Shri Vaishnav Institute of Technology and Science, Indore
(M.P.)
A Major Project Report onTYRE PRESSURE MONITORING
SYSTEMsubmitted as a partial fulfilment for Degree of
Bachelor of EngineeringInELECTRONICS & INSTRUMENTATION
ENGINEERING (Session: 2013-2014)
Guided by Submitted by
Mr Namit Gupta Shruti Gajbhiye Head of Department (0802EI101079)
S.V.I.T.S. Indore
Mr Chintan Patel Assistant Professor Rachana Jatwa S.V.I.T.S.
Indore (0802EI101079)
Shri Vaishnav Institute of Technology and Science Indore
(M.P.)
CERTIFICATEThis is to certify that the project entitledTIRE
PRESSURE MONITORING SYSTEM which is being submitted by Shruti
Gajbhiye(0802EI101070),Rachana Jatwa (0802EI101063), in the partial
fulfilment for the award of degree of Bachelor of Engineering from
Rajiv Gandhi Proudyogiki Vishwavidhyalaya, Bhopal M.P., is a record
of students own work carried by them under my guidance and
supervision.
Prof. Namit Gupta External Examiner Mr. Chintan PatelHead of
Department Project GuideS.V.I.T.S. Indore S.V.I.T.S. Indore
Ms Ishita Bhatnagar Mrs Neha MaheshwariProject Co-ordinator
Project Co-ordinatorS.V.I.T.S Indore S.V.I.T.S IndoreShri Vaishnav
Institute of Technology and Science Indore (M.P.)
DECLARATION
The project report entitledTYRE PRESSURE MONITORING
SYSTEMsubmitted by Shruti Gajbhiye (0802EI101070) and Rachana Jatwa
(0802EI101063), in the partial fulfilment for the award of degree
of Bachelor of Engineering from Rajiv Gandhi Proudyogiki
Vishwavidhyalaya, Bhopal M.P., is a record of our own work carried
by us under the guidance and supervision of our guide in the
Electronics and Instrumentation Department, S.V.I.T.S Indore .
SHRUTI GAJBHIYE RACHANA JATWA(0802EI101079) (0802EI101063)
Prof. Namit Gupta External Examiner Mr. Chintan patel Head of
Department Project GuideS.V.I.T.S. Indore S.V.I.T.S. Indore
ACKNOWLEDGMENT
We take great pleasure in expressing our deep sense of gratitude
to our esteemed institute Shri Vaishnav Institute of Technology and
Science for providing us the opportunity to complete this
project.
We are grateful to our project guide Mr. Chintan Patel, project
co-ordinator Ms. Ishita Bhatnagar and Mrs Neha Maheshwari and our
HOD Prof. Namit Gupta and our Director Dr. ING V.P. Singh for their
benevolence, kindness, help and guidance.
We also thank all the faculty members of our department for
helping us in completing the project successfully and for their
motivation.
Shruti Gajbhiye (0802EI101079) Rachana Jatwa (0802EI101063)
ABSTRACT
The project proposes a method to implement Tire Pressure
Monitoring System (TPMS) in vehicles. TPMS measures the air
pressure inside pneumatic tires of automobiles. The proposed TPMS
has an electronic unit that directly screws onto the stem of tire.
The unit includes a pressure transducer, microcontroller, RF
communication unit. Main components need to be calibrated to ensure
the consistency and precision of the prototype in reporting the
pressure. Calibration for pressure sensor is performed by simply
applying a known value of pressure and the output voltage is
measured. An on-board RF receiver communicates with the TPMS unit
and displays real-time tire pressure of all tires. The unit can be
easily detached and re-attached to the tire. Modification to the
tire is not required. Improper tire pressure is a safety issue that
is often overlooked or ignored. A drop in tire pressure by just a
few pounds per square inch (PSI) can result in the reduction of gas
mileage, tire life, safety, and vehicle performance. Correct tire
pressure is a critical factor in the safe operation and performance
of a motor vehicle. Over inflated tires often result in unnecessary
tire wear.Ease of use and understanding will create a system that
will minimize some of the possible dangers drivers face on the road
each day. System measures Pressure Wireless RF communications Tire
Interchangeability Light and Low Power Sensor System
CONTENTS
1) Introduction 1.1 Objective 1.2 Background 1.3 Project Scope
1.4 Components used
2) Block Diagram & Working
3) Technological Overview 3.1Pressure Transducer3.2
Microcontroller used3.3 RF communication unit
4) Hardware and Software specification 4.1 Introduction 4.2
Hardware 4.3 Software
5) Layout Design 5.1 Circuit Diagram 5.2 PCB Layout
6) Conclusion 7) Bibliography 8) Data Sheets
Chapter 1
INTRODUCTION
1.1 OBJECTIVE The objective of the project is to develop and
implement a tire pressure monitoring system.
1.2 BACKGROUND
A tire pressure monitoring system (TPMS) monitors air pressure
in the tires of a motor vehicle, and that generates a signal
indicative of the tire pressure in each of the tires to increase
the vehicle performance and safety. Correct tire pressure is a
critical factor in the safe operation and performance of a motor
vehicle. Over inflated tires often result in unnecessary tire wear,
reduced gas mileage and less than optimal vehicle performance as
well as vehicle safety.
This system is based on direct method of tire pressure
measurement. This system contains a direct tire pressure monitoring
principle, RF communication link and display unit for monitoring
the pressure of the tire. TPMS was introduced by General Motors in
March 1997 for the 5th generation (C5) Corvette in conjunction with
Goodyear run flat tires. The system uses sensors in the wheels and
a driver display which can show tire pressure at any wheel, plus
warnings for both high and low pressure.
1.3 PROJECT SCOPEThere are many ways to design and develop a
TPMS. This project requires extensive research that might widen up
the scope. Hence, the projects scope needs to be defined first in
order for this project to reach its objectives. Transmitting and
detection unit could be installed outside the tire, but this will
increases the risk of being damaged by external environment and
even get stolen. Hence, the proper position of the unit would be
inside the tyre where the measurement of the pressure value is
directly obtained. In order to place the transmitting and detection
unit inside the tire, considerations of size of the unit needs to
be taken. The size should be small enough to fit in inside the
tire. There are many ways to achieve wireless transmission. But
this project will be dedicated in using radio frequency method,
where receiver and transmitter are needed. Sensor is integrated
with the transmitting and detection unit, thus it requires power
supply. Traditional direct TPMS using battery as the solution but
it has a few problems. Hence, this project will design a system
that does not require battery. One of the alternatives is by using
piezoelectric method. When stress or pressure is applied on the
piezoelectric material, electric current will be produced. This
current will be used to power the transmitting and detection
unit.
1.4COMPONENTS USED:
1) PRESSURE TRANSDUCER(MPX2010DP)
2) MICROCONTROLLER(PIC16F877A)
3) RF COMMUNICATION UNIT(CC2500)
RF MODULE
PRESSURE TRANSDUCER
Chapter 2BLOCK DIAGRAM & WORKING
Display (lcd 16*2)Receiver RF module(cc2500)Microcontoller Lcd
Driver(PIC16F877A)
RECIEVER SECTION
WORKING
The sensor in the transmitting converts variation of the tyre
pressure into electric parameters which vary accordingly to
electronic component induction. Then, the electric parameters are
processed by a MCU in the transmitting and detection unit into
digital code signals. After identification of the ID of the digital
code signals in this unit) is completed, these code signals are
transmitted via a carrier frequency by a transmitter.
PIC16F877A microcontroller IC, PIC16F877A is an 8-bit
microcontroller with 8k14-bit flash program memory, 368 bytes of
RAM and many other extra peripherals like ADC, universal
synchronous asynchronous receiver transmitter, master synchronous
serial port, timers, compare capture and pulse-width modulation
modules, and analogue comparators. It is based on the reduced
instruction set computer (RISC) architecture.
The original data is recovered after the radio signals are
received and demodulated by the receiver antenna . Then, after
being processed by the MCU of receiving and display unit, the data
is displayed on the display screen. When the received data shows
the pressure in the tire lower or higher than the set limit, the
MCU will show on the display screen.
Chapter 3
TECHNOLOGICALOVERVIEW
3. TECHNOLOGICAL OVERVIEW:
3.1 PRESSURE SENSOR
The MPX2010DP silicon piezoresistive pressure sensors provide a
very accurate and linear voltage output directly proportional to
the applied pressure. These sensors house a single monolithic
silicon die with the strain gauge and thin film resistor network
integrated. The sensor is laser trimmed for precise span, offset
calibration.
Voltage Output versus Applied Differential PressureThe output
voltage of the differential or gauge sensor increases with
increasing pressure applied to the pressure side (P1) relative to
the vacuum side (P2). Similarly, output voltage increases as
increasing vacuum is applied to the vacuum side (P2) relative to
the pressure side (P1)
The Freescale MPX2010DP differential pressure sensor is
electrically equivalent to the 4-arm bridge circuit. From this
circuit, it can be seen that the output voltage from the pressure
sensor (taken between pins 2 and 4) is proportional to the DC power
supply voltage (applied between pins 3 and 1):
The pressure sensor is specified to output 25 mV when a
full-scale differential pressure of 1.45 psi is applied, when the
sensor is powered up by 10.0 VDC. However, only a +9.0 V battery is
available to operate the circuit.
The essence of piezoresistive pressure sensors is the Wheatstone
bridge. Bridge resistors R1,R2, R3 and R4 are arranged on a thin
silicon diaphragm such that when pressure is applied R1 and R2
increase in value while R3 and R4 decrease a similar amount.
Pressure on the diaphragm, therefore, unbalances the bridge and
produces a differential output signal. One of the fundamental
properties of this structure is that the differential output
voltage is directly proportional to bias voltage B+
OUTPUT VS PRESSURE
3.2 MICROCONTROLLER-PIC16F877A:PICis a family ofmodified Harvard
architecturemicrocontrollersmade byMicrochip Technology, derived
from the PIC1650originally developed byGeneral Instrument's
Microelectronics Division. The name PIC initially referred to
"Peripheral Interface Controller'" now it is "PIC'" only.PICs are
popular with both industrial developers and hobbyists alike due to
their low cost, wide availability, large user base, extensive
collection of application notes, availability of low cost or free
development tools, and serial programming (and re-programming with
flash memory) capability.The PIC16F887 is one of the latest
products fromMicrochip. It features all the components which modern
microcontrollers normally have. For its low price, wide range of
application, high quality and easy availability, it is an ideal
solution in applications such as: the control of different
processes in industry, machine control devices, measurement of
different values etc. Some of its main features are listed below.
RISC architecture Only 35 instructions to learn All single-cycle
instructions except branches Operating frequency 0-20 MHz Precision
internal oscillator Factory calibrated Software selectable
frequency range of 8MHz to 31KHz Power supply voltage 2.0-5.5V
Consumption: 220uA (2.0V, 4MHz), 11uA (2.0 V, 32 KHz) 50nA
(stand-by mode) Power-Saving Sleep Mode Brown-out Reset (BOR) with
software control option 35 input/output pins High current
source/sink for direct LED drive software and individually
programmablepull-upresistor Interrupt-on-Change pin 8K ROM memory
in FLASH technology Chip can be reprogrammed up to 100.000 times
In-Circuit Serial ProgrammingOption Chip can be programmed even
embedded in the target device 256 bytes EEPROM memory Data can be
written more than 1.000.000 times 368 bytes RAM memory A/D
converter: 14-channels 10-bit resolution 3 independent
timers/counters Watch-dog timer Analogue comparator module with Two
analogue comparators Fixed voltage reference (0.6V) Programmable
on-chip voltage reference PWM output steering control Enhanced
USART module Supports RS-485, RS-232 and LIN2.0 Auto-Baud
Detect
BLOCK DIAGRAM
Central Processor Unit (CPU) It is important to state that the
CPU is manufactured with in RISC technology an important factor
when deciding which microprocessor to use.RISCReduced Instruction
Set Computer, gives the PIC16F887 two great advantages: The CPU can
recognize only 35 simple instructions (In order to program some
other microcontrollers it is necessary to know more than 200
instructions by heart). The execution time is the same for all
instructions except two and lasts 4 clock cycles (oscillator
frequency is stabilized by a quartz crystal). The Jump and Branch
instructions execution time is 2 clock cycles. It means that if the
microcontrollers operating speed is 20MHz, execution time of each
instruction will be 200nS, i.e. the program will be executed at the
speed of 5 million instructions per second!
Fig. 1-4 CPU Memory
MemoryThis microcontroller has three types of memory- ROM, RAM
and EEPROM. All of them will be separately discussed since each has
specific functions, features and organization.ROM MemoryROM memory
is used to permanently save the program being executed. This is why
it is often called program memory. The PIC16F887 has 8Kb of ROM (in
total of 8192 locations). Since this ROM is made with FLASH
technology, its contents can be changed by providing a special
programming voltage (13V).
ROM Memory Concept
EEPROM MemorySimilar to program memory, the contents of EEPROM
is permanently saved, even the power goes off. However, unlike ROM,
the contents of the EEPROM can be changed during operation of the
microcontroller. That is why this memory (256 locations) is a
perfect one for permanently saving results created and used during
the operation.
RAM MemoryThis is the third and the most complex part of
microcontroller memory. In this case, it consists of two parts:
general-purpose registers and special-function registers (SFR).Even
though both groups of registers are cleared when power goes off and
even though they are manufactured in the same way and act in the
similar way, their functions do not have many things in common.
SFR and General Purpose Registers
General-Purpose RegistersGeneral-Purpose registers are used for
storing temporary data and results created during operation. For
example, if the program performs a counting (for example, counting
products on the assembly line), it is necessary to have a register
which stands for what we in everyday life call sum. Since the
microcontroller is not creative at all, it is necessary to specify
the address of some general purpose register and assign it a new
function. A simple program to increment the value of this register
by 1 after each product passes through a sensor, should be
created.Therefore, the microcontroller can execute that program
because it now knows what and where the sum which must be
incremented is. Similarly to this simple example, each program
variable must be preassigned some of general-purpose register.SFR
RegistersSpecial-Function registers are also RAM memory locations,
but unlike general-purpose registers, their purpose is
predetermined during manufacturing process and cannot be changed.
Since their bits are physically connected to particular circuits on
the chip (A/D converter, serial communication module, etc.), any
change of their contents directly affects the operation of the
microcontroller or some of its circuits. For example, by changing
the TRISA register, the function of each port A pin can be changed
in a way it acts as input or output. Another feature of these
memory locations is that they have their names (registers and their
bits), which considerably facilitates program writing. Since
high-level programming language can use the list of all registers
with their exact addresses, it is enough to specify the registers
name in order to read or change its contents.RAM Memory BanksThe
data memory is partitioned into four banks. Prior to accessing some
register during program writing (in order to read or change its
contents), it is necessary to select the bank which contains that
register. Two bits of the STATUS register are used for bank
selecting, which will be discussed later. In order to facilitate
operation, the most commonly used SFRs have the same address in all
banks which enables them to be easily accessed.
I/O PORTS Features and FunctionsOne of the most important
features of the microcontroller is a number of input/output pins
used for connection with peripherals. In this case, there are in
total of thirty-five general purpose I/O pins available, which is
quite enough for the most applications. In order pins operation can
match internal 8-bit organization, all of them are, similar to
registers, grouped into five so called ports denoted by A, B, C, D
and E. They all have several features in common: For practical
reasons, many I/O pins have two or three functions. If a pin is
used as any other function, it may not be used as a general purpose
input/output pin; and
Every port has its satellite, i.e. the corresponding TRIS
register: TRISA, TRISB, TRISC etc. which determines performance,
but not the contents of the port bits.
By clearing some bit of the TRIS register (bit=0), the
corresponding port pin is configured as output. Similarly, by
setting some bit of the TRIS register (bit=1), the corresponding
port pin is configured as input. This rule is easy to remember 0 =
Output, 1 = Input.
I/O Ports
Port A and TRISA RegisterPort A is an 8-bit wide, bidirectional
port. Bits of the TRISA and ANSEL control the PORTA pins. All Port
A pins act as digital inputs/outputs. Five of them can also be
analog inputs (denoted as AN):
Port A and TRISA RegisterAnalog Modules
Apart from a large number of digital I/O lines, the PIC16F887
contains 14 analog inputs. They enable the microcontroller to
recognize, not only whether a pin is driven to logic zero or one (0
or +5V), but to precisely measure its voltage and convert it into a
numerical value, i.e. digital format. The whole procedure takes
place in the A/D converter module which has the following features:
The converter generates a 10-bit binary result using the method of
successive approximation and stores the conversion results into the
ADC registers (ADRESL and ADRESH); There are 14 separate analog
inputs; The A/D converter allows conversion of an analog input
signal to a 10-bit binary representation of that signal; and By
selecting voltage references Vref- and Vref+, the minimal
resolution or quality of conversion may be adjusted to various
needs.ADC Mode and RegistersEven though the use of A/D converter
seems to be very complicated, it is basically very simple, simpler
than using timers and serial communication module, anyway.
ADC Mode and RegistersThe module is under the control of the
bits of four registers: ADRESH - Contains high byte of conversion
result; ADRESL - Contains low byte of conversion result; ADCON0 -
Control register 0; and ADCON1 Control register 1
ADRESH and ADRESL RegistersWhen converting an analog value into
a digital one, the result of the 10-bit A/D conversion will be
stored in these two registers. In order to deal with this value
easier, it can appear in two formats- left justified and right
justified. The ADFM bit of the ADCON1 register determines the
format of conversion result (see figure 7-2). In the event that A/D
converter is not used, these registers may be used as
general-purpose registers.
ADRESH and ADRESL RegistersA/D Acquisition RequirementsFor the
ADC to meet its specified accuracy, it is necessary to provide a
certain time delay between selecting specific analog input and
measurement itself. This time is called "acquisition time" and
mainly depends on the source impedance. There is an equation used
for accurately calculating this time, which in the worst case
amounts to approximately 20uS..ADCON0 Register
CHS3-CHS0 - Analog Channel Select bitsselect a pin or an analog
channel for conversion, i.e. voltage
measurement:CHS3CHS2CHS1CHS0CHANNELPIN
00000RA0/AN0
00011RA1/AN1
00102RA2/AN2
00113RA3/AN3
01004RA5/AN4
01015RE0/AN5
01106RE1/AN6
01117RE2/AN7
10008RB2/AN8
10019RB3/AN9
101010RB1/AN10
101111RB4/AN11
110012RB0/AN12
110113RB5/AN13
1110CVref
1111Vref = 0.6V
Analog Channel Status Bits
GO/DONE - A/D Conversion Status bitdetermines current status of
conversion: 1 - A/D conversion is in progress; and 0 - A/D
conversion is complete. This bit is automatically cleared by
hardware when the A/D conversion is completed.ADON - A/D On
bitenables A/D converter. 1 - A/D converter is enabled; and 0 - A/D
converter is disabled.ADCON1 Register
ADFM - A/D Result Format Select bit 1 - Conversion result right
justified. Six most significant bits of the ADRESLH are not used;
and 0 - Conversion result left justified. Six least significant
bits of the ADRESL are not used.VCFG1 - Voltage Reference
bitselects negative voltage reference source needed for A/D
converter operating. 1 - Negative voltage reference is applied on
the Vref- pin; and 0 - Voltage power supply Vss is used as negative
voltage reference source.VCFG0 - Voltage Reference bitselects
positive voltage reference source needed for A/D converter
operating. 1 - Positive voltage reference is applied on the Vref+
pin; and 0 - Voltage power supply Vdd is used as positive voltage
reference source.In Short:In order to measure voltage on an input
pin by A/D converter the following should be done:Step 1-
Configuring port: Write logic one (1) to the corresponding bit of
the TRIS register to configure it as input; and Write logic one (1)
to the corresponding bit of the ANSEL register to configure it as
analog input.Step 2- Configuring ADC module: Configure voltage
reference in the ADCON1 register; Select ADC conversion clock in
the ADCON0 register; Select one of input channels CH0-CH13 of the
ADCON0 register; Select data format using the ADFM bit of the
ADCON1 register; and Enable A/D converter by setting the ADON bit
of the ADCON0 register.Step 3- Configuring ADC interrupt
(optionally): Clear the ADIF bit; and Set the ADIE, PEIE and GIE
bits.Step 4- Wait for the required acquisition time (approximately
20uS) to pass.Step 5- Start conversion by setting the GO/DONE bit
of the ADCON0 register.Step 6- Wait for ADC conversion to complete.
It is necessary to check in program loop whether the GO/DONE pin is
cleared or wait for an A/D interrupt (must be previously
enabled).Step 7- Read ADC results: Read the ADRESH and ADRESL
registers.
MCLR pinLogic zero (0) on the MCLR pin causes immediate and
regular reset. It is recommended to be connected as shown in figure
below. The function of additional components is to sustain pure
logic one (1) during normal operation. If their values are such to
provide high logic level on the pin only upon T reset is over, the
microcontroller will immediately start operating. This feature may
be very useful when it is necessary to synchronize the operation of
the microcontroller with additional electronics or the operation of
several microcontrollers. Master Clear Pin
3.3 RF MODULE: CC2500
CC2500 RF Module is a transreceiver module which provides easy
to use RF communication at 2.4 Ghz. It can be used to transmit and
receive data at 9600 baud rates from any standard CMOS/TTL source.
This module is a direct line in replacement for your serial
communication it requires no extra hardware and no extra coding
toIt works in Half Duplex mode i.e. it provides communication in
both directions, but only one direction at same time .
Features: Supports Multiple Baud rates ( 9600 ) Works on ISM
band (2.4 GHz) No complex wireless connection software or intimate
knowledge of RF is required to connect our serial devices. Designed
to be as easy to use as cables. No external Antenna required. Plug
and play device. Works on 5 DC supply.
Specifications: Input Voltage - 5Volts DC Baud Rate - 9600 RS
232 Interface & TTL Interface Range Max 30 Mtrs - Line of
Sight
BLOCK DIAGRAM
Chapter 4Hardware and Software Description
4.SOFTWARE
4.1EAGLE 5.6EAGLE by CadSoft Computer is a flexible, expandable
and scriptableEDAapplication with schematic capture editor, PCB
layout editor, auto-router and CAMandBOMtools developed byCadSoft
Computer GmbH, Germany, since 1988. EAGLE was originally developed
to run as a 16-bit application underDOS, with support
forOS/2andWindowsadded later on. Starting with version 4.0, EAGLE
was converted to 32-bit. EAGLE version 4.0 also dropped support for
DOS and OS/2, but was among the first professional electronic CAD
tools available for Linux. A 32-bitDPMIversion of EAGLE 4.0 running
under DOS was available on special request in order to help support
existing customers, but was not released commercially. Starting
with version 4.13, EAGLE became available forMac OS X, with
versions before 5.0.0 still requiringX11. Version 5.0.0 officially
dropped support forWindows 9xandWindows NT3.x/4.x. EAGLE 6.0.0 no
longer supports Mac OS X on thePower PCplatform (only on Intel
Macs), and the minimum requirements have been changed to Mac OS X
10.6, Linux 2.6 and Windows XP.
EAGLE is popular among smaller design houses and in academia for
its favourable licensing terms and rich availability of component
libraries on the web. Hobbyists are attracted by the availability
of freeware licenses. ThePCBlayout editor allows back annotation to
the schematic and auto-routing to automatically connect traces
based on the connections defined in the schematic.
2.MPLAB IDE
MPLABX IDE is a software program that runs on a PC (Windows, Mac
OS, Linux) to develop applications for Microchip microcontrollers
and digital signal controllers. It is called an Integrated
Development Environment (IDE), because it provides a single
integrated environment to develop code for embedded
microcontrollers.MPLABX Integrated Development Environment brings
many changes to the PICmicrocontroller development tool chain.
Unlike previous versions of MPLABwhich were developed completely
in-house, MPLABX is based on the open source NetBeans IDE from
Oracle. Taking this path has allowed us to add many frequently
requested features very quickly and easily while also providing us
with a much more extensible architecture to bring you even more new
features in the future.COMPILER USED: MPLABC30 CCOMPILER
V2.0BURNER: PICKIT2
CODE DISCRIPTION:
TRANSMITTER SECTION#include#DEVICE ADC=10#fuses NOLVP, NOWDT,
XT#define RS232_XMIT PIN_C6#define RS232_RCV PIN_C7 // PIC line
which receives PC transmission #use delay(clock=4000000) // 4 MHz
OSC#use rs232(baud=9600, xmit=RS232_XMIT, rcv=RS232_RCV)
//void command(unsigned char);//void display(unsigned
char);//void hex_ascii(int16 d);//void dis_array(char a[]);
//----------------------------display------------------------------
void int_adc();int16 read_ch0();//int16 read_ch1();
#int_rda
void serial_isr(){ disable_interrupts(int_rda);
enable_interrupts(int_rda);}
void send_pc( int16);
void main(){ int16 pre_value; //enable_interrupts(global);
//enable_interrupts(int_rda); set_tris_a(0b00000000); while(1) {
pre_value = read_ch0(); send_pc(pre_value); delay_ms(200); } }
void send_pc( int16 value ){ int8 d_1000,d_100,d_10,d_1; d_1000
= value%10; value = value/10; d_100 = value%10; value = value/10;
d_10 = value%10; value = value/10; d_1 = value; putc(d_1+0x30);
delay_ms(10); putc(d_10+0x30); delay_ms(10); putc(d_100+0x30);
delay_ms(10); putc(d_1000+0x30); delay_ms(10); }
int16 read_ch0(){ int16 value; set_adc_channel(0); delay_ms(10);
read_ADC(ADC_START_ONLY); delay_ms(10); value = read_adc(
ADC_READ_ONLY); return(value);}
void port_int(){// SET_TRIS_A(0b00000011);
set_tris_b(0b00000000); set_tris_d(0b00000000);
set_tris_c(0b00000000);}
void int_adc(){ setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL); setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
}
/* void hex_ascii(int16 d){ int8 d_1000,d_100,d_10,d_1; d_1000 =
d%10; d = d/10; d_100 = d%10; d = d/10; d_10 = d%10; d = d/10; d_1
= d; display(d_1+0x30); display(d_10+0x30); display(d_100+0x30);
display(d_1000+0x30);
}
void int_lcd(){ command(0x38); delay_ms(2); command(0x01);
delay_ms(2); command(0x0e); delay_ms(2); command(0x06);
delay_ms(2); command(0x82); delay_ms(2);
display('*'); delay_ms(100); display('S'); delay_ms(100);
display('V'); delay_ms(100); display('I'); delay_ms(100);
display('T'); delay_ms(100); display(' '); delay_ms(100);
display('*'); delay_ms(100); command(0xc6); delay_ms(2);
display('*'); delay_ms(100); command(0xc6); delay_ms(2);
display('I'); delay_ms(100); display('N'); delay_ms(100);
display('D'); delay_ms(100); display('O'); delay_ms(100);
display('R'); delay_ms(100); display('E'); delay_ms(100);
}
void command(unsigned char c){
output_b(c); output_low(PIN_D5); output_high(PIN_D6);
delay_ms(2); output_low(PIN_D6); delay_ms(10); }
void display(unsigned char d){
output_b(d); output_high(PIN_D5); output_high(PIN_D6);
delay_ms(2); output_low(PIN_D6); delay_ms(10);}
RECEIVER SECTION#include#DEVICE ADC=10#fuses NOLVP, NOWDT,
XT#define RS232_XMIT PIN_C6#define RS232_RCV PIN_C7 // PIC line
which receives PC transmission #use delay(clock=4000000) // 4 MHz
OSC#use rs232(baud=9600, xmit=RS232_XMIT, rcv=RS232_RCV)
void command(unsigned char);void display(unsigned char);void
hex_ascii(int16 d);void dis_array(char a[]);
//----------------------------display------------------------------void
int_lcd();void int_adc();int16 read_ch0();int16 read_ch1();
char d_rec[4];
#int_rda
void serial_isr() {
disable_interrupts(int_rda);
d_rec[0] = getChar(); d_rec[1] = getChar(); d_rec[2] =
getChar(); d_rec[3] = getChar();
enable_interrupts(int_rda);
}
void send_pc( int16);
void main(){ int16 pre_value; enable_interrupts(global);
enable_interrupts(int_rda);
set_tris_d(0b11111111); set_tris_b(0b11111111); delay_ms(100);
int_lcd(); int_adc(); command(0x01); display('P'); display('r');
display('e'); display('s'); display('s'); display('u');
display('r'); display('e'); display(':'); display(' '); while(1) {
command(0x8a); display(d_rec[0]); display(d_rec[1]);
display(d_rec[2]); display(d_rec[3]); } }
/*void send_pc( int16 value ){ int8 d_1000,d_100,d_10,d_1;
d_1000 = value%10; value = value/10; d_100 = value%10; value =
value/10; d_10 = value%10; value = value/10; d_1 = value;
putc(d_1+0x30); delay_ms(10); putc(d_10+0x30); delay_ms(10);
putc(d_100+0x30); delay_ms(10); putc(d_1000+0x30); delay_ms(10);
}
void port_int(){// SET_TRIS_A(0b00000011);
set_tris_b(0b00000000); set_tris_d(0b00000000);
set_tris_c(0b11111111);}
*/void int_adc(){ setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_INTERNAL);// setup_psp(PSP_DISABLED);//
setup_spi(FALSE);// setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);//
setup_timer_1(T1_DISABLED);// setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC); setup_vref(FALSE);
}
void hex_ascii(int16 d){ int8 d_1000,d_100,d_10,d_1; d_1000 =
d%10; d = d/10; d_100 = d%10; d = d/10; d_10 = d%10; d = d/10; d_1
= d; display(d_1+0x30); display(d_10+0x30); display(d_100+0x30);
display(d_1000+0x30);
}
int16 read_ch0(){ int16 value; set_adc_channel(0); delay_ms(1);
read_ADC(ADC_START_ONLY); delay_ms(1); value = read_adc(
ADC_READ_ONLY); return(value);}
int16 read_ch1(){ int16 value; set_adc_channel(2); delay_ms(1);
read_ADC(ADC_START_ONLY); delay_ms(1); value = read_adc(
ADC_READ_ONLY); return(value);}void int_lcd(){ command(0x38);
delay_ms(2); command(0x01); delay_ms(2); command(0x0e);
delay_ms(2); command(0x06); delay_ms(2); command(0x82);
delay_ms(2);}
void command(unsigned char c){
output_d(c); output_low(PIN_B7); output_low(PIN_B6);
output_high(PIN_B5); delay_ms(2); output_low(PIN_B5); delay_ms(10);
}
void display(unsigned char d){
output_d(d); output_high(PIN_B7); output_low(PIN_B6);
output_high(PIN_B5); delay_ms(2); output_low(PIN_B5);
delay_ms(10);}
Chapter 5
Layout Design
CIRCUIT DESIGNING
TRANSMITTER SCHEMATIC
RECIEVER SCHEMATIC
PCB LAYOUT DESIGNING
TRANSMITTER LAYOUT
RECIEVER LAYOUT
ORIGINAL PCB
TRANSMITTER PCB
RECIEVER PCB
ORIGINAL CIRCUIT AFTER ASSEMBLING COMPONENTS
TRANSMITTER SECTION
RECIEVER SECTION
Chapter 6CONCLUSION
Conclusion
Direct tire pressure was accomplished with the design presented
here. The team has completed the design and construction after
completing the rigorous of investigating the problem from several
different perspectives. This investigation has led the team to
consider many different possibilities involving hardware, software,
design, and complication.
The system is also fairly inexpensive. There were significant
problems encountered during the construction of the project. The
alignment of the pressure sensor was the most difficult part. Then
the pressure sensor was calibrated for different readings from the
tire. The second problem was software problem. It took far longer
to diagnose and fix than we could have possibly anticipated.It was
a problem with the internal A/D converters in the microcontroller
of transmitter side. The A/D converter was not properly referencing
the incoming signals and causing Problem with the output. Also the
project is just a prototype of tire pressure monitoring system
which now measures the pressure of 1 tire and displays it on
LCD.
The team had tried its best to complete the project and present
it in a working conditions. Faults were diagnosed and
corrected.
Chapter 7BIBLOGRAPHY
Reference Links:
Electronics Today Radio Frequency know how Instructables
PICmicrocontroller tutorial Mplab x IDE tutorial
Chapter 8DATA SHEETS
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