M sc project report final

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University of Greenwich

School of Engineering

Declaration of Originality

I, the undersigned, declare that the work contained within this report is completely my

own. Any material that has not been originated by me has been clearly referred.

Name: .................................................................................................

Signature: .................................................................................................

Date: .................................................................................................

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ABSTRACT

Wireless communication has revolutionized the concurrent communication industry. Its

applications range from satellite transmission, radio and television broadcasting to mobile

phone. This project is aimed to create wireless hubs by using digital radio transmitter and

receiver and these hubs should be capable of communicate wirelessly in-between them. It

also intended that these hubs or short range devices will have mesh interconnection

capability. To achieve these purposes a small system in a form of PCB (Printed Circuit

Board) was designed and implemented containing Radio Module (ER400TRS), USB

interface (MM232R) and Microcontroller (PIC18F1320). ER400TRS made it possible to

employ a license-free carrier frequency like pan-European 433.05-434.79 MHz band.

MM232R was used to provide the communication link between PC and node, PIC18F1320

was chosen for its better performance. To fulfil the requirements of output and digital

inputs, LEDs and Switches were implemented.

The important part of this project was the transfer of packets of messages from one node or

PCB to another node and when three nodes were used they were organised in a straight

line so that the two end nodes cannot communicate directly with each other. To determine

how close nodes would need to be the signal strength against distance apart was critically

investigated by using existing PCB with a USB link and ER400TRS. Next was the

development of the appropriate hardware and software, for each node. Once it was done a

number of simple test were done to check the inputs/outputs, MM232R communication

with the PC and bi-directional communication using ER400TRS. Each test required a

compiler to compile the C code into a PIC readable format and a PIC programmer to burn

the program into the PIC. More or less, the deliverables and objectives of this project were

achieved by implementing bi-directional communication of messages between three nodes

or hubs.

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ACKNOWLEDGEMENT

I would like to thank number of personalities for their support and encouragement

throughout the duration of this project.

First of all I would like to thank my respected Supervisor Dr. R. C. Seals of School of

Engineering, University of Greenwich for initiating this project and for his continuous

help, support and patience. Special thanks to Mr. A. Feasy who always had the time and

motivation to help during the lab session.

I would also like to thank my family and friends for their support during this time, without

which it would have not been possible for me to achieve this goal.

Finally I dedicate this project to my family.

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Table of Contents

Declaration of Originality ....................................................................................................... i

ABSTRACT .......................................................................................................................... ii

ACKNOWLEDGEMENT ................................................................................................... iii

CHAPTER 1 ......................................................................................................................... 1

Introduction ........................................................................................................................... 1

1.1 Introduction ............................................................................................................. 1

1.2 Aims and Objectives ............................................................................................... 2

1.3 Project Deliverables ................................................................................................ 3

1.4 Project Constraints .................................................................................................. 3

CHAPTER 2 ......................................................................................................................... 4

Literature Review .................................................................................................................. 4

2.1 Communication System ............................................................................................... 4

2.2 Microcontroller System ............................................................................................... 7

2.3 Design of Printed Circuit Board .................................................................................. 7

CHAPTER 3 ......................................................................................................................... 8

Requirements Analysis ...................................................................................................... 8

3.1 Components Requirements Analysis ........................................................................... 8

3.2 Design Requirements Analysis .................................................................................... 9

3.3 Construction Requirements Analysis .......................................................................... 9

3.4 Programming Requirements Analysis ....................................................................... 10

3.5 Final to do list ............................................................................................................ 10

3.6 Testing Schedule ....................................................................................................... 11

CHAPTER 4 ....................................................................................................................... 12

Possible Solutions ............................................................................................................ 12

4.1 Communication System Solutions ........................................................................ 12

4.1.1 Node to Node Communication ....................................................................... 12

4.1.2 Communication between Node to PC ............................................................ 14

4.2 Microcontroller Solutions ...................................................................................... 15

4.2.1 Basic Stamp 2 (BS2) IC.................................................................................. 15

4.2.2 Programmable Logic Control ......................................................................... 15

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4.2.2 Atmel .............................................................................................................. 15

4.2.3 Microchip ....................................................................................................... 16

4.2.4 Selected Microcontroller ................................................................................ 16

4.3 Programming Solutions ......................................................................................... 17

4.4 PCB construction solution ..................................................................................... 18

4.4.1 Types of circuit board ..................................................................................... 18

4.4.2 Schematic and PCB design software .............................................................. 18

4.4.3 Drilling Methods ............................................................................................ 19

4.4.4 Soldering Methods .......................................................................................... 19

CHAPTER 5 ....................................................................................................................... 20

Problem Implementation ................................................................................................. 20

5.1 Hardware implementations .................................................................................... 20

5.1.1 Circuit design by ISIS .................................................................................... 20

5.1.2 Layout design by ARES ................................................................................. 23

5.1.3 List of Components ........................................................................................ 25

5.1.4 Drilling and soldering components................................................................. 26

5.1.5 Identifying Node Distance .............................................................................. 28

5.2 Software Implementation ...................................................................................... 29

5.2.1 Test Plan 1 ...................................................................................................... 30

5.2.2 Test Plan 2 ...................................................................................................... 32

5.2.3 Test Plan 3 ...................................................................................................... 34

5.2.4 Test Plan 4 (Final Code) ................................................................................. 34

5.2.5 Settings for Communication Test ................................................................... 38

CHAPTER 6 ....................................................................................................................... 39

Results ............................................................................................................................. 39

6.1 Test Plan 1 Results ................................................................................................ 39



6.4 Test Plan 4 (Final Code) Results ........................................................................... 44

6.4 Testing Schedule ................................................................................................... 47

CHAPTER 7 ....................................................................................................................... 48

Discussion ........................................................................................................................ 48

7.1 Discussion of Results ............................................................................................ 48

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7.2 Discussion of Gantt chart ...................................................................................... 49

CHAPTER 8 ....................................................................................................................... 50

Conclusion ....................................................................................................................... 50

CHAPTER 9 ....................................................................................................................... 51

Future Work ..................................................................................................................... 51

REFERENCES .................................................................................................................. 52

BIBLIOGRAPHY .............................................................................................................. 55

APPENDIX 1 ..................................................................................................................... 56

Header file code ............................................................................................................... 56

APPENDIX 2 ..................................................................................................................... 58

Test Plan 1: LED testing code ......................................................................................... 58

APPENDIX 3 ..................................................................................................................... 60

Test Plan 1: SWITCH testing code.................................................................................. 60

APPENDIX 4 ..................................................................................................................... 62

Test Plan 2: MM232R Transmission test code ................................................................ 62

APPENDIX 5 ..................................................................................................................... 64

Test Plan 2: MM232R Reception test code ..................................................................... 64

APPENDIX 6 ..................................................................................................................... 68

Test Plan 3: ER400TRS test code and flow chart ........................................................... 68

APPENDIX 7 ..................................................................................................................... 73

Test Plan 4: Final Code ................................................................................................... 73

APPENDIX 8 ..................................................................................................................... 83

Components Order From ................................................................................................. 83

APPENDIX 9 ..................................................................................................................... 84

Gantt Chart ...................................................................................................................... 84

APPENDIX 10 ................................................................................................................... 85

More project images ........................................................................................................ 85

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CHAPTER 1

Introduction

1.1 Introduction

One of the fastest growing fields of engineering world was Wireless communications. This

is the modern shape of physical wire communication Medias. Advancement of this

wireless technology was at peak in this century. New inventions of wireless

communication devices are happening day by day [1]. Existing devices are also

performing well. Research and development on wireless devices are also at peak. In simple

words a revolution of wireless communication has started [13]. Wireless communication

was the core theme of this project.

Wireless communication can be via radio frequency or microwave or infrared (IR) short

range communication. This project was using radio frequency for wireless communication

within the short range. In this project communication was in between adjacent buildings on

the Medway campus using Easy-Radio style digital radio transmitter and receiver modules.

The Easy-Radio style provides high performance, simple to use radio module that can bi-

directionally transfer data over a range up to 250m Line of Sight (LOS) [4]. This project

contained specific primary components to make the system work properly. These are

broken down into four simple components like data signal (computer interface or USB),

radio transceiver, microprocessor and Antenna system. In addition to being able to

communicate, it must also have a mesh interconnection capability. Initially communication

will be by sending single ASCII characters and then using the file transfer protocol.

Mainly this system required to have some form of intelligence such as PIC microprocessor

system in order to fulfil the requirements of this project.

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Figure 1.1: System block diagram.

1.2 Aims and Objectives

To design and develop a short range intelligent digital radio wireless hub was the main

goal of this project. This hub must be able communicate between adjacent buildings on the

Medway campus using digital transmitter and receiver modules (Easy-Radio). It also must

have some interfacing capability like four LEDs for output and four digital inputs, a local

USB interface and also mesh interconnection capability. For example, if one of the hubs

was placed into Hawke building and the other hub is on the Pembroke building of the

campus, messages could be passed from hub to hub to provide bi-directional

communication between them. To achieve the goal which is stated above the following

objectives have been set:

To research and investigate about issues in wireless technology and radio

frequency communication using a microcontroller.

To have a details idea about the digital radio transmitter and receiver modules, PIC

microprocessor systems and mesh topology.

To make Tx and Rx.

To familiarise with the present technology to create three wireless hubs using Easy-

Radio Transceiver.

To integrate all the required knowledge to a single design and to build the printed

circuit boards for the three Hubs and to test it.

PC 1 PC 3 PC 2

HOST (A) HOST (B) HOST (C)

Radio

Transceiver (A)

Radio

Transceiver (B)

Radio

Transceiver (C)

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1.3 Project Deliverables

The main objective of this project was to build three circuits which would have radio

module, USB interface and a microcontroller. These are the core components for final

digital wireless hub. Key areas of this project are as follows:

Design and implement more than two small systems containing a Transceiver

(Radio module), USB interface and a Microcontroller.

Implement bi-directional communication of ASCII characters between two hubs.

Implement bi-directional communication between more than two hubs arranged in

a straight line of maximum error free communication distances.

1.4 Project Constraints

The following two major constraints were taken into consideration for the project.

Lack of manpower: It was the aim that the cost of each PCB (Printed Circuit

Board) for the system would be as low as possible as many of them would be

made. It was planned to construct three PCBs within the limited cost which helped

to prove mesh interconnection capability. It was impossible to attend three nodes at

a time while testing. But this constraint was overcome by the help from author‟s

colleagues.

Time: There was a limitation of time for carrying out the practical lab based work.

Because the project labs were closed at the end of July‟11 for the summer vacation.

Weekly lab work and meeting with the supervisors helped in completing the lab

based tasks on time.

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CHAPTER 2

Literature Review

Good amount of work has been carried out by a number of engineers and researchers in the

field of digital radio wireless communication over a short range. This literature review

summarized what has been understood about wireless communication, digital radio

communication, short-range communication and its applications, Mesh interconnection

topology, Microcontroller, USB interface (MM232R), different steps for designing the

PCB and synchronous/asynchronous serial communication through the study of books,

past research papers, journals, datasheets and website information. Thematic analysis was

done and three specific themes were decided. They are Communication System,

Microcontroller System and Design of Printed Circuit Board.

2.1 Communication System

Wireless communication is the fastest growing part of the current communication

industry because of its widespread deployment. It was first developed in the pre-industrial

age [12]. Those systems used to transmit information over line-of-sight distances using

smoke signals, flashing mirrors. Wireless networks, both as stand-alone systems and as

part of the larger networking infrastructure. There is a gap between current and emerging

systems and the vision for future wireless applications shows that much work needs to be

done to make this vision a reality [1].

Digital radio communication means the analogue signal is digitized into zeros and ones

and then compressed and transmitted using a digital modulation scheme [1].

Communication across a wireless network is like a two-way radio communication. The

signal is transmitted into the open air, using an antenna which radiates energy at some

carrier frequency [14]. A transmitter does this job and it consists of a source of electrical

energy, which produces alternating current of a desired frequency of oscillation. The

propagation of energy depends on the frequency and the antenna and it can be

unidirectional or Omni-directional fashion. A wireless hub or router on the other end

receives the transmitted signal and decodes it [14]. This process also works in reverse.

Radio frequencies range from a few tens of hertz to three hundred gigahertz. This similar

mechanism is also used for walkie-talkies, cell phones and other devices.

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The term short-range typically means less 100 meter e.g. NFC (Near Field

Communication), Zigbee, Z-Wave, Wi-Fi and DECT (Digital Enhanced Cordless

Telecommunication) [4]. There are several technologies for different applications of short-

range wireless embedded devices like Bluetooth, Infrared Data Association, Home Radio

Frequency, Ultra-Wideband Radio and their applications in the workplace, home, public,

travel [24]. There are different design challenges for short-range wireless networks like

mesh topology issues, i.e. mesh networking and device issues, i.e. efficient and low-cost

issues and also their solution [23]. But sometimes devices cannot communicate wirelessly

within a short range like range less than 1 meter [28].

Mesh is one type of network topology where data is forwarded between the nodes until it

reaches the destination without the help of central node. Central node means hub or switch

or access point. This type of the communication depends on radio range of the nodes. An

example of such a network has given.

Figure 2.2: An example of mesh network.

Signal Radio

transmitter

Modulated

Signal

Demodulated

Signal

Signal Radio

Receiver

Transmission

Antenna

Reception

Antenna

Figure 2.1: Typical radio transmission and reception

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Start

Bit Data Bits

Parit

y Bit Stop Bits

In this project serial communication was required to communicate between node with the

PC. Serial communication means sending and receiving bytes of information one bit at a

time. This type of communication is basically used for transmitting information or data

between a computer and a peripheral device like programmable instrument. The serial port

on a computer is full duplex. Full duplex means it has separate lines for transmitting and

receiving data. That means they can send and receive at the same time. Parallel

communication is much faster than the serial because it allows transmission of a byte at a

once [26]. Generally, engineers use serial communication to transmit ASCII data. Such a

communication is completed using three transmission lines – ground, transmit and receive.

Synchronous and asynchronous are two forms of serial transmission. In the case of

synchronous communication the sender and receiver share a clock with each other. It

allows much faster rate than asynchronous communications, because additional bits are not

required for each data. On the other hand asynchronous means no synchronization,

because it allows data to be transmitted without the sender having to send a clock signal to

the receiver end. Description of some important serial parameters has given below:

Baud rate is basically the speed measurement for communication. It indicates the number

of bit transfers per second like 9600 baud means 9600 bits per second.

The end of communication for a single frame is indicated by the stop bit. Typically they

can be 1, 1.5 and 2 bits.

They are the measurement of the actual data bits in a transmission. The amount of actual

data may not be a full 8 bits all the time. It can be 5, 7, and 8 bits for frames.

Parity is used for error checking in serial communication. There are four types of parity

and they are even, odd, marked and spaced. It helps to detect data corruption which might

occur during transmission.

Figure 2.3: Typical character frame.

Character Frame

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2.2 Microcontroller System

Microcontroller is the nerve centre of this project. The wireless hub should have some

form of microcontroller based intelligence. Microcontrollers are not only used in home and

office appliances, instruments and machinery but also into everyone‟s daily life [11]. One

of the most important features of the microcontroller is to store and run a program. It can

be programmed to make decisions and perform functions [2]. Its ability to perform math

and logic function makes it extremely versatile. The microcontroller consists of a central

processing unit (CPU), random-access memory, read-only memory, electrically erasable

programmable read-only memory (EEPROM), input / output (110) lines, serial and parallel

ports, timers, and other built-in peripherals, such as analogue-to-digital and digital-to-

analogue converters [11]. BASIC STAMP 2 or PIC microprocessor system can be used

for this project. Microcontrollers were originally programmed using an assembly language,

but currently different types of high-level programming languages like C are using [11].

Writing program using an assembly language is hard and time consuming. But C is less

time consuming and also easier to modify and update. The next thing is actually

programming the information inside the microcontroller. It can be done using an

Assembler, which converts the program into a format that the PIC understands. Windows

based MPLAB is the best one currently. It includes an editor, simulator and assembler.

2.3 Design of Printed Circuit Board

The Printed Circuit Board (PCB) was an electronic circuit which allows electricity to move

across pathways created upon copper layer from the design. PCBs are used in every single

electronic device. They can be single sided, double sided or multilayer. A single sided

board has only one side for connection and the other side is for components [29]. This type

of board was used for this project. Creation of PCBs is skilful and lengthy task. It required

different steps like design, construction and testing. The very first step is the schematic

design. Schematic means a collection of electronic symbols connected together by using

virtual wires [29]. Then the final step was generating netlist. Fabricating of the PCB starts

when the generated netlist is fed into the circuit board layout tool. Main steps are

generating component footprints, placing those footprints and connecting those. Basically,

there is no right way to place and route a PCB, but there are plenty of ways. Good

placement of components always leads to good routing.

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CHAPTER 3

Requirements Analysis

This chapter provided what are the inputs, outputs of the desired system and how the

inputs were converted into outputs. As the project title “Short Range Intelligent Digital

Radio Wireless Hub” indicated the crucial requirements. Like-

Short Range suggested that the communication would be within the limited short

range (<100m). The final system should be capable of communicating between

buildings of Medway campus at University of Greenwich.

The word Intelligent on the title indicated the final system should have some form

of intelligence like a microprocessor system which would be the working brain of

this project.

Digital Radio meant communication system of the final system would be based on

the typical digital radio transmission and reception based.

Finally Wireless Hub indicated the type of communication system would be used

which is wireless. More than one hub was created to communicate between them

wirelessly within the short range.

3.1 Components Requirements Analysis

According to the first deliverable described on chapter 1 page 2, the final system should

contain ER400TRS as a radio module, MM232R as a USB interface and most importantly

a microcontroller. Other requirements were four LEDs for output and four digital inputs.

No external power supply would be used. Each node got the required power from the USB

connection (MM232R). Another important component requirement was the programming

connector even though it was not mentioned anywhere, which helped to burn the program

into the microcontroller. The ER400TRS radio module required a 50 ohm Antenna such as

a whip, helical or PCB loop. The University has a limitation on budget of £150 per project.

So throughout the project it was kept in mind that more than one PCB would be made.

Within that budget it was possible to build three PCBs of the same system. In case of

Power MM232R can supply no more than 100 mA from USB [5] and ER400TRS can

consume 23 mA while transmit, 12.5 mA while receiving [4]. Also the power consumption

of selected microcontroller as low as 0.1 uA in standby mode and 25 mA while active

mode. Each LED would take 5 mA (Approx.) and 10 mA for rest of the circuitry.

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3.2 Design Requirements Analysis

Design was the most important phase for any project. This phase has decided how

convenient it was to construct the PCB like was it too complicated to drill and solder or it

was easier. Programming the microcontroller also depended on this phase because how the

inputs and outputs are connected with the different ports of the microcontroller. There was

no specific design requirements mentioned for this project. At the beginning schematic

design was the primary step and requirement of this project. According to the requirement

four LEDs were used as an output and switches as a digital input. It was necessary to

identify how to connect the ER400TRS, MM232R, LEDs, Switches and the

Microcontroller along with the programming connector. When the schematic would be

done the generated netlist would be transferred to PCB layout design tool. The PCB should

be single sided. Along with the other required components four rubber feet should be

included and especially the connectors needed to be placed near the edge of the PCB for

easy access. Finally, the size of the copper pads for the DIL components must be oval

which would help for proper soldering. Distance between the nodes would be

approximately 20 to 25 m.

3.3 Construction Requirements Analysis

The designed PCB had several hole sizes for drilling. It was suggested to drill the larger

holes first, as this reduced the chance of accidentally under-drilling a hole. Three types of

sizes were required. Most of them are 0.8mm. Holes for the switches were 1mm and for

the rubber feet 4mm were required. Another essential requirement for this was to be

careful drilling. Because if it is not properly drilled the PCB will not be able to solder and

also it will not work as expected in testing session.

Soldering was done on the solder side of the PCB. This required following safety rules

because the soldering rod is maintained at the temperature of 325 oC. Good soldering is a

skill that is learnt by practise. Before starting soldering all the components should be

inserted properly. Then at the beginning the smallest components like resistors, LEDs,

Capacitors should be soldered first. The amount of solder must be accurate; if not there

will be chance of short circuit on the PCB. If excessive heating was done then the surface

of the PCB will be changed into a different colour which can cause problem later. Some of

the components are heat sensitive, so they should be soldered carefully. If any component

is soldered in the wrong place it must be removed immediately using unsoldering sucker.

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3.4 Programming Requirements Analysis

According to the last two deliverables of this project the following requirements were

determined.

Firstly, important part of the project was the transfer of packets of message from one node

to another node and they should be organised in a straight line so that the two end nodes

cannot communicate directly with each other. The structure of the message has given

below:

Secondly, there should be an acknowledgement reply from each node. For example, if

node A sends information to the node B. When node B received it will display the received

information and the acknowledgement reply like "Info Transferred" should be displayed

on the node A serial terminal.

All these requirements absolutely depend on how the programming was done. The

intelligence of the microcontroller would be decided by the programming or coding. It

required good knowledge of high-level programming or assembly language and also a in-

circuit programmer like MPLAB ICD2 or ICD3 to burn the program into the

microcontroller.

3.5 Final to do list

After going through all the functional requirements the final list of requirements was set

out as follows.

I. Identifying the inputs and outputs.

II. Identifying what type of oscillator would be used.

III. USB powered supply using MM232R.

IV. Implementing MCLR on the PCB or Hub.

V. Connection between ER400TRS and MM232R.

VI. Implementing ICD connector on the Hub or PCB.

Message Type Sender ID Message Length Message Receiver ID

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3.6 Testing Schedule

Test

No.

Purpose Expected Outcome

1 To ensure that the voltage on pin

14 of PIC18F1320 socket is at 5 V

Voltmeter will show exactly the

same value of supplied voltage on

those pin

2 To ensure all the outputs (LED) are

working [Test Plan 1]

LEDs will glow sequentially

according to the program

3 To ensure the reset switch is

working

LEDs will start to glow from the

beginning of sequence

4 To ensure all the inputs (SWITCH)

are working [Test Plan 1]

Each switch will glow pre-

assigned LED according to the

program

5 To ensure the MM232R

transmission is working

After the programming “Test

String” will be displayed on the

HyperTerminal window

6 To ensure the MM232R reception

is working

When the pre-defined command

will be received it will return user

defined command using Docklight

7 To ensure ER400TRS is working

for each PCB or Node

Each PCB will display its unique

modemid along with

“#modemidHello*

8 To ensure bi-directional

communication between three PCB

with mesh interconnection

capability

Each node will be able to receive,

transmit and forward the packet of

messages according to the inputs.

Table 3.1: Prepared test schedule according to the requirements

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CHAPTER 4

Possible Solutions

Depending on the requirements analysis described in the previous chapter, this chapter

went through the available problem solutions and look for the most suitable and best

solution and also the reasons behind it.

4.1 Communication System Solutions

4.1.1 Node to Node Communication

Communications are generally two types they are wired or wireless. But this

communication based project will be having wireless as the each node would be mobile

connected with the PC. Some of the options for the wireless communication have

explained below.

Bluetooth Communication

This was the new addition in the shot-range wireless communication. Bluetooth was

mostly heard for the cell phones it was one of the popular form of data transfer. It was used

for transferring pictures, contacts, videos, messages and many more. This technology was

not only used in mobile phones but also in computers and PDA (Personal Digital

Assistants) to GPS systems and heart monitoring devices. Bluetooth worked on 2.4GHz

unlicensed industrial, scientific and medical (ISM) band and it uses frequency-hopping

spread-spectrum (FHSS) Communication, that means to transmit data over different

frequencies at different time intervals which is called as hops, and there will be 1600 such

hops per second, one of the difference between the other wireless devices and Bluetooth is

that they communicate with each other automatically. That is whenever the two Bluetooth

devices come within the range they would communicate, it is known as paring.

Infrared Communication

This method of communication was mostly heard for television remote controls or air

conditioners and so on, it was also seen that IR communication is suitable for high speed

data transfer, the major reasons for the IR to be more used was its low cost and low power

consumption. Some of the major reasons for using IR in mobile environment are as

follows [1].

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1- High-speed of transmission: The first generation of IR transmission was 115.2kb/s but

as the time moved on it increased and presently it can work on 1 to 4 Mb/s of speed.

2- IR was a short range wireless communication, but it cannot transfer data outside a room,

this gives minimum problems to the user.

3- IR has no regulations such as in RF; the range of IR media is outside the scope of laws

pertaining to RF.

Major disadvantages of such a communication was basically limited range of transmission

and reception (<3m) and it also has various types of interference like fluorescent light, sun

light and so on.

Wireless Radio Communication

It was one of the requirements for this project that the communication method between one

node to another node would be using wireless radio communication (Easy-Radio style).

For this project Easy-Radio transceiver ER400TRS was considered as one of the solution

for the communication. It provided a bi-directional high speed data transfer. Obeying the

boundaries of the ISM bands (E.g. Pan-European 433.06 – 434.79 MHz band it was

possible to employ a license free approved Short Range Device with an effective radiated

power not exceeding 10mW [6].

Figure 4.1: ER400TRS device with pin out

Some important features of this device are as follows:

1. It has a low operating voltage of about 3.6 Volts.

2. It has a high sensitivity receiver a typical value is 105dBm @ 19.2 Kbps

3. A crystal controlled synthesiser is used for frequency accuracy.

4. A transparent data transmission is used by serial input and output.

5. Has a minimum power consumption that is less that 23mA for transmitting mode

and 12.5mA for receive mode.

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Some applications of this device are as follows:

1. It could be used for environmental sense and control

2. Has a high rate of remote data Acquisition

3. Electronic point of sale equipment

4.1.2 Communication between Node to PC

Node to PC communication played a vital role for this project. A serial UART interface

can accomplish this role. FTDI (Future Technology Devices International ltd.) produced

range of development modules for USB to Serial UART development interface like

UM232R, UM245R, MM232R and UB232R. MM232R was one of the core requirements

for this project. For that reason, it was used which provided a communication between the

PC and PCB.

MM232R was mini USB- serial UART interface integrated circuit module. It was also a

latest product form FTDI‟s. This device could be used as a microcontroller or external

logic by separating internal clock. It has been provided by more security feature that is

with the help of unique number that is burned into the device during manufacturing. Size

of the MM232R was also one of the factors as it is ultra-small 18.0mm x 21.5mm (0.7”x

0.8”) PCB. It has got 16 pins on it which are .1” pitched. This module supported RTS

(Ready to Send) or CTS (Clear to Send) hardware handshaking and is powered from the

USB port [5]. Some important features of it have given below.

Integrated Clock Circuit – No crystal or ceramic resonator is required because of its

built in clock circuit.

Integrated EEPROM - MM232R has an inbuilt EEPROM; a portion of the EEPROM

is also allocated for the user to store additional data. This EEPROM can be

programmed using the USB without the requirements of any external voltage source

Less external components - Reduced the material cost for USB interface designs

compare to its predecessor

Lower supply voltage – This module works at low ranges from 3.3 to 5.25V and so

the USB bus provided with a 3.3V that eliminates the requirement of the external

regulator.

MM232R was selected among other development modules because of its versatility and

simplicity. Specially, it can be configured as a USB self-powered [5]. Due to this

characteristic the final system did not require any external voltage regulator.

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4.2 Microcontroller Solutions

There are various options to be considered for the selection of the optimum

microcontroller such as the BS2 IC from Parallax Inc, Programmable logic controller

(PLC), or a microcontroller such as PIC form Microchip, AVR from Atmal and so on.

Different programming languages were used for controlling these microcontrollers like

visual basic, C/C++ or assembly language [2]. For industrial uses PLC became famous for

its easy programming language, code execution time and reliability. The key to selecting

the appropriate microcontroller depended on the understanding of the jargon, and

establishing priorities [23].

4.2.1 Basic Stamp 2 (BS2) IC

Basic stamp 2 was well known as BS2 IC. This can act as a controlling device in an

electronic device. It can be integrated into keypads, sensor, motors, switches, relays, lights

and so on. It has its own Programming language called as PBASIC. The operating voltage

required is from 5.5 volts whereas this project required working on even less voltages.

There are various kits available that can help one to understand and get used to the Basic

stamp.

4.2.2 Programmable Logic Control

PLCs are majorly used in industries to control processes. One of the definitions of PLC is

Microcomputer embedded in or attached to a device to perform switching, timing, or

machine or process control task. The advantage of a PLC over a microcontroller is that it is

easy to program, similar to microcontroller the PLC also accepts the analogues as well as

digital signals, but it do not need to be configured such as in microcontroller, one of the

major advantage over a microcontroller would be the ability to operate with both low as

well as high level voltages, the programming and execution can be done simultaneously.

4.2.2 Atmel

Atmel was one of the leading companies that produce broad range of microcontrollers like

8051, 8052 and so on. It gave a high range of code density from 2K bytes to 128K bytes, a

wide range of microcontrollers ranging from 8-bit to MCS-51 are more powerful and used

for industry standard. ISP (In-system programming) of Atmel also made it more flexible

and user friendly.

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4.2.3 Microchip

This company used to develop semiconductor devices since 1989 [20]. Microchip

engineers focused their aim to develop a controller that would be able to programmable,

with the ability of providing high output current and also the capabilities of having input

and output pins. The first PIC (Peripheral Interface Controller) Microcontroller was based

on RIDC (Reduced instruction set code) which could execute one instruction per clock

cycle at 20 MHz. Main advantages for using PIC are inexpensive, small instruction set to

learn, wide range of interface ability and RISC architecture [20]. Most importantly, this

microchip has design support like free MPLAB IDE (Integrated Development

Environment) and C compilers. PIC has different series like PIC10, PIC12, PIC16, PIC18,

PIC24 and PIC 32.

The following table showed the comparison among the microcontrollers.

Types Programming

language

Operating

voltage

Cost Development

Module

available?

Complexity

as a new

user?

BS2 PBASIC Built in 5 V

DC

Medium Yes Easy

PLC Ladder logic External

power supply

High Yes More

complex

Atmel FastAVR or C External 3.0V

to 3.6V DC

Low No Complex

PIC C External 5V

DC

Low No Complex

Table 4.1: Comparison of microcontrollers.

4.2.4 Selected Microcontroller

The decision of which microcontroller would be the best for this project was made based

on the number of input and output required and the amount of space required for the

program and also the simplicity. For those above reasons PIC18F1320 of Microchip

Technology Inc. was selected. This PIC18F1320 comes in 18, 20 and 28 pin packages

having similar features of PIC18F1220.

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They are used for their liner addressing, high performance, with enhanced flash

microcontroller along with 10-bit A/D and Nano Watt Technology. They can have the

speeds of 0 Hz to 40 MHz. This PIC has the power management ability such as when idle

CPU will be off and Peripherals will be on which was important in this project. The

maximum current can be 300 mA and maximum power dissipation of 1 Watt. It has two

ports (Port A & Port B).

4.3 Programming Solutions

Programming a PIC meant storing the program onto a PIC. It can be done by using

Assembly language or High-level language like C. The executable code for the PIC was

represented as a sequence of hexadecimal numbers called a hex code. Both the assembly

language and C required software to process their compiling into executable code which is

known as Compiler. A compiler converts a high level language program to machine

instructions for the targeted PIC. Rather than Assembly language C programming

language was used for this project. The major reasons for this decision have given below.

1. It is easier and less time consuming to write a program in C than in assembly.

2. C is also easier to modify and update.

3. Codes available in the function library can be used.

4. Programs are developed much more rapidly in C.

5. Code efficiency of compiled C programs is typically 80% of well-written

assembler program.

6. Another language C++ was too complex for use with the present generation of

PICs.

There are various C compilers available that target Microchip PICs like Hi-Tech,

Microchip and CCS. Hi-Tech C compiler has a good range of build-in functions and also

comes with source code for all its libraries. But it is more expensive than any other

compilers and does not have a code-generation wizard like CCS C compiler. Microchip C

compilers like C18 come free with the MPLAB IDE.

But for this project CCS C compiler was used. MPLAB IDE supported the Custom

Computer Services (CCS) language tools. Main reasons for selecting this have given

below.

1. CCS C was much easier to use.

2. Lots of sample C code was provided which explained a range of techniques and

features.

3. Built-in function libraries and standard C operators are specific to PIC registers.

4. It has device specific include files for each PIC microcontroller.

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Programs are edited and compiled to PIC microcontroller instructions on a computer. PIC

microcontroller instructions are uploaded from PC to PIC using ICD 3 debugger.

Figure 4.2: Process diagram of compiling and debugging.

Some features of MPLAB ICD3 have given below.

MPLAB ICD3 is powered by USB that make it more portable.

Improved performance for debugging and programming.

This debugger is 15 times faster than its earlier version in terms of programming.

It was designed for high speed processors that would help the embedded engineers

to debug the device in real-time.

4.4 PCB construction solution

4.4.1 Types of circuit board

Three types of boards are there. These are Breadboard, Stripboard and Printed Circuit

Board. Breadboard is the way of making temporary circuits for testing purposes. All the

components can be reused and no drilling or soldering is required. One side of the

stripboard is made of copper and the parallel strips of copper track are connected together.

It does not require drilling only soldering was required. Printed circuit boards need to be

designed first then it required drilling and soldering both to place the components and

make the connections. This was the best choice for this project to make a complete system

according to the requirement.

4.4.2 Schematic and PCB design software

Schematic and PCB design was the main section of the design phase of this project. Both

can be done using one package. This phase will decide how the circuit is going to work.

There are two ways to do this.

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First way was using WinQcad 52.6. It was complete electronics design software. It was

compatible with all the operating systems. It included a schematic design editor, a PCB

design editor and a compatible autorouter.

Second way was using Proteus PCB Design software. It has fully featured schematic

capture and World class shape based autorouter. This package was much more user

friendly and versatile compare to the WinQcad and it has a unique integrated 3D viewer.

The design for this project was required to do that using this software package. The

University of Greenwich has this software on its laboratory. For these reasons Proteus has

been used.

4.4.3 Drilling Methods

Drilling is one of the important phases of construction of the PCB. It can be done in

several ways. Variodrill was a high speed machine which combined drilling accuracy with

an increased level of user comfort. It rests on an adjustable base which allows the work

table to be tilted towards the user, thus reducing user fatigue. This machine has been used

for drilling all the components of 0.8mm diameter. A built in magnifier helped to view the

target with more accuracy. The manual drilling machine has also been used for drilling

holes for the rubber foots of 4mm diameter. When drilling with this particular machine, it

was important to hold the PCB down firmly, as the drill bit can snatch the board upwards

as it breaks through.

This manual machine was at the laboratory for different sizes of hole starting from 0.8mm

to 5mm. This was not used for the 0.8mm hole for this project because the other one

(Figure 4.7) was much more accurate and easier to drill.

4.4.4 Soldering Methods

Soldering can be done manually or automatically. One of the automatic systems is DS-01

Automatic DIP Soldering Systems. It has motorised drive and 0-6 seconds movement time

of the PCB during automatic soldering. The whole process is controlled by the motorised

drive unit which makes it independent of operator training and skills. But this has not been

used for this project. Because university does not provide such a system and as a beginner

soldering has been done manually by using a 30 Watt soldering iron.

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CHAPTER 5

Problem Implementation

The implementation for this project was divided into two parts hardware and software.

Hardware section consisted of designing the PCB, drilling, soldering and testing the power

and short circuit. Software section consisted of PIC18F1320 programming according to the

developed test plans.

5.1 Hardware implementations

5.1.1 Circuit design by ISIS

ISIS 7.7 was a part of the Proteus 7.7 circuit design and simulation software. The digital

radio wireless hub system for this project was designed by this software. First task was to

connect ER400TRS, PIC18F1320, MM232R and ICD connector together. There are

various points that were considered during the circuit design, the following are the points.

The number of inputs and outputs required

Whether the internal or external oscillator to be used

The 5 volts power supply

A switch would be required to MCLR in order to manually reset the program

Three LEDs would be connected to indicate the operation as an output

Four switches would be used as an input

The connection to the ER400TRS and MM232R

ICD connection to upload program on the PIC

A PIC microcontroller can control outputs and react to inputs. In PIC18F1320 port RA0 to

RA4 and RB0 to RB7 were bidirectional ports and they can be used as an input or output.

PIC18F1320 have overall 18pins including VDD (Pin no.14) and VSS (Pin no. 5). Three

LEDs were used as an output for the following purposes.

LED 1: Supply voltage

LED 2: Data Transfer-Transmit

LED 3: Data Transfer-Receive

LED1, LED2 and LED3 were connected respectively to the Pin no. 6, 2 and 1 of the PIC.

Four switches (SW) were used for general purposes as an input to the system. SW1, SW2,

SW3 and SW4 were connected accordingly to the Pin no. 15, 16, 17 and 18.

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Figure 5.1: LEDs and Switches.

Another issue was to properly operate the microcontroller it must be reset correctly. To do

that a simple normally open push button, a resistor, a capacitor and a diode were used. The

RC time constant for the reset circuit should be between 10ms and 20ms [20]. The circuit

of the following figure has an RC time constant of 10K X 1.0uF or 10ms.

Figure 5.2: PIC18F1320 reset circuit.

External power supply was not in the requirements for this project. So, it was necessary to

find a way to power the circuit. That is why MM232R was used because it has option to be

used as a BUS powered configuration or USB powered for the PCB. To do this pin 15

(USBPWR) and pin 14 (VCC50) should be connected together. Also the schematic capture

for MM232R and ER400TRS were not available on the ISIS library so it was required to

create one according to its pin description. The schematic capture of both the components

has given on the following page.

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Figure 5.3: MM232R and ER400TRS

Radio Module (ER400TRS) has 9 pins. Pin no. 2 (RF GND), 9 (GND) were connected to

the common ground line and pin no. 8 (VCC) was connected to the common power line.

Other pins were connected using following connection.

The schematic capture of the final circuit has given below.

Pin no.3 (RSSI)

Pin no. 4 (BUSY) Pin no. 11 (RB5)

Pin no. 7 (RA3)

Pin no.5 (DATA IN) Pin no. 9 (RB1)

Pin no.5 (DATA OUT) Pin no. 10 (RB5)

PIC

18F

1320 E

R400T

RS

Figure 5.4: Short range digital wireless hub circuit

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Figure 5.6: 4 way Rocker switch

5.1.2 Layout design by ARES

ARES was one of the important feature of the Proteus 7.7 professional, it was used to

design the layout of the PCB board. Once the ISIS schematic diagram was completed the

components and the design could be directly linked with the ARES with the help of the

„Netlist Transfer to ARES‟ present on the left hand top corner of the window. The

following steps are taken after that.

Step 1: The board edge of the PCB was drawn first and it was considered as 3.75x3.2

inch.

Step 2: Couple of components (ER400TRS and MM232R) were not in the ARES

library. So before transferring the netlist from the ISIS both the packages of the

components were created and saved. While transferring from the ISIS those newly

created packages were selected. All the other components were found on the ARES

library.

Figure 5.5: PCB layout of ER400TRS and MM232R.

Step 3: It was decided to use one DIP switch for digital input instead of using four

push buttons because it is easier to handle, cheap and also required less space on

the PCB.

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Step 4: Now all the components were placed using the Auto placer of ARES. As

per the requirement all the connectors like ICD connector and MM232R were

placed on the edge for easier convenience. According to the datasheet of the

ER400TRS, this radio module should be kept away from the circuitry that is why it

was moved towards the edge.

Step 5: Then at the four corners of the PCB four round through-hole pad (4mm

diameter) were placed for the rubber pad.

Step 6: After placing the components manual routing by using bottom copper was

done. There were few connections which could not be connected. But those were

indicated using Top Silk layer on ARES to use manual wire to connect them after

the construction.

The screendump of the completed PCB layout has given below.

Figure 5.7: Short range digital wireless hub PCB layout.

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After completing the PCB design it was printed. Three of the same PCBs were printed.

The bottom view of the printed circuit board has given on the following page.

Figure 5.8: Bottom view of the PCB.

5.1.3 List of Components

Components for three of the PCBs were identified and ordered from different electronic

component stores. The following table shows the list of the components.

Name Description Quantity

ER400TRS Radio Module 433 MHz 3

MM232R USB Module 3

PIC18F1320 DIP 18 IC (8 Bit) 3

LED Red 9

Diode 1 A, 100V 3

Capacitor 100 nF 12

Switch Push Button 3

Socket IC 18 way, DIL, PIC holder 3

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Rocker Switch DIL, 4 way 3

Capacitor 10 uF 3

Resistor 10 K Ohm, 5%(Tolerance) 15

Resistor 1 K Ohm, 1%(Tolerance) 12

Socket ICD connector, Vertical 3

Table 5.1: List of used components.

5.1.4 Drilling and soldering components

Drilling and soldering are the two important phase of constructing the PCB. Health and

safety requirements were maintained throughout the both the process.

The right drilling equipment, drill bits and techniques can make a big difference in the

quality of drilling. Drilling was done first when the PCB was printed. If the drill was not

perfect or smooth or holes were not in the required position it will create problems for

soldering. Safety precautions were taken to protect eyes from probable threats before

starting drilling. At the beginning all the holes of 0.8 mm were drilled with a good

alignment by using semi-automatic drilling machine at the laboratory. Then the drilling

machine of different sizes like 1mm for the push button and 3mm for the rubber feet was

drilled.

When drilling was completed it was time for inserting the components carefully.

PIC18F1320, LEDs and Diodes package has polarity. That is why they were inserted

according to their accurate direction. Because once the component is inserted and soldered

it is quite hard to pull that off. Proper soldering plays a vital role for the circuit to work

because if the soldering was not good enough there might be possibilities of miss

connections, short circuits and IC damage. Hand-soldering method was used for this

project. It involved applying heat and solder to the junction between a component lead and

its pad until the solder melts, forming the solder joint on the solder side of the PCB []. All

the small components like resistor, capacitor, diodes etc. were soldered first. Then the rest

of them were soldered.

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Figure 5.9: A PCB after drilling and soldering components

Here is the image of the completed three PCBs.

Figure 5.10: Three constructed PCBs.

ICD

Connector

DIP switch

Reset Switch

PIC18F1320 base

MM232R

ER400TRS

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After the construction of the three PCBs, then they were tested is there any short circuit or

not by using continuity option of multimeter. Then the power test was done to check

whether the PIC is getting the expected power (5 V) or not at the pin 14 of PIC18F1320.

Figure 5.11: PIC was getting 5.15 V

5.1.5 Identifying Node Distance

Before programming the PIC it was important to determine how close the nodes need to

be. Two existing PCBs were provided by the supervisor which has ER400TRS and

MM232R. Image of them has given on Appendix 10. They were used to obtain a graph of

signal strength against distance. Pin no. 3 of ER400TRS was for RSSI (Received Signal

Strength Indicator) and it provided an analogue output voltage. It ranges from 0 V to 1.2

V. The distance ranges from 1 M to 20 M. After this experiment it was decided to keep the

nodes around 10 to 15 M apart from each other. On the following page the final graph

along with the tables has given.

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Figure 5.12: Signal Strength against Distance graph with the table.

Another parameter for the construction of the PCB was the Antenna. Radio required an

antenna. According to the datasheet the length of the antenna would be 16.4 cms for the

frequency of 434MHz. A simple piece of wire was used as an antenna for each node.

5.2 Software Implementation

MPLAB was used as an Integrated Development Environment. CCS C was used as a

compiler. It was a third party language tool in MPLAB IDE. The whole software

implementation was divided into four test plans for the sequential towards the final code.

Test Plan 1: Input/output testing including LEDs and Switches.

Test Plan 2: MM232R test (Very important step prior checking the ER400TRS)

Test Plan 3: ER400TRS test (Transmit and Receive)

Test Plan 4: Final code to communicate among three nodes

At the beginning a header file named “EasyRadio.h” was created for initializing the PIC

for peripheral configuration. They are the settings that configure the PIC for the external

environment like Oscillator Type, MCLR pin usage, Code Protection, Brown-Out and

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Watchdog Timer usage, Low Voltage Programming etc. This header file was used for all

the programs by include it at the beginning. In this file the on board UART IO, LEDs IO,

DIP Switch IO were also defined. The full code with explanation has given on Appendix 1.

5.2.1 Test Plan 1

This test plan for input/output testing was divided into two parts. Firstly, LEDs were tested

then the Switches.

Expected outcome for the LEDs test was each LED will toggle sequentially after 500ms

delay. Here is the flowchart for it.

Figure 5.13: LED test flow diagram.

Here is the screendump of CCS C compiler while writing the code.

Figure 5.14: Screendump for the LED testing code (ER_LED.C)

The full program listing has given on Appendix 2.

START MCU

initialization Toggle

LED1

500ms delay

Toggle

LED3 500ms delay

Toggle

LED2 5000ms delay

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After this switches were tested. The mechanism for this program was firstly to identify

whether the Switch 4 (master switch) was on or not if it is on then Switch 1 will turn on

LED 1, Switch 2 will LED 2 and Switch 3 will LED 3 on. The full program listing with

description of this test has given on Appendix 3.

Start

MCU Initialization

Switch Test

If master switch/

switch4 ON?

LED1 Off

LED2 Off

LED3 Off

No

If switch1 On? LED1 Off

LED1 On


LED2 On


LED3 On

Yes

Yes

Yes

Yes

No

No

No

Figure 5.15: Flow chart for testing switches

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5.2.2 Test Plan 2

HyperTerminal and Docklight (V 1.9) are two testing, analysis and simulation tool for

serial communication. They were used for this project to monitor the communications.

Both of them quite same but the only difference was only the Docklight have the facility to

toggle the RTS pin. This phase of testing was for testing the MM232R was working or not.

MM232R was a bridge or communication link between the PC and PCB. So, it was very

important to check prior to the ER400TRS testing and final code. Two codes were written

and compiled for MM232R testing. First code transmitted the data string “Test String”

using TX pin of the MM232R in an infinite loop (Appendix 4). Here is the flow chart for

the program.

Figure 5.16: MM232R Data Send Test Flow Chart.

Here is the screendump of CCS C compiler while writing the ER_MM232R_TX.C code.

START MCU

initialization Send “Test

String” out to

RS232

500ms delay

Figure 5.17: Screendump for the MM232R Transmit testing

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The mechanism of the second code was that the main function waits for CTS (Clear To

Send) pin of MM232R to get high and then receives a string command on MM232R-

UART defined RX. If the received command is one of the predefined one it acknowledges

with “Command –n Received” otherwise it send “Undefined Command”. The full C

program along with the description has given in Appendix 5.Here is the flow chart of it.

Figure 5.18: MM232R test flow chart

START MCU Initialization

Wait and input

receive string

through RS232 i.e.

MM232R RX

If received string is

command string-1 i.e.

“$CMD1”

Send in-valid command

received acknowledge

through RS232 i.e.

MM232R TX

Send valid command

received acknowledge

through RS232 i.e.

MM232R TX



“$CMD2”



“$CMD3”

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5.2.3 Test Plan 3

ER400TRS was tested in this test plan. It required two of the PCBs connected with three

different computers. It was impossible to stay at three places at the same time to test. So,

the author took help from his colleagues to check the check the response from the other

two nodes. Mobile phone was used as a communication media between them.

The mechanisms used for this test depend on different combination of SWITCH1 and

SWITCH2. Combination would be different on both the end. Like if switch 1 and switch 2

are both on in Node A then it would assign “01” as modem id and this will display on the

Node B the id along with “#modemidHello*”. Again if switch 1 and switch 2 both are off

then modem id would be “04” and it would be displayed on other node. This flow chart

and the code with description for each line is given on the Appendix 6.

5.2.4 Test Plan 4 (Final Code)

Following are the details of how the final code was implemented and how it was supposed

to work i.e. expected results and actual results.

This code described three simple node designed to act as part of an experimental mesh

network in which every node has exactly same hardware and firmware. The goal of this

code to work in a manner where a message sent through a node to another can be received

and acknowledged. To achieve this, a simple routing scheme was implemented in the

firmware.

There were three nodes A, B and C. Every node is connected to PC‟s USB port using serial

to USB converter to send and receive serial data from PC using serial terminal software

like HyperTerminal of windows. Following command structure has been used to construct

a command.

[Message Type][Sender Id][Receiver Id][Message length][Message]

Example: 10310Hello

Here [Message Type] is 1

[Sender Id] is 0 (0 for PC)

[Receiver Id] is 3

[Message length] is 10 which was total length of the packet

[Message] is Hello

All data are in ASCII format which can be sent by typing on serial terminal.

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On the reception of this Command message from PC,

1- Node parses the data and verifies if the data message length and receive data length

are same. If not then send a message to PC that data length is invalid.

2- Check if the receiver id is in valid range. If the Id is the receiver is same as node id,

then a message is sent back to PC that node cannot send message to itself. Or if the

receiver id exceeds the valid range of nodes, a message is sent to PC that the

receiver id is invalid.

3- If data length and receiver id are valid, a packet containing the following format

was transmitted through RF module ER400TRS.

$[Sequence No][Message Type][Sender Id][Receiver Id][Message

length][Message]*

Example: #00111315Hello*

Here # sign is start of packet

[Sequence No] is 001 which is three digit auto incremented numbers on each new

message sent.

[Message Type] is 1

[Sender Id] is 1 node id (1-4 valid range) 1 = A, 2 = B and 3 = C here

[Receiver Id] is 3 (1-4 valid range)

[Message length] is 15 which is total length of the packet including # and *

[Message] is Hello

* Sign is end of packet.

On reception of this data message wirelessly through ER400TRS, it is parsed and

1 - Its length is verified i.e. data length and actual length is same, if not message is

discarded and no response message is sent in this case.

2 – If the receiver Id „2‟ and node id „2‟ is same a response message with the same format

as received message is sent to the sender „1‟ by changing the receiver and sender

information with same sequence number. This message identified as valid response from

receiver for the message sent earlier through the same sequence number which is notified

to the used by sending message usefully sent message to pc.

2 – If the receiver Id „3‟ and node id „2‟ is not the same and it is in valid range then the

message is transmitted as it is again. The idea is to send this message again with same

sender „1‟ and receiver id „3‟ is that if the receiver node „3‟ was not in the range of

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first node „1‟ and if the second node „2‟ is within range of both , the node 2 can

forward the message of „1‟ to „3‟ with same sequence number. The acknowledge

response from „3‟ is routed back to „1‟ following same path i.e. 3-2-1 with the same

sequence number generated at 1 on transmission.

The final code with proper description on each line has given on Appendix 7. As design

method two flow charts were created before programming. One was for command message

date reception and the other one was for data message reception as follows.

Figure 5.19: Command Message Data Reception flowchart

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Figure 5.20: Data Message Reception Flow chart.

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The following image shows where the three nodes were kept at Medway campus during

the code testing. The distance between Node A and B was approximate 20 m and between

B and C was approximate 25 m.

Figure 5.21: Placement of nodes obtained from Google Earth.

5.2.5 Settings for Communication Test

For the test plan 2, 3 and 4 it was required to configure the PORT settings for the

communication test for both the HyperTerminal and Docklight software, where Docklight

was a testing, analysis and simulation tool for serial communication protocols. The

following diagram shows how the port settings were done.

Figure 5.22: Configuration for the PORT settings.

Hyp

erTerm

inal D

ock

ligh

t

Node A

Node B

Node C

39 | P a g e

CHAPTER 6

Results

6.1 Test Plan 1 Results

Here is the screendump when the program for the LED test was downloaded into the

PIC18F1320 by using MPLAB IDE and ICD3.

Figure 6.1: LED glow program downloaded.

The following image shows when the LEDs were glowing sequentially with an interval of

500ms.

Figure 6.2: Glowing LEDs when programming was done.

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The following screendump shows when the program for the Switch test was downloaded

into the PIC18F1320 where four of the DIP switches worked as an output.

Figure 6.3: Switch_try program downloaded.

The following image shows all the LEDs glowed when Master Switch (Swicth 4) was off

after the program was burnt into the PIC. More images are on Appendix 10.

Figure 6.4: Working PCB (Node A) after the program.

Master Switch

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As mentioned on the previous chapter this test was basically for testing the MM232R

connection with the PC. It required both the HyperTerminal and Docklight to get the

results. The following screendump were taken when the program to test MM232R

transmission was burnt into the PIC.

Figure 6.5: MM232R_TX was downloaded.

The following screendump shows when “Test String” was appearing with a delay of 500

ms on the Hyperterminal window.

Figure 6.6: HyperTerminal window.

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The following screendump shows when the program to test the MM232R reception was

successfully programmed using MPLAB IDE.

Figure 6.7: MM232R_Test was downloaded.

As mentioned on the previous chapter to get the results in this case a HyperTerminal like

software Docklight was used because for this program to test it was required to toggle the

RTS pin before sending the command. Docklight has the facility to toggle the RTS pin.

Following is the screendump when the expected outcome obtained from the software.

Figure 6.8: Docklight window.

RTS pin Response when wrong

command was typed

Response when pre-defined

command was typed

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This test was for the ER400TRS. It required two PCBs (Node A and Node B)

simultaneously connected together with two individual PCs. The following screendump of

MPLAB IDE were captured when the programming was completed.

Figure 6.9: Downloaded ER400TRS_Test into the Microcontroller.

According to the program as described on previous chapter when SWITCH 1 and 2 will be

on it will display “#01 Hello*” on the other PCB and when SWITCH 1 and 2 will be off it

display “#04 Hello*”. Two PCBs Node A and Node B were used for this. On Node A

Switch 1 and 2 were off and on node B both of them were on. The following screendumps

shows the results from both the node.

Figure 6.10: Output from Node A.

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Figure 6.11: Output from Node B.

6.4 Test Plan 4 (Final Code) Results

The implementation for this final code has given on the previous chapter. This testing

required three of the PCBs (Nodes) to be connected with three different PCs at different

places but within the range. When the program was successfully build it was programmed

into three PCBs. The following screendump shows when the programming was done for

one PCB or node.

Figure 6.12: Downloaded EasyRadio.c into the PIC18F1320.

45 | P a g e

Individual pin configuration of DIP switches for individual PCB was assigned. Like on

Node A switch 1 and 2 was on, Node B switch 1 on and switch 2 off, Node C switch 1 and

2 was off. This fulfilled the requirement of digital input. For that reason the following

modemid was assigned for different pin configuration.

Node Modemid

A 04

B 02

C 01

Port bit configurations were as described on previous chapter. To test the bi-directional

communication Hyperterminal was used. To test the mechanism of the code some

conditions for input on the Hyperterminal window was decided. Here are the conditions.

Condition 1: „10210hello‟ from Node A

Condition 2: „10410samit‟ from Node B

Condition 3: „10410hello‟ from Node A [To test if the message is able to transfer in his

own node]

Condition 4: „10110samit‟ from Node A

Condition 5: „10210medway‟ from Node A [To test when an invalid length was typed]

Condition 6: „10110hello‟ from Node B

Condition 7: „10114howareyou‟ from Node A

Condition 8: „10112iamfine‟ from Node B

The following screendumps shows the responses from each node for each condition.

Response after condition 1








Figure 6.13: Node A screendump.

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Figure 6.14: Node B screendump

Figure 6.15: Node C screendump









Response after condition 7 Response after condition 8

Response after condition 4 Response after condition 6

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6.4 Testing Schedule

The following table of testing schedule summarises all the results.

Test

No.

Purpose Expected Outcome Pass or

Fail

1 To ensure that the voltage on pin

14 of PIC18F1320 socket is at 5 V

Voltmeter will show exactly the

same value of supplied voltage on

those pin

Pass

2 To ensure all the outputs (LED) are

working [Test Plan 1]

LEDs will glow sequentially

according to the program

Pass

3 To ensure the reset switch is

working

LEDs will start to glow from the

beginning of sequence

Pass

4 To ensure all the inputs (SWITCH)

are working [Test Plan 1]

Each switch will glow pre-

assigned LED according to the

program

Pass

5 To ensure the MM232R

transmission is working

After the programming “Test

String” will be displayed on the

HyperTerminal window

Pass

6 To ensure the MM232R reception

is working

When the pre-defined command

will be received it will return user

defined command using Docklight

Pass

7 To ensure ER400TRS is working

for each PCB or Node

Each PCB will display its unique

modemid along with

“#modemidHello*

Pass

8 To ensure bi-directional

communication between three PCB

with mesh interconnection

capability

Each node will be able to receive,

transmit and forward the packet of

messages according to the inputs.

Pass

Table 6.1: Testing Schedule with results.

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CHAPTER 7

Discussion

7.1 Discussion of Results

The objective of this project in start was to develop a node/modem that can be a part of a

mesh network to communicate with other modems in network through wireless module

ER400TRS. At the beginning the schematic capture for the required circuit did not take

time. Simulation was not possible with that schematic capture. But the design of PCB

layout took some time although the constructed PCB was working as expected. During the

PCB layout design as it was aimed to produce a single sided board to reduce the cost of

printing and also according to the datasheet of the ER400TRS single sided PCB was

preferred. And it was quite difficult to make all the connections using bottom copper to

make handy and small PCB. There were few connections left which was indicated by

using top silk from J1 to J6. After completion of drilling and soldering of the components

it was then connected using a black manual wire on three of the PCBs. Another one issue

to be discussed is the oscillator for the PIC. Internal oscillator was used for this project

because it was much simpler and easier and also sometimes difficult to get the external

oscillator to work even though internal oscillator was slightly less stable.

Test plan 1, 2 and 3 were successfully tested and accomplished. Three of them have given

the expected and accurate results. In the final code (Test Plan 4) of this project the modem

detection was not dynamic and it was fixed at the moment. DIP switches were used to

assign the dedicated modem id through hardware which should be dynamically assigned

during initialization of node. Also there should be adhoc based dynamic routing

mechanism implemented with RF power monitoring to know the corresponding modems

in range. So that every node may aware of their possible in range neighbour node and can

add it into its route. That means the DIP switch worked as a digital input and LEDs were

as an output. In the final code LED 1 was glowing to indicate the supply voltage on the

PCB, LED 2 was for transmitting and LED 3 for receiving. But only LED 1 and 2 were

glowing [Appendix 10]. The mechanism used for LED 2 and 3 was not working as

expected. One of the issues encountered that RF level/power was not being monitored first

problem was to know which modem was in the range and which was not. Also expected

results are not same as actual results and data was lost some times.

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Packet based messages were transferred in between the nodes. The only difference was the

Node C. This Node could not transmit any packet based messages it could only receive

and forward messages from other nodes. It might happen due to the RF conflict. At the

moment hit and trial based method was used to know the range and different improvement

in code and algorithm implemented to improve the routing mechanism to get the actual

results.

More testing and modification could make the condition better than present to found out

more possible errors, modification of physical structure, hardware and programmes.

7.2 Discussion of Gantt chart

Gantt chart was used to maintain a time schedule for completing an engineering project

like this within a fixed time range. This project consisted of four phases. They are

literature review, design, development and testing. First phase of literature has completed

on time. Design phase could not be completed on time that is why it was modified after the

initial version. This phase took longer time than it was planned and expected so this task

was not achieved on time. Schematic has also gone through couple of changes. Some

parallel tasks were required like while determining the signal strength designing and

implementing was also done at the same time. Three test plans along with the final code

were added this time in phase 4 of the Gantt chart. The updated and final version of the

Project Gantt chart, showing progress to date, is on the Appendix 9.

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CHAPTER 8

Conclusion

Wireless communication has been the best choice among all the other „over-the-air‟

technologies like Infrared, Bluetooth, DECT and so on. Wireless transmission of

„information‟, which can be digital data or file. This project focused on the current issue of

wireless communication within the short range. This short range wireless technology has

huge future market potential for entertainment, logistics, healthcare and automotive.

Presented experimental wireless hub has been successfully deployed as hardware and

software design using Easy-Radio Transceiver and PIC18F1320. This paper presents

details on the implementation of the whole system, coding techniques for all the test and

routing technique for the final code. The findings of this project were gained through a

background research and literature survey with related and vital references for

understanding current conditions, investigating the minimum requirements to analyse any

given problem for making to do list, explored some sample projects which has helped to

identify the possible solutions for the practical work for an outcome in uneven

circumstances. Subject to the limitation of equipment cost three PCBs or Nodes were made

with the similar configuration of systems. These were successfully designed and

implemented around the fixed laboratory period. To achieve the main purpose of this

project some objectives were set like testing core components of the system. For that

reason, three codes in C were written using CCS C and compiled using MBLAB IDE to

test the inputs/outputs, MM232R and ER400TRS. These also provided expected results.

These tests were very important prior to the final code because it required a serial terminal

from PC to the PCB or node to send messages to the node, MM232R served that purpose

and ER400TRS served as transceiver to wirelessly communicate. First two deliverables of

this project were achieved. Third deliverable was to implement bi-directional

communication between more two hubs or nodes were nearly accomplished. Experimental

results proved limited usability of the system although regular data transmission between

nodes has been shown. The learning outcomes from this project are microcontroller

programming for interfacing MM232R interfacing to communicate with PC over interface

USB, interfacing wireless module ER400TRS, PCB design and development, RF

communication essentials and basic routing techniques for Mesh networking.

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CHAPTER 9

Future Work

The future work comes into play in order to improve the present project. The aim of this

project was to build a wireless hub using Easy-Radio module, MM232R and PIC18F1320

that is capable of communicating wirelessly. Even though the project more or less had

achieved the goals, there are a large number of works need to be done and improved.

Such as currently on this project receiving characters for each node are displayed on the

HyperTerminal window. Currently, microcontroller devices are using LCD displays to

output visual information. Such a display can be implemented on the already constructed

PCB of this project. It will display the standard ASCII set of characters which will be

transmit or receive using their respective node. One of the other important improvements

that could be made on this project is to make it portable. Like instead of Thru-hole

components if SMT (Surface Mount Technology) components were used it will make the

PCB smaller in size and handy too. And also on this PCB instead of MM232R a female

USB connector can be implemented which will directly connect to the PC even though it

requires much more intelligence.

Currently a simple piece of wire was used as an antenna for each PCB or node. It can be

improved if Helical or Whip antennas and connectors were used instead of that. But due to

the limitation of costing it was not used. Such an antenna instead of a simple wire will

make the node more efficient. The distance between the nodes in this project was

approximate 20m which was not satisfactory. Implementing those antennas into the PCB

might improve the distance.

HyperTerminal was used to send the characters from one node to another with an

acknowledgement reply. In the future instead of sending characters File Transfer Protocols

like XModem could be used. XModem divides the data into a series of packets that are

sent to the receiver. In addition user interface can be implemented on this project. It will

allow users to interact with the nodes with images rather than text commands as now. GUI

(Graphic User Interface) can be created using Matlab or Text Interface using Microsoft

C/C++ or Visual C or Visual Basic.

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REFERENCES

1. Goldsmith Andrea (2005), „Wireless Communications‟, Publisher: Cambridge

University Press, ISBN 0-521-83716-2

2. Iovine John (2004), „PIC Microcontroller Project Book‟, Second Edition, Publisher:

McGraw-Hill, ISBN 0-07-143704-5

3. Nick Hunn (2010), „Essentials of Short-range wireless‟, Publisher: Cambridge

University Press, ISBN 978-0-521-76069-0

4. Easy-Radio ER400TRS Transceiver (2003), LPRS Data Sheet, Available at:

http://www.robot-electronics.co.uk/datasheets/Easy-Radio%20ER400TRS%201-2.pdf,

[Date accessed: 12/04/2011]

5. MM232R USB-Serial UART development module datasheet version 1.1 (2010),

Available at:

http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_MM232R.pdf

[Date accessed: 11/04/2011]

6. D. Langwald, P. Groppe and B. vom Berg (2003), „Wireless RS232 link Using license-

exempt Short Range Devices (SRDs)‟, Elektor Electronics

7. A. Sikora (2004), „Design challenges for short-range wireless networks‟, IEE

Proceedings-Communications, Vol. 151, No. 5. ISSN-20040742.

8. O. Mirabella, Lo Bello, A. Raucea (2007), „Improving routing in long-distance wireless

mesh networks via a distributed embedded router‟, Journal of Parallel and Distributed

Computing, ISSN-0743-7315

9. Barnes, Stuart J. (2002), „Under the skin: short-range embedded wireless technology‟,

International Journal of Information Management 22(2002) 165-179, ISSN-0268-

4012/02.

10. Ian F. Akyildiz, Xudong Wang, Weilin Wang (2005), „Wireless mesh networks: a

survey‟, Computer Networks 47 (2005) 445–487, ISSN-1389-1286.

11. A.H.G. Al-Dhaher (2001), „Integrating hardware and software for the development

of microcontroller bases systems‟, Microprocessors and Microsystems 25(2001) 317-

328, ISSN-0141-9331/01.

12. James M. Conrad, Ivan Howitt (2006), „Introducing Student to Communications

Concepts Using Optical and Low-Power Wireless Devices‟, Turk J Elec Engin,

VOL.14, NO.1, ISSN-1401-2006.

13. David C. Chou, David C. Yen (2001), „Wireless communication: the next wave of

Internet Technology‟, Technology in Society 23(2001) 217-226, ISSN- 0160-791X/01.

http://www.robot-electronics.co.uk/datasheets/Easy-Radio%20ER400TRS%201-2.pdf

http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_MM232R.pdf

53 | P a g e

14. Marshall Brain, Tracy V. Wilson, „How WiFi works?‟, Available at:

http://computer.howstuffworks.com/wireless-network1.htm [Date accessed 24th

April‟2011]

15. Electronic Projects (2010), Available at: http://www.electronic-

engineering.ch/microchip/ [Date accessed: 26th

April‟2011]

16. What‟s a microcontroller? Student Guide, Version 2.2, PARALLEX, ISBN 1-

928982-02-6,p1-5

17. K. Fazel, P. Robertson, O. Klank, F. Vanselow (1998). ‟ Concept of a wireless

indoor video communications system‟, Signal Processing: Image Communication 12

(1998) 193-208, ISSN- 0923-5965/98.

18. S. Salmons, G.T. Gunning, I. Taylor, S.R.W. Grainger, D.J. Hitchings, J.

Blackhurst, J.C. Jarvis (2001),‟ASIC or PIC? Implantable stimulators based on semi-

custom CMOS technology or low-power microcontroller architecture‟, Medical

Engineering & Physics 23 (2001) 37–43, ISSN- 1350-4533/01.

19. Behzad Razavi (1997),‟Recent Advances in RF Integrated Circuits‟, IEEE

Communications Magazine, ISSN- 0163-6804/97.

20. Barry B. Brey (2008),‟Applying PIC18 Microcontrollers‟, Publisher: Pearson

Prentice Hall, ISBN- 0-13-088546-0

21. Olin Lathrop, Embed Inc. (2009),‟ In-circuit Serial Programming

(ICSP)‟,Available at: http://www.embedinc.com/picprg/icsp.htm [Date accessed: 20th

June‟2011]

22. Remigiusz Olejnik (2010), „An Experimental Wireless Mesh Network Node Based

on AVR ATmega 16 Microcontroller and RFM12B Radio Module‟, Computer

Network: 17th Conference, ISSN-7796-105.

23. J.P. Carmo, J.H. Correia (2009), „Low-power/low-voltage RF microsystems for

wireless sensors networks‟, Microelectronics journal 40(2009), ISSN-0026-2692.

24. Mikko Sallinen, Esko Strömmer and Pirkka Tukeva (2009), „Short-Range

Communication in Ubiquitous Professional and Consumer Applications‟, Available at:

http://ercim-news.ercim.eu/en76/special/short-range-communication-in-ubiquitous-

professional-and-consumer-applications [Date accessed: 1st October‟2011]

25. Srividya Iyer, „RSSI - Receive Signal Strength Indicator‟, Available at:

http://www.birds-eye.net/definition/r/rssi-receive_signal_strength_indicator.shtml [Date

accessed: 15th

October‟2011]

26. National Instruments (2004), „Serial Port Communication‟, Available at:

http://cnx.org/content/m12293/latest/ [Date accessed: 24th

August‟2011]

http://computer.howstuffworks.com/wireless-network1.htm

http://www.electronic-engineering.ch/microchip/

http://www.electronic-engineering.ch/microchip/

http://www.embedinc.com/picprg/icsp.htm

http://ercim-news.ercim.eu/en76/special/short-range-communication-in-ubiquitous-professional-and-consumer-applications

http://ercim-news.ercim.eu/en76/special/short-range-communication-in-ubiquitous-professional-and-consumer-applications

http://www.birds-eye.net/definition/r/rssi-receive_signal_strength_indicator.shtml

http://cnx.org/content/m12293/latest/

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27. David G. Wright, Timothy J. Williams, Jefferey D. Wick (2005), „Method of

Programming USB Microcontrollers‟, United States Patent.

28. Raja Banerjea (2007), „Short-range Wireless Communication‟, United States Patent

Application Publication.

29. Jan Axelson (1993), ‟Making Printed Circuit Boards‟, Publisher: Janet Loise

Axelson, ISBN: 0-8306-3950-0

30. Harry J. R. Dutton (1998), „Understanding Optical Communications‟, International

Technical Support Organization.

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BIBLIOGRAPHY

1. Muhammad Ali Mazidi, Rolin D. McKinlay, Danny Causey (2008),‟PIC

Microcontroller and Embedded Systems‟, Publisher: Pearson International Edition,

ISBN-0-13-600902-6.

2. Ibrahim, Dogan (2008),‟ Advanced PIC Microcontroller Projects in C: From USB

to RTOS with the PIC 18F Series‟, Publisher: Elsevier Science & Technology,

ISBN- 9780750686112.

3. Details of pic ICSP and how to use it for pic microcontrollers, Available at:

http://www.best-microcontroller-projects.com/pic-icsp.html [Dates accessed: 22nd

September‟2011]

4. RF and Communications Fundamentals, Available at:

http://zone.ni.com/devzone/cda/tut/p/id/3992#toc0. [Date accessed: 25th

September‟2011]

http://www.best-microcontroller-projects.com/pic-icsp.html

http://zone.ni.com/devzone/cda/tut/p/id/3992#toc0

56 | P a g e

APPENDIX 1

Header file code

//****************************************************************

// Module EasyRadio.h by Samit

// Description: This module provides the peripherial configuration

for the used microcontroller in Easy Radio PCB module.

//****************************************************************

//****************************************************************

// Includes

//****************************************************************

*

#include <18F1320.h> // Microcontroller used

//****************************************************************

*

// Configuration of fues settings

//****************************************************************

*

#device ICD=TRUE // ICD enabled

#device adc=10 // 10-bit ADC setting

#FUSES NOWDT // No Watch Dog Timer

#FUSES WDT128 // Watch Dog Timer uses 1:128

Postscale

#FUSES INTRC_IO // Internal RC Osc, no CLKOUT

#FUSES NOFCMEN // Fail-safe clock monitor

disabled

#FUSES NOBROWNOUT // No brownout reset

#FUSES PUT // Power Up Timer

#FUSES NOCPD // No EE protection

#FUSES NOSTVREN // Stack full/underflow will not

cause reset

#FUSES DEBUG // Debug mode for use with ICD

#FUSES NOLVP // No low voltage prgming,

B3(PIC16) or B5(PIC18) used for I/O

#FUSES NOWRT // Program memory not write

protected

#FUSES NOWRTD // Data EEPROM not write

protected

#FUSES NOWRTC // Configuration not registers

write protected

#FUSES IESO // Internal External Switch Over

mode enabled

#FUSES NOEBTR // Memory not protected from

table reads

#FUSES NOEBTRB // Boot block not protected from

table reads

#FUSES MCLR // Master Clear pin enabled

#FUSES NOPROTECT // Code not protected from

reading

#FUSES NOCPB // No Boot Block code protection

#FUSES NOWRTB // Boot block not write protected

#use delay(clock=4000000) // (Dont Care)Internal RC

Oscilator used

// On board UART IO definations

#use rs232(baud=9600, xmit=PIN_B6,rcv=PIN_B7, STREAM = MM232R )

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#use rs232(baud=19200,xmit=PIN_B1,rcv=PIN_B4,UART1,STREAM =

ER400)

// On board LEDs IO definations

#define LED1 PIN_A2 // First LED for supply voltage

#define LED2 PIN_A1 // Second LED for data transmit

#define LED3 PIN_A0 // Third LED for data receive

// On board Dip switch IO definations

#define SWITCH1 PIN_A6 // General purpose switch 1 input

#define SWITCH2 PIN_A7 // General purpose switch 2 input

#define SWITCH3 PIN_B2 // General purpose switch 3 input

#define SWITCH4 PIN_B3 // General purpose switch 4 input

// On board MM232R IO definations

#define CTS_MM232R PIN_B0

//****************************************************************

*

// End of file

//****************************************************************

*

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APPENDIX 2

Test Plan 1: LED testing code

//****************************************************************

*

// Module ER_LED.c by Samit

// Description: This module provides the functionalities to test

// the LEDs on Easy Radio PCB

//****************************************************************

*

// Includes

//****************************************************************

*

#include "EasyRadio.h"

//****************************************************************

*

// Pragmas and Constant Defines

//****************************************************************

*

#define LED_STATE_DELAY 500 // Half second delay selected for

inter LED state

//****************************************************************

*

// Local Function Prototypes

//****************************************************************

*

void LEDTest(void);

//****************************************************************

*

// main(void)

// Main function defines the microcontroller's inbuilt peripherial

// settings and then enters into infinite loop of LED test routine

//****************************************************************

*

void main()

{

setup_adc_ports(sAN0|VSS_VDD);

setup_adc(ADC_CLOCK_DIV_64|ADC_TAD_MUL_20);

setup_wdt(WDT_OFF);

setup_timer_0(RTCC_INTERNAL);

setup_timer_1(T1_DISABLED);

setup_timer_2(T2_DISABLED,0,1);

setup_timer_3(T3_DISABLED|T3_DIV_BY_1);

disable_interrupts(INT_RDA);

disable_interrupts(GLOBAL);

LEDTest();

}

//****************************************************************

*

// LEDTest(void)

// This function toggles the LEDs one by one in an infinite loop

with a pre-defined LED_STATE_DELAY delay

//****************************************************************

*

void LEDTest(void)

59 | P a g e

{

while(1)

{

output_toggle(LED1);

delay_ms(LED_STATE_DELAY);





}

}

//****************************************************************

*

// End of file

//****************************************************************

*

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APPENDIX 3

Test Plan 1: SWITCH testing code

//****************************************************************

*

// Module ER_SWITCH.c by Samit


the Switches on Easy Radio PCB

//****************************************************************

*

//****************************************************************

*

// Includes

//****************************************************************

*


//****************************************************************

*


//****************************************************************

*

#define MASTER_SWITCH SWITCH4 // This switch enables or disable

all switches

#define LED_STATE_DELAY 500 // Half second delay selected for

inter LED state

//****************************************************************

*


//****************************************************************

*

void SwitchTest(void);

//****************************************************************

*

// main(void)

// Main function defines the microcontroller's inbuilt peripherial

// settings and then enters into infinite loop of Swtich test

routine

//****************************************************************

*

void main()

{



setup_wdt(WDT_OFF);







SwitchTest();

}

//****************************************************************

*

// SwtichTest(void)

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// This function first check the master switch,if it is on then it

checks other switches and on/off LEDs accordingly

//****************************************************************

*

void SwitchTest(void)

{

while(1)

{

if(input(MASTER_SWITCH)) // If master switch is on,

check other switches

{

// Check if switch 1 is on, put LED1 on

if(input(SWITCH1))

{

output_high(LED1);

}

else

{

output_low(LED1);

}


if(input(SWITCH2))

{

output_high(LED2);

}

else

{

output_low(LED2);

}


if(input(SWITCH3))

{

output_high(LED3);

}

else

{

output_low(LED3);

}

}

else

{

// If master switch is off, Off all LEDs

output_low(LED1);

output_low(LED2);

output_low(LED3);

}

}

}

//****************************************************************

*

// End of file

//****************************************************************

*

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APPENDIX 4

Test Plan 2: MM232R Transmission test code

//***************************************************************** // Module MM232R.c by Samit // Description: This module provides the functionalities to test the MM232R data transmission from PIC //***************************************************************** //***************************************************************** // Includes //***************************************************************** #include "EasyRadio.h" #include "String.h" //***************************************************************** // Pragmas and Constant Defines //**************************************************************** //***************************************************************** // Local Function Prototypes //***************************************************************** void MM232R_TXTest(void); //***************************************************************** // main(void) // Main function defines the microcontroller's inbuilt peripheral settings and then enters into infinite loop of data send routine //***************************************************************** void main() { setup_adc_ports(sAN0|VSS_VDD); setup_adc(ADC_CLOCK_DIV_64|ADC_TAD_MUL_20); setup_wdt(WDT_OFF); setup_timer_0(RTCC_INTERNAL); setup_timer_1(T1_DISABLED); setup_timer_2(T2_DISABLED,0,1); setup_timer_3(T3_DISABLED|T3_DIV_BY_1); disable_interrupts(INT_RDA); disable_interrupts(GLOBAL); MM232R_TXTest(); } //***************************************************************** // MM232R_TXTest(void) // This function transmit the data string "Test String" using TX pin of MM232R in an infinite loop //***************************************************************** void MM232R_TXTest(void) { unsigned char MMsg[] = {"Test String\n\r"}; while(1) { fputs(MMsg,MM232R); delay_ms(500); // Half second delay } }

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//***************************************************************** // End of file //*****************************************************************

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APPENDIX 5

Test Plan 2: MM232R Reception test code

//****************************************************************

*

// Module MM232R.c by Samit


the MM232R communication with PIC

//****************************************************************

*

//****************************************************************

*

// Includes

//****************************************************************

*


#include "String.h"

//****************************************************************

*


//****************************************************************

*

//****************************************************************

*


//****************************************************************

*

void MM232RTest(void);

//****************************************************************

*

// main(void)

// Main function defines the microcontroller's inbuilt peripheral

settings and then enters into infinite loop of MM232R test routine

//****************************************************************

*

void main()

{

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setup_wdt(WDT_OFF);







MM232RTest();

}

//****************************************************************

*

// MM232RTest(void)

// This function waits for CTS pin of MM232R to get high and then

receives a string command received on it MM232R-UART defined RX.

// If the received command is one of the predefined one it

acknowledges with "Command - n Received" otherwise it send

"Undefined Command"

//****************************************************************

*

void MM232RTest(void)

{

unsigned char MMsg[10];

unsigned char CMD1[]={"$CMD1\r\0"};



signed int res;

while(1)

{

res = -1;

// Get string from rs232 i.e mm232r rx

fgets(MMsg,MM232R);

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// Valid command string length should be greater than 3

if(strlen(MMsg)>3)

{

// See if command1 is received by comaring two strings

res = strcmp(MMsg,CMD1);

// If command-1 string is matched

if(res == 0 )

{

// Send acknowledge back through mm232r i.e. valid

command-1 is received

fputs("COMAND - 1 Received\n\r");

}

else

{

// See if command2 is received by comaring two

strings



if(res == 0 )

{

// Send acknowledge back through mm232r i.e.

valid command-2 is received


}

else

{

// See if command2 is received by comaring two

strings



if(res == 0 )

{

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// Send acknowledge back through mm232r

i.e. valid command-3 is received


}

else

{

// Any other string recievied through mm232r is an undefined

command and its acknowledge is sent back

fputs("Undefined Command\n\r");

}

}

}

}

}

}

//****************************************************************

*

// End of file

//****************************************************************

*

68 | P a g e

APPENDIX 6

Test Plan 3: ER400TRS test code and flow chart

Start

MCU Initialization

ER400TRS Test

If Switch1 on? And

Switch2 on?

If Switch1 on? And

Switch2 off?

If Switch1 on? And

Switch2 off?

Transmit “Hello

modemId”

message thought

ER400TRS

Modem Id = 01

Modem Id = 02

Modem Id = 03

If Switch1 off? And

Switch2 off?Modem Id = 04

If any data received

through ER400TRS in 1

second

Send received data

string through

MM232R Tx

Yes

Yes

Yes

Yes

Yes

No

No

No

No

No

69 | P a g e

//****************************************************************

*

// Module ER400TRS.c by Samit


the ER400TRS data transmission.

//****************************************************************

*

//****************************************************************

*

// Includes

//****************************************************************

*


#include "String.h"

//****************************************************************

*


//****************************************************************

*

unsigned char str[30];

unsigned index = 0;

unsigned int cmdCompFlg = 0;

//****************************************************************

*


//****************************************************************

*

void MM232R_TXTest(void);

//****************************************************************

*

// RDA_isr(void)

// This function is used as interrupt service routine of UART data

// receieve(Not used in this program)

//****************************************************************

*

#int_RDA

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void RDA_isr(void)

{

unsigned char c;

c = fgetc(ER400);

if(!cmdCompFlg)

{

if(c == '#')

{

index = 0;

}

else if(c=='*' || index > 20)

{

cmdCompFlg = 1;

}

str[index++]= c;

}

}

//****************************************************************

*

// main(void)


settings and then enters into infinite loop of data send routine

//****************************************************************

*

void main()

{



setup_wdt(WDT_OFF);




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enable_interrupts(INT_RDA);

enable_interrupts(GLOBAL);

set_tris_b(0b00010000);

MM232R_TXTest();

}

//****************************************************************

*

// MM232R_TXTest(void)

// This function transmit the data string "Test String" using TX

pin of MM232R in an infinite loop

//****************************************************************

*

void MM232R_TXTest(void)

{

unsigned char MMsg[] = {"#01,Hello*\r"};

unsigned int modemId = 0;

int16 i;

while(1)

{

if(input(SWITCH1) && input(SWITCH2))

{

modemId = 01;

}

else if (input(SWITCH1) && !input(SWITCH2))

{

modemId = 02;

}

else if (!input(SWITCH1) && input(SWITCH2))

{

modemId = 03;

}

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else if (!input(SWITCH1) && !input(SWITCH2))

{

modemId = 04;

}

sprintf(MMsg,"#%02d,Hello*\r",modemId);

fputs(MMsg,ER400);

for(i=0;i<1000;i++)

{

delay_ms(1);

}

if(cmdCompFlg == 1)

{

fputs(str,MM232R);

cmdCompFlg = 0;

index = 0;

}

}

}

//****************************************************************

*

// End of file

//****************************************************************

*

73 | P a g e

APPENDIX 7

Test Plan 4: Final Code

//****************************************************************

*

// Module EasyRadio.c by Samit


the EasyRadio modem as mesh network nodes. MM232R connected to

PC’s USB port and serial terminal program used to send the command

to send and see the data communication status between the nodes.

//****************************************************************

*

//****************************************************************

*

// Includes

//****************************************************************

*


#include "String.h"

#define MAX_NUMBER_OF_NODES 4 // Number of nodes may be 0-

255, 4 used here

#define MAX_DATA_SIZE 60 // Maximum size of data packet

in bytes

#define STARTUP_DELAY 1000 // In milliseconds

#define INTER_TRANSMIT_DELAY 20 // Delay between sending two

consecutive packets

#define NODE1 1 // Node 1 id




#define COMMAND_LEN_OFST1 3 // Length byte offset in

command data packet

#define COMMAND_LEN_OFST2 4 // Length byte offset in

command data packet

#define DATA_LEN_OFST1 7 // Length byte offset in data

packet

#define DATA_LEN_OFST2 8 // Length byte offset in data

packet

74 | P a g e

#define RECV_ID_OFFSET 5 // Receiver node id data byte

position

#define SEND_ID_OFFSET 6 // Sender node id data byte

position

#define ASCII_CHAR_OFFSET 48 // Value used to covert

to/from Ascii

//****************************************************************

*


//****************************************************************

*

unsigned index = 0; // General purpose index

variables

int16 i;

unsigned int cmdCompFlg = 0; // ER400TRS data packet

receive complete flag

unsigned int modemId = 0; // Id of the modem/node

unsigned int seqN=0; // Sequence number for each

new message

unsigned char str[MAX_DATA_SIZE]; // Data byte array used to

recieve/send data through ER400TRS

unsigned char MMsg[MAX_DATA_SIZE]; // Data byte array used to

receive/send data thgouth MM232R

//****************************************************************

*


//****************************************************************

*

void MM232R_TXTest(void);

void checkRFData(void);

void CheckMM232Data(void);

void MCUInit(void);

void ReadModemId(void);

//****************************************************************

*

75 | P a g e

// RDA_isr(void)

// This function is used as interrupt service routine of UART data

// receieve(Data recieve through ER400TRS captured here)

//****************************************************************

*

#int_RDA

void RDA_isr(void)

{

unsigned char c;

c = fgetc(ER400);

if(!cmdCompFlg)

{

// Mark the start of the RF data packet

if(c == '#')

{

// Reset the packet index

index = 0;

}

else if(c=='*' || index > MAX_DATA_SIZE)

{

// Complete packet is received and ready for parsing

cmdCompFlg = 1;

}

str[index++]= c;

}

}

//****************************************************************

*

// main(void)

76 | P a g e


settings, USART Receive interrupt enables and then enters into

infinite loop of data send and receive routine

//****************************************************************

*

void main()

{

// Microcontroller intialization

MCUInit();

// Read modem id

ReadModemId();

// Enable microcontroller interrupt for USART receive

enable_interrupts(INT_RDA);

enable_interrupts(GLOBAL);

// The infinite program loop

while(1)

{

// If there is any data available from MM232R i.e. PC/User

if(kbhit(MM232R))

{

// Get string from rs232 i.e mm232r rx

fgets(MMsg,MM232R);

// If any valid command received through PC/User

CheckMM232Data();

}

// If the ER400TRS data packet received

if(cmdCompFlg == 1)

{

// Check and parse the data to send the respone

77 | P a g e

str[index]='\0';

cmdCompFlg =0;

CheckRFData();

}

}

}

//****************************************************************

*

// MCUInit(void)

// Microcontroller initialization includes setting up the ADC,

timers and clock, IO ports modes and a little start up delay

//****************************************************************

*

void MCUInit(void)

{



setup_wdt(WDT_OFF);





set_tris_b(0b00011100);

set_tris_A(0b11111000);

delay_ms(STARTUP_DELAY);

}

//****************************************************************

*

// ReadModemId(void)

// Two switches are used as modem/node ID. This function checks

those switches and store the information accordingly

//****************************************************************

*

78 | P a g e

void ReadModemId(void)

{

if(input(SWITCH1) && input(SWITCH2))

{

modemId = NODE1;

}

else if (input(SWITCH1) && !input(SWITCH2))

{

modemId = NODE2;

}

else if (!input(SWITCH1) && input(SWITCH2))

{

modemId = NODE3;

}

else if (!input(SWITCH1) && !input(SWITCH2))

{

modemId = NODE4;

}

sprintf(MMsg,"Node [%02u] found \n\r\0",modemId);

fputs(MMsg,MM232R);

}

//****************************************************************

*

// CheckMM232Data(void)

// This function is responsible to receive and parse the serial

data received through PC serial terminal in the form of command

packet. The valid format for command packet is

[MTYP][FRM][TO][LEN][DATA]. If a valid command packet is received,

this function will send the RF data packet accordingly

//****************************************************************

*

void CheckMM232Data(void)

79 | P a g e

{

// Receiver node

unsigned int rId = 0;

// Length of packet in bytes recieved

unsigned int len = 0;

unsigned char msgStr[50];

unsigned char j;

// Get the length in bytes of recieved command packet

len = (MMsg[COMMAND_LEN_OFST1]-ASCII_CHAR_OFFSET) *10 +

MMsg[COMMAND_LEN_OFST2]-ASCII_CHAR_OFFSET;

if(strlen(MMsg) == len && strlen(MMsg) <= 40) // Valid command

length

{

if(MMsg[0] == '1' ) // Message send command

{

rId = (MMsg[2]-ASCII_CHAR_OFFSET);

if(rId == modemId) // If this is node id

{

sprintf(MMsg,"Node [%02u] cannot send message to

itself\n\r\0",modemId);

fputs(MMsg,MM232R);

}

else if(rId == 0 || rId > MAX_NUMBER_OF_NODES) //

Invalid node id

{

sprintf(MMsg,"Node [%02u] is invalid \n\r\0",rId);

fputs(MMsg,MM232R);

}

else // Send messange

{

MMsg[1] = modemId+ASCII_CHAR_OFFSET;

MMsg[len] = '*';

MMsg[len+1] = '\0';

80 | P a g e

len+=5;

MMsg[COMMAND_LEN_OFST1] =

(len/10)+ASCII_CHAR_OFFSET;;

MMsg[COMMAND_LEN_OFST2] =

(len%10)+ASCII_CHAR_OFFSET;

fprintf(ER400,"#%03u\0",seqN);

fprintf(ER400,"%s\0",MMsg);

delay_ms(INTER_TRANSMIT_DELAY);

j = 0;

for(i=COMMAND_LEN_OFST2+1;i<(len-5);i++)

{

msgStr[j] = MMsg[i];

j++;

}

fprintf(MM232R,"#%03u:",seqN);

fputs(msgStr);

fprintf(MM232R,"Node [%02u] sending message to

[%02u] \n\r\0",modemId,rId);

seqN++;

}

}

}

else // Invalid data length

{

sprintf(MMsg,"Invalid data length: Node[%02u]

\n\r\0",modemId);

fputs(MMsg,MM232R);

}

}

//****************************************************************

*

// CheckRFData(void)

// This function is responsible to receive and parse the serial

data received through ER400TRS module wirelessly. The data

81 | P a g e

received is in the form of a packet whih has the similar format of

the command packet except. The starting and ending packet marker

characters # and *. If a valid format data packet received, this

function will send the RF data packet accordingly.

//****************************************************************

*

void CheckRFData()

{

unsigned int rId = 0;

unsigned int fid = 0;

unsigned int len = (str[DATA_LEN_OFST1]-ASCII_CHAR_OFFSET)*10

+ (str[DATA_LEN_OFST2]-ASCII_CHAR_OFFSET);

unsigned int sNo = (str[1]-ASCII_CHAR_OFFSET)*100+((str[2]-

ASCII_CHAR_OFFSET)*10)+str[3]-ASCII_CHAR_OFFSET;

// Reciver ans sender node id

fId = (str[5]-ASCII_CHAR_OFFSET);

rId = (str[6]-ASCII_CHAR_OFFSET);

// Check for valid lenght

if(strlen(str) == len && strlen(str) <= 50) // Valid command

length

{

if( str[4] == '1' ) // Message send command

{

if(rId != fId)

{

if(rId == modemId) // Send Acknowledge

{

if(sNo == (seqN-1))

{

sprintf(MMsg,"[%02u] Message[%03u]

successfully delivered to node[%02u] \n\r\0",modemId,sno,fId);

fputs(MMsg,MM232R);

}

else

{

82 | P a g e

strcpy(mmsg,str);

MMsg[RECV_ID_OFFSET] =

rId+ASCII_CHAR_OFFSET;

MMsg[SEND_ID_OFFSET] =

fId+ASCII_CHAR_OFFSET;



fprintf(MM232R,"Node [%02u] replying

message[%03u] to [%02u] \n\r\0",modemId,sNo,fId);

}

}

else // Forward message

{

if(sNo != (seqN-1))

{

strcpy(mmsg,str);

MMsg[RECV_ID_OFFSET] =

fId+ASCII_CHAR_OFFSET;

MMsg[SEND_ID_OFFSET] =

rId+ASCII_CHAR_OFFSET;



fprintf(MM232R,"Node [%02u] forwarding

message[%03u] of [0%02u] to [%02u] \n\r\0",modemId,sNo,fid,rId);

}

}

}

}

}

}

//****************************************************************

// End of file

//****************************************************************

*

83 | P a g e

APPENDIX 8

Components Order From

84 | P a g e

APPENDIX 9

Gantt Chart

85 | P a g e

APPENDIX 10

More project images

When SWITCH 2 was off LED 2 turned ON.

When SWICTH 1 and 2 were off LED 1 and 2 turned ON.

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Existing PCB which was used to measure signal strength against distance apart.

ER400TRS Transceiver

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Image of the PCB (Node A) when Final Code was testing

Image of the MM232R,

Image of PIC18F1320,

88 | P a g e

Image of the used drilling machine in laboratory,

Date post:	13-May-2015
Category:	Technology
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