Zigbee Centralized Fire Detection Network Computer Science Essay

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Control over fire is one of the most important discoveries ever made by mankind, with applications ranging from cooking food to the internal combustion engine. And well as fire can be a very destructive force which can easily claim lives of people, burn buildings and other structures to the ground and damage material things. Therefore fire safety has become a necessity in the present world of busy lives. As a solution, a centralized fire security system can be implemented in order to make sure that people, properties and the buildings are safe from fire.

The past several years have witnessed a rapid growth of wireless networking. However, up to now wireless networking has been mainly focused on high-speed communications, and relatively long range applications such as the IEEE 802.11 Wireless Local Area Network (WLAN) standards. The first well known standard focusing on Low-Rate Wireless Personal Area Networks (LR-WPAN) was Bluetooth. However it has limited capacity for networking of many nodes. There are many wireless monitoring and control applications in industrial and home environments which require longer battery life, lower data rates and less complexity than those from existing standards. For such wireless applications, a new standard called IEEE 802.15.4 has been developed by IEEE. The new standard is also called ZigBee. Under this project, it is expected to develop a model fire detection system using a Zigbee development kit where centralized monitoring can be implemented.

1.2 Aim and Objectives

The primary aim of this project is to design a wireless centralized security system to an office or a building using zigbee protocol where centralized monitoring is required, using wireless sensor nodes.

The main objective of this project is to implement a proper security system which can manage security matters and provide safety and protect people and well as their buildings and offices.

Chapter 2

2.5. Zigbee Nodes

Basically there are three types of nodes which exist in a Zigbee network. They are coordinator, router and end device. Devices can be classified according to their functionalities,

Full Function Devices (FFD) implement the full IEEE 802.15.4/ZigBee protocol stack

Reduced Function Devices (RFD) implements a subset of the protocol stack.

2.5.1 ZigBee Coordinator (ZC)

One for each ZigBee Network;

Initiates and configures Network formation;

Acts as an IEEE 802.15.4 Personal Area Network (PAN) Coordinator

Acts as ZigBee Router (ZR) once the network is formed

Full Functional Device (FFD) - implements the full protocol stack If the network is operating in beacon-enabled mode, the ZC will send periodic beacon frames that will serve to synchronize the rest of the nodes. In a Cluster-Tree network all ZR will receive beacon from their parents and send their own beacons to synchronize nodes belonging to their clusters

2.5.2 ZigBee Router (ZR)

Participates in multi-hop routing of messages in mesh and Cluster-Tree networks; Associates with ZC or with previously associated ZR in Cluster-Tree topologies

Acts as an IEEE 802.15.4 PAN Coordinator

Full Functional Device (FFD) - implements the full protocol stack.

2.5.3 ZigBee End Device (ZED)

Does not allow other devices to associate with it

Does not participate in routing

Just a sensor/actuator node

Can be a Reduced Function Device (RFD) - implementing a reduced subset of the Protocol stack

Chapter 5

5.1 Hardware Overview

5.1.1 JN5139 Evaluation kit

For this project JN5139 EK010 evaluation kit was used. Jennic's evaluation kit provides a complete environment for the rapid development of wireless connectivity applications based on the JN5139 wireless microcontroller. The evaluation kits comprise the following hardware components, and are numbered to name them as follows.

Figure JN5129 Evaluation kit [getting started]

One controller board

Four sensor boards (two with an SMA connector and other two with integrated antennas)

2 high power plug in modules

3 SMA connector antennas

2 USB to serial (FTDI) cables

One pack of 10AAA batteries to power the sensor boards

CD ROM containing the user guide documentation [1]

5.1.2 JN5139 Microcontroller

The JN5139 is a low power, low cost wireless microcontroller suitable for IEEE802.15.4 and ZigBee applications. The device integrates a 32-bit RISC processor, with a fully compliant 2.4GHz IEEE802.15.4 transceiver, 192kB of ROM, 96kB of RAM, and a rich mixture of analogue and digital peripherals.

The cost sensitive ROM/RAM architecture supports the storage of system software, including protocol stacks, routing tables and application code/data. An external flash memory is used to store application code that is bootloaded into internal RAM and executed at runtime.

The device integrates hardware MAC and AES encryption accelerators, power saving and timed sleep modes, and mechanisms for security key and program code encryption. These features all make for a highly efficient, low power, single chip wireless microcontroller for battery-powered applications. [2]

Figure JN5139 Microcontroller

5.2 Software Overview

In order to develop the applications using the Jennic Zigbee evaluation kit, first of all the Jennic System Developer's Kit (SDK) should be installed. Following are the pre-requisites for wireless network application development.

• A machine with the following specification:

Windows Vista, XP or 2000 operating system

At least 240 MB of hard disk space available

• Administrator rights on the machine

• The following SDK installers from the evaluation kit CD or the Jennic web site:

JN-SW-4030-SDK-Libraries-vX.Y.exe

JN-SW-4031-SDK-Toolchain-vX.Y.exe [3]

5.2.1 SDK Toolchain

This installs the Jennic software tools that require for preparing the wireless network applications. These utilities include development, compiler and Flash programming tools. Components that can be installed from SDK Toolchain can be listed as follows [3],

Components

Comments

Jenie API

Needed for applications that use Jenie

JenNet stack software

Needed for applications that use Jenie or AT-Jenie

ZigBee APIs and stack software

Needed for applications that use ZigBee

IEEE 802.15.4 API and stack software

Needed for all implementations

Table 5 Toolchain Components

5.2.2 SDK Libraries

This installs the Jennic software libraries that will help streamline the application development. These libraries include Application Programming Interfaces (APIs) for the Jenie, ZigBee and IEEE 802.15.4 protocols, as well as a parser for the AT-Jenie command set. Components that can be installed from SDK Libraries can be listed as follows [3],

Components

Comments

Cygwin

This is the Cygwin CLI (Command Line Interface) which emulates Linux.

Flash Programmer

This is the JN51xx Flash Programmer that you will need to download your compiled applications to the Flash memory of the 5139 device.

Code Blocks

This is where the application program is built and compiled. This is a full-featured, open source IDE (Integrated Development Interface).

Jennic Compiler Tool

These tools include the JN5139 compiler and the linker, where are always needed.

Table 5 Libraries Components

Chapter 6

6.1 Hardware Implementation

To implement this project several hardware components were used such as smoke detectors, Jennic Zigbee evaluation kit, PCB boards, a PC, and transistors (2N2222). An Ionization smoke detector was used for this project since the network completely based on the smoke detection. Below is the description of the smoke alarm used for the project.

6.1.1 Product Description

The Ei100L is an Ionization Smoke Alarm that runs on a 9V battery (supplied with the alarm). Ionization smoke alarms operate on the principle that electrical current flowing between electrodes in an ionization chamber is reduced when smoke particles enter. Ionization technology gives a rapid response to fast flaming fires.

Figure : Ei100L Ionization Smoke Alarm with Escape Light

6.1.1.1 Main Features and specifications

High intensity light beam powered by alkaline battery

High sensitivity - responds to all standard fires

Dual ionization chamber - quick response to fast flaming fires

Battery powered - 9 volt (supplied)

Built in sounder to give a minimum sound output of 85dB(A) at 3m

Bleeps every 40 seconds when battery needs replacing

Test Button simulates smoke - use to check performance at least monthly

Compact size

Operation temperature - 0c- 40c (32 ° F - 104 ° F)

Ambient humidity - 10- 90%

Alarm level- 85Decibels at 3 meters

6.1.1.2 Operation

The smoke detector will activate the built in sounder upon sensing smoke particles. In parallel the bright emergency light turns on. The voltage to the escape light bulb here was varied from 0.8 V to 8.5V. A voltage divider was used to bring down the voltage around 2.5V since the input voltage to the Zigbee module should be between 0V to 3.3V.Output voltage from the voltage divider was supplied pin 10 and pin 38 of the module which represents input and ground receptively. It was noticed that when there is no smoke detected, there is a small voltage of 0.6V when the batteries are inserted to the smoke detector. There for power transistor (2N2222A) was integrated to the circuit because it can act as a switch. This passes all the voltages above 0.7V. Therefore when no smoke is detected no voltage across the transistor and it is 'OFF' and when smoke is detected the output voltage of 0.8V to 8.5V will make the transistor turn 'ON' by having a voltage of 2.5V across the two pins and a current flow through the transistor from collector to emitter.

6.1.2 Module Pins

The positive output from the transistor is connected to the pin 10 while the negative output from the smoke detector is connected to the pin 38 which is grounded. Pins that can be used are listed as follows,

Pin

Signal

Primary function

Secondary function

Board function

10

DIO9

Timer0 capture(input)

Digital I/O

SW1

12

DIO11

Timer1 clock/gate(input)

Digital I/O

SW2

38

GND

Ground

40

GND

Ground

Table Expansion Connector Pin outs

6.1.3 Circuit diagram

The voltage divider consists of two resistors in series respectively xxxx and xxxx. Since the input voltage to the Zigbee module should be between 0V to 3.3V, below formula was used to calculate the resistor values.

Vout.Vin

Vout.Vin

Vout xxxxx

Figure Circuit diagram

6.2 Software Implementation

6.2.1 C programming coding and functions used in the coordinator

Each module in the Evaluation kit is programmed to carry out its own functions once they are switched on. Following table shows the functions which are programmed for coordinator to accommodate its specific functions.[4]

Name

Description

AppColdStart

Initialises system and runs main loop.

vInit

Initialises Zigbee stack and hardware. Final action is to start BOS.

vTxSerialDataFrame

Transmits node data (address and sensor readings) to host via serial port

vToggleLed

Gets called by a BOS timer and toggles LED1 to indicate we are alive

JZA_vAppEventHandler

Called regularly by the task scheduler. This function reads the hardware event queue and processes the events therein. It is important that this function exits after a relatively short time so that the other tasks are not adversely affected.

JZA_vPeripheralEvent

Called when a hardware event causes an interrupt. This function is called from within the interrupt context so should be brief. In this case, the information is placed on a simple FIFO queue to be processed later.

JZA_boAppStart

Called by Zigbee stack during initialisation. Sets up the profile information and starts the networking activity

JZA_pu8AfMsgObject

Called when a MSG transaction has been received with a matching endpoint.

JZA_vStackEvent

Called by Zigbee stack to pass an event up to the application.

Table Programming coding and functions

Chapter 11

11.1 Cost Analysis

Hardware component

Quantity

Cost per one component (£)

Total cost (£)

Zigbee evaluation kit(Jennic-JN5139)

01

295

295

Smoke detector with the escape light

01

10.99

10.99

Transistor (2N2222)

01

1.13

1.13

Resistors (Ω)

01

0.12

0.12

Resistors (Ω)

01

0.15

0.15

Wires(red, black, brown and yellow)

50cm each

0.89

3.56

Strip board

01

3.73

3.73

9V Battery

01

2.59

2.59

Total cost 317.27

Table 1-1 Cost calculation table

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