features, and packaging. Some RF transmitters include visual or
audible alarms or LED indicators that signal operating modes such as power on or reception.
Other devices attach to coaxial cables or include a connector or port to which an antenna can be
attached. Typically, RF transmitters that are rated for outdoor use feature a heavy-duty
waterproof design. Devices with internal calibration and a frequency range switch are also
available.
RF transmitters are used in a variety of applications and industries. Often, devices that are
used with integrated circuits (ICs) incorporate surface mount technology (SMT), through hole
technology (THT), and flat pack. In the telecommunications industry, RF transmitters are
designed to fit in a metal rack that can be installed in a cabinet. RF transmitters are also used in
radios and in electronic article surveillance systems (EAS) found in retail stores. Inventory
management systems use RF transmitters as an alternative to barcodes.
1.8.1 RF transmitter ST-TX01-ASK:
General Description:
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The ST-TX01-ASK is an ASK Hybrid transmitter module. The ST-TX01-ASK is
designed by the Saw Resonator, with an effective low cost, small size, and simple-to-use for
designing.
Frequency Range: 315 / 433.92 MHZ.
Supply Voltage: 3~12V.
Output Power: 4~16dBm
Circuit Shape: Saw
Applications
Wireless security systems
Car Alarm systems
Remote controls.
Sensor reporting
Automation systems
55
Fig: Pin Description of the Transmitter module
Fig: Interfacing TX module to a Micro controller
1.9 RF receiver section:
56
RF receivers are electronic devices that separate radio signals from one another and convert
specific signals into audio, video, or data formats. RF receivers use an antenna to receive
transmitted radio signals and a tuner to separate a specific signal from all of the other signals that
the antenna receives. Detectors or demodulators then extract information that was encoded before
transmission. There are several ways to decode or modulate this information, including amplitude
modulation (AM) and frequency modulation (FM). Radio techniques limit localized interference
and noise. With direct sequence spread spectrum, signals are spread over a large band by
multiplexing the signal with a code or signature that modulates each bit. With frequency hopping
spread spectrum, signals move through a narrow set of channels in a sequential, cyclical, and
predetermined pattern.
Selecting RF receivers requires an understanding of modulation methods such as
AM and FM. On-off key (OOK), the simplest form of modulation, consists of turning the signal
on or off. Amplitude modulation (AM) causes the base band signal to vary the amplitude or
height of the carrier wave to create the desired information content. Frequency modulation (FM)
causes the instantaneous frequency of a sine wave carrier to depart from the center frequency by
an amount proportional to the instantaneous value of the modulating signal. Amplitude shift key
(ASK) transmits data by varying the amplitude of the transmitted signal. Frequency shift key
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(FSK) is a digital modulation scheme using two or more output frequencies. Phase shift key
(PSK) is a digital modulation scheme in which the phase of the transmitted signal is varied in
accordance with the base band data signal.
RF receivers vary in terms of performance specifications such as sensitivity,
digital sampling rate, measurement resolution, operating frequency, and communication interface.
Sensitivity is the minimum input signal required to produce a specified output signal having a
specified signal-to-noise (S/N) ratio. Digital sampling rate is the rate at which samples can be
drawn from a digital signal in kilo samples per second. Measurement resolution is the minimum
digital resolution, while operating frequency is the range of received signals. Communication
interface is the method used to output data to computers. Parallel interfaces include general-
purpose interface bus (GPIB), which is also known as IEEE 488 and HPIB Protocol. Serial
interfaces include universal serial bus (USB), RS232, and RS485.
Additional considerations when selecting RF receivers include supply voltage,
supply current, receiver inputs, RF connectors, special features, and packaging. Some RF
receivers include visual or audible alarms or LED indicators that signal operating modes such as
power on or reception. Other devices attach to coaxial cables or include a connector or port to
which an antenna can be attached. Typically, RF receivers that are rated for outdoor use feature a
heavy-duty waterproof design. Devices with internal calibration and a frequency range switch are
also available.
RF receiver ST-RX04-ASK:
Description:
The RX04 is a low power ASK receiver IC which is fully compatible with the
MitelKESRX01 IC and is suitable for use in a variety of low power radio applications including
remote keyless entry. The RX04 is based on a single-
Conversion, super-heterodyne receiver architecture and incorporates an entire phase-locked loop
(PLL) for precise local oscillator generation.
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Applications:
Car security system
Wireless security systems
Sensor reporting
automation system
Remote Keyless entry
Features
Low power consumption.
Easy for application.
On-Chip VCO with integrated PLL using crystal oscillator reference.
Integrated IF and data filters.
Operation temperature range : ﹣10℃~+60℃
Operation voltage: 5 Volts.
Available frequency at : 315/434 MHz
Functional description:
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Fig: RF receiver module.
Fig: RF receiver module.
1.10 Encoder:
Features:
Operating voltage
o 18 PIN DIP
o Operating Voltage : 2.4V ~ 12V
o Low Power and High Noise Immunity
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o CMOS Technology
o Low Standby Current and Minimum Transmission Word
o Built-in Oscillator needs only 5% Resistor
o Easy Interface with and RF or an Infrared transmission medium
o Minimal External Components
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 12ĘN data bits. Each ad-dress/data input can be
set to one of the two logic states. The programmed addresses/data are transmitted together with the header
bits
The HT12E Encoder ICs are series of CMOS LSIs for Remote Control system applications. They are
capable of Encoding 12 bit of information which consists of N address bits and 12-N data bits. Each
address/data input is externally ternary programmable if bonded out.
This has single channel for data transfer, thus serial data communication is used
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Application Circuits:
62
Fig 22: Application circuit of HT12E
Flow Chart:
Fig 23: Flow chat for data transmission in HT12E
1.10 Decoder:
63
Features - Decoder
o 18 PIN DIP
o Operating Voltage : 2.4V ~ 12.0V
o Low Power and High Noise Immunity
o CMOS Technology
o Low Stand by Current
o Ternary address setting
o Capable of Decoding 12 bits of Information
o 8 ~ 12 Address Pins and 0 ~ 4 Data Pins
o Received Data are checked 2 times, Built in Oscillator needs only 5% resistor
o VT goes high during a valid transmission
o Easy Interface with an RF of IR transmission medium
o Minimal External Components
Applications
_ Burglar alarm system
_ Smoke and fire alarm system
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_ Garage door controllers
_ Car door controllers
_ Car alarm system
_ Security system
_ Cordless telephones
_ Other remote control systems
General Description
The 212 decoders are a series of CMOS LSIs for remote control system applications. They are
paired with Holteks 212 series of encoders (refer to the encoder/decoder cross reference table).
For proper operation, a pair of encoder/decoder with the same number of addresses and data
format should be chosen. The decoders receive serial addresses 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. The 212 series of decoders are
capable of decoding informations that consist of N bits of address and 12_N bits of data. Of this
series, the HT12D is arranged to provide 8 address bits and 4 data bits, and HT12F is used to
decode 12 bits of address information.
Notes: Data type: L stands for latch type data output.
VT can be used as a momentary data output.
65
Fig 25: Block Diagram of HT 12D Decoder
Functional Description
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 receive data that
are transmitted by an encoder and interpret 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 activates the
oscillator, which in turn decodes the incoming address and data. The decoders will then check the
received address three times continuously. If the received 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 received. The output of the VT pin is high only when the transmission is
valid. Otherwise it is always low.
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
data remain unchanged until new data are received.
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Fig : Timing Diagram of Decoder HT12D
Fig: Application circuit of HT12D
1.12 Relays:
A relay is an electrically operated switch. Many relays use an electromagnet to operate a
switching mechanism mechanically, but other operating principles are also used. Relays are used
67
where it is necessary to control a circuit by a low-power signal (with complete electrical isolation
between control and controlled circuits), or where several circuits must be controlled by one
signal. The first relays were used in long distance telegraph circuits, repeating the signal coming
in from one circuit and re-transmitting it to another. Relays were used extensively in telephone
exchanges and early computers to perform logical operations.
A type of relay that can handle the high power required to directly control an electric motor or
other loads is called a contactor. Solid-state relays control power circuits with no moving parts,
instead using a semiconductor device to perform switching. Relays with calibrated operating
characteristics and sometimes multiple operating coils are used to protect electrical circuits from
overload or faults; in modern electric power systems these functions are performed by digital
instruments still called "protective relays".
1.12.1 Design and operation:
A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core, an iron
yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and one
or more sets of contacts (there are two in the relay pictured). The armature is hinged to the yoke
and mechanically linked to one or more sets of moving contacts. It is held in place by a spring so
that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition,
one of the two sets of contacts in the relay pictured is closed, and the other set is open. Other
relays may have more or fewer sets of contacts depending on their function. The relay in the
picture also has a wire connecting the armature to the yoke. This ensures continuity of the circuit
between the moving contacts on the armature, and the circuit track on the printed circuit
board (PCB) via the yoke, which is soldered to the PCB.
When an electric current is passed through the coil it generates a magnetic field that activates the
armature and the consequent movement of the movable contact either makes or breaks
(depending upon construction) a connection with a fixed contact. If the set of contacts was closed
when the relay was de-energized, then the movement opens the contacts and breaks the
connection, and vice versa if the contacts were open. When the current to the coil is switched off,
the armature is returned by a force, approximately half as strong as the magnetic force, to its
relaxed position. Usually this force is provided by a spring, but gravity is also used commonly in
industrial motor starters. Most relays are manufactured to operate quickly. In a low-voltage
application this reduces noise; in a high voltage or current application it reduces arcing.
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When the coil is energized with direct current, a diode is often placed across the coil to dissipate
the energy from the collapsing magnetic field at deactivation, which would otherwise generate
a voltage spike dangerous to semiconductor circuit components. Some automotive relays include
a diode inside the relay case. Alternatively, a contact protection network consisting of a capacitor
and resistor in series (snubbed circuit) may absorb the surge. If the coil is designed to be
energized with alternating (AC), a small copper "shading ring" can be crimped to the end of the
solenoid, creating a small out-of-phase current which increases the minimum pull on the armature
during the AC cycle.[1]
A solid-state relay uses a thruster or other solid-state switching device, activated by the control
signal, to switch the controlled load, instead of a solenoid. Anoptocoupler (a light-emitting
diode (LED) coupled with a photo transistor) can be used to isolate control and controlled
circuits.
Fig: Relay switches
Relay internal circuit:
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Fig: Normally closed Fig: Normally open
NORMALLY CLOSED RELAYS:
The operation of a Normally Closed relay is the same to that of a Normally Open relay,
Except backwards. In other words, when the relay control coil is NOT energized, the relay
Switch contacts are closed, completing the circuit through pins 2 and 4. When the control
Coil is energized, the relay switch contacts opens, which breaks the circuit open and no
Continuity exists between pins 2 and 4.
DE - ENERGIZED (OFF) ENERGIZED (ON)
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1.13 Linear keypad:
This section basically consists of a Linear Keypad. Basically a Keypad can be classified into 2
categories. One is Linear Keypad and the other is Matrix keypad.
Matrix Keypad: This Keypad got keys arranged in the form of Rows and Columns. That is why the name
Matrix Keypad. According to this keypad, In order to find the key being pressed the keypad need to be
scanned by making rows as i/p and columns as output or vice versa.This Keypad is used in places where
one needs to connect more no. Of keys with less no. Of data lines.
Linear Keypad: This Keypad got ‘n’ no. Of keys connected to ‘n’ data lines.This Keypad is used in places
where one needs to connect less number Of keys
1.14 LED(Lighting Emitting Diodes):
It is a semiconductor diode having radioactive recombination. It requires a definite amount
of energy to generate an electron-hole pair.
The same energy is released when an electron recombines with a hole. This released energy
may result in the emission of photon and such a recombination. Hear the amount of energy
released when the electro reverts from the conduction band to the valence band appears in the
form of radiation. Alternatively the released energy may result in a series of phonons causing
lattice vibration. Finally the released energy may be transferred to another electron. The
recombination radiation may be lie in the infra-red and visible light spectrum. In forward is
peaked around the band gap energy and the phenomenon is called injection luminescence. I n a
junction biased in the avalanche break down region , there results a spectrum of photons carrying
much higher energies . Almost White light then gets emitted from micro-plasma breakdown
region in silicon junction. Diodes having radioactive recombination are termed as Light
Emitting Diode, abbreviated as LEDs.
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In gallium arsenide diode, recombination is predominantly a radiation recombination and
the probability of this radio active recombination far exceeds that in either germanium or silicon .
Hence Ga As LED has much higher efficiency in terms of
Photons emitted per carrier. The internal efficiency of Ga As LED may be very close to 100% but
because of high index of refraction, only a small fraction of the internal radiation can usually
come out of the device surface. In spite of this low efficiency of actually radiated light , these
LEDs are efficiency used as light emitters in visual display units and in optically coupled circuits,
The efficiency of light generation increases with the increase of injected current and with
decreases in temperature. The light so generated is concentrated near the junction since most of
the charge carriers are obtained within one diffusion length of the diode junction.
The following are the merits of LEDs over conventional incandescent and other types of lamps
1. Low working voltages and currents
2. Less power consumption
3. Very fast action
4. Emission of monochromatic light
5. small size and weight
6. No effect of mechanical vibrations
7. Extremely long life
Typical LED uses a forward voltage of about 2V and current of 5 to 10mA.
GaAs LED produces infra-red light while red, green and orange lights are produced by
gallium arsenide phosphide (GaAs) and gallium phosphide(Gap) .
Light Emitting Diodes (LEDs)
Example: Circuit symbol:
Function
72
LEDs emit light when an electric current passes through them.
5. Circuit Description:
RF Modules are used wireless transfer data. This makes them most suitable for remote control
applications, as in where you need to control some machines or robots without getting in touch
with them (may be due to various reasons like safety, etc). Now depending upon the type of
application, the RF module is chosen. For short range wireless control applications, an ASK RF
Transmitter-Receiver Module of frequency 315 MHz or 433 MHz is most suitable. The main
objective of this project is to control the traffic, whenever any time any VIP is coming in that way
by using RF TRANSMITTER section send the message to that RF RECEIVER. RF RECEIVER
will receive that information given to the micro controller, in that particular way green light will
73
be ON for clearing the traffic and remaining ways stopped by indicating red light. Whenever
VIPs entering in that particular way then entered the keys for exiting in that way then also they
can enter the keys. The same procedure will be followed by four sides of the road. The signaling
from the four sides will be taken into consideration.
SOFTWARE COMPONENTS
ABOUT SOFTWARE
Software used is:
*Keil software for C programming
*Express PCB for lay out design
*Express SCH for schematic design
74
KEIL µVision3
What's New in µVision3?
µVision3 adds many new features to the Editor like Text Templates, Quick Function Navigation,
and Syntax Coloring with brace high lighting Configuration Wizard for dialog based startup and
debugger setup. µVision3 is fully compatible to µVision2 and can be used in parallel with
µVision2.
What is µVision3?
µVision3 is an IDE (Integrated Development Environment) that helps you write, compile, and
debug embedded programs. It encapsulates the following components:
A project manager.
A make facility.
Tool configuration.
Editor.
A powerful debugger.
Express PCB
Express PCB is a Circuit Design Software and PCB manufacturing service. One
can learn almost everything you need to know about Express PCB from the help topics included
with the programs given.
Details:
Express PCB, Version 5.6.0
Express SCH
The Express SCH schematic design program is very easy to use. This software
enables the user to draw the Schematics with drag and drop options.
A Quick Start Guide is provided by which the user can learn how to use it.
Details:
75
Express SCH, Version 5.6.0
EMBEDDED C:
The programming Language used here in this project is an Embedded C
Language. This Embedded C Language is different from the generic C language in few things
like
a) Data types
b) Access over the architecture addresses.
The Embedded C Programming Language forms the user friendly language with access over Port
addresses, SFR Register addresses etc.
Embedded C Data types:
Data Types Size in Bits Data Range/Usage
unsigned char 8-bit 0-255
signed char 8-bit -128 to +127
unsigned int 16-bit 0 to 65535
signed int 16-bit -32,768 to +32,767
sbit 1-bit SFR bit addressable only
bit 1-bit RAM bit addressable only
sfr 8-bit RAM addresses 80-FFH
only
Signed char:
o Used to represent the – or + values.
76
o As a result, we have only 7 bits for the magnitude of the signed number, giving us values
from -128 to +127.
6. SOFTWARE
µVision3
µVision3 is an IDE (Integrated Development Environment) that helps you write, compile, and
debug embedded programs. It encapsulates the following components:
A project manager.
A make facility.
Tool configuration.
77
Editor.
A powerful debugger.
To help you get started, several example programs (located in the \C51\Examples, \C251\
Examples, \C166\Examples, and \ARM\...\Examples) are provided.
HELLO is a simple program that prints the string "Hello World" using the Serial
Interface.
Building an Application in µVision2
To build (compile, assemble, and link) an application in µVision2, you must:
1. Select Project - (for example, 166\EXAMPLES\HELLO\HELLO.UV2).
2. Select Project - Rebuild all target files or Build target.
µVision2 compiles, assembles, and links the files in your project.
1.17 Creating Your Own Application in µVision2
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, 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.
Debugging an Application in µVision2
To debug an application created using µVision2, you must:
1. Select Debug - Start/Stop Debug Session.
78
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.
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
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
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 microcontroller you
use. We are using for our examples the Philips 80C51RD+ CPU. This selection sets necessary
tool options for the 80C51RD+ device and simplifies in this way the tool Configuration.
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.
Once you have successfully generated your application you can start debugging.
79
After you have tested your application, it is required to create an Intel HEX file to
download the software into an EPROM programmer or simulator. µVision2 creates HEX files
with each build process when Create HEX files under Options for Target – Output is enabled.
You may start your PROM programming utility after the make process when you specify the
program under the option Run User Program #1.
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
being done.
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
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.
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.
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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.
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 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.
1.18 Embedded ‘C’ :
What is an embedded system?
An embedded system is an application that contains at least one programmable computer
and which is used by individuals who are, in the main, unaware that the system is computer-
based.
Which programming language should you use?
Having decided to use an 8051 processor as the basis of your embedded system, the next key
decision that needs to be made is the choice of programming language. In order to identify a
suitable language for embedded systems, we might begin by making the following observations:
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Computers (such as microcontroller, microprocessor or DSP chips) only accept
instructions in ‘machine code’ (‘object codes’). Machine code is, by definition, in the
language of the computer, rather than that of the programmer. Interpretation of the code
by the programmer is difficult and error prone.
All software, whether in assembly, C, C++, Java or Ada must ultimately be translated
into machine code in order to be executed by the computer.
Embedded processors – like the 8051 – have limited processor power and very limited
memory available: the language used must be efficient.
The language chosen should be in common use.
8. Program
1.19 For Transmitter section:
1. #include <avr/io.h>
2. #include <util/delay.h>
3. #include "usart.h"
4. // initialize adc
5. void adc_init()
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6. {
7. // AREF = AVcc
8. ADMUX = (1<<REFS0);
9.
10. // ADC Enable and prescaler of 128
11. // 16000000/128 = 125000
12. ADCSRA = (1<<ADEN)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);
13. }
14. // read adc value
15. uint16_t adc_read(uint8_t ch)
16. {
17. // select the corresponding channel 0~7
18. // ANDing with '7' will always keep the value
19. // of 'ch' between 0 and 7
20. ch &= 0b00000111; // AND operation with 7
21. ADMUX = (ADMUX & 0xF8)|ch; // clears the bottom 3 bits before ORing
22. // start single conversion
23. // write '1' to ADSC
24. ADCSRA |= (1<<ADSC);
25. // wait for conversion to complete
26. // ADSC becomes '0' again
27. // till then, run loop continuously
28. while(ADCSRA & (1<<ADSC));
29. return (ADC);
30. }
31. void main()
32. {
33. char data,int_buffer[10];
34. USARTInit(416);
35. uint8_t data;
36. uint16_t adc_result;
37. adc_init();
38. while(1)
39. {
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40. adc_result=ReadADC(0);
41. data=adc
42. UWriteData('J');
43. UWriteData('A');
44. UWriteData(data);
45. UWriteData(~data);
46. UWriteData('Z');
47. _delay_loop_2(0);
48. _delay_loop_2(0);
49. _delay_loop_2(0);
50. _delay_loop_2(0);
51. }
52. }
1.20 For Receiver section:
1. #include <avr/io.h>
2. #include "usart.h"
3. #include
4. void Wait()
5. {
6. uint8_t i;
7. for(i=0;i<50;i++)
8. {
9. _delay_loop_2(0);
10. _delay_loop_2(0);
11. _delay_loop_2(0);
12. }
13. }
14. void main()
15. {
16. uint8_t i;
17. uint8_t packet[5],data=0;
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18. DDRC|=0xFF;
19. USARTInit(416);
20. while(1)
21. {
22. while(!UDataAvailable());
23. if(UReadData()!='A') continue;
24. while(!UDataAvailable());
25. if(UReadData()!='A') continue;
26.
27. while(UDataAvailable()!=3);
28. //Get the packet
29. for(i=2;i<5;i++)
30. {
31. packet[i]=UReadData();
32. }
33. //Is it ok?
34. if(packet[2]!=((uint8_t)~packet[3])) continue;
35. if(packet[4]!='Z') continue;
36. //The packet is ok
37. data=packet[2];
38. PORTC=data;
39. TCCR1A|=(1<<COM1A1)|(1<<COM1B1)|(1<<WGM11);
40. TCCR1B|=(1<<WGM13)|(1<<WGM12)|(1<<CS11)|(1<<CS10);
41. ICR1=4999;
42. DDRD|=(1<<PD4)|(1<<PD5);
43. while(1)
44. {
45. if(0<=data<=96) OCR1A=0;
46. if(97<=data<=135) OCR1A=97; //0 degree
47. if(316<=data<=424) OCR1A=316; //90 degree
48. if(425<=data534) OCR1A=535; //180 dgree
49. }
50. }
51. }
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9. Conclusion
This project is based on mainly on the home appliances by which we can control all of them at a
time so that the there would be a lot of time saving and easily handled at a time.
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.
Firstly, the equipment is suggested clearly and the saperate texture for them is implemented and
tested and worked out successfully
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Secondly, using highly advanced IC’s and with the help of growing technology the project has been
successfully implemented.
10. Applications
1. These are mainly used in house hold appliances
2. At a time any four house hold appliances can be controlled such as fan, light, etc…
This project can be used in house hold appliances. With this project we can monitor the different
appliances in house. Thus this project makes the idea form any anotherised vehicles in the
industry.
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10. References
http://maxembedded.com
http://www.lpc-uk.com
http://en.wikipedia.org/wiki/Relay
http://www.autoshop101.com/forms/hweb2.pdf
http://www.atmel.com/products/wireless/default.aspx
http://www.futurlec.com/Atmel/ATMEGA8.shtml
http://en.wikipedia.org/wiki/Radio_frequency
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www.franklin.com
www.keil.com
www.8051projects.com
www.microsoftsearch.com
www.geocities.com
www.alldatasheet.com
www.bioenable.com
8051-MICROCONTROLLER AND EMBEDDED SYSTEMS.
Mohd. Mazidi.
The 8051 Micro controller Architecture, Programming & Applications
-Kenneth J.Ayala
Fundamentals Of Micro processors and Micro computers
-B.Ram
Micro processor Architecture, Programming & Applications
-Ramesh S. Gaonkar
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