ABSTRACT
Gesture
vocalizer is a large scale microcontroller based system being designed to
facilitate the communication among the dumb and deaf communities and their
communication with the normal people. This system can be dynamically
reconfigured to work as a “smart device”. Gesture vocalizer discussed is
basically a data glove and a microcontroller based system. Data glove can
detect almost all the movements of a hand and microcontroller based system
converts some specified movements into human recognizable voice. The data glove
is equipped with two types of sensors: The bend sensors and accelerometers as
tilt sensors. This system is beneficial for dumb people such that their hands
will speak having worn the gesture vocalizer data glove.
INTRODUCTION
“Speech”
and “gestures” are the expressions, which are mostly used in communication
between human beings. Learning of their use begins with the first years of
life. Research is in progress that aims to integrate gesture as an expression
in Human-Computer Interaction (HCI).
In
human communication, the use of speech and gestures is completely coordinated.
Machine gesture and sign language recognition is about recognition of gestures
and sign language using computers. A number of hardware techniques are used for
gathering information about body positioning; typically either image-based
(using cameras, moving lights etc.) or device-based (using instrumented gloves,
position trackers etc.).
However,
getting the data is only the first step. The second step, that of recognizing
the sign or gesture once it has been captured is much more challenging,
especially in a continuous stream.
This
project analyses the data from an instrumented data glove for use in
recognition of some signs and gestures. A system is developed for recognizing
these signs and their conversion into speech.
The
results will show that despite the noise and accuracy constraints of the
equipment, reasonable accuracy rates have been achieved.
Fig.1: gesture vocalizer system
MOTIVATION
The motivation of this project is the problem faced when dumb
people communicate with blind,deaf and normal communities.
Since all gestures used by dumb people are not understood by
normal or blind people the gesture vocalizer comes into play. Where the gestures
used by dumb people are converted into voice.
Likewise the gestures are also displayed on an LCD (Liquid
crystal display), hence helping the communication between deaf and dumb people.
Therefore the aim of the project is to create a glove, which
allows interaction of the dumb people with blind, deaf and normal people, with
no greater effort than wearing a glove which can be part of one’s daily attire.
SYSTEM DESCRIPTION
Block
diagram of the system is shown in Fig.1.1. The system is consisted of the
following modules:
•
Data Glove
•
Tilt detection
•
Gesture detection
•
Speech Synthesis
•
LCD Display
Data
glove is consisted of two sensors; bend sensors and tilt sensor. The output of
the tilt sensors is detected by the tilt detection module, while the output of
the bend sensors, and the overall gesture of the hand are detected by the
gesture detection module. Gesture detection module gives low input to the voice
record and playback module. The voice record and playback module outputs
message with respect to each input from the gesture detection module. And the
same output is also displayed on the LCD.
Fig.2:
Block diagram of the system
DATA GLOVE
The
main module of the project is the data glove. It mainly consists of two sensors;
bend sensor and tilt sensor.
FLEX SENSOR
In
this project,the data glove is equipped with three bend or flex sensors, each
of the bend sensor is meant to be fixed on one of the finger of the hand glove
for the monitoring and sensing of static movements of the fingers of the hand.
One
side of the sensor is printed with a polymer ink that has conductive particles
embedded in it. When the sensor is straight, the particles give the ink a
resistance of about 30k Ohms. When the sensor is bent away from the ink, the
conductive particles move further apart, increasing this resistance (to about
50k Ohms when the sensor is bent to 90ยบ as in the diagram below). When the
sensor straightens out again, the resistance returns to the original value. By
measuring the resistance, you can determine how much the sensor is being bent.
Fig.3: Bend sensor operation
General features
- Angle Displacement Measurement
- Bends and Flexes physically with motion device
- Possible Uses
1.
Robotics
2.
Gaming
(Virtual Motion)
3.
Medical
Devices
4.
Computer
Peripherals
5.
Musical
Instruments
6.
Physical
Therapy
- Simple Construction
- Low Profile
3.1.2
Mechanical Specifications
-Life Cycle: >1 million
-Height: 0.43mm (0.017")
-Temperature Range: -35°C to +80°C
3.1.3
Electrical Specifications
-Flat Resistance: 25K Ohms
-Resistance Tolerance: ±30%
-Bend Resistance Range: 45K to 125K Ohms (depending on
bend radius)
Fig.5: Different angles of
the flex sensor
TILT SENSOR
Accelerometer in the Gesture Vocalizer system is used as a tilt sensor, which checks the tilting of the hand. ADXL335 is the accelerometer used in the system. The accelerometer has an analog output, and this analog output varies from 1.5 volts to 3.5 volts.It uses a single structure for sensing the X, Y, and Z axes. As a result, the three axes’ sense directions are highly orthogonal and have little cross-axis sensitivity. Mechanical misalignment of the sensor due to the package is the chief source of cross-axis sensitivity. Mechanical misalignment can, of course, be calibrated out at the system level.
.
The user can select the bandwidth of the accelerometer using the CX, CY, and CZ capacitors at the XOUT, YOUT, and ZOUT pins. Bandwidths can be selected to suit the application, with a range of 0.5 Hz to 1600 Hz for the X and Y axes, and a range of 0.5 Hz to 550 Hz for the Z axis.
The user can select the bandwidth of the accelerometer using the CX, CY, and CZ capacitors at the XOUT, YOUT, and ZOUT pins. Bandwidths can be selected to suit the application, with a range of 0.5 Hz to 1600 Hz for the X and Y axes, and a range of 0.5 Hz to 550 Hz for the Z axis.
The ADXL335 is available in a small, low profile, 4 mm × 4 mm ×
1.45 mm, 16-lead, plastic lead frame chip scale package (LFCSP_LQ).It’s a cost sensitive and low power consumption
device used for motion- and tilt-sensing measurement.
It’s applications are found in:
·
Mobile
devices
·
Gaming
systems
·
Disk
drive protection
·
Image
stabilization
Fig.8: Functional block diagram of
ADXL335
THEORY OF
OPERATION
The ADXL335 is a
complete 3-axis acceleration measurement system. The ADXL335 has a measurement
range of ±3 g mini-mum. It contains a polysilicon surface-micro-machined
sensor and signal conditioning circuitry to implement an open-loop acceleration
measurement architecture. The output signals are analog voltages that are
proportional to acceleration. The accelerometer can measure the static
acceleration of gravity in tilt-sensing applications as well as dynamic
acceleration resulting from motion, shock, or vibration.
The sensor is a
polysilicon surface micro-machined structure built on top of a silicon wafer.
Polysilicon springs suspend the structure over the surface of the wafer and
provide a resistance against acceleration forces. Deflection of the structure
is measured using a differential capacitor that consists of independent fixed
plates and plates attached to the moving mass. The fixed plates are driven by
180° out-of-phase square waves. Acceleration deflects the moving mass and
unbalances the differential capacitor resulting in a sensor output whose
amplitude is proportional to acceleration. Phase-sensitive demodulation
techniques are then used to determine the magnitude and direction of the
acceleration.
The
demodulator output is amplified and brought off-chip through a 32 kฮฉ resistor.
The user then sets the signal bandwidth of the device by adding a capacitor.
This filtering improves measurement resolution and helps prevent aliasing.
MECHANICAL SENSOR
The ADXL335 uses
a single structure for sensing the X, Y, and Z axes. As a result, the three
axes’ sense directions are highly orthogonal and have little cross-axis
sensitivity. Mechanical misalignment of the sensor due to the package is the
chief source of cross-axis sensitivity. Mechanical misalignment can, of course,
be calibrated out at the system level.
PERFORMANCE
Rather than using additional temperature
compensation circuitry, innovative design techniques ensure that high
performance is built in to the ADXL335. As a result, there is no quantization
error or non-monotonic behaviour, and temperature hysteresis is very low
(typically less than 3 mg over the −25°C to +70°C temperature range).
PIN CONFIGURATION AND FUNCTION DESCRIPTION
Fig.9: Pin diagram of ADXL335
PIN DESCRIPTION
Pin
No.
|
Mnemonic
|
Mnemonic
|
1
|
NC
|
No
Connect
|
2
|
ST
|
Self-Test
|
3
|
COM
|
Common.
|
4
|
NC
|
No
Connect
|
5
|
COM
|
Common.
|
6
|
COM
|
Common.
|
7
|
COM
|
Common.
|
8
|
ZOUT
|
Z
Channel Output.
|
9
|
NC
|
No
Connect
|
10
|
YOUT
|
Y
Channel Output.
|
11
|
NC
|
No
Connect
|
12
|
XOUT
|
X
Channel Output.
|
13
|
NC
|
No
Connect
|
14
|
VS
|
Supply
Voltage (1.8 V to 3.6 V)
|
15
|
VS
|
Supply
Voltage (1.8 V to 3.6 V)
|
16
|
NC
|
No
Connect
|
EP
|
Exposed
Pad
|
Not
internally connected. Solder for mechanical integrity
|
Table 1: Pin Description of ADXL 335
TILT DETECTION
The
basic function of this module is to detect the tilting of the hand and to send
the corresponding signal to the gesture detection module.The output, which is obtained
from the accelerometer after amplification, is an analog output. To deal with
this analog output, and to make it useful for further use, it is required to
change it into some form, which is detectable by the microcontroller.Hence the
analog output of the accelerometer is converted into digital form.
This
tilt detection module in the gesture vocalizer system is a three axis system,
which can detect the tilt of the hand in three axes. An inbuilt ADC in
PIC18F25K20 microcontroller in the gesture detection module can be used to
convert the outputs of accelerometer into digital form.
Microcontroller
receives the data of the ADC, and saves them,for the further use. Next step for
the microcontroller is to check the data from the ADC. The microcontroller
checkswhether the data received from the ADC is some recognizable data, or
useless one. Meaningful means that the tilt of the hand is some meaningful tilt
and hand is signaling some defined gesture, or a part of the gesture, because
gesture means a complete motion of the hand in which the bending of the finger
is also involved. The microcontroller compares the values received from the ADC
with the predefined values, which are present in the memory of the
microcontroller and on the basis of this comparison the microcontroller decides
that, if the gesture a meaningful gesture.
Fig.10: The gravity range with respect to different degrees
If
the hand is signaling a meaningful gesture then the microcontroller moves
towards the next step. The signal generated is different for every valid gesture.
On the basis of this signal, which is, sent by the tilt detection module, the “gesture
detection” module comprising of the microcontroller, checks the gestures as a
whole, and takes some decisions. The “gesture detection module” comprising of
the microcontroller, sends data to the voice record and playback module that
knows the meaning of each data.
BEND DETECTION
The bend detection module is also an important part of the system. The bend sensors are fixed to 3 fingers of the data glove, and are basically responsible for the detection of the bend of the fingers.
Even
a little bend of the finger is detected at this stage of the system. The
bending of the finger has infinite levels of bends, and the system is very
sensitive to the bending of the finger. Now the bending of each finger is
quantized into ten levels. At any stage, the finger must be at one of these
levels, and it can easily be determined how much the finger is bent. So that
individual bending of each finger can be captured. System knows how much each
finger is bent. Now the next step is to combine the movement of each finger and
name it a particular gesture of the hand.
Now
the system reads the movements of three fingers as a whole, rather than reading
the individual finger. Having read bending of the fingers, the system checks
whether the bend is some meaningful bend, or a useless or undefined bend. If
the bending of the fingers gives some meaningful gesture, then system moves
towards the next step.
In
the next step the system checks the data, which was sent by tilt detection
module at port one of the microcontroller. The data sent by this module shows
whether the tilt of the hand is giving some meaningful gesture or it is
undefined. If the tilt of the hand is also meaningful then it means that the
gesture as a whole is a meaningful gesture.
So
far it is detected by the system whether thegesture given by hand is some
meaningful gesture, or auseless one. If the gesture is meaningful, the
systemsends data to the voice record and playback module. This data can
represent differentgestures.
GESTURE DETECTION
The
Gesture detection module comprises of a microcontroller namely PIC18F25K20.
This module processes the gestures detected by the tilt and bend detection
modules to generate voice, by providing processed signal to voice record and
playback IC,APR9600 and also to the alphanumeric LCD,JHD162A to display the
same in text form.
PIC18F25K20
PIC is a family of modified
Harvard architecturemicrocontrollers made by Microchip
Technology,
derived from the PIC1650 originally developed by General Instrument's Micro-electronics Division. The name PIC
initially referred to "Peripheral
Interface Controller".
PICs are popular with both industrial developers and hobbyists alike due to their low cost, wide availability, large user base, extensive collection of application notes, availability of low cost or free development tools, and serial programming (and re-programming with flash memory) capability.
The
features of PIC18F25K20 are as follows:
High-Performance RISC CPU:
•
C Compiler Optimized Architecture:
-
Optional extended instruction set designed to optimize re-entrant code
•
Up to 1024 bytes Data EEPROM
•
Up to 64 Kbytes Linear Program Memory Addressing
•
Up to 3936 bytes Linear Data Memory Addressing
•
Up to 16 MIPS Operation
•
16-bit Wide Instructions, 8-bit Wide Data Path
•
Priority Levels for Interrupts
•
31-Level, Software Accessible Hardware Stack
•
8 x 8 Single-Cycle Hardware Multiplier
Flexible Oscillator Structure:
•
Precision 16 MHz Internal Oscillator Block:
- Factory calibrated to ± 1%
-
Software selectable frequencies range of31 kHz to 16 MHz
-
64 MHz performance available using PLL –no external components required
•
Four Crystal modes up to 64 MHz
•
Two External Clock modes up to 64 MHz
•
4X Phase Lock Loop (PLL)
•
Secondary Oscillator using Timer1 @ 32 kHz
•
Fail-Safe Clock Monitor:
-
Allows for safe shutdown if peripheral clockstops
-
Two-Speed Oscillator Start-up
Special Microcontroller Features:
•
Operating Voltage Range: 1.8V to 3.6V
•
Self-Programmable under Software Control
•
Programmable 16-Level High/Low-VoltageDetection (HLVD) module:
-
Interrupt on High/Low-Voltage Detection
•
Programmable Brown-out Reset (BOR):
-
With software enable option
•
Extended Watchdog Timer (WDT):
-
Programmable period from 4 ms to 131s
•
Single-Supply 3V In-Circuit SerialProgramming™ (ICSP™) via Two Pins
•
In-Circuit Debug (ICD) via Two Pins
Extreme
Low-Power Management with nanoWatt XLP:
•
Sleep mode: < 100 nA @ 1.8V
•
Watchdog Timer: < 800 nA @ 1.8V
•
Timer1 Oscillator: < 800 nA @ 32 kHz and 1.8V
Analog Features:
•
Analog-to-Digital Converter (ADC) module:
-
10-bit resolution, 13 External Channels
-
Auto-acquisition capability
-
Conversion available during Sleep
-
1.2V Fixed Voltage Reference (FVR) channel
-
Independent input multiplexing
•
Analog Comparator module:
-
Two rail-to-rail analog comparators
-
Independent input multiplexing
•
Voltage Reference (VREF) module:
-
Programmable (% VDD), 16 steps
-
Two 16-level voltage ranges using VREF pins
Peripheral Highlights:
•
Up to 35 I/O Pins plus 1 Input-only Pin:
-
High-Current Sink/Source 25 mA/25 mA
-
Three programmable external interrupts
-
Four programmable interruptonchange
-
Eight programmable weak pull-ups
-
Programmable slew rate
•
Capture/Compare/PWM (CCP) module
•
Enhanced CCP (ECCP) module:
-
One, two or four PWM outputs
-
Selectable polarity
- Programmable
dead time
- Auto-Shutdown
and Auto-Restart
• Master
Synchronous Serial Port (MSSP) module
- 3-wire SPI
(supports all 4 modes)
- I2C™ Master
and Slave modes with address mask
• Enhanced
Universal Synchronous Asynchronous Receiver Transmitter (EUSART) module:
- Supports
RS-485, RS-232 and LIN
- RS-232
operation using internal oscillator
- Auto-Wake-up
on Break
-Auto-BaudDetect
Advantages
The PIC architectures have these advantages:
- Small
instruction set to learn
- RISC architecture
- Built
in oscillator with selectable speeds
- Easy
entry level, in circuit programming plus in circuit debugging PICKit units available from
Microchip.com for less than $50
- Inexpensive
microcontrollers
Wide range of interfaces including I²C, SPI, USB, USART, A/D, programmable comparators, PWM, LIN, CAN, PSP, and Ethernet.
6.1.8
Limitations
The PIC
architectures have these limitations:
- One accumulator
- Register-bank switching is required to access the entire
RAM of many devices
- Operations and registers
are not orthogonal; some instructions can
address RAM and/or immediate constants, while others
can only use the accumulator
The
following stack limitations have been addressed in the PIC18 series, but
still apply to earlier cores:
- The hardware call stack
is not addressable, so preemptivetask
switching
cannot be implemented
Software-implemented stacks are not efficient, so it is difficult to generate reentrant code and support local variables
Fig. 12: PIC18F25K20 IC
AMICUS 18 BOARD
What does the name Amicus mean ?
The name Amicus derives from the Latin word Amici, meaning friend. An Amicus is a person who speaks or performs on your behalf. The Amicus18 board will become your best friend, allowing a freedom to perform tasks that you never dreamed possible.
The IC, PIC18F25K20 is supported by Amicus 18 board.For programming simply connect the USB port of the Ami18 to a computer or connect a power supply / battery to get started. The Ami18 presents itself as a standard serial port on the PC. The Ami18 can be programmed directly from the USB port, so there is no need for a special programmer. The board can also be programmed directly from the In Circuit Serial Programming (ICSP™) adapter compatible with Microchip PICkit 2 or PICkit 3 programmers.
Fig 13: Different components of Ami18 board
Coming
to the software the board can be programmed with any PIC® language like C18,
Swordfish, PICbasic and the free
Proton Amicus18 software. The PIC18F25K20 on the board is
supplied pre-burned with a boot loader program that allows user to upload new
code without the use of an external hardware programmer.
VOICE RECORD AND
PLAYBACK
This
module of the system consists of APR9600 voice record and playback IC,amplifier
circuitry. APR9600
is a low-cost high performance sound record/replay IC incorporating flash
analogstorage technique. Recorded sound is retained even after power supply is
removed from themodule. The replayed sound exhibits high quality with a low
noise level. Sampling rate for a 60second recording period is 4.2 kHz that
gives a sound record/replay bandwidth of 20Hz to 2.1 kHz.
However,
by changing an oscillation resistor, a sampling rate as high as 8.0 kHz can be achieved.This
shortens the total length of sound recording to 32 seconds. Total sound
recording time can be varied from 32 seconds to 60 seconds by changing the
value of asingle resistor.
The
IC can operate in one of two modes: serial mode and parallel mode. In serial
access mode, sound can be recorded in 256 sections. In parallel access mode,
sound can berecorded in 2, 4 or 8 sections. It ispossible to control the IC
using external digital circuitry such as micro-controllers and computers.The
APR9600 has a 28 pin DIP package. And supply voltage is between 4.5V to 6.5V.
Duringrecording and replaying, current consumption is 25 mA. In idle mode, the
current drops to 1 mA.
Fig 14: APR9600 with speaker
The
APR9600 experimental board is an assembled PCB board consisting of an APR9600
IC, anelectret microphone, support components and necessary switches to allow
users to explore all functions of the APR9600 chip. The oscillation resistor is
chosen so that the total recording periodis 60 seconds with a sampling rate of
4.2 kHz. The board measures 80mm by 55mm.
Fig 15: APR9600 Experimental board
During
sound recording, sound is picked up by the microphone. A microphone pre -amplifier
amplifies the voltage signal from the microphone. An AGC circuit is included in
the pre-amplifier, the extent of which is controlled by an external capacitor
and resistor. If the voltage level of a sound signal is around 100 mV peak-to-peak,
the signal can be fed directly into the IC through ANA IN pin (pin 20). The
sound signal passes through a filter and a sampling and hold circuit. The
analog voltage is then written into non-volatile flash analog RAMs.
During
sound replaying, the IC’s control circuit reads analog data from flash RAMs.
The signal then passes through a low-pass filter, a power amplifier and output
to an 8 to 16 Ohm speaker.
The
function of this voice record and playback module is to produce voice against
the respective gesture. APR9600 produces output when it receives a low input
signal. Therefore each pin in APR9600 is recorded with a message and as and
when the particular pin receives a low input signal the respective message is
played back.
When
the microcontroller receives the data from the “bend and tilt detection” module
it compares the data with the predefined values. On the basis of this
comparison the microcontroller comes to know that which gesture does the hand
make. When a predefined gesture is recognized by the microcontroller it sends
low input to the respective pin of APR9600. When APR9600 receives low signal it
plays the message stored in the particular pin through the speaker.
Features of APR9600
• Single-chip, high-quality voice recording &
playback solution
- No external ICs required
- Minimum external components
• Non-volatile Flash memory technology
- No battery backup required
• User-Selectable messaging options
- Random access of multiple fixed-duration messages
- Sequential access of multiple variable-duration
messages
• User-friendly, easy-to-use operation
- Programming & development systems not required
- Level-activated recording & edge-activated play
back switches
• Low power consumption
- Operating current: 25 mA typical
- Standby current: 1 uA typical
- Automatic power-down
• Chip Enable pin for simple message expansion
Fig.16:
Pin-out of APR9600
7.2.1
Pin functions of APR9600
Pin
|
Name
|
Functions
|
1
|
-M1
|
Select 1st section of sound or serial mode recording and replaying
control
(low active)
|
2
|
-M2
|
Select 2nd section or fast forward control in serial mode (low active)
|
3
|
-M3
|
Select 3 rd section of sound
|
4
|
-M4
|
Select 4th section of sound
|
5
|
-M5
|
Select 5th section of sound
|
6
|
-M6
|
Select 6th section of sound
|
7
|
OSCR
|
Resistor to set clock frequency.
|
8
|
-M7
|
Select 7th section of sound or IC overflow indication
|
9
|
-M8
|
Select 8th section of sound or select mode
|
10
|
-BUSY
|
Busy (low active)
|
11
|
BE
|
=1, beep when a key is pressed
=0, do not beep
|
12
|
VSSD
|
Digital circuit ground
|
13
|
VSSA
|
Analogue circuit ground
|
14
|
SP+
|
Speaker, positive end
|
15
|
SP-
|
Speaker, negative end
|
16
|
VCCA
|
Analogue circuit power supply
|
17
|
MICIN
|
Microphone input (electret type microphone)
|
18
|
MICREF
|
Microphone reference input
|
19
|
AGC
|
AGC control
|
20
|
ANA-IN
|
Audio input (accept a signal of 100 mV p-to-p)
|
21
|
ANA-OUT
|
Audio output from the microphone amplifier
|
22
|
STROBE
|
During recording and replaying, it produces a strobe signal
|
23
|
CE
|
Reset sound track counter to zero/ Stop or Start / Stop
|
24
|
MSEL1
|
Mode selection 1
|
25
|
MSEL2
|
Mode selection 2
|
26
|
EXTCLK
|
External clock input
|
27
|
CLK
|
=0 to record, =1 to replay
|
28
|
VCCD
|
Digital circuit power supply
|
Table
2: Pin description of APR9600
LCD DISPLAY
By
using the gesture vocalizer the dumb people can communicate with the normal
people and with the blind people as well, but the question arises that how can
the dumb people communicate with the deaf people. The solution to this problem
is to translate the gestures, which are made by the hand, into some text form.
The text is displayed on LCD.
The
gestures are already being detected by the “Gesture Detection” module. This
module sends signal to the voice record and playback module, the same signal is sent to the LCD
display module. The microcontroller is controlling the LCD. A signal against each
gesture is received by LCD displaymodule. The LCD display module checks
eachsignal, and compares it with the already storedvalues. On the basis of this
comparison themicrocontroller takes the decision what should bedisplayed,
having taken the decision the microcontroller send an four bit address to the
LCD, this four bit address, tells the LCD, what should be displayed.
A liquid crystal display (LCD)
is a flat panel,electronic visual or video display that uses the light
modulating properties of liquid crystals (LCs).
Fig.17: Working of
LCD
LCDs are used in a wide range of
applications, including computer monitors, television, instrument panels, aircraft
cockpit displays etc. They are common in consumer devices such as video
players, gaming devices, clocks, watches, calculators, and telephones.
LCDs have replaced cathode ray
tube (CRT) displays in most applications. They are available in a wider range
of screen sizes than CRT and plasma displays, and since they do not use
phosphorus, they cannot suffer image burn-in. LCDs are, however, susceptible to
image persistence.
The LCD is more energy efficient
and offers safer disposal than a CRT. Its low electrical power consumption
enables it to be used in battery-powered electronic equipment. It is an electronically
modulated optical device made up of any number of segments filled with liquid
crystals and arrayed in front of a light source (backlight) or reflector to
produce images in color or monochrome. The most flexible ones use an array of
small pixels.
Fig. 18 : JHD162A
LCD
Here a 16 x 2 alphanumeric LCD,
namely JHD162A has been used. An alphanumeric LCD is one which can display both
alphabets and numbers. Here 16 x 2 implies 16 characters x 2 rows. JHD162A LCD
is reflective in nature and can have green,yellow or grey displays.
Fig.19: Functional
block diagram of 16 x 2 alphanumeric LCD
Specifications
Important factors to consider when evaluating an
LCD:
Resolution
versus range:
Fundamentally
resolution is the granularity (or number of levels) with which a performance
feature of the display is divided. Resolution is often confused with range or
the total end-to-end output of the display. Each of the major features of a
display has both a resolution and a range that are tied to each other but very
different. Frequently the range is an inherent limitation of the display while
the resolution is a function of the electronics that make the display work.
Spatial performance:
LCD’s come in only one size for a variety of applications
and a variety of resolutions within each of those applications. LCD spatial
performance is also sometimes described in terms of a "dot pitch".
The size (or spatial range) of an LCD is always described in terms of the
diagonal distance from one corner to its opposite. This is an historical
remnant from the early days of CRT television when CRT screens were
manufactured on the bottoms of glass bottles, a direct extension of cathode ray
tubes used in oscilloscopes. The diameter of the bottle determined the size of
the screen. Later, when televisions went to a more square format, the square
screens were measured diagonally to compare with the older round screens.
Temporal/timing
performance:
Contrary
to spatial performance, temporal performance is a feature where smaller is
better. Specifically, the range is the pixel response time of an LCD, or how quickly you can change a
sub-pixel's brightness from one level to another. For LCD monitors, this is
measured in btb (black to black) or gtg (gray to gray). These different types
of measurements make comparison difficult. Further, this number is almost never
published in sales advertising.
Colour depth or colour support:
It’s is sometimes expressed in bits, either as the number
of bits per sub-pixel or the number of bits per pixel. This can be ambiguous as
an 8-bit colour LCD can be 8 total bits spread between red, green, and blue or
8 bits each for each colour in a different display. Further, LCDs sometimes use
a technique called dithering which is time averaging colours to get
intermediate colours such as alternating between two different colours to get a
colour in between. This doubles the number of colours that can be displayed;
however this is done at the expense of the temporal performance of the display.
Dithering is commonly used on computer displays where the images are mostly
static and the temporal performance is unimportant.
Brightness and contrast ratio:
Brightness and contrast ratio:
Contrast ratio is the ratio of the brightness of a full-on pixel
to a full-off pixel and as such, would be directly tied to brightness if not
for the invention of the blinking backlight (or burst dimming). The LCD itself is only a light valve, it does not
generate light; the light comes from a backlight that is either a florescent
tube or a set of LEDs. The blinking backlight was developed to improve the
motion performance of LCDs by turning the backlight off while the liquid
crystals were in transition from one image to another.
However,
a side benefit of the blinking backlight was infinite contrast. The contrast
reported on most LCDs is what the LCD is qualified at, not its actual
performance. In any case, there are two large caveats to contrast ratio as a
measure of LCD performance.
Advantages and disadvantages
Advantages
- Very compact and light.
- Low power consumption.
- No geometric distortion.
- Little or no flicker
depending on backlight technology.
- Not affected by screen burn-in.
- Can be made in almost any
size or shape.
- No theoretical resolution
limit.
Disadvantages
- Limited viewing angle, causing colour,
saturation, contrast and brightness to vary, even within the intended
viewing angle, by variations in posture.
- Bleeding and uneven
backlighting in some monitors, causing brightness and distortion,
especially towards the edges.
- Smearing and ghosting
artifacts caused by slow response times (>8 ms) and "sample and
hold" operation.
- Only one native
resolution.
Displaying resolutions either requires a video scaler, lowering perceptual
quality, or display at 1:1
pixel mapping, in which images will be physically too large or
won't fill the whole screen.
- Fixed bit depth, many cheaper LCDs are
only able to display 262,000 colours. 8-bit S-IPS panels can display 16
million colours and have significantly better black level, but are
expensive and have slower response time.
- Low bit depth results in
images with unnatural or excessive contrast.
- Input lag
- Dead or stuck pixels may occur during
manufacturing or through use.
- In a constant-on
situation, thermalization may occur, which is when only part of the screen
has overheated and looks discoloured compared to the rest of the screen.
- Not all LCDs are designed
to allow easy replacement of the backlight.
- Cannot be used with light
guns/pens.
- Loss of contrast in high
temperature environments.
LOUDSPEAKER
A
loudspeaker is used in this project to play the voice that has been recorded
using voice record and playback IC APR9600. The analog output from the voice
record and playback IC APR9600 is given to the loudspeaker.
A
loudspeaker (or
"speaker") is an electroacoustic transducer that produces sound in
response to an electrical audio signal input. Non-electrical loudspeakers were
developed as accessories to telephone systems, but electronic amplification by
vacuum tube made loudspeakers more generally useful.
The
most common form of loudspeaker uses a paper cone supporting a voice coil
electromagnet acting on a permanent magnet, but many other types exist. Where
accurate reproduction of sound is required, multiple loudspeakers may be used,
each reproducing a part of the audible frequency range.
Miniature loudspeakers are found in devices
such as radio and TV receivers, and many forms of music players. Larger
loudspeaker systems are used for music, sound reinforcement in theatres and
concerts, and in public address systems.
Fig. 20:An inexpensive low fidelity 3.5 inch speaker
SOFTWARE
Proton Amicus 18 complier
- Proton BASIC source code editor - with colour syntax highlighter
- Compiler - Full version of Proton Basic for the PIC® Microcontroller with full integration to MPLAB® for debugging, if required.
- Programmer - automated USB programming of the Amicus18 Board - no external programmer is required.
The Amicus18tm IDE has been designed to maximize programmer productivity by providing highly integrated and intuitive interface to the tools required to develop on the Amicus 18 hardware. The Amicus18 IDE provides many features for authoring, modifying, compiling, deploying and debugging your programmes. Your program can be compiled while being written, providing instant feedback on syntax errors. This results in an uninterrupted workflow from writing the program code through compiling to downloading the program to the Amicus18 hardware.
Comprehensive documentation and a helpful and friendly support environment, make using Amicus18 an easy and enjoyable experience for beginners and seasoned programmers.
CONCLUSION
This project describes the design and working of asystem which is useful for dumb, deaf and blind people to communicate with one another and with the normal people, and hence the project proves to be socially active. The dumb people use their standard sign language which is not easily understandable by common people and blind people cannot see their gestures. This system converts the sign language into voice which is easily understandable by blind and normal people.
The sign language is also translated into
some text form, to facilitate the deaf people as
well. This text corresponding to the
gesture is displayed on LCD.
The project is user friendly and
cost-effective due to its simplicity. The hardware is easy to construct, the
only challenging part being placing the accelerometer on the glove. The project
works in real time environment by producing voice and text corresponding to the
gestures made by the one wearing the glove.
regards ,
prem
regards ,
prem