Touchscreen and Zigbee Assistant in Airlines

www.final-yearproject.com | www.finalyearthesis.com

ABSTRACT

The main aim of this project is to construct a user friendly multi-language communication system for illiterate/dumb people traveling by Airlines. As

we have different languages in our world and its impossible for us to know all the languages. So, in this project we are building a device that helps them in

expressing their needs with other language people (Air hostess) i.e. request them if we need anything in the flight like coffee, tea, drinks etc.

In this project we use GLCD and Touch screen Technology to make it easy even to illiterates as it is also included with images, which indicates the

needs. This even reduces the difficulty to airhostess in receiving the customers with different languages. Here for wireless communication purpose we use Zigbee

technology.

ZigBee is a wireless technology developed as an open global standard to address the unique needs of low-cost, low-power, wireless sensor networks.

Zigbee is the set of specs built around the IEEE 802.15.4 wireless protocol.

As Zigbee is the upcoming technology in wireless field, we had tried to demonstrate its way of functionality and various aspects like kinds,

advantages and disadvantages using a small application of controlling the any kind of electronic devices and machines. The Zigbee technology is broadly adopted

for bulk and fast data transmission over a dedicated channel.

This project consists of Zigbee based system that transmits the wireless signals according to the input given by the user using touch screen. At the

receiver (airhostess) end the information will be displayed on GLCD in English language. Here when user sends his need through touch screen, then micro

controller transmits that information through Zigbee transmitter. The information received by the Zigbee receiver will be displayed on GLCD.

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http://www.finalyearthesis.com/

http://www.final-yearproject.com/

http://www.wisegeek.com/what-is-the-ieee.htm


INDEX

CHAPTER Page No: 1. INTRODUCTION 1

2. BLOCK DIAGRAM 3

3. CIRCUIT DIAGRAM 4

4. POWER SUPPLY 7

5. PIC 16F73 9

5.1 FEATURES 9

5.2 PIN DESCRIPTION 16

5.3 APPLICATIONS 28

6.TOUCHSCREEN SENSOR 29

6.1 GRAPHIC LCD WITH TOUCHSCREEN 33

6.2 TECHNOLOGIES 37

7. ZIGBEE TECHNOLOGY 43

8.GLCD 128x64 52

9. ADVANTAGES and APPLICATIONS 57

10. CODING 58

11. FUTURE SCOPE 64

12. CONCLUSION 65

13.BIBLIOGRAPHY 66

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LIST OF FIGURES Page No

2.1: Block Diagram 3

3.1: Touch Screen Airlines assistant Transmitter 4

3.2: Touch Screen Airlines assistant Receiver 5

5.1.1: Harvard vs von Neuman Block Architecture 13

5.1.2:Clock/ Instruction cycle 14

5.1.3: Instruction pipeline flow 15

5.2.1: pin diagram of PIC16f73 17

6.1: Working of Resistive Touch Screens 30

6.2: Block Diagram of Touch Screen Interface 32

6.1.1: Graphic LCD with Touch Screen 33

6.1.2: GLCD with Resistive Touch Screens 34

6.1.3: Four Wire Resistive Touch Screens 34

6.1.4: working of Resistive Touch Screens 35

7.1: ZIGBEE Stack Architecture 46

7.2 :ZIGBEE Topologies 48

7.3: ZIGBEE Network Model 49

8.1: Graphical LCD 53

LIST OF TABLES Page No

6.2 : Comparison of touch screen technologies 41

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1.INTRODUCTION

The main aim of this project is to construct a user friendly multi-language

communication system for illiterate/dumb people traveling by Airlines. As we have different

languages in our world and its impossible for us to know all the languages.

So, in this project we are building a device that helps them in expressing their needs with

other language people (Air hostess) i.e. request them if we need anything in the flight like coffee,

tea, drinks etc.

In this project we use GLCD and Touch screen Technology to make it easy even to

illiterates as it is also included with images, which indicates the needs. This even reduces the

difficulty to airhostess in receiving the customers with different languages. Here for wireless

communication purpose we use Zigbee technology.

ZigBee is a wireless technology developed as an open global standard to address the

unique needs of low-cost, low-power, wireless sensor networks. Zigbee is the set of specs built

around the IEEE 802.15.4 wireless protocol.

As Zigbee is the upcoming technology in wireless field, we had tried to demonstrate its

way of functionality and various aspects like kinds, advantages and disadvantages using a small

application of controlling the any kind of electronic devices and machines. The Zigbee

technology is broadly adopted for bulk and fast data transmission over a dedicated channel.

This project consists of Zigbee based system that transmits the wireless signals according

to the input given by the user using touch screen. At the receiver (airhostess) end the information

will be displayed on GLCD in English language.

Here when user sends his need through touch screen, then micro controller transmits that

information through Zigbee transmitter. The information received by the Zigbee receiver will be

displayed on GLCD.

This project provides us with the learning’s on the following aspects

Interfacing touch screen sensor with Microcontroller.

Characteristics of touch screen sensor.

Graphical LCD User Interface design.

Zigbee receiver.

Zigbee transmitter.

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Embedded C programming.

PCB designing.

The major building blocks of this project are

Two Microcontroller based Control Units with regulated power supply.

Two Graphical LCDs.

Two GLCD Drivers.

Touch Screen Driver.

Zigbee (Xbee) based Transmitter.

Zigbee (Xbee) based Receiver.

LED Indicators.

Buzzer.

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2. BLOCK DIAGRAM

Description

This project consists of Zigbee based system that transmits the wireless signals according

to the input given by the user using touch screen. At the receiver (airhostess) end the information

will be displayed on GLCD in English language. The Zigbee technology is broadly adopted for

bulk and fast data transmission over a dedicated channel.

Here when user sends his need through touch screen, then micro controller transmits that

information through Zigbee transmitter. The information received by the Zigbee receiver will be

displayed on GLCD.

2.1 Block Diagram

Figure 2.1: Block Diagram

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3.CIRCUIT DIAGRAM

Transmitter

Figure 3.1: Touch Screen Airlines assistant Transmitter

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Receiver

Figure 3.2: Touch Screen Airlines assistant Receiver

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Snap shot for the circuit diagram

4. POWER SUPPLY

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Power supply is the major concern for every electronic device .Since the controller and

other devices used are low power devices there is a need to step down the voltage and as well as

rectify the output to convert the output to a constant dc

Transformer

Transformer is a device used to increment or decrement the input voltage given as per the

requirement. The transformers are classified into two types depending upon their functionality

they are Step up transformer and Step down transformer.

Here we use a step down transformer for stepping down the house hold ac power supply

i.e. the 230-240V power supply to 5V. We use a 5-0-5V center tapped step down

transformer.Rectifier

The output of the transformer is an ac and should be rectified to a constant dc for this it is

necessary to feed the output of the transformer to a rectifier. The rectifier is employed to convert

the alternating ac to a constant dc. There are many rectifiers available in the market some of

them are Half wave rectifier,Full wave rectifier and Bridge rectifier

The rectification is done by using one or more diodes connected in series or parallel. If

only one diode is used then only first half cycle is rectified and it is termed as half wave

rectification and the rectifier used is termed as Half wave rectifier.

If two diodes are employed in parallel then both positive and negative half cycles are

rectified and this is full wave rectification and the rectifier is termed as Full wave rectifier.

If the diodes are arranged in the form of bridge then it is termed as Bridge rectifier,it acts

as a full wave rectifier.These rectifiers are available in the market in the form of integrated chips.

Voltage Regulator

The voltage regulator is used for the voltage regulation purpose. We use IC 7805 voltage

regulator.The IC number has a specific significance. The number 78 represents the series while

05 represent the output voltage generated by the IC

LED

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We employ a light emitting diode for testing the functionality of the power supply circuit.

Here we use a 5 volts LED which is connected in series with the power supply circuit it verifies

the functioning of the power supply.

LED’s are also employed in other areas for many purposes. The following are the

advantages of using LED’s.

It helps us while troubleshooting the device i.e. when the device is malfunctioning it

would be easy to detect where the actual problem araised.

LED employed with microcontroller verifies whether data is being transmitted.

It verifies the functionality of the power supply.

5.PIC16F73

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5.1 FEATURES

The PIC16f73 CMOS FLASH-based 8-bit microcontroller is upward compatible with the

PIC16C5x, PIC12Cxxx and PIC16C7x devices. It features 200 ns instruction execution, 256

bytes of EEPROM data memory, self programming, an ICD, 2 Comparators, 8 channels of 8 bit

Analog-to-Digital (A/D) converter, 2 capture/compare/PWM functions, a synchronous serial port

that can be configured as either 3-wire SPI or 2-wire I2C bus, a USART, and a Parallel Slave

Port.

High Performance RISC CPU

Only 35 single word instructions to learn

All single cycle instructions except for program branches which are two-cycle

Operating speed: DC 20 MHz clock input, DC 200 ns instruction cycle

Up to 8K x 14 words of FLASH Program Memory

Up to 368 x 8 bytes of Data Memory (RAM)

Pin out compatible to the PIC16C73B/74B/76/77

Pin out compatible to the PIC16F873/874/876/877

Interrupt capability (up to 12 sources)

Eight level deep hardware stack

Direct, Indirect and Relative Addressing modes

Processor read access to program memory

Special Microcontroller Features

Power up Timer (PWRT) and oscillator Start up Timer (OST)

Watchdog Timer (WDT) with its own on chip RCoscillator for reliable operation

Programmable code protection

Power saving SLEEP mode

Selectable oscillator options

In Circuit Serial Programmingvia twoPins

Peripheral Features

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Timer0: 8-bit timer/counter with 8-bit prescaler

Timer1: 16-bit timer/counter with prescaler can be incremented during Sleep via

external crystal/clock

Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler

Two Capture, Compare, PWM modules

16-bit Capture input; max resolution 12.5 ns

16-bit Compare; max resolution 200 ns

PWM max resolution is 10-bit

Synchronous Serial Port (SSP) with SPI (Master mode) and I2C (Slave)

8-bit, up to 8-channel Analog-to-Digital converter

Synchronous Serial Port (SSP) with SPI (Master mode) and I2C (Slave)

Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI)

Parallel Slave Port (PSP), 8-bits wide with external RD, WR and CS controls (40/44-

pin Only)

Brown-out detection circuitry for Brown-Out Reset

Analog Comparator module

2 analog comparators

Programmable on-chip voltage reference module

Programmable input multiplexing from device inputs and internal VREF

Comparator outputs are externally accessible

CMOS Technology

Low power, high speed CMOS FLASH technology

Fully static design

Wide operating voltage range: 2.0V to 5.5V

High Sink/Source Current: 25 mA

Industrial temperature range

Low power consumption

< 2 mA typical @ 5V, 4 MHz,

A typical @ 3V, 32 kHz

< 1 μA typical standby current

Following are the major blocks of PIC Microcontroller.

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Program Memory (FLASH)

It is used for storing a written program. Since memory made in FLASH technology can

be programmed and cleared more than once, it makes this microcontroller suitable for device

development.

EEPROM

It is usually used for storing important data that must not be lost if power supply suddenly

stops. For instance, one such data is an assigned temperature in temperature regulators. If during

a loss of power supply this data was lost, we would have to make the adjustment once again

upon return of supply. Thus our device looses on self-reliance.

RAM

Data memory used by a program during its execution. In RAM are stored all inter-results

or temporary data during run-time.

FREE RUN TIMER

It is an 8-bit register inside a microcontroller that works independently of the program.

On every fourth clock of the oscillator it increments its value until it reaches the maximum (255),

and then it starts counting over again from zero. As we know the exact timing between each two

increments of the timer contents, timer can be used for measuring time which is very useful with

some devices.

CPU

Ithas a role of connective element between other blocks in the microcontroller. It

coordinates the work of other blocks and executes the user program.Central processing unit

(CPU) is the brain of a microcontroller. This part is responsible for finding and fetching the right

instruction which needs to be executed, for decoding that instruction and finally for its execution.

Central processing unit connects all parts of the microcontroller into one whole. Surely,

its most important function is to decode program instructions. When programmer writes a

program, instructions have a clear form like MOVLW 0x20. However, in order for a

microcontroller to understand that, this letter form of an instruction must be translated into a

series of zeros and ones which is called an opcode.

This transition from a letter to binary form is done by translators such as assembler

translator (also known as an assembler). Instruction thus fetched from program memory must be

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decoded by a central processing unit. We can then select from the table of all the instructions a

set of actions, which execute a assigned task defined by instruction.

As instructions may within themselves contain assignments, which require different

transfers of data from one memory into another, from memory onto ports, or some other

calculations, CPU must be connected with all parts of the microcontroller. This is made possible

through a data bus and an address bus.

Arithmetic logic unit is responsible for performing operations of adding, subtracting,

moving (left or right within a register) and logic operations. Moving data inside a register is also

known as shifting. PIC16f73 contains an 8-bit arithmetic logic unit and 8-bit work registers.

In instructions with two operands, ordinarily one operand is in work register (W register),

and the other is one of the registers or a constant. By operand we mean the contents on which

some operation is being done, and a register is any one of the GPR or SFR registers. GPR is an

abbreviation for 'General Purposes Registers', and SFR for 'Special Function Registers'.

In instructions with one operand, an operand is either W register or one of the registers.

As an addition in doing operations in arithmetic and logic, ALU controls status bits (bits found in

STATUS register). Execution of some instructions affects status bits, which depends on the

result itself. Depending on which instruction is being executed, ALU can affect values of Carry

(C), Digit Carry (DC), and Zero (Z) bits in STATUS register.

These devices have a host of features to maximize system reliability, minimize cost

through elimination of external components, provide power saving operating modes and offer

code protection.

These devices have a Watchdog Timer, which can be enabled or disabled, using a

configuration bit. It turns off its own RC oscillator for added reliability SLEEP mode is designed

to offer a very low current power down mode. The user can wake up from SLEEP through

external RESET, watchdog Timer wake up, or through an interrupt.

There are two Timers that offer necessary delays on power up. One is the oscillator start

up timer intended to keep the chip in RESET until the crystal oscillator is stable. The other is the

power up timer, which provides a fixed delay of 72ms on power up only

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Figure 5.1.1: Harvard vs Von Neuman Block Architecture

CISC and RISC

It has already been said that PIC16f73 has RISC architecture. Harvard architecture is a

newer concept than Von Neumann. It rose out of the need to speed up the work of a

microcontroller. In Harvard architecture data bus and address bus are separate. Thus a greater

flow of data is possible through the central processing unit and of course a greater speed of work.

Separating a program from data memory makes it further possible for instructions not to

have to be 8 bit words. PIC16f73 uses 14 bits for instructions which allows for all instructions to

be one word instructions. It is also typical for Harvard architecture to have fewer instructions

than von-Neumann's, and to have instructions usually executed in one cycle.

Microcontrollers with Harvard architecture are also called RISC Microcontrollers. RISC

stands for Reduced Instruction Set Computer. Microcontrollers with Von Neumann's architecture

are called CISC microcontrollers.Title CISC stands for Complex Instruction Set Computer.

Since PIC16f73 is a RISC Microcontroller that means that it has a reduced set of

instructions more precisely 35 instructions. All of these instructions are executed in one cycle

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except for jump and branch instructions. PIC16f73 usually reaches results of 2:1 in code

compression and 4:1 in speed in relation to other 8 bit microcontrollers.

Clock / instruction cycle

Clock is microcontroller’s main starter and is obtained from an external component called

an oscillator. Clock from the oscillator enters a microcontroller via OSC1 pin where internal

circuit of a microcontroller divides the clock into four even clocks Q1, Q2, Q3 and Q4 which do

not overlap. These four clocks make up one instruction cycle during which one instruction is

executed.

Execution of instruction starts by calling an instruction that is next in string. Instruction is

called from program memory on every Q1 and is written in instruction register on Q4. Decoding

and execution of instruction are done between the next Q1 and Q4 cycles.

On the following diagram we can see the relationship between instruction cycle and clock

of the oscillator (OSC1) as well as that of internal clocks Q1 to Q4. Program counter holds

information about the address of the next instruction.

Figure 5.1.2:Clock/ Instruction cycle

Pipelining

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Instruction cycle consists of cycles Q1, Q2, Q3 and Q4. Cycles of calling and executing

instructions are connected in such a way that in order to make a call one instruction cycle is

needed and one more is needed for decoding and execution.

However due to pipelining each instruction is effectively executed in one cycle. If

instruction causes a change on program counter and PC doesn't point to the following but to

some other address, two cycles are needed for executing an instruction.

This is so because instruction must be processed again, but this time from the right

address. Cycle of calling begins with Q1 clock, by writing into instruction register (IR).

Decoding and executing begins with Q2, Q3 and Q4 clocks.

Figure 5.1.3: Instruction pipeline flow

TCY0 reads in instruction MOVLW 55h (it doesn't matter to us what instruction

was executed, because there is no rectangle pictured on the bottom).TCY1 executes instruction

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MOVLW 55h and reads in MOVWF PORTB.TCY2 executes MOVWF PORTB and reads in

CALL SUB_1.TCY3 executes a call of a subprogram CALL SUB_1, and reads in instruction

BSF PORTA, BIT3.

As this instruction is not the one we need, or is not the first instruction of a subprogram

SUB_1 whose execution is next in order, instruction must be read in again. This is a good

example of an instruction needing more than one cycle. .

5.2 PIN DESCRIPTION

PIC16f73 has a total of 40 pins. It is most frequently found in a DIP40 type of case but

can also be found in SMD case which is smaller from a DIP. DIP is an abbreviation for Dual In

Package. SMD is an abbreviation for Surface Mount Devices suggesting that holes for pins to go

through when mounting aren't necessary in soldering this type of a component.

PIC 16f73/76 devices are available only in 28 pin packages, while PIC16f74/77 devices

are available in 40 pin and 44 pin packages. All devices in the PIC16f7X family share common

architecture, with the following differences

The PIC16f73 and PIC16f76 have one half of the total on chip memory of the

PIC16f77.

The 28 pin devices have 3 I/O ports, while the 40 and 44 pin devices have 5 I/O

ports.

The 28 pin devices have 11 interrupts, while the 40 and 44 pin devices have 12.

The 28 pin devices have 5 A/D input channels, while the 40 and 44 pin devices

have 8.

The parallel slave port is implemented only on the 40 and 44 pin devices.

Pin Diagram

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Figure 5.2.1: pin diagram of PIC16f73

There are 40 pins on PIC16f73. Most of them can be used as an IO pin. Others are already for

specific functions. By utilizing all of this pin so many application can be done such as

1. LCD connect to Port B pin.

2. LED connect to any pin declared as output.

3. Relay and Motor connect to any pin declared as output.

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4. External EEPROM to connect to I2C interface pin RC3 and RC4 (SCL and SDA)

5. LDR, Potentiometer and sensor to connect to analog input pin such as RA0.

6. RC7 for the serial communication interface using RS232 protocol.

Clock Generator

Oscillator circuit is used for providing a microcontroller with a clock. Clock is needed so

that microcontroller could execute a program or program instructions.PIC16f73 can work with

four different configurations of an oscillator.

Since configurations with crystal oscillator and Resistor Capacitor are the ones that are

used most frequently these are the only ones we will mention here. Microcontroller type with a

crystal oscillator has in its designation XT and a microcontroller with Resistor Capacitor pair has

a designation RC.

XT Oscillator

Crystal oscillator is kept in metal housing with two pins where you have written down the

frequency at which crystal oscillates. One ceramic capacitor of 30pF whose other end is

connected to the ground needs to be connected with each pin. Oscillator and capacitors can be

packed in joint case with three pins. Such element is called ceramic resonator and is represented

in charts like the one below.

Center pins of the element is the ground, while end pins are connected with OSC1 and

OSC2 pins on the microcontroller. When designing a device the rule is to place an oscillator

nearer a microcontroller so as to avoid any interference on lines on which microcontroller is

receiving a clock. RC Oscillator.

In applications where great time precision is not necessary, RC oscillator offers

additional savings during purchase. Resonant frequency of RC oscillator depends on supply

voltage rate, resistance R, capacity C and working temperature. It should be mentioned here that

resonant frequency is also influenced by normal variations in process parameters, by tolerance of

external R and C components, etc.

Reset

Reset is used for putting the microcontroller into a 'known' condition. That practically

means that microcontroller can behave rather inaccurately under certain undesirable conditions.

In order to continue its proper functioning it has to be reset, meaning all registers would be

placed in a starting position.

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Reset is not only used when microcontroller doesn't behave the way we want it to, but

can also be used when trying out a device as an interrupt in program execution, or to get a

microcontroller ready when loading a program.

In order to prevent from bringing a logical zero to MCLR pin accidentally (line above it

means that reset is activated by a logical zero), MCLR has to be connected via resistor to the

positive supply pole. Resistor should be between 5 and 10K.This kind of resistor, whose function

is to keep a certain line on a logical one as a preventive, is called a pull up.

Microcontroller PIC16f73 knows several sources of resets:

Reset during power on, POR (Power-On Reset)

Reset during regular work by bringing logical zero to MCLR microcontroller's pin

Reset during SLEEP regime

Reset at watchdog timer (WDT) overflow

Reset during at WDT overflow during SLEEP work regime.

The first one occurs each time a power supply is brought to the microcontroller and

serves to bring all registers to a starting position initial state. The second one is a product of

purposeful bringing in of a logical zero to MCLR pin during normal operation of the

microcontroller. This second one is often used in program development.

During a reset, RAM memory locations are not being reset. They are unknown during a

power up and are not changed at any reset. Unlike these, SFR registers are reset to a starting

position initial state. One of the most important effects of a reset is setting a program counter

(PC) to zero (0000h), which enables the program to start executing from the first written

instruction.

Reset at supply voltage drop below the permissible (Brown-out Reset)

Impulse for resetting during voltage voltage-up is generated by microcontroller itself when it

detects an increase in supply VDD (in a range from 1.2V to 1.8V).

That impulse lasts 72ms which is enough time for an oscillator to get stabilized. These

72ms are provided by an internal PWRT timer, which has its own RC oscillator.

Microcontroller is in a reset mode as long as PWRT is active. However, as device is

working, problem arises when supply doesn't drop to zero but falls below the limit that

guarantees Microcontrollers proper functioning.

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This is a likely case in practice, especially in industrial environment where disturbances

and instability of supply are an everyday occurrence. To solve this problem we need to make

sure that microcontroller is in a reset state each time supply falls below the approved limit.

PORTS

Port refers to a group of pins on a microcontroller which can be accessed simultaneously,

or on which we can set the desired combination of zeros and ones, or read from them an existing

status. Physically, port is a register inside a microcontroller, which is connected by wires to the

pins of a microcontroller. Ports represent physical connection of Central Processing Unit with an

outside world.

Microcontroller uses them in order to monitor or control other components or devices.

Due to functionality, some pins have twofold roles like PA4/TOCKI for instance, which is in the

same time the fourth bit of port A and an external input for free-run counter.

Selection of one of these two pin functions is done in one of the configuration registers.

An illustration of this is the fifth bit T0CS in OPTION register. By selecting one of the functions

the other one is disabled.

All port pins can be designated as input or output, according to the needs of a device

that's being developed. In order to define a pin as input or output pin, the right combination of

zeros and ones must be written in TRIS register. If the appropriate bit of TRIS register contains

logical "1", then that pin is an input pin, and if the opposite is true, it's an output pin. Every port

has its proper TRIS register.

Thus, port A has TRISA, and port B has TRISB. Pin direction can be changed during the

course of work which is particularly fitting for one-line communication where data flow

constantly changes direction. PORTA and PORTB state registers are located in bank 0, while

TRISA and TRISB pin direction registers are located in bank 1.

PORTB and TRISB

PORTB has adjoined 8 pins. The appropriate register for data direction is TRISB. Setting

a bit in TRISB register defines the corresponding port pin as input, and resetting a bit in TRISB

register defines the corresponding port pin as output.

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Each PORTB pin has a weak internal pull-up resistor (resistor which defines a line to

logic one) which can be activated by resetting the seventh bit RBPU in OPTION register. These

'pull-up' resistors are automatically being turned off when port pin is configured as an output.

When a microcontroller is started, pull-ups are disabled. Four pins PORTB, RB7:RB4

can cause an interrupt, which occurs when their status changes from logical one into logical zero

and opposite.

Only pins configured as input can cause this interrupt to occur (if any RB7:RB4 pin is

configured as an output, an interrupt won't be generated at the change of status.) This interrupt

option along with internal pull-up resistors makes it easier to solve common problems.

we find in practice like for instance that of matrix keyboard. If rows on the keyboard are

connected to these pins, each push on a key will then cause an interrupt. A microcontroller will

determine which key is at hand while processing an interrupt It is not recommended to refer to

port B at the same time that interrupt is being processed.

PORTA and TRISA

PORTA has 5 adjoining pins. The corresponding register for data direction is TRISA at

address 85h. Like with port B, setting a bit in TRISA register defines also the corresponding port

pin as input, and clearing a bit in TRISA register defines the corresponding port pin as output.It

is important to note that PORTA pin RA4 can be input only.

On that pin is also situated an external input for timer TMR0. Whether RA4 will be a

standard input or an input for a counter depends on T0CS bit (TMR0 Clock Source Select bit).

This pin enables the timer TMR0 to increment either from internal oscillator or via external

impulses on RA4/T0CKI pin.

Memory organization

PIC16f73 has two separate memory blocks, one for data and the other for program.

EEPROM memory with GPR and SFR registers in RAM memory make up the data block, while

FLASH memory makes up the program block. The program memory and data memory have

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separate buses so that concurrent access can occur. The program memory can be read internally

by user code.

Program memory

The PIC16F7X devices have a 13 bit program counter capable of addressing an 8K word

X 14 bit program memory space. The PIC16F77/76 devices have 8K words of FLASH program

memory and the PIC16F73/74 devices have 4K words. The RESET vector is at 0000h and the

interrupt vector is at 0004h.

Program memory has been carried out in FLASH technology which makes it possible to

program a microcontroller many times before it's installed into a device, and even after its

installment if eventual changes in program or process parameters should occur. The size of

program memory is 1024 locations with 14 bits width where locations zero and four are reserved

for reset and interrupt vector.

The FLASH program memory is readable during normal operation over the entire VDD

range..it is indirectly addressed through the Special Function Registers. Up to 14 bit numbers can

be stored into the memory for use as caliberation parameters, serial numbers, packed 7 bit

ASCII, etc.

Executing a program memory location containing data that forms an invalid instruction

results in a NOP. There are five SFRs used to read the program and memory. Those registers are

PMCON1, PMDATA, PMDATH, PMADR, PMADRH.

A program memory location may be read by the writing two bytes of the address to the

PMADR and PMADRH registers and then setting control bit RD. once the read control bit is set,

the microcontroller will use the next two instruction cycles to read the data.

The data is available in the PMDATA and PMDATH registers after the second NOP

instruction. Therefore it can be read as two bytes in the following instructions. The PMDATA

and PMDATH registers will hold this value until the next read operation.

Data memory

The Data memory is partitioned into multiple banks, which contain the General purpose

registers and the Special function registers. Bits RP1 and RP0 are the bank select bits. Each bank

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extends up to 7Fh. The lower locations of each bank are reserved for the Special Function

Registers. Above the Special Function Registers are the General Purpose Registers, implemented

as static RAM.

All implemented banks contain Special Function Registers. Some frequently used

Special function registers from one bank may be mirrored in another bank for code reduction and

quicker access.

The General Purpose Register file can be accessed directly or indirectly through the File

Select Register FSR. The Special Function Registers used by the CPU and peripheral modules

for controlling the desired operations of the device. These registers are implemented as static

RAM. The Special Function Registers can be classified into two sets they are core and

peripheral.

Data memory consists of EEPROM and RAM memories. EEPROM memory consists of

256 eight-bit locations whose contents are not lost during loosing of power supply. EEPROM is

not directly addressable, but is accessed indirectly through EEADR and EEDATA registers. As

EEPROM memory usually serves for storing important parameters, there is a strict procedure for

writing in EEPROM which must be followed in order to avoid accidental writing.

RAM memory for data occupies space on a memory map from location 0x0C to 0x4F

which comes to 68 locations. Locations of RAM memory are also called GPR registers which is

an abbreviation for General Purpose Registers. GPR registers can be accessed regardless of

which bank is selected at the moment.

Memory Banks

Beside this 'length' division to SFR and GPR registers, memory map is also divided in

'width'to two areas called 'banks'. Selecting one of the banks is done via RP0 bit in STATUS

register. Bank selection can be also made via directive bankselafter which name of the register

to be accessed is specified. In this manner, there is no need to memorize which register is in

which bank.

Program Counter

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The program counter is a 13 bits wide. The low byte comes from the PCL register, which

is a readable and writableregister. The upper bits are not readable, but are indirectly writable to

through the PCLATH register. On any RESET, the upper bits of the PC will be cleared

Program counter (PC) is a 13-bit register that contains the address of the instruction being

executed. It is physically carried out as a combination of a 5-bit register PCLATH for the five

higher bits of the address, and the 8-bit register PCL for the lower 8 bits of the address.

By its incrementing or change (i.e. in case of jumps) microcontroller executes program

instructions step-by-step.

Stack

PIC16F73 has a 13-bit stack with 8 levels, or in other words, a group of 8 memory

locations, 13 bits wide, with special purpose. The stack space is not part of either program or

data space and the stack pointer is not readable or writable. The PC is pushed onto the stack

when a CALL instruction is executed, or an interrupt causes branch. Its basic role is to keep the

value of program counter after a jump from the main program to an address of a subprogram.

In order for a program to know how to go back to the point where it started from, it has

to return the value of a program counter from a stack. When moving from a program to a

subprogram, program counter is being pushed onto a stack (example of this is CALL

instruction).

When executing instructions such as RETURN, RETLW or RETFIE which were

executed at the end of a subprogram, program counter was taken from a stack so that program

could continue where was stopped before it was interrupted.

These operations of placing on and taking off from a program counter stack are called

PUSH and POP, and are named according to similar instructions on some bigger

Microcontrollers.

The stack operates as a circular buffer. This means that after the stack has been pushed

eight times, the ninth PUSH overwrites the value that was stored from the first push. The tenth

push overwrites the second push.

In System Programming

27




In order to program a program memory, microcontroller must be set to special working

mode by bringing up MCLR pin to 13.5V, and supply voltage Vdd has to be stabilized between

4.5V to 5.5V. Program memory can be programmed serially using two 'data/clock' pins, which

must previously be separated from device lines, so that errors wouldn't come up during

programming.

Addressing modes

RAM memory locations can be accessed directly or indirectly.

Direct Addressing

Direct Addressing is done through a 9-bit address. This address is obtained by connecting

7th bit of direct address of an instruction with two bits (RP1, RP0) from STATUS register. Any

access to SFR registers is an example of direct addressing.

Indirect Addressing

Indirect unlike direct addressing does not take an address from an instruction but derives

it from IRP bit of STATUS and FSR registers. Addressed location is accessed via INDF register

which in fact holds the address indicated by a FSR. In other words, any instruction which uses

INDF as its register in reality accesses data indicated by a FSR register.

Let's say, for instance, that one general-purpose register (GPR) at address 0Fh contains a

value of 20. By writing a value of 0Fh in FSR register we will get a register indicator at address

0Fh, and by reading from INDF register, we will get a value of 20, which means that we have

read from the first register its value without accessing it directly (but via FSR and INDF).

It appears that this type of addressing does not have any advantages over direct

addressing, but certain needs do exist during programming which can be solved smoothly only

through indirect addressing.

Indirect addressing is very convenient for manipulating data arrays located in GPR

registers. In this case, it is necessary to initialize FSR register with a starting address of the array,

and the rest of the data can be accessed by incrementing the FSR register.

Such examples include sending a set of data via serial communication, working with

buffers and indicators, or erasing a part of RAM memory (16 locations) as in the following

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instance.Reading data from INDF register when the contents of FSR register is equal to zero

returns the value of zero, and writing to it results in NOP operation (no operation).

Interrupts

Interrupts are a mechanism of a microcontroller, which enables it to respond to some

events at the moment they occur, regardless of what microcontroller is doing at the time. This is

a very important part, because it provides connection between a microcontroller and

environment, which surrounds it.

Generally, each interrupt changes the program flow, interrupts it and after executing an

interrupt subprogram (interrupt routine) it continues from that same point on. Control register of

an interrupt is called INTCON and can be accessed regardless of the bank selected. Its role is to

allow or disallowed interrupts, and in case they are not allowed, it registers single interrupt

requests through its own bits.

PIC16f73 has four interrupt sources

Termination of writing data to EEPROM

TMR0 interrupt caused by timer overflow

Interrupt during alteration on RB4, RB5, RB6 and RB7 pins of port B.

External interrupt from RB0/INT pin of microcontroller

Free-run timer TMR0

Timers are usually the most complicated parts of a microcontroller, so it is necessary to

set aside more time for understanding them thoroughly. Through their application it is possible to

establish relations between a real dimension such as "time" and a variable which represents

status of a timer within a microcontroller. Physically, timer is a register whose value is

continually increasing to 255, and then it starts all over again: 0, 1, 2, 3, 4...255....0,1, 2, 3......etc.

This incrementing is done in the background of everything a microcontroller does. It is up to

programmer to think up a way how he will take advantage of this characteristic for his needs.

One of the ways is increasing some variable on each timer overflow. If we know how much time

a timer needs to make one complete round, then multiplying the value of a variable by that time

will yield the total amount of elapsed time.

PIC16f73 has an 8-bit timer. Number of bits determines what value timer counts to

before starting to count from zero again. In the case of an 8-bit timer, that number is 256. A

29




simplified scheme of relation between a timer and a prescaler is represented on the previous

diagram.

Prescaler is a name for the part of a microcontroller which divides oscillator clock before

it will reach logic that increases timer status. Number which divides a clock is defined through

first three bits in OPTION register.

The highest divisor is 256. This actually means that only at every 256th clock, timer

value would increase by one. This provides us with the ability to measure longer timer periods.

After each count up to 255, timer resets its value to zero and starts with a new cycle of counting

to 255. During each transition from 255 to zero, T0IF bit in INTCOM register is set. If interrupts

are allowed to occur, this can be taken advantage of in generating interrupts and in processing

interrupt routine.

It is up to programmer to reset T0IF bit in interrupt routine, so that new interrupt or new

overflow could be detected. Beside the internal oscillator clock, timer status can also be

increased by the external clock on RA4/TOCKI pin.

Choosing one of these two options is done in OPTION register through T0CS bit. If this

option of external clock was selected, it would be possible to define the edge of a signal (rising

or falling), on which timer would increase its value.

In practice, one of the typical example that is solved via external clock and a timer is counting

full turns of an axis of some production machine, like transformer winder for instance. Let's wind

four metal screws on the axis of a winder. These four screws will represent metal convexity.

Let's place now the inductive sensor at a distance of 5mm from the head of a screw.

Inductive sensor will generate the falling signal every time the head of the screw is parallel with

sensor head. Each signal will represent one fourth of a full turn, and the sum of all full turns will

be found in TMR0 timer. Program can easily read this data from the timer through a data bus.

EEPROM Data memory

PIC16f73 has 256 bytes of EEPROM memory locations on addresses from 00h to 63h

that can be written to or read from. The most important characteristic of this memory is that it

does not lose its contents with the loss of power supply.

Data can be retained in EEPROM without power supply for up to 40 years (as

manufacturer of PIC16f73 microcontroller states), and up to 1 million cycles of writing can be

executed.

30




In practice, EEPROM memory is used for storing important data or process parameters.

One such parameter is a given temperature, assigned when setting up a temperature regulator to

some process.

If that data wasn't retained, it would be necessary to adjust a given temperature after each

loss of supply. Since this is very impractical (and even dangerous), manufacturers of

microcontrollers have began installing one smaller type of EEPROM memory.

EEPROM memory is placed in a special memory space and can be accessed through

special registers. These registers are

EEDATA Holds read data or that to be written.

EEADR Contains an address of EEPROM location being accessed.

EECON1 Contains control bits.

EECON2 This register does not exist physically and serves to protect EEPROM

from accidental writing.

5.3 APPLICATIONS

PIC16F73 perfectly fits many uses, from automotive industries and controlling home

appliances to industrial instruments, remote sensors, electrical door locks and safety devices. It is

also ideal for smart cards as well as for battery supplied devices because of its low consumption.

EEPROM memory makes it easier to apply microcontrollers to devices where permanent

storage of various parameters is needed (codes for transmitters, motor speed, receiver

frequencies, etc.).

Low cost, low consumption, easy handling and flexibility make PIC16F73 applicable

even in areas where microcontrollers had not previously been considered (example: timer

functions, interface replacement in larger systems, coprocessor applications, etc.).

In System Programmability of this chip (along with using only two pins in data transfer)

makes possible the flexibility of a product, after assembling and testing have been completed.

This capability can be used to create assembly-line production, to store calibration data available

only after final testing, or it can be used to improve programs on finished products.

6. TOUCH SCREEN SENSOR

Introduction

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A Touch Screens is any monitor based either on LCD or CRT technology which accepts

direct on screen input. The ability for direct onscreen input is facilitated by an external (light

pen) or an internal device (touch overlay and controller) that relays the X, Y coordinates to the

computer.

Touch screen sensors are composed of a transparent touch screen surface surrounded by a

sensor array that provides positional information to a processor. A touch screen sensor enables

the display to be used as input device and replaces the keyboard or mouse as the primary method

of input for interacting with a display's content. Touch screen sensors can be attached to

computers and handheld devices.

There are several basic types of touch screen sensors. Examples include capacitive glass

touch screen sensors, resistive touch screens, and complete touch screen systems. A capacitive

glass touch screen sensor is placed on a touch screen panel that is coated with indium tin oxide.

The panel conducts a continuous electrical current across the sensor in order to detect changes in

capacitance.

A resistive touch screen panel is also coated with a thin-film, but in order to produce an

electrically resistive layer. Each change in electrical resistance is marked as a touch event and

sent to a controller for processing.

A complete touch screen system allows a user to operate a computer or terminal by

touching the display screen. A touch screen system consists of a touch screen sensor array, a

controller card, and a software driver.

Selecting touch screen sensors requires an analysis of performance specifications and

application requirements. In general, resistive touch screens provide only 75% clarity. They are

available in 12.1 in., 15.0 in., 17.1 in., 18.1 in., 19.1 in., and 20.1 in. models. Four-wire, 5-wire,

and 8-wire resistive touch screens are commonly available. We are mostly using the 4 wire

resistive touch sensor.

Touch screen sensors are used in many applications. Some touch screen sensors are used

in pen digitizers for signature capture, smart phones, or personal digital assistants (PDAs). Other

touch screen sensors are used in ATMs or portable game consoles. Specialized touch screen

sensors can also be used in information appliances.

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RESISTIVE TOUCH SCREEN TECHNOLOGY

Resistive LCD touch screen monitors rely on a touch overlay, which is composed of a

flexible top layer and a rigid bottom layer separated by insulating dots, attached to a touch screen

controller. The inside surface of each of the two layers is coated with a transparent metal oxide

coating (ITO) that facilitates a gradient across each layer when voltage is applied.

Pressing the flexible top sheet creates electrical contact between the resistive layers,

producing a switch closing in the circuit. The control electronics alternate voltage between the

layers and pass the resulting X and Y touch coordinates to the touch screen controller. The touch

screen controller data is then passed on to the computer operating system for processing.

Resistive Touch Screens are composed of two flexible sheets coated with a

resistive material and separated by an air gap or microdots. When contact is made to the surface

of the Touch Screens, the two sheets are pressed together, registering the precise location of the

touch. Because the Touch Screens senses input from contact with nearly any object (finger,

stylus/pen, palm) resistive Touch Screens are a type of "passive" technology.

Working of Resistive Touch Screens

Figure 6.1: Working of Resistive Touch Screens

1. Polyester Film

2. Upper Resistive circuit Layer

3. Conductive ITO (Transparent Metal Coating).

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4. Lower Resistive Circuit Layer

5. Insulating Dots

6. Glass/Acrylic Substrate

7. Touching the overlay surface causes the (2) Upper Resistive Circuit Layer to contact the (4)

Lower Resistive Circuit Layer, producing a circuit switch from the activated area.

8. The touch screen controller gets the alternating voltages between the (7) two circuit layers and

converts them into the digital X and Y coordinates of the activated area.

Because of its versatility and cost-effectiveness, resistive touch screen technology is the

touch technology of choice for many markets and applications. Resistive touch screens are used

in food service, retail point-of-sale (POS), medical monitoring devices, industrial process control

and instrumentation, portable and handheld products.

Resistive Touch Screen technology possesses many advantages over other alternative

touch Screen technologies (acoustic wave, capacitive, Near Field imaging, and infrared). Highly

durable, resistive Touch Screens are less susceptible to contaminants that easily infect acoustic

waveTouch Screens.

In addition, resistive Touch Screens are less sensitive to the effects of severe scratches

that would incapacitate capacitive Touch Screens. For industrial applications, resistive Touch

Screens are more cost-effective solutions than Near Field Imaging Touch Screens.

A four-wire resistive touch screen panel consists of two flexible layers uniformly coated

with a transparent resistive material and separated by an air gap. Electrodes placed along the

edges of the layers provide a means for exciting and monitoring the touch screen.

Block Diagram of Touch Screen Interface

34




Figure 6.2: Block Diagram of Touch Screen Interface

When a position is measured on a 4-wire touch screen, voltage is applied across the

screen in the Y direction; and a touch presses the layers together, where a voltage can be read

from one of the X electrodes. The contact made as a result of the touch creates a voltage divider

at that point, so the Y coordinate can be determined; the process then repeats with the X direction

being driven, and a reading is taken from one of the Y electrodes.

A touch-screen controller is simply an ADC that has built-in switches to control which

electrodes are driven and which electrodes are used as the input to the ADC. An Analog Devices

AD7843 scans the X and Y axes and determines the unique voltage drop for each axis. The four

electrodes for scanning are labeled X+, X-, Y+, and Y-. These electrodes are connected to the

AD7843 touch screen controller and the touch sensor is scanned and the analog voltages read.

The four touch electrodes are connected to the inputs X+, X-, Y+, and Y- of the AD7843.

A selected axis (X or Y) pair of electrodes is energized with a static voltage and the voltage of

the positive electrode of the other pair in the 4 wire touch panel is measured.

The sensed voltage is measured and converted to either an 8 bit or 12 bit resolution. A

digital word representing the voltage at the contacting point on the touch panel is created and

sent out via a high speed SPI serial interface.

6.1 GRAPHIC LCD WITH TOUCHSCREEN

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These GLCD have common display drivers like KS0108 and T6963C and 4 wire

resistive Touch Screens. There is no need for touch screen digitizer/controller for micro

controllers having on chip ADC with four analog channels. Just connect the four wire of touch

screen to analog inputs and read the respective digital data for X and Y direction of touched

point.

Fig 6.1.1: Graphic LCD with Touch Screen

Comparisons of all Resistive Touch Technologies (4-, 5-, 6-, 7-, and 8-Wire)

Resistive Touch Screens are used in more applications than any other touch technology–

for example, PDAs, point-of-sale, industrial, medical, and office automation, as well as

consumer electronics. All variations of Resistive Touch Screens have some things in common:

They are all constructed similarly in layers-a back layer such as glass with a uniform

resistive coating plus a polyester coversheet, with the layers separated by tiny insulating

dots. When the screen is touched, it pushes the conductive coating on the coversheet against

the coating on the glass, making electrical contact. The voltages produced are the analog

representation of the position touched. An electronic controller converts these voltages into

digital X and Y coordinates which are then transmitted to the host computer.

Because Resistive Touch Screens are force activated, all kinds of touch input devices can

activate the screen, including fingers, fingernails, styluses, gloved hands, and credit cards.

All have similar optical properties, resistance to chemicals and abuse.

36




Both the Touch Screens and its electronics are simple to integrate into imbedded systems,

thereby providing one of the most practical and cost-effective Touch Screens solutions.

Figure 6.1.2: GLCD with Resistive Touch Screens

FOUR WIRE RESISTIVE

Four-wire resistive technology is the simplest to understand and manufacture. It uses

both the upper and lower layers in the Touch Screens "sandwich" to determine the X and Y

coordinates. Typically constructed with uniform resistive coatings of indium tin oxide (ITO on

the inner sides of the layers and silver buss bars along the edges, the combination sets up lines of

equal potential in both X and Y.

Figure 6.1.3: Four Wire Resistive Touch Screens

In the illustration below, the controller first applies 5V to the back layer. Upon touch, it

probes the analog voltage with the coversheet, reading 2.5V, which represents a left-right

37




position or X axis. It then flips the process, applying 5V to the coversheet, and probes from the

back layer to calculate an up-down position or Y axis. At any time, only three of the four wires

are in use (5V, ground, and probe).

Figure 6.1.4: working of Resistive Touch Screens

The primary drawback of four-wire technology is that one coordinate axis (usually the Y

axis), uses the outer layer, the flexible coversheet, as a uniform voltage gradient. The constant

flexing that occurs on the outer coversheet with use will eventually cause microscopic cracks in

the ITO coating, changing its electrical characteristics (resistance), degrading the linearity and

accuracy of this axis.

Unsurprisingly, four-wire Touch Screens are not known for their durability. Typically,

they test only to about 1 million touches with a finger-far less when activated by a pointed stylus

which speeds the degradation process. Some four-wire products even specify 100,000 activations

within a rather large, 20 mm x 20 mm area.

In the real world of point-of-sale applications, a level of 100,000 activations with hard,

pointed styluses (including fingernails, credit cards, ballpoint pens, etc.) is considered normal

usage in just a few months' time.Also, accuracy can drift with environmental changes.

The polyester coversheet expands and contracts with temperature and humidity changes,

thereby causing long-term degradation to the coatings as well as drift in the touch location.

38




While all of these drawbacks can be insignificant in smaller sizes, they become

increasingly apparent the larger theTouch Screens. Therefore Elo normally recommends four-

wire Touch Screensin applications with a display size of 6.4" or smaller.

However, the relative low cost, inherent low power consumption, and common

availability of chipset controllers with support from imbedded operating systems, makes Elo

AT4 four-wire Touch Screens ideal for hand-held devices such as PDAs, wearable computers,

and many consumer devices.

4 WireResistive Add-on/Internal Touch Screen for less demanding touch applications. Great for

general use, demos, trade shows, proto-typing, proof of concepts, low cost touch requirement.4-

wire analog resistive touch technology is suitable for applications that require ease of integration,

low power consumption, lightweight, portability, cost effectiveness and compact mechanism.

Affordable, durable and versatile, the 4-wire resistive touch screens are primarily used in

mobile applications, such as smart phones, PDAs, e-books, web pads, digital cameras, GPS, and

other consumer or office electronics.

Features:

Input Method: Stylus, Finger, Gloved Hand

Widest Range in Sizes: 1.4" ~ 21"

High Transmission Rate

Low Power Consumption

Narrow Boarder Design

Writing and Signature Capture Capability

Various Constructions Available:

Film/Glass

Film/Strengthened Glass

Film/Film/PC

Sunlight Readability Available

Palm Rejection Model Available

6.2 TECHNOLOGIES

There are a number of types of Touch Screens technology.

Resistive

39




A resistive Touch Screens panel is composed of several layers, the most important of

which are two thin, metallic, electrically conductive layers separated by a narrow gap. When an

object, such as a finger, presses down on a point on the panel's outer surface the two metallic

layers become connected at that point the panel then behaves as a pair of voltage dividers with

connected outputs.

This causes a change in the electrical current which is registered as a touch event and sent

to the controller for processing. Resistive Touch Screenscan also support Multi touch.

Surface acoustic wave

Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the

Touch Screens panel. When the panel is touched, a portion of the wave is absorbed. This change

in the ultrasonic waves registers the position of the touch event and sends this information to the

controller for processing.

Surface wave Touch Screens panels can be damaged by outside elements. Contaminants

on the surface can also interfere with the functionality of the Touch Screens.

Capacitive

A capacitive Touch Screens panel consists of an insulator such as glass, coated with a

transparent conductor such as indium tin oxide (ITO). As the human body is also a conductor,

touching the surface of the screen results in a distortion of the local electrostatic field,

measurable as a change in capacitance.

Different technologies may be used to determine the location of the touch. The location

can be passed to a computer running a software application which will calculate how the user's

touch relates to the computer software.

Surface Capacitance

In this basic technology, only one side of the insulator is coated with a conductive layer.

A small voltage is applied to the layer, resulting in a uniform electrostatic field. When a

conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically

formed.

The sensor's controller can determine the location of the touch indirectly from the change

in the capacitance as measured from the four corners of the panel. As it has no moving parts, it is

moderately durable but has limited resolution, is prone to false signals from parasitic capacitive

40




coupling, and needs calibration during manufacture. It is therefore most often used in simple

applications such as industrial controls.

Projected Capacitance

Projected Capacitive Touch (PCT) technology is a capacitive technology which permits

more accurate and flexible operation, by etching the conductive layer. An XY array is formed

either by etching a single layer to form a grid pattern of electrodes, or by etching two separate,

perpendicular layers of conductive material with parallel lines or tracks to form the grid

(comparable to the pixel grid found in many LCD displays).

Applying voltage to the array creates a grid of capacitors. Bringing a finger or conductive

stylus close to the surface of the sensor changes the local electrostatic field. The capacitance

change at every individual point on the grid can be measured to accurately determine the touch

location.

The use of a grid permits a higher resolution than resistive technology and also allows

multi-touch operation. The greater resolution of PCT allows operation without direct contact,

such that the conducting layers can be coated with further protective insulating layers, and

operates even under screen protectors, or behind weather and vandal-proof glass.

PCT is used in a wide range of applications including point of sale systems, smart

phones, and public information kiosks. Visual Planet's VIPs Interactive Foil is an example of a

kiosk PCT product, where a gloved hand can register a touch on a sensor surface through a glass

window.

Examples of consumer devices using projected capacitive Touch Screens include Apple

Inc.'s iPhone and IPOD Touch, HTC's G1, and HTC Hero, Palm Inc.'s Palm Pre and Palm Pixi

and more recently the LG KM900 Arena, Microsoft's Zune HD and Sony Walkman X series.

Infrared

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Conventional optical-touch systems use an array of infrared (IR) light-emitting diodes

(LEDs) on two adjacent bezel edges of a display, with photo sensors placed on the two opposite

bezel edges to analyze the system and determine a touch event.

The LED and photo sensor pairs create a grid of light beams across the display. An

object (such as a finger or pen) that touches the screen interrupts the light beams, causing a

measured decrease in light at the corresponding photo sensors. The measured photo sensor

outputs can be used to locate a touch-point coordinate.

Widespread adoption of infrared Touch Screen has been hampered by two factors: the

relatively high cost of the technology compared to competing touch technologies and the issue of

performance in bright ambient light.

This latter problem is a result of background light increasing the noise floor at the optical

sensor, sometimes to such a degree that the touch screen’s LED light cannot be detected at all,

causing a temporary failure of the touch screen. This is most pronounced in direct sunlight

conditions where the sun has a very high energy distribution in the infrared region.

However, certain features of infrared touch remain desirable and represent attributes of

the ideal Touch Screen, including the option to eliminate the glass or plastic overlay that most

other touch technologies require in front of the display.

In many cases, this overlay is coated with an electrically conducting transparent material

such as ITO, which reduces the optical quality of the display. This advantage of optical Touch

Screen is extremely important for many device and display vendors since devices are often sold

on the perceived quality of the user display experience.

Another feature of infrared touch which has been long desired is the digital nature of the

sensor output when compared to many other touch systems that rely on analog-signal processing

to determine a touch position.

These competing analog systems normally require continual re-calibration,have a

complex signal-processing demand (which adds cost and power consumption), demonstrate

reduced accuracy and precision compared to a digital system, and have longer-term system-

failure modes due to the operating environment.

Strain gauge

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In a strain gauge configuration, also called force panel technology, the screen is spring-

mounted on the four corners and strain gauges are used to determine deflection when the screen

is touched.

This technology has been around since the 1960s but new advances by Vissumo and F-

Origin have made the solution commercially viable. It can also measure the Z-axis and the force

of a person's touch. Such screens are typically used in exposed public systems such as ticket

machines due to their resistance to vandalism.

Optical imaging

A relatively-modern development in Touch Screen technology, two or more image

sensors are placed around the edges (mostly the corners) of the screen. Infrared backlights are

placed in the camera's field of view on the other sides of the screen.

A touch shows up as a shadow and each pair of cameras can then be triangulated to locate

the touch or even measure the size of the touching object (see visual hull). This technology is

growing in popularity, due to its scalability, versatility, and affordability, especially for larger

units.

Advantages of Four wire Resistive Touch Screen Sensors

It is working well even the surface suffered scraped damage if its glass won't been

hurt.

Our touch panel could be operated in the environment with -10 to 70 degree for

automobile.

Warranty is as longer as 1 year for normal operating with 5,000,000 touching times.

We provide touch panel with high transparency (more than 78%). It is quite clear

even our monitor with low transparency.

We could customize various sizes for customers' request between 1.8 to 19 inch.

It is easy to install into varied brands of monitor

Comparison of Touch Screen Technologies

43




Technology 4-Wire SAW 5-Wire Infrared Capacitive

Durability: 5 year 5 Year 3 Year 3 Year 2 Year

Stability: High Higher High High Ok

Transparency: Ok Good Good Good Ok

Installation:Built-in/On

wall

Built-in/On

wall

Built-in/On

wallOn wall Built-in

Touch: Anything Finger/Pen Anything Sharp Conductive

Intense light-

resistant:Good Good Good Bad Bad

Response time: <10ms 10ms <15ms <20ms <15ms

Following Speed: Good low Good Good Good

Excursion: No Small Big Big Big

Monitor option: CRT CRT CRT or LCDCRT or

LCDCRT or LCD

Waterproof: Good Ok Good Ok Good

Table 6.2 :Comparison of touch screen technologies

Advantages

Plug and play compatible.

Support complete line of windows and Linux os.

Support panels of curve type for CRT and flat type for LCD.

Character recognition for English, Chinese and Japanese languages.

Can support any special request for panel, controller or driver

Four wire Resistive Touch Screen Specification

input mode: Stylus pen or finger

operation temperature: -10 degree to 60 degree 20%rh ~ 85%rh

storage temperature: -20 degree to 80 degree 10%rh ~ 90%rh

transparency: More than 78%

linearity: X less than 1.5%, y less than 1.5%

chattering: Less than 15ms

44




hardness: 3h

knock test: 5,000,000 time

Applications of FourWire ResistiveTouch Screen

Light industrial.

Home appliances.

Portable sport devices.

Access control terminals.

Portable medical devices.

7. ZIGBEE TECHNOLOGY

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Introduction

When we hold the TV remote and wish to use it we have to necessarily point our control

at the device. This one-way, line-of-sight, short-range communication uses infrared (IR) sensors

to enable communication and control and it is possible to operate the TV remotely only with its

control unit.

Add other home theatre modules, an air- conditioner and remotely enabled fans and lights

to our room, and we become a juggler who has to handle not only these remotes, but also more

numbers that will accompany other home appliances we are likely to use.

Some remotes do serve to control more than one device after ‘memorizing' access codes,

but this interoperability is restricted to LOS, that too only for a set of related equipment, like the

different units of a home entertainment system

Now picture a home with entertainment units, security systems including fire alarm,

smoke detector and burglar alarm, air-conditioners and kitchen appliances all within whispering

distance from each other and imagine a single unit that talks with all the devices, no longer

depending on line-of-sight, and traffic no longer being one-way.

This means that the devices and the control unit would all need a common standard to

enable intelligible communication. ZIGBEE is such a standard for embedded application

software and has been ratified in late 2004 under IEEE 802.15.4 Wireless Networking Standards.

ZIGBEE is an established set of specifications for wireless personal area networking

(WPAN), i.e., digital radio connections between computers and related devices. This kind of

network eliminates use of physical data buses like USB and Ethernet cables. The devices could

include telephones, hand-held digital assistants, sensors and controls located within a few meters

of each other.

ZIGBEE is one of the global standards of communication protocol formulated by the

relevant task force under the IEEE 802.15 working group. The fourth in the series, WPAN Low

Rate/ZIGBEE is the newest and provides specifications for devices that have low data rates,

consume very low power and are thus characterized by long battery life.

Other standards like Blue tooth and IrDA address high data rate applications such as

voice, video and LAN communications.

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The ZIGBEE Alliance has been set up as “an association of companies working together

to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control

products based on an open global standard”.

Once a manufacturer enrolls in this Alliance for a fee, he can have access to the standard

and implement it in his products in the form of ZIGBEE chipsets that would be built into the end

devices. Philips, Motorola, Intel, HP are all members of the Alliance. The goal is “to provide the

consumer with ultimate flexibility, mobility, and ease of use by building wireless intelligence

and capabilities into every day devices.

ZIGBEE technology will be embedded in a wide range of products and applications

across consumer, commercial, industrial and government markets worldwide. For the first time,

companies will have a standards-based wireless platform optimized for the unique needs of

remote monitoring and control applications, including simplicity, reliability, low-cost and low-

power”.

The target networks encompass a wide range of devices with low data rates in the

Industrial, Scientific and Medical (ISM) radio bands, with building-automation controls like

intruder/fire alarms, thermostats and remote (wireless) switches, video/audio remote controls

likely to be the most popular applications.

So far sensor and control devices have been marketed as proprietary items for want of a

standard. With acceptance and implementation of ZIGBEE , interoperability will be enabled in

multi-purpose, self-organizing mesh networks.

ZigBee is a wireless technology developed as an open global standard to address the

unique needs of low-cost, low-power, wireless sensor networks. Zigbee is the set of specs built

around the IEEE 802.15.4 wireless protocol.

As Zigbee is the upcoming technology in wireless field, we had tried to demonstrate its

way of functionality and various aspects like kinds, advantages and disadvantages using a small

application of controlling the any kind of electronic devices and machines. The Zigbee

technology is broadly adopted for bulk and fast data transmission over a dedicated channel.

Architecture

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Though WPAN implies a reach of only a few meters, 30 feet in the case of ZIGBEE , the

network will have several layers, so designed as to enable interpersonal communication within

the network, connection to a network of higher level and ultimately an uplink to the Web.

The ZIGBEE Standard has evolved standardized sets of solutions, called ‘layers'. These

layers facilitate the features that make ZIGBEE very attractive: low cost, easy implementation,

reliable data transfer, short-range operations, Very low power consumption and adequate

security features.

Network and Application Support layer

The network layer permits growth of network sans high power transmitters. This layer

can handle huge numbers of nodes. This level in the ZIGBEE architecture includes the ZIGBEE

Device Object (ZDO), user-defined application profile(s) and the Application Support (APS)

sub-layer.

The APS sub-layer's responsibilities include maintenance of tables that enable matching

between two devices and communication among them, and also discovery, the aspect that

identifies other devices that operate in the operating space of any device.

The responsibility of determining the nature of the device (Coordinator / FFD or RFD) in

the network, commencing and replying to binding requests and ensuring a secure relationship

between devices rests with the ZDO (ZIGBEE Define Object). The user-defined application

refers to the end device that conforms to the ZIGBEE Standard.

Physical (PHY) layer

The IEEE802.15.4 PHY physical layer accommodates high levels of integration by using

direct sequence to permit simplicity in the analog circuitry and enable cheaper implementations.

Media Access Control (MAC) layer

The IEEE802.15.4 MAC media access control layer permits use of several topologies

without introducing complexity and is meant to work with large numbers of devices.

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Figure 7.1: ZIGBEE Stack Architecture

Device Types

There are three different ZIGBEE device types that operate on these layers in any self-

organizing application network. These devices have 64-bit IEEE addresses, with option to enable

shorter addresses to reduce packet size, and work in either of two addressing modes – star and

peer-to-peer.

The ZIGBEE coordinator node: There is one, and only one, ZIGBEE coordinator in each

network to act as the router to other networks, and can be likened to the root of a (network)

tree. It is designed to store information about the network.

The full function device FFD: The FFD is an intermediary router transmitting data from

other devices. It needs lesser memory than the ZIGBEE coordinator node, and entails lesser

manufacturing costs. It can operate in all topologies and can act as a coordinator.

The reduced function device RFD: This device is just capable of talking in the network; it

cannot relay data from other devices. Requiring even less memory, (no flash, very little

ROM and RAM), an RFD will thus be cheaper than an FFD. This device talks only to a

network coordinator and can be implemented very simply in star topology.

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ZigbeeCharacterictics

The focus of network applications under the IEEE 802.15.4 / ZIGBEE standard include

the features of low power consumption, needed for only two major modes (Tx/Rx or Sleep), high

density of nodes per network, low costs and simple implementation.

2.4GHz and 868/915 MHz dual PHY modes. This represents three license-free bands:

2.4- 2.4835 GHz, 868-870 MHz and 902-928 MHz. The number of channels allotted to each

frequency band is fixed at sixteen (numbered 11-26), one (numbered 0) and ten (numbered

1-10) respectively.

The higher frequency band is applicable worldwide, and the lower band in the areas of North

America, Europe, Australia and New Zealand.

Low power consumption, with battery life ranging from months to years. Considering the

number of devices with remotes in use at present, it is easy to see that more numbers of

batteries need to be provisioned every so often, entailing regular (as well as timely),

recurring expenditure.

In the ZIGBEE standard, longer battery life is achievable by either of two means: continuous

network connection and slow but sure battery drain, or intermittent connection and even

slower battery drain.

Maximum data rates allowed for each of these frequency bands are fixed as 250 kbps @2.4

GHz, 40 kbps @ 915 MHz, and 20 kbps @868MHz.

High throughput and low latency for low duty-cycle applications (<0.1%)

Channel access using Carrier Sense Multiple Access with Collision Avoidance

(CSMA - CA)

Addressing space of up to 64 bit IEEE address devices, 65,535 networks

50m typical range

Fully reliable hand shaked data transfer protocol.

Different topologies as illustrated below: star, peer-to-peer, mesh

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Figure 7.2 :ZIGBEE Topologies

Traffic Types

ZIGBEE /IEEE 802.15.4 addresses three typical traffic types. IEEE 802.15.4 MAC can

accommodate all the types.

Data is periodic isThe application dictates the rate, and the sensor activates, checks for

data and deactivates.

Data is intermittent isThe application, or other stimulus, determines the rate, as in the case

of say smoke detectors. The device needs to connect to the network only when

communication is necessitated. This type enables optimum saving on energy.

Data is repetitive, and the rate is fixed a priori. Depending on allotted time slots, called

GTS (guaranteed time slot), devices operate for fixed durations.

ZIGBEE employs either of two modes, beacon or non-beacon to enable the to-and-fro

data traffic. Beacon mode is used when the coordinator runs on batteries and thus offers

maximum power savings, whereas the non-beacon mode finds favor when the coordinator is

mains powered. In the beacon mode, a device watches out for the coordinator's beacon that gets

transmitted at periodically, locks on and looks for messages addressed to it.

If message transmission is complete, the coordinator dictates a schedule for the next

beacon so that the device ‘goes to sleep'; in fact, the coordinator itself switches to sleep mode.

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Network Model

The functions of the Coordinator, which usually remains in the receptive mode,

encompass network set-up, beacon transmission, node management, storage of node information

and message routing between nodes.

The network node, however, is meant to save energy (and so ‘sleeps' for long periods)

and its functions include searching for network availability, data transfer, checks for pending

data and queries for data from the coordinator.

Figure 7.3: ZIGBEE Network Model

For the sake of simplicity without jeopardizing robustness, this particular IEEE standard

defines a quartet frame structure and a super-frame structure used optionally only by the

coordinator.

The four frame structures are

Beacon frame for transmission of beacons

Data frame for all data transfers

Acknowledgement frame for successful frame receipt confirmations

MAC command frame

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These frame structures and the coordinator's super-frame structure play critical roles in

security of data and integrity in transmission.

All protocol layers contribute headers and footers to the frame structure, such that the

total overheads for each data packet range are from 15 octets (for short addresses) to 31 octets

(for 64-bit addresses).

The coordinator lays down the format for the super-frame for sending beacons after every

15.38 ms or/and multiples thereof, up to 252s.

This interval is determined a priori and the coordinator thus enables sixteen time slots of

identical width between beacons so that channel access is contention-less. Within each time slot,

access is contention-based. Nonetheless, the coordinator provides as many as seven GTS

(guaranteed time slots) for every beacon interval to ensure better quality.

Technology Comparisons

The “Why ZIGBEE” question has always had an implied, but never quite worded

follower phrase “when there is Blue tooth”. A comparative study of the two can be found in

ZIGBEE 'Wireless Control That Simply Works’.

The bandwidth of Blue tooth is 1 Mbps, ZIGBEE is one-fourth of this value. The

strength of Blue tooth lies in its ability to allow interoperability and replacement of

cables,ZIGBEE ,of course, is low costs and long battery life.

In terms of protocol stack size, ZIGBEE 32 KB is about one-third of the stack size

necessary in other wireless technologies (for limited capability end devices, the stack size is as

low as 4 KB).

Most important in any meaningful comparison are the diverse application areas of all

the different wireless technologies. Blue tooth is meant for such target areas as wireless USB's,

handsets and headsets, whereas ZIGBEE is meant to cater to the sensors and remote controls

market and other battery operated products.

In a gist, it may be said that they are neither complementary standards nor competitors,

but just essential standards for different targeted applications. The earlier Blue tooth targets

interfaces between PDA and other device (mobile phone / printer etc) and cordless audio

applications.

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The IEEE 802.15.4–based ZIGBEE is designed for remote controls and sensors, which

are very many in number, but need only small data packets and, mainly, extremely low power

consumption for (long) life. Therefore they are naturally different in their approach to their

respective application arenas.

ZIGBEE Applications

The ZIGBEE Alliance targets applications "across consumer, commercial, industrial and

government markets worldwide".

Unwired applications are highly sought after in many networks that are characterized by

numerous nodes consuming minimum power and enjoying long battery lives.

ZIGBEE technology is designed to best suit these applications, for the reason that it

enables reduced costs of development, very fast market adoption, and rapid ROI.

AIRBEE Wireless Inc has tied up with Radio crafts AS to deliver "out-of-the-

box"ZIGBEE ready solutions, the former supplying the software and the latter making the

module platforms. With even light controls and thermostat producers joining the ZIGBEE

Alliance, the list is growing healthily and includes big OEM names like HP, Philips, Motorola

and Intel.

WithZIGBEE designed to enable two-way communications, not only will the consumer

be able to monitor and keep track of domestic utilities usage, but also feed it to a computer

system for data analysis.

A recent analyst report issued by West Technology Research Solutions estimates that by

the year 2008, "annual shipments forZIGBEE chipsets into the home automation segment alone

will exceed 339 million units," and will show up in "light switches, fire and smoke detectors,

thermostats, appliances in the kitchen, video and audio remote controls, landscaping, and

security systems."

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8.GLCD 128x64

Introduction

This 128x64 graphic LCD is the latest high quality offering from Crystal Fonts. This

production unit is much more than just a surplus LCD found on many electronics sites. This

CFAX model comes with an EL backlight and a 4-wire analog touch screen! You can use it for

anything.

Features

Ultra thin and light TAB construction

Wide viewing angles

Built-in controller: Samsung KS0713 (data sheet 850K).

Great for hand held instruments, cell phones, PDAs, etc.

Ultra low power consumption

Dimensions

56.0mm x 42.5mm Module Outline (less tab)

52.0mm x 33.5mm Viewing Area

47.76mm x 30.29mm Active Area

0.35mm x 0.40mm Dot Pitch

Salient features of the Interface with Graphical LCD Display are

Programming of additional vacuum signals and other Pheripheric equipment signals

possible.

Up to Different languages are included and can be selected:

English, German, French, Spanish, Chinese, etc.

Standard molding machine interface [SPI & E12]

Full diagnosis with text error messages

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LCD port

The LCD port provides the 14 standard signals required to interface to nearly all standard

alphanumeric character mode displays from 8 to 80 characters. VDD provides +5 volt regulated

power to the display (VSS is Ground). VEE ranges from 0 (maximum intensity) to 2 volts

(minimum intensity) with the adjustment of the variable resistor located just above next to the

power input.

The E signal is an active high enable, which is asserted when the processor makes a

memory access within the address range of 0xFE00 to 0xFEFF. RS and R/W are control lines for

the display. In order to meet the timing requirements for all standard LCD displays, these are

connected to the processor's address lines so they are asserted and remain stable while E is

asserted. Because of this, separate locations are used to read and write to the LCD.

Description

Graphical LCD 128x64 controlled with the ATMega16, the graphic LCD GLCD

HG1286418C-VA with a S6B0107/S6B0108 controller is used. See below for the pinout of the

display. The display has 8 data bits and 5 control bits. The databits are hooked to PORTB and the

control bits are hooked to PORTD of the Mega16.

Figure 8.1: Graphical LCD

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A small PCB board is made for easy connection to the microcontroller. The program is

made with the BASCOM-AVR compiler. The program shows text and a picture on the display.

A library file needs to be included in theprogram, the library contains commands to

control the display like

Setfont - Sets the current font which can be used on the graphical displays.

Lcdat - shows text on the display

$BGF - Includes a BASCOM Graphic File in the program.

Showpic - shows a graphic file on the display

Line - draws a line on the display

Circle - draws a circle on the display

Pset - Sets a single pixel on the display

There are several fonts available like a 8x8 font and a 16x16 font, but the font file

consume memory, the large the font file the larger the program becomes.

The core is used to provide a wishbone compliant interface to a graphical LCD. Currently

it supports the Crystalfontz CFAG12864 family, which is based on the KS0108B controller.

Other graphical LCDs may be supported at a later date.

Advantages

No time consuming graphic programming

Free Windows™ LCD simulator and development software

No expensive software licenses required.

Easy to learn powerful commands

Fast development, drastically reduced time-to-market

Touch-screen driver and analogue touch-screen included

Minimal electronics required to drive the display i.e memory, I/O, low cost CPU

Hardware cost savings due to the onboard memory and low pin count interface.

Variety of serial interfaces ( 5V RS-232, I²C, SPI )

Breakout boards with USB, RS232 and RS485 interface

Display requires only a single +5V supply

Extremely compact construction with DIP connectors at the back of LCD

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Stylish black alum. bezel and mounting system available

LCD is available with analogue touch screen (order option -TP)

Monochrome LCD's are available in blue/white, white/black positive FSTN and Amber

Only best quality materials used

Long products availability, recommended for industrial products

Applications

Medical equipment

Electronic test equipment

Industrial machinery Interface

Serial terminal

Advertising system

EPOS

Restaurant ordering systems

Gaming box

Security systems

R&D Test units

Climatizing units

PLC Interface

Simulators

Environmental monitoring

Lab development

Student projects

Home automation

PC external display

HMI operator interface.

Advantages of Graphic LCDs

Download high quality fonts of any size, style or language easily and quickly

Create graphics using primitives such as bitmaps, pixels, lines, rectangles and bar graphs.

Software Control

Backlight & Contrast is adjustable in most models

4 different brightness settings

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General Purpose Output (20mA drive)

Line wrap and Auto screen

scroll Bar Graphs and Large Digits

Speed settings

Splash/Start-up Screen

Features

Speeds from 19.2Kbps to a lighting fast 115Kbps

96 bit buffer

15872 bytes of memory! Store up to 30 full image screens

Upload your own fonts for a customized look

Communicate over RS232 or I2C

Optional wide voltage efficient power regulator from +7 to +30Vdc

Extended Black and white ST (MST) Tran missive mode

Built-in CCFL backlight40 characters x 18 line capability240 x 128 dot graphic display

Excellent readability and high-contrast ratio

Built-in LCD controller (T6963C)

Wide operating temperature range (0° to 50°C)

Some examples of graphic LCD controller chips are the Toshiba T6963, Seiko-Epson

SED1330, and Hitachi HD61202. Here, we will be primarily concerned with character LCD

modules that have the Hitachi HD44780 controller built-in.

9. ADVANTAGES and APPLICATIONS

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The Advantagesof this project are

Its operation is simple and easy

It is less expensive

It is highly efficient

Power required is less

Faster and secure data transmission

User friendly and easy to install.

The Applicationsof this project are

It is used in airlines

It is applicable in hospitals

It is used in restaurents

Very useful even for illiterates.

Helpful in abroad to express user’s needs.

Deaf and dump people also can interact with others.

Can be used with any languages.

10. CODING

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//Source Code for Touch Screen Airlines Assistant Project (transmitter)

#include <16F73.h>

#use delay(clock=20000000)

#use rs232 (baud = 9600, xmit=PIN_B0,rcv=PIN_B1,stream=WIRELESS) // WIRELESS communication

unsigned long x_coord, y_coord;

voidsend_data(char sdata[]){fputs(sdata,WIRELESS); }

unsigned long GetX(){unsigned long result; set_adc_channel(0);output_low(PIN_A2);output_high(PIN_A3); result = read_adc();return result; }

unsigned long GetY(){unsigned long result; set_adc_channel(1);output_low(PIN_A3);output_high(PIN_A2);result = read_adc();return result; }

void main(){char text[25];

output_high(PIN_C4);delay_ms(1000);

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output_low(PIN_C4);delay_ms(1000);output_high(PIN_C4);delay_ms(1000);output_low(PIN_C4);

while(1) {

x_coord = GetX(); //get X- coordinates of touched location on to variable x_coord

y_coord = GetY(); //Get the Y-coordingates of touched location

if((x_coord> 25) && (x_coord< 85) && (y_coord> 25) && (y_coord< 125)) {sprintf(text,"1");send_data(text);output_high(PIN_C4); }else if((x_coord> 25) && (x_coord< 85) && (y_coord> 150) && (y_coord< 240)) {sprintf(text,"2");send_data(text);output_high(PIN_C4); }

else if((x_coord> 90) && (x_coord< 140) && (y_coord> 25) && (y_coord< 125)) {sprintf(text,"3");send_data(text);output_high(PIN_C4); }else if((x_coord> 90) && (x_coord< 140) && (y_coord> 150) && (y_coord< 240)) {sprintf(text,"4");send_data(text);output_high(PIN_C4); }else if((x_coord> 145) && (x_coord< 190) && (y_coord> 25) && (y_coord< 125)) { sprintf(text,"5");send_data(text);output_high(PIN_C4);

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}else if((x_coord> 145) && (x_coord< 190) && (y_coord> 150) && (y_coord< 240)) {sprintf(text,"6");send_data(text);output_high(PIN_C4); }else if((x_coord> 195) && (x_coord< 250) && (y_coord> 25) && (y_coord< 125)) {output_high(PIN_C3); //LED Lamp ON

}else if((x_coord> 195) && (x_coord< 250) && (y_coord> 150) && (y_coord< 240)) {output_low(PIN_C3); //LED Lamp OFF } delay_ms(100);output_low(PIN_C4); }}

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//Source Code for Touch Screen Airlines Assistant Project (Receiver)#include <16F73.h>

#use delay(clock=20000000) //crystal oscillator

#use rs232 (baud = 9600, xmit=PIN_B1,rcv=PIN_B0,stream=WIRELESS) // WIRELESS communication

#include <nokiaGLCD.c> //For Nokia Graphical LCD

void main(){char text[25]; //For capturing the textcharch;

//Following code is for Health Check (microcontroller)output_high(PIN_C4); //LED ONdelay_ms(1000);output_low(PIN_C4); //LED OFFdelay_ms(1000);output_high(PIN_C4); //LED ONdelay_ms(1000);output_low(PIN_C4); //LED OFF

nokia_init(); //Initialise Nokia GLCD

//Nokia LCD got 6 row and 21 columns

nokia_clear_screen(); //Clear the screen contents

nokia_gotoxy(2,1); //Go to row number-1 and column number 2

sprintf(text," TOUCH SCREEN"); //this copies the text "TOUCH SCREEN" into the variable text.

printf(nokia_printchar,"%s",text); //Print the text on to LCD

delay_ms(1000); //wait for 1000 milli seconds

nokia_gotoxy(2,3); //third row second columnsprintf(text," AIR LINES"); //copies the text into text variableprintf(nokia_printchar,"%s",text);delay_ms(500);

nokia_gotoxy(2,5); //Fifth row and second column

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sprintf(text," ASSISTANT");printf(nokia_printchar,"%s",text);delay_ms(2000);

nokia_clear_screen(); //clear LCD contentsnokia_gotoxy(3,3);sprintf(text,"*** READY ***");printf(nokia_printchar,"%s",text);delay_ms(1000);

while(1) //Infinite loop starts here {

if(!input(PIN_A0)) //If the clear button pressed, then clear the requests on LCD {output_high(PIN_C3); delay_ms(500); //Long Beepoutput_low(PIN_C3);

nokia_clear_screen();nokia_gotoxy(4,1);printf(nokia_printchar," NO");nokia_gotoxy(4,3);printf(nokia_printchar," PENDING");nokia_gotoxy(4,5);printf(nokia_printchar," REQUESTS");output_low(PIN_C4); }

ch = fgetc(WIRELESS); //get character

nokia_clear_screen(); // clear Nokia screen LCD

nokia_gotoxy(1,1);printf(nokia_printchar," SEAT NO: A9");output_high(PIN_C4); //LED ONswitch(ch) //switch to the block based on character received. {case '1':nokia_gotoxy(4,3);printf(nokia_printchar," REQUESTING");nokia_gotoxy(4,5);printf(nokia_printchar," WATER");

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break;

case '2': nokia_gotoxy(4,3);printf(nokia_printchar," REQUESTING");nokia_gotoxy(4,5);printf(nokia_printchar," FOOD");break;

case '3': nokia_gotoxy(4,3);printf(nokia_printchar," REQUESTING");nokia_gotoxy(4,5);printf(nokia_printchar," MEDICINE");break;

case '4': nokia_gotoxy(4,3);printf(nokia_printchar," REQUESTING");nokia_gotoxy(4,5);printf(nokia_printchar," BED SHEET");break;case '5': nokia_gotoxy(4,3);printf(nokia_printchar," REQUESTING");nokia_gotoxy(4,5);printf(nokia_printchar," SNACKS");break;case '6': nokia_gotoxy(4,3);printf(nokia_printchar," REQUESTING");nokia_gotoxy(4,5);printf(nokia_printchar," MAGAZINE");break; } //end of switch statement }}

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11. FUTURE SCOPE

As we have different languages in our world and its impossible for us to know all the languages. So, in this project we are building a device that

helps them in expressing their needs with other language people. As Zigbee is the upcoming technology in wireless field. The Zigbee technology is broadly

adopted for bulk and fast data transmission over a dedicated channel.

This is used for sending and receiving the information with the otherlanguage people in

airlinesusing Touch screen and GLCD.Theproject“TOUCHSCREEN AND ZIGBEE BASED

WIRELESSCOMMUNICATION ASSISTANT FOR DUMB/ILLITERATES IN AIRLINES”

has been successfully designed and tested. Integrating features of all the hardware components

used have developed it. Presence of every module has been reasoned out and placed carefully

thus contributing to the best working of the unit. Secondly, using highly advanced IC’s,

microcontrollers and with the help of growing technology the project has been successfully

implemented

12. CONCLUSION

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The main aim of this project is to construct a user friendly multi-language communication system for illiterate/dumb people travelling by Airlines. As

we have different languages in our world and its impossible for us to know all the languages. So, in this project we are building a device that helps them in

expressing their needs with other language people (Air hostess) i.e. request them if we need anything in the flight like coffee, tea, drinks etc.

In this project we use GLCD and Touch screen Technology to make it easy even to illiterates as it is also included with images, which indicates the

needs. This even reduces the difficulty to airhostess in receiving the customers with different languages. Here for wireless communication purpose we use Zigbee

technology.

As Zigbee is the upcoming technology in wireless field, we had tried to demonstrate its way of functionality and various aspects like kinds,

advantages and disadvantages using a small application of controlling the any kind of electronic devices and machines. The Zigbee technology is broadly adopted

for bulk and fast data transmission over a dedicated channel.

13. BIBLIOGRAPHY

REFERENCES

Embedded Design with the PIC 18F452Micro Controller by John Peatman,published

2003 by prentice Hall.

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PIC Micro Controller An Introduction to software & hardware interfacing,1stEdition,Han

Way Huang, Leo Chartrand, published 2004 by DelmavCengage Learning.

Potter, R., Weldon, L. and Shneiderman, B. Improving the accuracy of touch screen: An

experimental evaluation of three strategies. Proc. CHI'88. (Washington, D.C., May, 1988), ACM

Press, 27-32.

Designing Embedded systems with PIC MicroController, second Edition: Principles and

Applications by Tim Wilmshurst, published 2009 by Newnes, 2nd edition.

WEB SITES

www.freescale.com

www.networkworld.com

www.touchscreens.com

www.wikipedia.com

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Touchscreen and Zigbee Assistant in Airlines

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