[Project report]digital speedometer with password enabled speed controlling(1)dip

DIGITAL SPEEDOMETER WITH PASSWORD
ENABLE SPEED CONTROLLING
A PROJECT REPORT
ABSTRACT
The main aim of this project is to design a digital speedometer with
password enabled with speed limit controlling. This simple system shows the
ability to apply speed limit controlling techniques to the vehicle. Our digital
speedometer takes input from vehicle speedometer cable and executes the speed
limit controlling action.
The system comprises of keypad, LCD display and microcontroller unit. The
user interface includes keypad through which the password will be accepted by the
microcontroller. Microcontroller controls the over speed of vehicle.

List of Figures
Figure No. Figure Description Page No.
2.1 Basic Block Diagram 3
2.2 Circuit Diagram 4
2.3 Circuit Diagram of Speed Sensor input 5
2.4 Pin Diagram of IC LM324 7
2.5 Block Diagram of AT80S52 9
2.6 Pin Diagram of AT80S52 10
2.7 Pin Diagram of IC7805 15
2.8 Pin Diagram of EL1602 LCD 16
2.9 Circuit Diagram of keypad 18
2.10 Flowchart 19

List of Tables
Table No. Table Description Page No.
2.1 Pin Description of LM324 8
2.2 Pin Description of IC7805 16
2.3 Pin Description of EL1602 LCD 17
2.4 Keypad Output Arrangement 18

List of Abbreviation
Sr no. Short form Full form
1 LCD Liquid crystal display
2 LED Light emitting diode
3 OP-AMP Operational amplifier
4 RAM Random access memory
5 TTL Transistor transistor logic
6 IIL Integrated input logic
7 SFR Special function resister
8 ALE Address Latch Enable
9 PSEN Program Store Enable
10 EA External Access
11 ISP In-System Programmable
12 ASCII American standard coded
for information
interchange
13 PCB Printed circuit board

CONTENTS PAGE NO.
1 : Introduction 1
2 : Problem Identification & Methodology 2
2. Aim 2
2.1 Purpose 2
2.2 Working principle 2
2.3 System design 3
2.4 Working 6
2.4.1 IC LM324 7
2.4.2 Microcontroller AT80S52 9
2.4.2.1 PIN Description of AT80S52 11
2.4.2.2 Features of AT80S52 14
2.4.3 IC7805 15
2.4.4 EL1602 LCD 16
2.4.5 Keypad 18
3 : Software (as per project) 19
3.1 Flowchart 19
3.2 Program 20
4 : Application and Merits/demerits 25
4.1 Application 25
4.2 Merits 25
4.3 Demerits 25
4.4 Conclusion 25
5 : References 26
6 : Appendix 26

Chapter 1 : Introduction
1. INTRODUCTION
Digital speedometer with password and speed limit controlling is different think and technology
for automobiles. This instrument is normally used in maintaining the speed in that your vehicle is
operating, and is extremely useful in roadways and highways that have a fixed speed limit. The
system generally consists of numerical keypad, LCD and microcontroller unit. The speed sensor
system is easy to build. LCD and keypad are interfaced with microcontroller using program.
Keypad allows us to enter password to access the vehicle. Instead of the numerical password we
can also use the finger print scanner as a password. This speedometer system can be used in any
vehicle like bikes, cars, trucks, buses and any kind of vehicle. This system is very useful for the
beginner drivers and who drives over speedy in city and highways.
This research details the construction and building of a digital speedometer circuit that may be
interfaced to control the speed limit of vehicle. The circuit is trained to calculate the speed and
check that it is under speed limit or not. If it is over speedy than circuit controls the speed
automatically. This system increases the vehicle fuel efficiency and life.
Currently most vehicles are provided with analog speedometer which is less accurate than digital
speedometer. Also many vehicles are provided digital speedometer. The limitation of this
speedometer is that they don’ t have speed controlling facility. This limitation is overcome in
our project.

Chapter 2 : PROBLEM IDENTIFICATION &
METHODOLOGY
2. AIM
The aim of our project is to design a digital speedometer with password enable speed
controlling. Our speedometer can calculate and display the speed of vehicle and also control the
speed if it goes over speed.
2.1 PURPOSE
The purpose of the project is to develop a system, which to control the speed of vehicle in order
to avoid accidents occur.
2.2 WORKING PRINCIPAL
The system takes password input and check it is correct or not, if it is true than allows to drive
over speed but if it is false than activate the speed limit function.
The speed is sensed in form of pulse by op-amp comparator and given to microcontroller which
calculates the pulses per second and display the speed. It also compares the speed with stored
speed limit data and if it is over the speed limit than turn off the relay which is connected with
the ignition power supply. So speed will decreases and when it comes below speed limit than
turn on supply and continues.

2.3 SYSTEM DESIGN
This part introduces our approach of creating a system of a Digital speedometer which is
password enabled with speed controlling function.
Fig.2.1 Basic Block Diagram of Digital Speedometer with Password Enable Speed
Controlling

Fig.2.3 Circuit Diagram of Speed Sensor input

2.4 WORKING
A digital speedometer is an instrument in a vehicle that is used for indicating the speed in which
it is actually traveling. It is at the same time useful for knowing the range that was traveled by
the vehicle.
First when the key is turn on a message “ ENTER PASSWORD” is displayed on the EL1602
16*2 LCD. The password is entered using 3*4 numeric keypad. Pre-defined password is stored
in the memory of microcontroller AT80S52. Entered password is compared with stored
password. If it’ s true than display the second menu display “ Drive” , “ Setting” . The setting
menu includes the facility to change the speed limit and password. By entering in the “ Drive”
menu user can drive above the speed limit.
If the password is false than system turn on the speed limit function, in which speed is
continuously compared with the stored speed limit and displayed on LCD. If speed is above the
limit than system turn off the relay which is connected with the ignition power supply, so power
is disconnected and speed decreases. Now, when speed comes below the speed limit, system turn
on the relay and continuously follows this process.
At speed sensor pulses are generated using infrared LED and receiver. It can be also generated
by using magnetic reed relay sensor. These pulses are given at the op-amp LM324 comparator
which produces pulse train. These pulses given to pin no.14, 15 of port 3.4 & 3.5 of
microcontroller 8052.
With the help of pulse input we can calculate the speed by calculating the frequency at input.
This frequency is multiplied by the distance travel by wheel in one rotation. The calculations are
as follow:
Circumference of the wheel= 2πr (where ‘r’ is in cm)
= 2×3.14×30

= 188.4 cm or 1.884 meters
Let’s assume that in 1 second the wheel completes one revolution. In other words, in one second,
the bike has covered 1.88 meters.
Therefore the speed in km/hour:
=N×1.88×3600/1000
= N×6.784 or N×6.8
Where ‘ N’ is the number of revolutions per second.
‘ 6.8’ is a constant and only ‘ N’ varies;
For example, if ‘ N’ is 5, the speed equals 5x6.8= 34 km/hour.
Lcd port 1
Keypad port 2.0 to 2.6
Output port 2.7
Input port 3.2 or port 3.3
2.4.1 IC LM324
LM324 is a 14pin IC consisting of four independent operational amplifiers (op-amps)
compensated in a single package. Op-amps are high gain electronic voltage amplifier with
differential input and, usually, a single-ended output. The output voltage is many times higher
than the voltage difference between input terminals of an op-amp.

Fig 2.4 Pin Diagram of IC LM324
These op-amps are operated by a single power supply LM324 and need for a dual supply is
eliminated. They can be used as amplifiers, comparators, oscillators, rectifiers etc. The
conventional op-amp applications can be more easily implemented with LM324.
Table 2.1: Pin Description of LM324
Pin
No
Function Name
1 Output of 1st comparator Output 1
2 Inverting input of 1st comparator Input 1-
3 Non-inverting input of 1st comparator Input 1+
4 Supply voltage; 5V (up to 32V) Vcc
5 Non-inverting input of 2nd comparator Input 2+
6 Inverting input of 2nd comparator Input 2-

7 Output of 2nd comparator Output 2
8 Output of 3rd comparator Output 3
9 Inverting input of 3rd comparator Input 3-
10 Non-inverting input of 3rd comparator Input 3+
11 Ground (0V) Ground
12 Non-inverting input of 4th comparator Input 4+
13 Inverting input of 4th comparator Input 4-
14 Output of 4th comparator Output 4

2.4.2 MICROCONTROLLER AT80S52
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-
system programmable Flash memory. The device is manufactured using Atmel’ s high density
nonvolatile memory technology and is compatible with the industry standard 80C51 instruction
set and pin out. The on chip Flash allows the program memory to be reprogrammed in-system
or by a conventional nonvolatile memory programmer.

Fig 2.5 Block Diagram of AT80S52
By combining a versatile 8-bit CPU within system programmable Flash on a monolithic chip, the
Atmel AT89S52 is a powerful microcontroller which provides a highly flexible and cost effective
solution to many embedded control applications.
The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32
I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six vector two level
interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In
addition, the AT89S52 is designed with static logic for operation down to zero frequency and
supports two software selectable power saving modes. The Idle Mode stops the CPU while
allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning.
The Power down mode saves the RAM contents but freezes the oscillator, disabling all other
chip functions until the next interrupt or hardware reset.

Fig 2.6 PIN Diagram of AT80S52
2.4.2.1 PIN Description of AT80S52
VCC
Supply voltage.
Port 0
Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can sink eight
TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs.
Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses
to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also
receives the code bytes during Flash programming and outputs the code bytes during program
verification.

Port 1
Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output buffers can
sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the
internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being
pulled low will source current (IIL) because of the internal pull-ups. In addition, P1.0 and P1.1
can be configured to be the timer/counter 2 external count input (P1.0/T2) and the
timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 1
also receives the low-order address bytes during Flash programming and verification.
Port Pin Alternate Functions
P1.0 T2 (external count input to Timer/Counter 2), clock-out
P1.1 T2EX (Timer/Counter 2 capture/reload trigger and direction control)
P1.5 MOSI (used for In-System Programming)
P1.6 MISO (used for In-System Programming)
P1.7 SCK (used for In-System Programming)
Port 2
pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order
address byte during fetches from external program memory and during accesses to external
data memory that uses 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong
internal pull-ups when emitting 1s. During accesses to external data memory that uses 8-bit
addresses (MOVX @ RI) Port 2 emits the contents of the P2 Special Function Register. Port 2
also receives the high-order address bits and some control signals during Flash programming
and verification.

Port 3
pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals
for Flash programming and verification. Port 3 also serves the functions of various special
features of the AT89S52, as shown in the following table.
Port Pin Alternate Functions
P3.0 RXD (serial input port)
P3.1 TXD (serial output port)
P3.2 INT0 (external interrupt 0)
P3.3 INT1 (external interrupt 1)
P3.4 T0 (timer 0 external input)
P3.5 T1 (timer 1 external input)
P3.6 WR (external data memory write strobe)
P3.7 RD (external data memory read strobe)
RST
Reset input. A high on this pin for two machine cycles while the oscillator is running resets the
device. This pin drives high for 98 oscillator periods after the Watchdog times out. The DISRTO
bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit
DISRTO, the RESET HIGH out feature is enabled.
ALE/PROG’
Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during
accesses to external memory. This pin is also the program pulse input (PROG) during Flash

programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator
frequency and may be used for external timing or clocking purposes. Note, however, that one
ALE pulse is skipped during each access to external data memory. If desired, ALE operation can
be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a
MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit
has no effect if the microcontroller is in external execution mode.
PSEN
Program Store Enable (PSEN) is the read strobe to external program memory. When the
AT89S52 is executing code from external program memory, PSEN is activated twice each
machine cycle, except that two PSEN activations are skipped during each access to external
data memory.
EA/VPP
External Access Enable. EA must be strapped to GND in order to enable the device to fetch code
from external program memory locations starting at 0000H up to FFFFH. Note, however, that if
lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC
for internal program executions. This pin also receives the 12-volt programming enable voltage
(VPP) during Flash programming.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
2.4.2.2 Features of AT80S52

• Compatible with MCS®-51 Products
• 8K Bytes of In-System Programmable (ISP) Flash Memory
• 4.0V to 5.5V Operating Range
• Fully Static Operation: 0 Hz to 33 MHz
• Three-level Program Memory Lock
• 256 x 8-bit Internal RAM
• 32 Programmable I/O Lines
• Three 16-bit Timer/Counters
• Eight Interrupt Sources
• Full Duplex UART Serial Channel
• Low-power Idle and Power-down Modes
• Interrupt Recovery from Power-down Mode
• Watchdog Timer
• Dual Data Pointer

2.4.3 IC7805
7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear
voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give
the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant
value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides
+5V regulated power supply. Capacitors of suitable values can be connected at input and
output pins depending upon the respective voltage levels.
Fig 2.7 PIN Diagram of IC7805

Table 2.2: Pin Description of IC7805
Pin No Function Name
1 Input voltage (5V-18V) Input
2 Ground (0V) Ground
3 Regulated output; 5V (4.8V-5.2V) Output
2.4.4 EL1602 LCD
LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of
applications. A 16x2 LCD display is very basic module and is very commonly used in various
devices and circuits. These modules are preferred over seven segments and other multi
segment LEDs. The reasons being: LCDs are economical; easily programmable; have no
limitation of displaying special & even custom characters (unlike in seven segments),
animations and so on.

Fig 2.8 Pin Diagram of EL1602 LCD
A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD
each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command
and Data.
The command register stores the command instructions given to the LCD. A command is an
instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the
cursor position, controlling display etc. The data register stores the data to be displayed on the
LCD. The data is the ASCII value of the character to be displayed on the LCD. Click to learn more
about internal structure of a LCD.
Table 2.3 Pin Description of EL1602 LCD
Pin No. Symbol Level Description
1 Vss 0V Ground
2 Vdd 5.0V Supply Voltage for logic (option +3V)
3 Vo (Variable) Operating voltage for LCD
4 RS H/L H:DATA, L:Instruction code
5 R/W H/L H:Read(MPU->Module)L:Write(MPU->Module)
6 E H,H->L Chip enable signal
7 DB0 H/L Data bit 0
15 A/ Vee - Power supply for LED backlight ( + ) /Negative voltage
output

16 K - Power supply for LED backlight (GND )
2.4.5 KEYPAD
A low profile 3 x 4 keypad of compact size suitable for use on hand held and other small
equipment. A single rectangular cut is required to fit the keypad through the front panel and four
mounting holes are required for the retention of the keypad. The conductive rubber contacts
require a low operating force, but have a positive action to give the operator feedback.
Connections are terminated to solder pads on the PCB at the lower edge of the switch.
Fig 2.9 Circuit Diagram of keypad
Table 2.4 KEYPAD OUTPUT ARRANGEMENT
Output pin no. Symbols
1 -
2 Col. 2
3 Row 1
4 Col. 1
5 Row 4
6 Col. 3

7 Row 3
8 Row 2
9 -
10 -
Chapter 3 : Software
3.1. FLOWCHART
Start
Enter password
Turn on relay
Check speed
<=speed limit
Turn off relayTurn on relay
Enter no.
1.Drive
2.setting
Turn on relay
End
1.New password
2. New limit
New password New limit
Display speed
Display speedDisplay speed
No
Yes
False True
1 2
1 2

3.2. PROGRAM
#include<stdio.h>
#include<conio.h>
void main()
{
int a=1234,b,c,g,e,f,sl,ch,ca;
// char ch,ca;
clrscr();
printf("Enter the password : ");
scanf("%d",&b);
if(a==b)
{
printf("1. Main menu ");
printf("n2. Drive menu");
printf("nEnter your choice : ");
scanf("%d",&ch);
switch (ch)
{

case 1:
printf("n 1. Change Password ");
printf("n 2. Change Speed limite ");
printf("nEnter your choice : ");
scanf("%d",&ca);
switch (ca)
{
case 1:
printf("Enter your current password : ");
scanf("%d",&c);
if (a==c)
{
printf("nEnter your new password : ");
scanf("%d",g);
printf("nRe-enetr the password : ");
scanf("%d",e);
if (g==e)

{
printf("nYour password changed
successfully.");
}
else
{
printf("nPassword do not
match...");
}
}
else
{
printf("nYou enter the wrong
password...");
}
break;
case 2:
printf("nEnter your password : ");
scanf("%d",&f);

if(a==f)
{
printf("nEnter your new speed limit : ");
scanf("%d",&sl);
printf("Your speed limit changed
successfully.. ");
}
else
{
printf("You entered the wrong
password...");
}
break;
default:
printf("n Incorrect choice");
break;
}
break;
case 2:

printf("n Do you want to over drive?");
printf("n 1. Yes");
printf("n 2. No");
printf("n Enter your choice : ");
break;
default:
printf("n Incorrect choice");
break;
}
}
else
printf("Incorrect passwrd");
getch();
}

Chapter 4 : Application and Merits/demerits
4.1 APPLICATION
 In vehicles to display speed
 In vehicles as speed protector
 It can be used to control the speed of heavy motor and drive speed
4.2 MERITS
 Easy user interface
 Speed is easy to read due to back lighted LCD
 Prevent accidents at high speed
 Consumption of fuel is less
 Password protection
4.3 DEMERITS
 If microcontroller fails than we can’ t start the vehicle
 Time consuming
4.4 CONCLUSION
By this digital speedometer we can control the over speed of vehicle and also protect it from
theft. By it we observe that consumption of fuel will decreases.

REFERENCES
[1].Muhammad ali mazidi, “ The 8051 microcontroller & embedded systems” , Pearson, 2nd
edition.
[2]. www.howstuffworks.com
[3]. www.wikipedia.org
[4]. www.engineersgarage.com
APPENDIX

[Project report]digital speedometer with password enabled speed controlling(1)dip

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