Introduction
In older days, the inventories were not as huge as they are today. So it was possible to search items in the inventories manually. But with the passage of time, it has all changed. Today’s modern inventories are so gigantic that the use of some automatic mechanism for quick accessing of items seems inevitable.
To solve this problem, here we have devised a
wireless automatic rapid inventory access system using zigbee which can be very
useful in large industries and big shops for quick accessing of items from
large number of drawers in inventories. This Wireless system with a host
computer has a convenient Graphical User Interface (GUI). Zigbee radios are
used at the transmitting and receiving ends to provide wireless functionality.
The wireless rapid inventory access system has a host
computer having Graphical User Interface (GUI). This GUI is created by using the
GUIDE (GUI Development Environment application of the MATLAB (MATrix
LABoratory). It is compulsory for the user to enter the password to prevent
any unauthorized access to continue. On entering the correct password the
operator can use the inventory access system.
This GUI has push buttons representing items of the inventory. A Zigbee
mounted onto a Zigbee explorer is connected to the host computer which is
configured as the coordinator. Another Zigbee present on the receiving end is
configured as the router. The Zigbees are configured by using the X-CTU
software. When the user clicks on the push buttons of the GUI the Zigbee at the
transmitting end sends serial data. The Zigbee at the receiving end receives
the data serially and sends it to the serial receive pin (Rx) of the
microcontroller (PIC18F452). LEDs, which represent the drawers, are connected
to the port of the MCU. The LEDs that correspond to the clicked button glow up
and simultaneously an alarm is raised by the buzzer. This is an alarm for the
office assistant to fetch the items from the inventory. Now the drawers indicated by glowing LEDs can be accessed easily
and quickly without any delay and confusion. After receiving the desired item
on the counter, the LEDs can be turned off by clicking the corresponding
buttons in the GUI.
But sometimes,
when the alarm is raised, the office assistant may be busy with some other
task, so it may not be possible to fetch items immediately. By the time office assistant
is busy with some other work, more items may also be ordered by the computer
operator by glowing more other LEDs causing raising of the alarm again. When
the office assistant finds himself free, all the ordered items can be fetched
altogether.
1.3 History
Modern inventories are really huge in size but it was not the case,
many years back in the past. In those days, the inventories were much smaller
in size as compared to the modern inventories. So it was not much difficult to
look for items in the inventories manually. For even larger inventories, one
thing that would be done was, to increase the labor force engaged in fetching
the ordered items from the inventories but even that couldn’t help, as it
wasn’t prudential to hire so many laborers for this job. Not only this, it
often led to confusions and misunderstandings in communication.
But as the inventories grew larger and larger it seemed impossible
to search the desired items in the inventories manually. So it was essential to
devise some automatic technique to solve this problem. So today’s modern
industries have some electronic mechanism to find out the items from big
inventories. The advantages of the automatic inventory access systems are, the
reduced time to access the desired item and that too without any kind of
communication gap.
1.4
Need of proposed research work
Since big industries and shops have large
inventories having large number of drawers and it is very difficult to access
desired items from a large sized warehouse having large number of drawers. Also
the office assistant may not be available to serve at that moment. Because of
this it takes long time to access the desired items from the inventories and
also causes confusion while accessing correct drawers.
1.5
Significance of proposed research work
To solve the above mentioned problems rapid
inventory access
system has a LED for each drawer wherein the items are stored. LEDs will glow
corresponding to the selected items by the host computer and
an alarm will be raised by a buzzer indicating an order to the office
assistant to fetch items from the
inventory without any need of communication with the computer operator. Now
corresponding drawers having glowing LEDs can be accessed easily and quickly
without any delay and confusion. This system uses a
password protected Graphical User Interface
(GUI) for
authorized access. This GUI is created by using
MATLAB software. GUIDE application of the MATLAB is used to make the GUI. This
GUI will have buttons to represent inventory items. On clicking the GUI push
buttons corresponding LEDs will glow in the inventory. The LEDs can be turned
off by clicking the corresponding buttons in the GUI, after receiving the
desired item on the counter.
1.6 Motivation
of the work
When I was a trainee at ‘SONY INDIA’ in New Delhi, I
came across the problems related to the accessing of items from the inventory
there. I observed there, that whenever any item was ordered to be fetched from
the inventory, it really took lot of time. There was communication gap between
the office assistant and the person who ordered the item. He often would fetch wrong item and that too
with some delay.
Sometimes the office assistant would not be present
there to serve so it was annoying to look for him first, before the items could
be fetched. Not only this, when he was busy with some work while some item was
ordered, he would forget to fetch the item. so it was essential to remind him
of it again and again. That was really cumbersome. Thus the inventory accessing system had lots of
problems and was inefficient.
So I felt the need of some automatic electronic
solution to deal with this problem and finally came up with the mechanism which
could address all the problems mentioned above. This includes a computer having
a convenient and password protected Graphical User Interface (GUI). Zigbee
radios are used at the transmitting and receiving ends for wireless
functionality.
When the computer operator selects items by the
computer using GUI on clicking the push buttons, an alarm is raised by the
buzzer and LEDs of the corresponding drawers glow in the inventory. This would
be an order to the office assistant to fetch the items from the inventory. Now the drawers indicated by glowing
LEDs can be accessed easily and quickly without any delay and confusion. The LEDs can be turned off
by clicking the corresponding buttons in the GUI, after receiving the desired
item on the counter.
But some time it may be the case that, when the
alarm is raised, the office assistant may be busy with some other task, so the
office assistant may not serve immediately. By the time office assistant is
busy with some other work, more items may also be ordered by the computer
operator by glowing more other LEDs that causes raising the alarm again. When
the office assistant finds himself free, all the ordered items can be fetched
altogether.
1.7
Objectives of the proposed research work
·
To design and develop a rapid inventory
access system to speed
up the accessing of items-
A
major problem faced by big industries and large shops is to find items in their
large inventories. In very large inventories it is not easy to search the
desired item manually. Not only this, delay and confusion becomes inevitable in
this manual process. This problem can be solved by wirelessly glowing LEDs for drawers in the
inventory for the desired items.
· To
design and develop a wireless inventory access
system using Zigbee radios-
With the
help of Zigbee the mechanism of accessing items from the large inventories can
be made wireless. Zigbees of different ranges of operation are available as per
the size and the location of the inventory. Here we have used one Zigbee at the
transmitting end and other at the receiving end. For larger industries the
number of Zigbees at the receiving end (nodes) can be increased
accordingly.
· To
design a window for password protection to check unauthorized access
It is mandatory to enter password to continue the
operation. Graphical User Interface is made by using the MATLAB software. GUIDE
application of the MATLAB is used to make the GUI. The user is first
encountered with a password window, which requires the user to enter password
to continue. This prevents any unauthorized access.
· To
create a convenient Graphical User Interface (GUI) for the host computer.
After
entering the password the user will be allowed to use the application. In order
to fetch any item from the inventory, user will have to press the corresponding
push buttons of the GUI. Thus on pressing the buttons corresponding LEDs will
glow in the inventory for the drawers. After receiving the desired item on the counter,
the LEDs can be turned off by clicking the corresponding buttons in the GUI.
·
To raise an alarm to the office
assistant to fetch items from the inventory-
On selecting items using the
host computer by clicking the push buttons of the GUI, an alarm will be raised
by the buzzer and LEDs of the corresponding drawers will glow in inventory.
Sometimes when the alarm is raised the office assistant may be busy with some
other tasks, because of this it may not be possible to fetch items immediately.
By the time office assistant is busy with some other work, more items may also
be ordered by the computer operator by glowing more other LEDs causing raising
of the alarm again. When the office assistant finds himself free, all the
ordered items can be fetched altogether easily and quickly without any delay
and confusion.
3.1
Hardware design
The main components
used in the hardware design of the proposed work are: microcontroller (PIC18F452),
zigbee and the power supply. These components have been described as follows-
3.1.1
Microcontroller
Microcontroller
has a crucial role in any control unit. A microcontroller not only has a
microprocessor but also has memory and input-output peripherals. Other major
components of the microcontroller include counters, timers, ADC etc. The
peripherals of the microcontroller are programmable. Microcontroller has the
flash programmable memory along with the RAM. The flash memory can be
reprogrammed many times with the help of a program burner kit and the
supporting software.
3.1.1.1 Features of
PIC18F452
·
It is having high
performance and flash memory
·
It is having 32 kb of
code space,1536 bytes of RAM
·
It is having 256 bytes
of EEPROM
·
It runs up to 40 MHz of
clock speed
·
PLL option is available
which can be enabled or disabled via programming. With the use of PLL the clock
frequency get multiplied by four. In this case maximum frequency for external;
crystal is 10 MHz
·
It is having an USB
interface
3.1.1.2
Peripheral features:
·
High current
sink/source
·
3 interrupt pins
externally
·
Timer0 is 8-bit/16-bit
timer/counter with a 8 bit programmable prescalar.
·
Timer1 module is a
16-bit timer/counter.Timer2 module is an 8-bit timer/counter with 8 bit period
register which is a time base for PWM.
·
period register
(time-base for PWM)
·
Timer3 module: 16-bit
timer/counter
·
Secondary oscillator
clock option - Timer1/Timer3
·
Two Capture/Compare/PWM
(CCP) modules.
·
CCP pins that can be
configured as:
·
Capture input: capture
is 16-bit,
·
Max. resolution 6.25 ns
(TCY/16)
·
Compare is 16-bit, max.
resolution 100 ns (TCY)
·
PWM output: PWM
resolution is 1- to 10-bit,
·
Max. PWM freq. @: 8-bit
resolution = 156 kHz
·
10-bit resolution = 39
kHz
·
Master Synchronous
Serial Port (MSSP) module.
3.1.1.3
Operating modes
·
3 wire SPI™
·
Master and Slave mode (I2C)
3.1.2
Zigbee
3.1.2.1
ZigBee module:
ZigBee is a wireless
transmission protocol and low power digital radio. It is based on an IEEE
802.15.4 standard for PANs. Unlicensed ISM bands use ZigBee modules. Power
consumption is of vital importance in embedded systems so ZigBee radio modules
are used extensively. Coordinator,
router and end-device are the main categories of ZigBee devices in a
ZigBee network. In a ZigBee network each device has a unique 16 bit PAN ID.
3.1.2.2
Device types
· ZigBee Coordinator (ZC):
The coordinator which is an active device acts as the network tree master. It
can also act as a bridge to connect to other ZigBee which might be present in
outside networks. Each network must have one ZC, because its purpose is to
start the network during the communication process. It starts PAN by choosing a
RF channel and a PAN ID.
· ZigBee Router (ZR): Besides acting
as a coordinator, it can also work as a router, which can forward the data,
received by it from one network to another. When it has established connection
with ZigBee Coordinator, the operation
can be started.
· ZigBee End Device (ZED):
In this mode the ZigBee acts as a dependent device. It can only talk either to
the coordinator or to the router. This functionality helps the node network to
be in the sleep mode for a given time and hence providing longer battery life.
Before sending any sensor data a ZigBee
End Device must join PAN in same manner as a router. As it does not have to store the values in it,
so a very small amount of memory is required. Therefore it is less expensive to
manufacture as well to the network designer as compared to a ZR or ZC.
3.1.2.3 Device
Addressing:
16-bit Network address is assigned to
a ZigBee device when it connects to a ZigBee network and contains a 64-bit device address. The
manufacturer assigns this 64-bit address. This 64-bit address is the serial
number of the ZgBee device. Network Address and Device Address are used to
establish the communication between the ZigBee devices. These ZigBee devices
generally find application in point to point mesh networks. Ad-hoc networks can
be formed with these devices. It has a defined rate of 250 kbps. It finds
application in wireless street light control, traffic management systems,
wireless home automation, electrical meters with automatic reading output and
other various devices that are used by consumers in homes and industrial
equipments. ZigBee is used in those applications which require short range of
transmission and where wireless transmission of data is to be done at low
rates. Hence, the zigbee technology is very simple and less expensive than
other Wireless Personal Area Networks. As compared to Bluetooth, the ZigBee is
much better in terms of cost and energy consumption and range of transmission.
The bit rate of transmission depends on the frequency band. On 2.4 GHz band the
typical bit rate is of 250 kbps, 40 kbps at 915MHz and 20 kbps at 868 Mhz. ZigBee
device is configured by the use of X-CTU software.
We have a dc power supply of 5volts, on which
the microcontroller operates and the zigbee needs to be interfaced to the
microcontroller, but since the Zigbee operates at 3.3V (max). So it is required
to convert the voltage from 5V to 3.3V. This can be done by using LM1117 IC.
Zigbee adapter board is used as a base
for the zigbee.
The zigbee adapter has LM1117 IC which converts the
voltage from 5 volts to 3.3 volts, as required by the zigbee for its operation.
Zigbee pins are inserted into the zigbee base. Here out of twenty pins of the
zigbee device, we use only three pins. These three pins are- 3.3 volts input power
supply, ground and transmit pin. The pins of LM1117 IC with their description
are-
Vcc- This pin in connected to the 5V DC power
supply.
Gnd- It is used for the ground.
Dout-
It provides output of 3.3 volts, required by the zigbee device.
3.1.3.1
Transformer
Transformers have the capability to
transfer electrical
energy from one circuit to another with the help of inductively coupled conductors. Transformers can be used either to transform the voltage from high to
low (step down) or from low to high (step up). Transformer has two sets
of winding. One set of winding is called as primary winding while the other is
the secondary winding. These two sets of winding are wrapped generally on a
soft iron core. The primary coils is used to apply the input voltage while the
output voltage is taken out from the secondary windings. The core of the transformer
is made of dielectric material thus
provides insulation between primary and secondary coils. Image of the
transformer is shown in the figure 3.14.
When
varying current (AC) is applied to the primary windings of the transformer, a
varying magnetic field is produced in the primary windings. This changing
magnetic field is associated to the secondary windings of the transformer
through the core of the transformer. Because of this varying magnetic field in
the secondary windings, an electro-magnetic field is induced. This phenomenon
is known as the inductive coupling and the voltage produced in the secondary
windings of the transformer due to this phenomenon is known as the Electro
Magnetic Force (EMF).
According
to the Faraday’s law of Electro-Magnetic Induction (EMI) when a conductor is
placed in a changing magnetic field then EMF is induced in the conductor and
this induced EMF is directly proportional to the rate of change of flux and
number of turns in the conductor coil.
Hence by
Faraday's law of Electro-Magnetic
Induction (EMI)-
Combining ratio of (1) & (2)
Where a= turns ratio
For step-down transformers, a > 1
While for step-up transformers, a
< 1
3.1.3.2
Voltage regulator (LM7805)
3.1.3.3
Diode
Diode is an electronic component having two terminals, which allows
current to flow only in one direction and offers very high resistance to the
current in other direction. A semiconductor diode has a p-n
junction which is responsible for the flow of current in only one direction.
When the p terminal of the diode is at higher
potential as compared to the n terminal then the diode is forward biased and
current is allowed to flow from p side to n side. But when the p terminal is at
lower potential than the n side then the diode in reversed biased s does not allow
current to flow in this case since it offers ideally infinite resistance to the
current flow.
In
this project the diodes have been used to design a bridge rectifier which is a
full wave rectifier, to convert alternating current to direct current.
3.1.4
Light Emitting Diode (LED)
A light-emitting diode (LED) is made of
semiconductor material. For manufacturing the LED a direct band
gap semiconductor is used which is mostly, gallium arsenide (GaAs). When the
charge carriers recombine with the majority carrier on the other side on
crossing the junction, photons
are emitted. The color of the light emitted from the LED depends on the
material used in manufacturing. Wavelengths (or colors)[ from
the infrared to the near ultraviolet may be produced. LED is shown in the figure 3.17.
3.1.5
Buzzer
A
buzzer may be of mechanical, piezoelectric or electromechanical type. It is
used as a device for audio signaling. In this project the buzzer works as an
alarm to the office assistant to fetch items from the inventory.
4 SOFTWARE
DEVELOPMENT
4.1 mikroC
mikroC is
a development tool used for the PIC microcontrollers. microC is used to develop
embedded system applications. It is very easy for the programmer to develop
applications with the help of powerful microC tool. Not only it makes the programming easy to the
programmer but also the high performance features are also retained.
PIC microcontroller is used extensively in the
world. C language is used mostly to program the microcontrollers, since it
becomes much easier to program the microcontroller in C, because of large
libraries available in the C language. Various features made available to the
user by the microC includes- ANSI compliant compiler, very
advanced Integrated Development Environment, comprehensive
documentation, large libraries for hardware, and enriched set of examples.
4.1.1 Features of mikroC
Following
features are included in the microC to help the user in programming complex
applications-
- C source code can be written using the
built-in code editor.
- mikroC libraries are available to
improve the speed of the programming. It supports various types of
microcontrollers viz. PIC12, PIC16 and
PIC18.
- Code explorer can be used to monitor
structure of the program.
- microC also has the facility of the
integrated debugger to debug executable logic and to inspect program flow.
- A large source of examples is
provided in the microC. These programs are ready to use in the
programming.
4.2
MATLAB
MATLAB
stands for the “MATrix LABoratory”. It is a language for high-performance
technical computing which includes visualization, computation, and programming
in a user friendly environment. In MATLAB problems and their solutions are
represented in common mathematical notations.
4.2.1 MATLAB
Environment
MATLAB is a high-level technical computing language for data
visualization, algorithm development, numeric computation and data analysis. It
is possible to solve technical computing problems using the MATLAB product very
fast, not possible to obtain with traditional programming languages.
MATLAB can
be used in a myriad of applications, which includes control design, signal and
image processing, test and measurement, communications, financial modeling,
computational biology and analysis.
Using
MATLAB it is easy to document and share our work. MATLAB code can be integrated
with another applications and languages, and MATLAB algorithms and applications
can be distributed. These Features are mentioned below:
- High
level technical computing language
- Development
environment to manage files, code and data
- Interactive
tools for design and problem solving
- Various
mathematical functions
- Two
dimensional and three dimensional
graphics functions to visualize data
- Building
custom GUI Tools
4.2.2 The MATLAB System
The MATLAB system comprises the following
main parts:
·
Desktop tools and development environment
MATLAB provides the desktop tools and development environment
to help us use MATLAB files and functions more productively. Most of these tools
are GUIs. These are viz. the MATLAB desktop and Command Window, an editor,
debugger and code analyzer etc.
·
Mathematical Function Library
Library available in MATLAB for mathematical functions
has a large collection of basic mathematical functions along with highly
advanced functions.
·
The Language
The language used in MATLAB is a
high level matrix/array language having control flow statements, data
structures, input-output and object oriented features of the programming.
·
Graphics
MATLAB provides facilities for
showing matrices and vectors by using graphs. It consists of functions for 2-D
and 3-D data visualization, animation and presentation graphics. With the help
of low level functions available in MATLAB appearance of graphics can be fully
customized. Not only this, we can build
complete GUIs on MATLAB applications.
·
External Interfaces
Writing C/C++
and Fortran programs interacting with MATLAB are allowed by the external
interfaces library which includes facilities for calling routines from MATLAB
known as dynamic linking, for reading and writing MAT-files and calling MATLAB
as a computational engine.
4.2.3 Overview
of GUIDE
GUIDE is the acronym for GUI Development
Environment. GUIDE provides various tools which helps in creating GUIs. GUIDE
can be greatly helpful in designing graphical user interfaces. Two tasks are
required to be performed to create GUIs which are mentioned below-
·
Layout
the GUI.
The Layout Editor available in GUIDE contains various icons
to help us make GUIs. These include icons for button, edit text, static text,
toggle button etc. It is very easy to use any component depicted in the toolbox
by clicking on it and to use it in our GUI. GUI layout is stored in a FIG-file.
·
Program
the GUI.
On creating the GUI in the layout editor, a MATLAB program
file is automatically generated by GUIDE. This program file has the control of
the GUI. The GUI is initialized by the code present in that file. When the user
clicks on the GUI component commands are executed. We can add our own code to
the callbacks with the help of MATLAB editor to make it perform what we want. Callbacks are the functions which
respond to user’s action. It is also possible to create GUIs by writing code in
MATLAB without using GUIDE in the MATLAB command window as shown in the figure
4.1.
On
clicking on the GUIDE icon available in the MATLAB command window as shown in
figure 4.1, a new window ‘GUIDE Quick start’ appears. The ‘GUIDE Quick start’
window is shown in the figure 4.2. Now to make new GUI, click on the ‘create
new GUI’ button, select ‘Blank GUI (default)’ and click on ‘OK’ button. Now the
Layout Editor opens, having various component icons to create GUI. The Layout
Editor is shown in the figure 4.3.
4.3
X-CTU
X-CTU
is a tool that configures ZigBee modules with whatever settings required. First
step is to install X-CTU software. After this, ZigBee modules configuration
begins. A point-to-point network is required to be constructed, which means
that the two devices will communicate with each other. For this purpose, one
ZigBee should be configured as a Coordinator (or Master), because it is
mandatory to have one coordinator in each network and the other should be
configured as a Router (or end device). So a Coordinator is created that will
manage the network of ZigBee, here a network consists of one more ZigBee
module. To begin, we need to take our ZigBee module (xbee radio) and insert it
onto the XBee Explorer device and connect it to computer through RS232 serial
port.
Further steps are given below:
After connecting the ZigBee with the
computer, double click the X-CTU icon and a window s will open. This window
looks like as shown in the figure 4.4.
Now click on the discover devices to
discover the radio device. On clicking on this icon a window appears as
depicted in the figure 4.5. On selecting the port to be scanned, click on next
button.
As we click on the next button a window
appears allowing to set port parameters. These port parameters include baud rate,
data bits, parity, stop bits and flow control. These parameters have been shown
in the figure 4.6. After setting all these parameters, click on the finish
button. Now as shown in the figure 4.7, click on the ‘add selected device’
button.
Now the radio module gets added. At this
stage the radio module can be configured. To configure it, click on the icon of
the radio module to show its properties and to configure it.
Now
the properties will be visible as depicted in the figure 4.8. After this, click
on the update firmware icon. On clicking on the icon a window appears as shown
in the figure 4.9. In this window select Zigbee Coordinator AT from the
function set and 20A7 (Newest) from the Firmware version. Now click on the
update button. On updating, it is time to configure the radio module.
To make the radio modules (zigbee
devices) to communicate with each other it is essential to edit the addressing
settings appropriately. So as clear from the figure 4.10, in the destination
address high (DH) and destination address low (DL) write the serial number high
(SH) and serial number low (SL) of the radio module, to be configured as the
router. Write ‘coordinator’ in the Node Identifier (NI) to identify the device
as the coordinator. After finishing all this, click on the ‘write radio
settings’ icon.
The radio module (
zigbee module) can now be removed from the XBee Explorer . Now insert the other zigbee module into the XBee
Explorer to configure it as the ROUTER. Discover device and add the device in
the same way, as was done for the coordinator device and click on the update
Firmware . The update Firmware window is shown in the figure 4.11. Now select
the Zigbee Router AT from the function set and 22A7 (Newest) from the Firmware
version and click on update button.
After successful
firmware updation, edit the addressing settings as depicted in the figure 4.12.
In the Destination address High (DH) and Destination address Low (DL) write the
Serial number High (SH) and Serial number Low (SL) of the radio module,
configured as the COORDINATOR. Write ‘ROUTER’ in the Node Identifier (NI) to
identify the device as the router and click on the ‘write radio settings’ icon.
4.4
PCB DESIGN AND FABRICATION
In this chapter the software used to design the PCB
has been discussed. This chapter elaborates the steps taken to develop the
layout of the hardware circuitry.
4.4.1
Eagle software
After testing all the possible modules using general
purpose PCB, the final hardware of the product is developed. PCB is designed
using ‘Eagle’ software.
4.4.1.1
Schematic diagram
The first step in the PCB designing is the schematic
design. The schematic provides the visual representation of the connections of
the electronic circuit used. The schematic diagram can easily be made with the
help of eagle software since various electronic components are present in this
software to be used directly. It’s easy to select the components, place them
and connect them with wires.
4.4.1.2
PCB designing
The next step is to create the layout and produce
the PCB. The steps used to design the PCB are as follows-
·
The schematic file is
synchronized with the PCB document and errors are corrected, if any.
·
Components are grouped
and aligned so that the connected components are grouped together to reduce the
length of the connections.
·
Dependent components
are placed as close as possible to each other.
·
Now the PCB layout is
done manually so as to ensure best possible layout with minimum number of
jumper wires.
·
Then DRC (Design Rule
Check) is used to correct any errors in the PCB design.
·
As a final check a
netlist is generated directly from the PCB and checked against the schematic to
ensure that there is no problem in the PCB.
·
This PCB is submitted
for manufacturing finally.
4.4.2 PCB design rules
Printed Circuit Board is an integral
part of any electronic product and its design plays an important role in the design
of the product. The general rules for design of PCBs are listed below.
4.4.2.1 Component Placing Concepts
· General
rule is to place those components, whose position is fixed for final fitting
and Inter-connections. Then place the components, which are connected to these
fixed components.
· Components
should be placed on the grid of 2.5mm.
· Larger
components are placed first and the space in between is filled with smaller ones.
· All
components should be placed in such a manner that dismounting of the other components
is not necessary if they have to be replaced.
· Components
should be placed in a row or a column so that it gives good overview.
4.4.2.2 Conductor routing concepts
· The
simple rule is that the conductor length should be as short as possible. In simple
circuits where lot of space is available, conductors can be run in any
direction so as to give the shortest interconnection length.
· Conductor
forming sharp angles should be avoided otherwise these will give problem in
etching.
· Where
one or several conductors have to pass between pads or other conducting areas, the
spacing has to be equally distributed.
· Minimum
spacing is applied only where it cannot be avoided otherwise higher spacing should
be given.
· In
double- sided PCBs, it is normal practice to draw the tracks on components side
in the direction of y-axis and tracks on solder side in the direction of
x-axis.
· Distribute
maximum number of tracks on the solder side and the rest on the component side.
4.4.2.3 Hole-Diameter Rules
The number of holes diameter on a PCB
has to be kept minimum.
· Satisfactory
soldering results are usually obtained if the diameter of the finalized and plated
holes gives about 0.2-0.5 mm clearance as compared with the nominal diameter of
the component lead.
· Hole
diameter = effective lead diameter + hole location tolerance (PTH) + 0.2mm
4.4.2.4 Solder Pad Diameter Rules
· In
PCBs with PTH (plated through hole ), the widths of the annular ring should be
at least 0.5 mm, but without PTH the annular rings must be more because there
is no through-hole plating to give mechanical strength to the solder pads.
· As
a rule solder pad diameter is approximately 3 times the component lead
diameter.
· The
pads are placed always exactly and properly centered on grid intersections.
· The
conductor width should always be less than the solder pad diameter. The pattern
around the hole should be maintained as uniformly as possible to enable
symmetrical solder joints.
4.4.2.5 Conductor Shapes
Sharp corners and acute angle bends in
conductors should be avoided.
4.4.2.6 Voltage and Ground Distribution
Rule
All the voltage & Ground connectors
should have minimum length. Analog & Digital ground should be different.
4.4.3 PCB design factors
While taking into consideration the
above rule, the designer should not neglect the various factors which influence
the design of PCBs. These design factors are listed as follows.
4.4.3.1 Design Elements
Design inputs, which are provided by the
equipment designer to the PCB designer, are known as Design Elements. The
various elements to be considered are:-
· Board
Size (minimum and maximum)
· Number
of Layers (single sided or double sided or multi layered)
· Hole
Sizes
· Board
Thickness
· Conductor
Widths
· External
Connections
· Mounting
Holes
· Type
of circuit (analog or digital)
· Component
details with Specification
4.4.3.2 Electrical Design Factors
There are some important factors that
must be accounted for a proper printed circuit board design. Resistance and
capacitance are the most important design factors. Copper conductor tracks on a
PCB have a finite resistively, which introduces a voltage drop proportional to
the current flowing in the particular conductor.
4.4.3.3 Mechanical Design Factors
The various mechanical factors that have
to be taken into consideration for designing of a PCB are:
· Horizontal
or vertical board mounting, as a consequence of other factors such as heat and
dust.
· The
board size should be optimum and compatible with the PCB manufacturing process.
· Proper
hole diameter should be provided for component mounting.
· Board
mounting holes should be provided.
· Heavy
components should be adequately fixed.
4.4.4 PCB design
These PCBs are developed for the
hardware implementation of all the modules. Layouts are made through the
software ‘eagle’. Circuit design is shown below:
RESULTS
AND DISCUSSION
On entering incorrect password, a message window will pop up,
displaying ‘invalid password’ as shown in the figure 5.2. The password box gets
cleared automatically, on entering the incorrect password. This allows the user
to enter the password again without erasing the wrong password.
After
entering the correct password the user will be allowed to use the application.
The user would see the buttons as shown in figure 5.3. These buttons correspond
to some item in the inventory. In order to fetch any item from the inventory,
user will have to press the corresponding push buttons of the GUI. Thus on
pressing the buttons corresponding LEDs will glow in the inventory for the
drawers.
On clicking on the HAND TOOLS button, a window
containing two panels of buttons appears, as shown in the figure 5.4. Using the
buttons of the first panel, the LEDs can be turned on to fetch any desired
item, while with the help of second panel the LEDs can be turned off, after
receiving the desired item on the counter. In the same manner on clicking on
the MEASURING TOOLS or BENCH TOOLS buttons, windows corresponding to the
measuring tools or bench tools appear, as depicted in figure 5.5 and figure 5.6
respectively.
The GUI has two sets of panels having buttons, viz. LED ON panel
and LED OFF panel to turn the LEDs on or off. Now on selecting the desired
items by clicking on the buttons available in the LED ON panel of the GUI.
The figure 5.7 shows first LED in glowing condition, on clicking the SCREW
DRIVER button of the HAND TOOLS [LED ON] panel. As the LED glows, the BUZZER alarm
is also raised, as an indication to the office assistant, to fetch items from
the inventory. In the same manner, figure 5.8 depicts the second LED glowing
with the buzzer alarm on clicking the SOLDERING IRON button of the HAND TOOLS
[LED ON] panel.
Now as illustrated in the figure 5.9 second LED
turns off on clicking the SOLDERING IRON button of the HAND TOOLS [LED OFF]
panel. This LED is turned off by the computer operator on receiving the desired
item on the counter.
Figure 5.10 shows the image of various LEDs glowing
after clicking the corresponding buttons in the GUI of the respective LED ON
panels, with
the buzzer alarm. In figure 5.11, image showing various LEDs glowing with the
buzzer alarm, as in case of the figure 5.10 except one blue LED in off status,
after clicking the corresponding button of the LED OFF panel in the GUI, is
shown.
CONCLUSION
AND FUTURE SCOPE
6.1
Conclusion
This wireless automatic rapid inventory access
system using Zigbee can prove to be very useful in big industries and shops to quickly
access various items from inventories. A host computer having Graphical User
Interface (GUI), Zigbee radio devices at transmitting and receiving ends are
used to do it wirelessly.
The inventory access system contains a Graphical User
Interface (GUI) supported computer at the transmitting side. It is essential
for the user to enter the password to prevent any unauthorized access. On
entering the correct password the user can use the inventory access system. The
GUI has two sets of panels having buttons, viz. LED ON panel and LED OFF panel
to turn the LEDs on or off. Now on selecting the desired items by clicking on
the buttons available in the LED ON panel of the GUI, the Zigbee connected to
the computer through Zigbee explorer, transmits the serial data. This data is
received serially by the Zigbee at the receiving end. Now the data arrives at
the serial receive pin of the microcontroller and the corresponding LEDs glow
which are connected to the port of the microcontroller and simultaneously an
alarm will be raised by the buzzer. This will be the alarm to the office
assistant to fetch the items from the inventory. Now the drawers indicated by
glowing LEDs can be accessed easily and quickly without any delay and
confusion. Now the computer operator can turn off the LEDs, after receiving the
desired item on the counter, by clicking the corresponding buttons of the LED
OFF panel of the GUI.
6.2
Future scope
Following
modifications and advancements are possible in this proposed work in
future:
· More
number of Zigbee modules may be used at the receiving end to create more nodes
to make the system more useful for larger industries and shops to handle large
number of drawers.
· Xbee
radios of larger range may be used for huge inventories.
· Opening
of the drawers can also be made automatic.
· DBMS
can be designed to perform many more other functions of data handling and
responding to queries related to inventories.
· Graphical
User Interface (GUI) may have more other features to improve the convenience of
the user.
· Security
features can also be added to ensure more secured access.
