“RF CONTROLLED CAR”
A MINI-PROJECT REPORT
PATEL PARESHKUMAR A.(120810108003)
PADHIAR NIRMAL G. (120810108005)
PATEL AKASH R. (120810108014)
In fulfillment for the award of the degree
BACHELOR OF ENGINEERING
Electrical & Electronics Engineering
Venus International College of Technology, Bhoyan Rathod – Gandhinagar.
Gujarat Technological University, Ahmadabad.
Venus International College of Technology, Bhoyan Rathod - Gandhinagar
Department of Electrical & Electronics Engineering
This is to certify that the project entitled “RF CONTROLLED CAR” has been
carried out by PATEL PARESHKUMAR A., PADHIAR NIRMAL G., PATEL
AKASH R. within four walls of Venus International College of Technology under
my guidance in fulfillment of the degree of Bachelor of Engineering in Electrical
& Electronics Engineering (6th Semester) of Gujarat Technological University,
Ahmedabad during the academic year 2014-15.
Internal Guide: Head of the Department:
Prof. RISHIKESH AGRAWAL Prof. P. K. Jani
The project “RF CONTROLLED CAR” could not have turned out into a
successful working model without the kind support and help of many individuals
and the collage itself. I would like to extend my sincere thanks to all of them.
We are highly indebted to VENUS INTERNATIONAL COLLEGE OF
TECHNOLOGY for their guidance and constant supervision as well as for
providing necessary information regarding the project and also for their support in
completing the project.
Firstly we would like to express our gratitude towards the DIRECTOR of this
college Dr. A.K.Chaturvedi and the HOD of electrical and electronics department:
Prof. Pranav K. Jani for their kind co-operation and encouragement which helped
us in completion of this project carried in the collage premise without experiencing
hurdles. A great help and support was obtained from our internal guide Prof.
Rishikesh Agrawal without whom the fault clearance at certain level would not
have been possible.
Our thanks and appreciations also goes to the colleague in developing the project
and people who have willingly helped us out with their abilities.
The last but not the least, a very special thanks to our parents and relatives for their
moral support which gave us strength to make this project.
This project was about to study how the wireless technology has advanced in
today‟s world. Radio frequency controlled car is one such great example which
always fantasizes the world about the exploring of the technology. Now-a-days the
modern trend has made more emphasis on performing the tasks wirelessly. This in
turns leaves a greater impact on the youth which motivates them to continue the
progress and the inventions of the technology.
This project basically deals with the operation on the performance of the car
through the radio frequency signals. Transmitter at the senders end on transmitting
the signal is thereby received by the receiver which acts as an order for the driver
IC to carry out the following instructions. Any object which makes a motion
wirelessly is a robot and so this car is too a robot which acts as an artificial
intelligence performing the called out instructions.
This project being on the basic level when carried out on the higher level can do
wonders if used in the correct directions for the betterment of the nation and
List of Tables
Table No. Description Page No.
1.1 Frequency band 1
3.1 Pin function of L293D 19
3.2 Logic of driver IC 20
4.1 Logic of driver IC 22
4.2 Direction of car 22
List of Figures
Figure No. Description Page No.
1.1 cosmetic treatment 3
1.2 RF chip inside the body for spy purpose 4
2.1 Radio Frequency Generator 6
2.2 Block diagram of phase locked loop synthesizer 8
2.3 Block Diagram of a Basic Direct Digital Synthesizer (DDS) 8
2.4 Block diagram of a generic RF signal generator 9
3.1 Block diagram of RF controlled car 15
3.2 Circuit diagram of RF transmitter section circuit 16
3.3 Circuit diagram of RF receiver section circuit 17
3.4 ASK RF module 18
3.5 Pins for ASK RF module 19
3.6 pin diagram encoder IC 20
3.7 pin diagram encoder IC (zoomed 21
3.8 pin diagram of decoder 23
3.9 pin diagram of decoder (zoomed) 23
3.10 pin diagram if driver IC L293D 25
3.11 circuit of 7805 voltage regulator 27
3.12 IC 7805 voltage regulator 28
Table of Contents
List of Tables iii
List of Figures iv
1 Introduction to Radio Frequency 1
1.1 Introduction 1
1.2 Special Properties of Radio Frequency 2
1.3 Radio Communication 2
1.4 Working areas of Radio Frequencies 3
1.5 Main Objective 5
2 Radio Frequency generation and its side aspects 6
2.1 Generation of Radio Frequency 6
2.1.1 Types of RF signal generator 6
2.1.2 RF signal generator operation 8
2.2 Aspects 11
2.2.1 Advantages 12
2.2.2 Disadvantages 12
2.1.3 Applications 13
3 RF Controlled Car 14
3.1 Basics 14
3.1.1 Radio frequency remote control 14
3.1.2 Radio Frequency Remote Controlled
3.2 block diagram 15
3.3 Circuit diagram 16
3.4 electronic components and modules
3.4.1 3.4.1 HT12E encoder IC 19
3.4.2 HT12D decoder IC 21
3.4.3 Driver IC L293D 23
3.4.4 Voltage Regulators 25
4 Result and Analysis
4.1 Result 28
4.2 Analysis 29
5 Conclusion and future scope 30
5.1 Conclusion 30
5.2 Future Scope 30
Chapter – 1
Introduction to Radio Frequency
Radio frequency (RF) is a rate of oscillation in the range of around 3 kHz to 300 GHz, which
corresponds to the frequency of radio waves, and the alternating currents which carry radio
signals. RF usually refers to electrical rather than mechanical oscillations;
Although radio frequency is a rate of oscillation, the term "radio frequency" or its abbreviation
"RF" are also used as a synonym for radio – i.e. to describe the use of wireless communication,
as opposed to communication via electric wires. Examples include:
Radio frequency power and signal interface.
Table 1.1 Frequency band
1.2 Special Properties of Radio Frequency
Electric currents that oscillate at radio frequencies have special properties not shared by direct
current or alternating current of lower frequencies.
The energy in an RF current can radiate off a conductor into space as electromagnetic
waves (radio waves); this is the basis of radio technology.
RF current does not penetrate deeply into electrical conductors but tends to flow
along their surfaces; this is known as the skin effect. For this reason, when the human
body comes in contact with high power RF currents it can cause superficial but
serious burns called RF burns.
RF currents applied to the body often do not cause the painful sensation of electric
shock as do lower frequency currents. This is because the current changes direction
too quickly to trigger depolarization of nerve membranes.
RF current can easily ionize air, creating a conductive path through it. This property
is exploited by "high frequency" units used in electric arc welding, which use
currents at higher frequencies than power distribution uses.
The ability to appear to flow through paths that contain insulating material, like
the dielectric insulator of a capacitor.
When conducted by an ordinary electric cable, RF current has a tendency to reflect
from discontinuities in the cable such as connectors and travel back down the cable
toward the source, causing a condition called standing waves, so RF current must be
carried by specialized types of cable called transmission line.
1.3 Radio Communication
To receive radio signals an antenna must be used. However, since the antenna will pick up
thousands of radio signals at a time, a radio tuner is necessary to tune into a particular frequency
(or frequency range). This is typically done via a resonator – in its simplest form, a circuit with
a capacitor and an inductor form a tuned circuit. The resonator amplifies oscillations within a
particular frequency band, while reducing oscillations at other frequencies outside the band.
Another method to isolate a particular radio frequency is by oversampling (which gets a wide
range of frequencies) and picking out the frequencies of interest, as done in software defined
The distance over which radio communications is useful depends significantly on things other
than wavelength, such as transmitter power, receiver quality, type, size, and height of antenna,
mode of transmission, noise, and interfering signals.
1.4 Working areas of Radio Frequencies
Radio frequency (RF) energy, in the form of radiating waves or electrical currents, has been used
in medical treatments for over 75 years, generally for minimally invasive surgeries, using
radiofrequency and cryoablation, including the treatment of sleep apnea. Magnetic resonance
imaging (MRI) uses radio frequency waves to generate images of the human body.
Radio frequencies are sometimes used as a form of cosmetic treatment that can tighten skin,
reduce fat, or promote healing.
Fig 1.1 Cosmetic treatment
In weapon areas, a heat ray is a RF harassment device that makes use of microwave radio
frequencies to create an unpleasant heating effect in the upper layer of the skin. A publicly
known heat ray weapon called the Active Denial System was developed by the US military as an
experimental weapon to deny the enemy access to an area. Also, see death ray which is a heat ray
weapon that delivers electromagnetic energy at levels that injure human tissue. The inventor of
the death ray, Harry Grindell Matthews, claims to have lost sight in his left eye while developing
his death ray weapon based on a primitive microwave magnetron from the 1920s
Radio frequency has also been used in the military areas for spying and keeping a track on their
mission and their objectives. The equipment is so small that it can fit anywhere and everywhere.
Usually they are put inside the body to keep it as a secret.
Fig 1.2:- RF chip inside the body for spy purpose
Since radio frequency radiation has both an electric and a magnetic component, it is often
convenient to express intensity of radiation field in terms of units specific to each component.
The unit volts per meter (V/m) is used for the electric component, and the unit amperes per
meter (A/m) is used for the magnetic component. One can speak of an electromagnetic field, and
these units are used to provide information about the levels of electric and magnetic field
strength at a measurement location.
Another commonly used unit for characterizing an RF electromagnetic field is power density.
Power density is most accurately used when the point of measurement is far enough away from
the RF emitter to be located in what is referred to as the far field zone of the radiation pattern. In
closer proximity to the transmitter, i.e., in the "near field" zone, the physical relationships
between the electric and magnetic components of the field can be complex, and it is best to use
the field strength units discussed above. Power density is measured in terms of power per unit
area, for example, mill watts per square centimetre (mW/cm²). When speaking of frequencies in
the microwave range and higher, power density is usually used to express intensity since
exposures that might occur would likely be in the far field zone.
1.5 Main Objective
Communication systems play a major role in maintaining communication between humans or
organizations or institutions or even people get entertainment programs or news or other
television or radio broadcasting programs via wired or wireless communication systems. To
overcome disadvantages of wired communications, advancement in technology has resulted in
the development of most advanced wireless communication systems including wireless radio
frequency technology, infrared technology, GSM technology, and so on. These wireless
communication systems can be used to transmit different types of signals from transmitting end
to receiving end. The control signal from transmitter is sent to the receiver which is connected to
an object or device or vehicle that is to be remotely controlled. For example, IR remote is used to
control TV remotely. Similarly, this article mentions about a wirelessly controlled robot
controlled using radio frequency technology. A robot which would perform tasks assigned to it
through rf signals. Being the part of the wireless technology this would serve an immense ease to
the people to do some stuff without and mechanical energy lost. Now-a-days the technology
growing very fast the adaption of this technology will become inevitable in the near future.
Chapter – 2
Radio Frequency generation and its side aspects
2.1 Generation of Radio Frequency
Radio frequency signal generators (RF signal generators) are a particularly useful item of test
equipment widely used in RF microwave design and test applications.
These microwave and RF signal generators come in a variety of forms and with a host of
facilities and capabilities.
In order to gain the most from any RF signal generator or microwave signal generator, it is
necessary to have an understanding of its operation and the capabilities it possesses.
Fig 2.1:- Radio Frequency Generator
2.1.1 Types of RF signal generator
It is possible to design radio frequency signal generators in a variety of ways. Also with
developments that have been made in electronics circuitry over the years, different techniques
have evolved. It can be said that there are two forms of signal generator that can be used:
Free running RF signal generators: These signal generators are rarely used these days
as their frequency tends to drift. However they do have the advantage that the signal
produced is very clean and does not have the level of noise (phase noise) either side of
the main signal that is present on some other radio frequency signal generators.
Some signal generators used a form of frequency locked loop to provide a means of
adding some frequency stability while still retaining the very low levels of phase noise.
Again, these are not common these days because the performance of RF signal generators
using frequency synthesizer technology has considerably improved.
Synthesized radio frequency signal generators: Virtually all radio frequency signal
generators used today employ frequency synthesizers. Using this technique enables
frequencies to be entered directly from a keypad, or via remote control and it also enables
the output signal to be determined very accurately. The accuracy being dependent upon
either an internal reference oscillator that can have a very high degree of accuracy, or the
signal can be locked to an external frequency reference which can be exceedingly
There are two main techniques that are used within synthesized RF signal generators:
Phase locked loop synthesizer: Phase locked loop synthesizers are used within most
RF signal generators as they enable signals to be generated over a wide range of
frequencies with a relatively low level of spurious signals. Phase locked loop synthesizer
technology is well developed and enables high performance RF signal generators to be
produced using them.
Direct Digital Synthesizer, DDS: Direct digital synthesis techniques may be used in
RF signal generators. They enable very fine frequency increments to be achieved
relatively easily. However the maximum limit of a DDS is normally much lower than the
top frequencies required for the signal generator, so they are used in conjunction with
phase locked loops to give the required frequency range.
Fig 2.2:-Block diagram of phase locked loop synthesizer
Fig 2.3:- Block Diagram of a Basic Direct Digital Synthesizer (DDS).
2.1.2 RF signal generator operation
In order to understand the operation of a generic microwave or RF signal generator it is useful to
understand what is included in terms of a basic block diagram.
Fig 2.4:- Block diagram of a generic RF signal generator
The diagram shows a very simplified block diagram for an RF / Microwave signal generator.
From this, it can be seen that the generator has a few major blocks within it:
Oscillator: The most important block within the RF signal generator is the oscillator
itself. This can be any form of oscillator, but today it would almost certainly be formed
from a frequency synthesizer. This oscillator would take commands from the controller
and be set to the required frequency.
Amplifier: The output from the oscillator will need amplifying. This will be achieved
using a special amplifier module. This will amplify the signal, typically to a fixed level. It
would have a loop around it to maintain the output level accurately at all frequencies and
Attenuator: An attenuator is placed on the output of the signal generator. This serves to
ensure accurate source impedance is maintained as well as allowing the generator level to
be adjusted very accurately. In particular the relative power levels i.e. when changing
from one level to another are very accurate and represent the accuracy of the attenuator. It
is worth noting that the output impedance is less accurately defined for the highest signal
levels where the attenuation is less.
Control: Advanced processors are used to ensure that the RF and microwave signal
generator is easy to control and is also able to take remote control commands. The
processor will control all aspects of the operation of the test equipment.
RF signal generator functions:
Microwave and RF signal generators are able to offer a large variety of functions and facilities
these days. These include some that are detailed below:
Frequency range: Naturally the frequency range of the RF signal generator is of
paramount importance. It must be able to cover all the frequencies that are likely to need
to be generated. For example when testing a receiver in an item of equipment, be it a
mobile phone or any other radio receiver, it is necessary to be able to check not only the
operating frequency, but other frequencies where the issues such as image rejection, etc.
Output level: The output range for an RF and microwave signal generator is normally
controlled to a relatively high degree of accuracy. The output within the generator itself is
maintained at a constant level and then passed through a high grade variable attenuator.
These are normally switch to give the highest degree of accuracy. The range is normally
limited at the top end by the final amplifier in the RF signal generator.
Modulation: Some RF or microwave signal generators have inbuilt oscillators that can
apply modulation to the output signal. Others also have the ability to apply modulation
from an external source. With modulation formats for applications such as mobile
communications becoming more complicated, so the capabilities of RF signal generators
have had to become more flexible, some allowing complex modulation formats such as
QPSK, QAM and the like. Signal generators that support complex modulation are often
referred to as vector signal generators.
Sweep: On some RF signal generators it is necessary to sweep the signal over a range.
Some generators offer this capability.
Control: There are many options for controlling RF and microwave signal generators
these days. While they tend to have traditional front panel controls, there are also many
options for remote control. Most items of laboratory bench test equipment come with
GPIB fitted as standard, but options such as RS-232, and Ethernet / LXI. Rack
technologies where instrument cards are slotted into a rack with other items of test
equipment are also popular. The first of these was VXI, but cheaper options such as PXI
and PXI express are more widely used.
Radio frequency signal generators are a form of electronic test equipment found in virtually
every radio frequency design or test laboratory. These signal generators are used wherever an RF
signals needs to be supplied to a circuit or unit that is being developed or tested. As such RF
signal generators are essential items for RF development and testing.
A car wherein the main role is played by rf is called a radio frequency controlled car. This is a
wirelessly controlled car as the name suggests wherein the signals are transmitted and received
through the antenna on both the sides.
There will be two parts in this complete model i.e. transmitter and the receiver. The transmitter
will send the signal which will be received by the receiver and the tasks instructed by the
transmitter will be executed. Here RF method to run the car is selected because it can travel a
longer area as compared to the IR type. Radio frequency are in the waveform which becomes
easy for the signal to get transmitted as they can reach to the receiver via reflection through the
walls. The waveforms do not get distracted so easily on getting hit to the wall. In the IR type
there has to be a sight communication between the transmitter and the receiver to communicate.
IR communications are therefore mainly used in the remote control for the television, air
conditions etc. in this type of transmission if the communicating path is obstructed by any object
be it an opaque, translucent or a transparent device it gets distorted and the complete information
is not transferred. This is also considered as one of the main disadvantages that it needs a sight
communication. The information which is being transmitted through the IR type of
communication technology is not secured as the chance of getting distorted and being lost is
more than compared to that of the RF type communication system.
The transmission of the information being in the sinusoidal waveform doesn‟t get distorted as the
have the tendency to transmit the signal with the help of reflection. If the number of reflections
or hitting increases than some certain decided value the chances of loss of information may arise.
The first advantage of RF over IR is in the improved user experience and much better
RF does not require the typical IR point-and-shoot action anymore. You can walk
anywhere in the house and use the remote.
The RF remote control can transmit its signal through walls, doors and furniture, which
makes it possible to install the set top box in a closed cabinet or a closet.
Another benefit of RF over IR is that RF allows two-way communication and enables a
status display on the remote.
This direct interaction with the end-user will allow the service provider to send messages
to the remote control display.
The combination of non-line-of-sight operation and bi-directional communications also
enables one of the most nerve soothing features of RF remote controls - a simple yet
efficient “find-me” function
The main disadvantage of radio frequency or radio waves is that it is harmful to health and skin
Large doses of radio waves are believed to cause cancer, leukemia and other disorders.
Exposures to RFs have been unofficially linked to sleep disorders, headaches, and other
1. Radio waves have the longest wavelength among the EM waves: from a few centimetres
to several hundred metres.
2. Radio waves are produced by electric current oscillating in electric circuit containing a
coil and a capacitor
3. They are used radio and television communication.
4. Radio waves act as carrier waves for the audio signals and video signals. The advantage
is that the radio signals travel at a speed of 3.0*10^8 m/s.
The process of combining audio and video signal is known as modulation.
Television transmission uses very high frequency (VHF) or ultra-high frequency (UHF) radio
RF Controlled Car
3.1.1 Radio frequency remote control
Radio frequency controlled car is basically divided into two parts i.e. transmitter and the
receiver. Radio frequency remote consists of transmitter at the transmitter end and a receiver at
the receiver end connected, which is connected to a remote circuit that is to be controlled. A
control signal is transferred from transmitter end in the form of electromagnetic waves or radio
waves such that to control the device remotely, which is connected to the receiver end. This
control signal is transmitted using electromagnetic waves or radio waves of radio frequency.
Thus, the control signal received at the receiver end can be used to control.
3.1.2 Radio Frequency Remote Controlled Wireless Car
Radio frequency controlled robotic vehicle is designed using a robotic vehicle that is interfaced
with radio frequency remote control. RF transmitter is used by control panel or controlling
person and RF receiver is connected to the robotic vehicle that is to be controlled remotely.
Radio frequency remote control works over an adequate range by facilitating with proper
3.2 Block diagram
Fig3.1 Block diagram of RF controlled car
The above shown figure is the block diagram of the entire radio frequency controlled car. Here
we are using an ASK transmitter receiver module. Remote which is having a transmitter is used
to transmit the signal from one point to another. There are controlling switches used which are
used pinpoint which way the car should take a turn and move. The supply when applied to the
switches it gives to the encoder which encodes the signal .this encoded signal is then sent to the
RF-Tx transmitter which is used to perform the task of transmitting the signal from one end to
The antenna is attached on both the modules which acts as a source to catch and transmit the
signals. The signal which is transmitted by the transmitter is caught by the receiver in the
receiving section with the help of the antenna. This signal is then sent to the decoder IC .The
decoder sends the signal to the motor driver which then ultimately drives the motor connected to
3.3 Circuit diagram
The circuit if the robot car is divided into two parts (i). Transmitter and (ii) Receiver. The first
circuit diagram is the transmitter and followed by the receiver. The receiver has been supplied
with a voltage regulator IC 7805 which will give a 5 volt DC supply to the circuit from 12 volt
DC main supply.
In the transmitter section circuit has there are 5 switches used in the circuit for controlling the
direction of the car. Four of them are used to give the direction instruction to the receiver and the
fifth switch is used to switch on or off the switching control. It acts as the main switch for the
transmitter section. The diode in the circuit with the help of the logic gates using binary
language instructs the receiver for performing the tasks. Transmitter uses an encoder which IC
i.e. HT-12E which encodes the voltage signal in the binary language which is the connected to
the switches. There is a transmitter ASK-RF-TX used which is capable of sending data to the
Fig3.2 Circuit diagram of RF transmitter section circuit
Fig 3.3 Circuit diagram of RF receiver section circuit
The receiver section has three ICs and one receiver module. It consists of a decoder HT-12D,
driver IC L293D, voltage regulator IC 7805 and the receiver module ASK-RF-Rx. The working
of the car starts with the 7805IC voltage regulator wherein the input voltage given to it is 12 volt
DC and it converts that 12 volt to 5 volt DC. There are two 16 pins ICs as encoder and the
decoder which are connected to the switches and transmitter and to the driver IC along with the
voltage regulator respectively.
Each of the IC has its own basic properties and functions which have been discussed in detail in
the below section. Wireless transmission can be done by using 433 MHz or 315MHz ASK RF
Transmitter and Receiver modules. In these modules digital data is represented by different
amplitudes of the carrier wave, hence this modulation is known as Amplitude Shift Keying
(ASK). Radio Frequency (RF) transmission is more strong and reliable than Infrared (IR)
transmission due to following reasons:
Radio Frequency signals can travel longer distances than Infrared.
Only line of sight communication is possible through Infrared while radio frequency signals can
be transmitted even when there is an obstacle.
Infrared signals will get interfered by other IR sources but signals on one frequency band in RF
will not interfered by other frequency RF signals.
3.4 electronic components and modules used:-
There are many components being used in this project and they are as follows:-
8 Resistors of 560Ω
HT12E encoder IC and HT12D decoder IC,
ASK RF transmitter and receiver,
Robotic Wheels and a battery
Voltage regulator 7805
3.4.1 ASK RF transmitter and receiver
The ASK transmitter Module employs a crystal-stabilized oscillator, ensuring accurate
frequency control for best range performance. There is no requirement of external RF
components except Antenna. Amplitude-shift keying (ASK) is a form of amplitude
modulation that represents digital data as variations in the amplitude of a carrier. In an ASK
system, the binary symbol 1 is represented by transmitting a fixed-amplitude carrier wave and
fixed frequency for a bit duration of T seconds. If the signal value is 1 then the carrier signal will
be transmitted; otherwise, a signal value of 0 will be transmitted.
Fig 3.4 ASK RF module
Fig 3.5 Pins for ASK RF module
This is an ideal for remote control applications where low cost and longer range is required. The
transmitter operates from a 3-12V supply, making it ideal for battery-powered applications. The
transmitter employs a SAW-stabilized oscillator, ensuring accurate frequency control for best
range performance. Range of transmitter is approx 100 meters.
RF Transmitter 433 MHz ASK Features:
Frequency Range: 433.92 MHZ.
Supply Voltage: 3~12V.
Output Power : 4~16dBm
This is an Hybrid 433Mhz RF receiver module and is ideal for short-range wireless control
applications where quality is a primary concern. The receiver module requires no external RF
components except for the antenna. The super-regenerative design exhibits exceptional
sensitivity at a very low cost.
RF Receiver 433 MHz ASK Features:
Integrated IF and data filters.
Receiver Frequency: 433.92 MHZ
Typical sensitivity: -110dBm
Supply Current: 2.85mA
IF Frequency: 280KHz
Low power consumption.
Operation voltage: 5 Volts.
3.4.2 HT12E encoder IC
HT12E is a 212
series encoder IC widely used in remote control and very common among Radio
Frequency RF applications. This HT12E IC capable of converting 12 bit Parallel data inputs into
serial outputs. These bits are classified into 8 (A0-A7) address bits and 4(AD0-AD3) data bits.
Using the address pins we can provide 8 bit security code for secured data transmission between
the encoder and the decoder. The encoder and decoder should use the same address and data
format. HT12E is capable of operating in a wide Voltage range from 2.4V to 12V and also
consists of a built in oscillator.
The figure below will clear this
Fig 3.6 Pin diagram encoder IC
Fig 3.7 Pin diagram encoder IC (zoomed)
The encoder has four input lines. These lines are used to give input which we want to encode. In
encoding, we are wrapping up the data which means if we want to send a binary signal „1001‟ to
other end, we have to make data pins as „1001‟. Now, to make data pin like this, what we need to
do is to give high or 5 volts (which in digital means „1‟) to pins „D0‟ and „D3‟ while we have to
provide pins „D1‟ and „D2‟ with 0 volt. (Ground). This altogether gives us „1001‟ which is
transmitted out from the „Data out‟ pin of the HT12E. The input given to data pin is in parallel
form which is being transmitted into serial form from the data output pin.
PIN DESCRIPTION OF IC HT12E:
The pin Description of the IC HT12E was pretty simple to understand with total of 18 pins.
VDD and VSS: Positive and negative power supply pins.
OSC1 and OSC2: Input and output pins of the internal oscillator present inside the IC.
TE: This pin is used for enabling the transmission; a low signal in this pin will enable the
transmission of data bits.
A0 - A7: These are the input address pins used for secured transmission of this data. These pins
can be connected to VSS or left open.
AD0 - AD3: This pins are feeding data into the IC. These pins may be connected to VSS or
may be left open for sending LOW or HIGH bits to the encoder.
DOUT: The output of the encoder can be obtained through this pin and can be connected to the
Working of IC HT12E:
HT12E starts working with a low signal on the TE pin. After receiving a low signal the HT12E
starts the transmission of 4 data bits. And the output cycle will repeat based on the status of the
TE pin in the IC. If the TE pin retains the low signal the cycle repeats as long as the low signal in
the TE pin exists. The encoder IC will be in standby mode if the TE pin is disabled and thus the
status of this pin was necessary for encoding process. The address of these bits can be set
through A0 - A7 and the same scheme should be used in decoders to retrieve the signal bits.
3.4.3 HT12D decoder IC
HT12D is a 212
series decoder IC for remote control applications. It is commonly used for radio
frequency (RF) wireless applications. By using the paired HT12E encoder and HT12D decoder
we can transmit 12 bits of parallel data serially. HT12D simply converts serial data to its input to
12 bit parallel data. These 12 bit parallel data is divided in to 8 address bits and 4 data bits. Using
8 address bits we can provide 8 bit security code for 4 bit data and can be used to address
multiple receivers by using the same transmitter. The serial input data is compared with the local
addresses three times continuously. The input data code is decoded when no error or unmatched
codes are found. A valid transmission in indicated by a high signal at VT pin.
Fig 3.8 Pin diagram of decoder
Fig 3.9 Pin diagram of decoder (zoomed)
A0~A11 (HT12F) -- Input pins for address A0~A11 setting. These pins can be externally set to
VSS or left open.
A0~A7 (HT12D) -- Input pins for address A0~A7 setting. These pins can be externally set to
VSS or left open.
D8~D11 (HT12D) -- Output data pins, power-on state is low.
DIN Serial data input pin
VT Valid transmission, active high
OSC1 Oscillator input pin
OSC2 Oscillator output pin
VSS - Negative power supply, ground
VDD - Positive power supply
3.4.4 Driver IC L293D:-
Motor Driver ICs are primarily used in autonomous robotics only. Also most microprocessors
operate at low voltages and require a small amount of current to operate while the motors require
a relatively higher voltages and current. Thus current cannot be supplied to the motors from the
microprocessor. This is the primary need for the motor driver IC.
The L293D IC receives signals from the decoder and transmits the relative signal to the motors.
It has two voltage pins, one of which is used to draw current for the working of the L293D and
the other is used to apply voltage to the motors. The L293D switches it output signal according
to the input received from the decoder. For Example: If the decoder sends a 1(digital high) to the
Input Pin of L293D, then the L293D transmits a 1(digital high) to the motor from its Output Pin.
An important thing to note is that the L293D simply transmits the signal it receives. It does not
change the signal in any case.
The L293D is a 16 pin IC, with eight pins, on each side, dedicated to the controlling of a motor.
There are 2 INPUT pins, 2 OUTPUT pins and 1 ENABLE pin for each motor.
Fig 3.10 Pin diagram if driver IC L293D
Pin No. Pin Characteristics
Enable 1-2, when this is HIGH the left part of the IC will work and when it is low the
left part won‟t work. So, this is the Master Control pin for the left part of IC
2 INPUT 1, when this pin is HIGH the current will flow though output 1
3 OUTPUT 1, this pin should be connected to one of the terminal of motor
4,5 GND, ground pins
6 OUTPUT 2, this pin should be connected to one of the terminal of motor
7 INPUT 2, when this pin is HIGH the current will flow though output 2
VC, this is the voltage which will be supplied to the motor. So, if you are driving 12 V
DC motors then make sure that this pin is supplied with 12 V
16 VSS, this is the power source to the IC. So, this pin should be supplied with 5 V
15 INPUT 4, when this pin is HIGH the current will flow though output 4
14 OUTPUT 4, this pin should be connected to one of the terminal of motor
13,12 GND, ground pins
11 OUTPUT 3, this pin should be connected to one of the terminal of motor
10 INPUT 3, when this pin is HIGH the current will flow though output 3
Enable 3-4, when this is HIGH the right part of the IC will work and when it is low the
right part won‟t work. So, this is the Master Control pin for the right part of IC
Table 3.1 Pin functions of L293D
Now depending upon the values of the Input and Enable the motors will rotate in either
clockwise or anticlockwise direction with full speed (when Enable is HIGH) or with less speed
(when Enable is provided with PWM). Let us assume for Left Motor when Enable is HIGH and
Input 1 and Input 2 are HIGH and LOW respectively then the motor will move in clockwise
direction. So the behaviour of the motor depending on the input conditions will be as follows:
INPUT 1 INPUT 2 ENABLE 1,2 Result
0 0 1 Stop
0 1 1 Anti-clockwise rotation
1 0 1 Clockwise rotation
1 1 1 Stop
0 1 50% duty cycle Anti-clockwise rotation with half speed
1 0 50% duty cycle Clockwise rotation with half speed
Table 3.2 Logic of driver IC
3.4.5 Voltage Regulators
Voltage regulator IC's are the IC‟s that are used to regulate voltage. IC 7805 is a 5V Voltage
Regulator that restricts the voltage output to 5V and draws 5V regulated power supply. It comes
with provision to add heat sink.
The maximum value for input to the voltage regulator is 35V. It can provide a constant
steady voltage flow of 5V for higher voltage input till the threshold limit of 35V. If the voltage is
near to 7.5V then it does not produce any heat and hence no need for heat sink. If the voltage
input is more, then excess electricity is liberated as heat from 7805.
Fig 3.11:-circuit of 7805 voltage regulator
It regulates a steady output of 5V if the input voltage is in rage of 7.2V to 35V. Hence to
avoid power loss try to maintain the input to 7.2V. In some circuitry voltage fluctuation is fatal
(for e.g. Microcontroller), for such situation to ensure constant voltage IC 7805 Voltage
Regulator is used.
IC 7805 is a series of 78XX voltage regulators. It‟s a standard, from the name the last two
digits 05 denotes the amount of voltage that it regulates. Hence a 7805 would regulate 5v and
7806 would regulate 6V and so on.
The schematic given below shows how to use a 7805 IC, there are 3 pins in IC 7805, pin 1 takes
the input voltage and pin 3 produces the output voltage. The GND of both input and out are
given to pin 2.
Fig 3.12 IC 7805 voltage regulator
Result and Analysis
INPUT 1 INPUT 2 ENABLE 1,2 Result
0 0 1 Stop
0 1 1 Anti-clockwise rotation
1 0 1 Clockwise rotation
1 1 1 Stop
0 1 50% duty cycle Anti-clockwise rotation with half speed
1 0 50% duty cycle Clockwise rotation with half speed
Table 4.1:- logic of driver IC
Here the above table which is been shown gives the logic calculation of the instruction that are
given. As the instruction that are given to the driver IC it gives the directional rotation to the
motor and thus when two motor are rotate in certain direction the car also moves in its specified
Left Motor Direction Right Motor Direction Direction of Car
Forward Forward Forward
Forward Backward Right
Backward Forward Left
Backward Backward Backward
Table 4.2 Direction of the car
The car which has been designed in the project consisting of two modules namely: transmitter
and the receiver send the signals from one end to another and due to this the motor on getting the
signals the motor drives in either forward or reverse direction.
If both the motor i.e. left and right moves in the forward direction then the direction of
the car is in the forward direction.
When the left motor moves in the forward direction and the right motor in the reversed
direction then the resultant direction of the car will be in the right direction.
The left motor moving in the reversed direction and the right motor in the forward
direction then the final direction of the car will be in the left direction.
And finally when both the motor i.e. left and the right move in the reversed direction then
the ultimately direction of the car will be in the reversed direction.
From the project made it is understood that the use of the radio frequency can be used in the
driving a simple robot car with the use of transmitter and receiver. The driver IC which is being
connected to the decoder is also a great help to the project which can get programmed and can
give out the called instruction for various occasions signaled by the transmitter with the help of
antenna and the encoder.
The voltage regulator on getting a power supply gives out a stable dc voltage of 5 volt. This
prevents the other components especially the decoder and the receiver module from the getting
The led in the receiver circuit gives an ease in understanding about the receiving of the signal
from the transmitter end. This led when glows it indicates that the signal is transmitted.
Conclusion and future scope
A transmitter on the one side sends the radio signals to the receiver end. The antenna on both the
side of the module are used as a help to catch the signals which are been transmitted through the
transmitter. The receivers on receiving the signal with the help of the decoder decode the signal
and are transmitted to the motor driver IC. The motors which are connected to the driver IC on
getting the logic signals turns on and gives the direction to the car.
5.2 Future Scope
Radio frequency which helps in the communication of the information has increased its value for
the use of the same in future. With the advancement of technology in the radio frequency a
gesture control robot is one of the finest projects which can be worked upon. Herein the gestures
gives out by the person are sensed by the RF module which performs the task as shown by the