Residential network for smart healthcare

Residential network for smart healthcare


The development in a residential network for smart healthcare is broad up a new horizon for continuous long-term monitoring of assisted and independent-living residents. The introduction part provides the project background, some related works, aims and objectives as well as chapter guideline of the report.


Assisted living residencesare referred to as who requires assistance for daily living activities. Additionally the residence frequently is coordinated with third party healthcare and service providers on the resident's behalf. Assisted living emerged in the 1990's as the next step of continuing care for people who cannot live independently in a private residence, but who also do not require the 24-hour medical care provided by a nursing home.

The implementation of assisted living technology exists today since 1980s when microelectromechanical systems (MEMS) have been used in the medical industry for a variety of silicon pressure, accelerometer, and custom microstructure applications.

As the world's population ages, those suffering from diseases of elderly and disability are increasing day by day. So the raising healthcare costs and the increasing elderly population are placing a strain on current health care service. Elderly patient and disable, especially those with chronic conditions, requires long-term monitoring. By using modern home automation system provides those 24 hours monitoring and continuous care in home environment. Different wearable sensors build a sensor network in the device for measuring various data and send to receiver by using wireless communication. This system can be utilized in individual patient home or care home system. So the service providers can monitor a number of patients at a time. Nowadays the care home service providers are using assistive living technology for providing better service.

The sensor network system integrates into a device. Some wearable on the patient and some placed inside the living space such as bed, wall etc. They together inform the healthcare provider about the health status of the resident. Data is collected, aggregated, pre-processed, stored, and acted upon using a variety of sensors and devices. Data can be sending through power line, radio frequency (RF), Wi-Fi, inferred or Bluetooth etc.


With the population is growing older, the demand for healthcare is growing rapidly. To meet the demand for more healthcare people are starting to look for new healthcare technology in less expensive way. Healthcare for elderly people is a huge area with lots of potentials. So many universities and companies are doing different kind of research within the area.

Imperial Collage of London has developed UbiMon. It is aimed at addressing general issues related to using wearable and implantable sensors for distributed mobile monitoring.[6] UbiMon designed devices for wearable communicator performing multi-sensor interfacing, automated techniques for integrating multi-sensory data leading to an intervention strategy as well as preliminary clinical evaluation for management of patients with ischemic and arrhythmic heart disease (Cardiovascular disease)

CodeBlue and Mercury is wireless sensor network for medical care. Both are developed by Harvard University. The applications of wireless sensor network technology to a range of medical applications, including pre-hospital and in-hospital emergency care, disaster response, and stroke patient rehabilitation.[3] Mercury includes long sensor node lifetime, autonomous operation, and the need for the system to automatically tune its behaviour in response to fluctuations in radio bandwidth and energy availability. An earlier version of Mercury (v1.0) is used on the patient of Parkinson (Motor neuron disease) and Epilepsy (Brain Disease).

MIT researched on wireless blood pressure monitor system. They have built a wearable blood pressure sensor that can provide continuous, 24-hour monitoring. This device monitors patient high blood pressure and sends data through radio frequency. It could help diagnose hypertension, heart disease as well.

Microsoft Corporation researched on HealthGear, a real-time wearable system for monitoring, visualizing and analyzing physiological signals. It is set of non-invasive physiological sensors wirelessly connected via Bluetooth to a cell phone which stores, transmits and analyzes the data.

BT(British Telecom) and Anchor Trust has developed together a system that is capable of monitoring people's movements and looking for deviations from a 'normal' pattern of behaviour that may indicate a potential problem.

European Commission is funded on mobile healthcare project called Mobihealth. It is the implementation of GPRS or UMTS services in healthcare. The MobiHealth system allows patients to be fully mobile whilst undergoing health monitoring. The patients wear a lightweight monitoring system - the MobiHealth BAN (Body Area Network) - which is customized to their individual health needs. [10] So it helps to monitor of patients status and progress as well as quick handling of emergency situations.

Royal Philips Electronics has introduced Lifeline with AutoAlert, a medical alert service which is able to detect falls and call for help for elder people. The alert system consists of pendant-style button worn around the neck which can be pressed to call for help at any time.

Corventis is maker of wireless CHF (Congestive Heart Failure) monitoring devices that measure heart rate, heart rate variability, respiratory rate, fluid status and activity. Piix designed to clinically validate remote wireless monitoring technology in proactively managing heart failure patients and reducing hospital readmissions.

CardioNet provides a remote heart monitoring system where ECG signals are transmitted to a PDA (Personal Digital Assistant) and then routed to the central server by using the cellular network [5]


The main aim of this project is to design a device which helps assisted living by sending data such as heart beat, pulse reading, blood pressure, temperature or movement etc. through various data transmitting media named Wi-Fi, Bluetooth, Inferred, Radio Frequency or power transmission line etc. Design sensors networking and embedded devices which have made it feasible to monitor and provide medical and other assistance to people in their homes. The designed device aims to send data to the existing Smart Home System (InterHome).

The main object can be divided into two parts. First part is to work on hardware and second part is software.

Choose particular sensor and connection media for those.

Here choose the LIS302DL accelerometer for movement monitoring and DIS1624 temperature sensor. Both sensors are connectable with I2C-Bus and SPI. Here sensors are connected with I2C-Bus of Meridian/P microcontroller. The details explanation I2C-Bus and Meridian/P is give in section 2.4 and 3.2.1.

Choose a communication medium.

This is very essential part for this project. As it will decide how the device is communicate with the smart home device. There are many ways to transmit the data through device but here prefer wireless communication via radio frequency (RF). So the device designed with XBee communication system. The details of XBee communication system is given in section 2.5.

Build the hardware design in breadboard by using required components.

At first work on paper based designed then work on breadboard design. So after getting all components, designed the system on breadboard. Some components need adaptor to work on breadboard like XBee, IC of MSOP (Mini Small Outline Package) pin. Explanation of connection of breadboard is given in section 4.1.1.

By using C# or Java write the code for sensor network and microcontroller.

For this embedded device using Meridian/P microcontroller. So write the programming code for device in C# on .Net Microframework. In section 2.3 details on .NET Microframework is explained.

Test the whole designed device to the assisted controller.

After completing the whole design and programming, test the whole system. Sometimes requires modification in hardware design and programming code. The result analysed form the output of the system. The detail provides in Chapter 5.


Before working on this project, the feasibility report is generated. That carried out to determine the working stages, outline design, proposal in terms of software and hardware requirements to handle the completion of the project

Due to recent advances in sensor networks and embedded technologies, designed health monitoring devices have become practically feasible.


This report provides information on the design and development of assistive living device. A brief outline of the report is given below.

Chapter 1:

This chapter introduces with assisted living technology and project background. Some related research from different universities and companies as well as aims and objectives also discussed. It includes the brief description of the organisation of report and project feasibility.

Chapter 2:

All background information which is related with this project has been discussed in this section. It covers home automation, InterHome, .NET Microframework, I2C Bus and XBee communication system.

Chapter 3:

This chapter discusses on whole system overview and design. Here shows how the project is designed and forwarded to the development. Also include block diagram of the project and the schematic diagram of the design. Design of each part has been explained in this section. The connections between Meridian/P and all other components are shown here. The components include sensor unit, communication unit and power management unit.

Chapter 4:

Discussed on hardware and software implementation in this section. PCB design and Breadboard design are introduced in hardware implementation. The programming code of each component and whole system is explained in software implementation section.

Chapter 5:

The output result is analysed in this chapter. The output from accelerometer and temperature sensor is discussed. Analysis of the result is explained in different situations.

Chapter 6:

Project management is very essential part in project handling. Time management, resource analysis and risk assessment have been briefly discussed in this chapter.

Chapter 7:

This chapter concludes the whole project work. Here discuss on the objectives that are given in section 1.3. Also evaluates if any additional objective is done for project work. Commercial aspects of assistive living technology are discussed in this chapter. Future development and recommendations are provided here for more useful applications.


Due to high increase the number of aging population expresses that the automatic home monitoring will represent major challenge near future. Advances in communication system, sensors, and embedded devices have made feasible to monitor and provide medical and other assistance to assisted people in their homes. With the aid of modern technology make the home more comfortable and caring for elder people. Aging populations will be benefitted from reduced costs and improved healthcare through assisted living based technologies. These systems provide more usability, reliability, and security. This is extensible system that combines software and hardware. The system can also provide information to diverse clinicians on 24 hours based. This report presents the system architecture for extension on assisted living that allows independent, secure, low-cost and emergency detection for assistive people. The approach is based on XBee communication system. The designed device will send data to smart home system. Additionally a server can be connected that collects and maintains assisted persons' records. The designed system shows the feasibility and new opportunity of an approach to assisted living systems.


Home automation is becoming more popular around the world and is becoming a common practice. The process of home automation works by making everything in the house automatically controlled using technology to control and do the jobs that would normally do manually. Nowadays home automation takes care of a lot of different activities in the house.The term may be used in contrast to the more mainstream "building automation", which refers to industrial uses of similar technology, particularly the automatic or semi-automatic control of lighting, doors and windows,heating, ventilation and air conditioning, and security and surveillance systems. Home automation technique can be applied in the control ofhome entertainment systems, houseplantwatering and kitchen applications. There are four types of home control system named power line carrier system, wireless system, and hardwired system and IP control. Power line carrier system is X10 based system. It operates through existing wire lines. Wireless system is based on the data transmission through radio frequency technology. Hardwired system introduces systems which can operate over high-grade communications cable. IP control means that house operates like its own secure Internet via a Web server, or a computer network. For this project wireless system is used but IP (Internet Protocol) control system can be applicable in future application.

Now home automationfocuses on making home for theelderlyanddisabled more safe and comfortable. Here using home automation system to monitor their daily activities. This system provides more options for the assistive people who would prefer to stay in the comfort of their homes rather than move to a healthcare facility. Home automation is being implemented for assistive living in order to offer more independence and safety.


The home which is operating through automated system is called Smart Home. Smart Home designs in the concept of Home Automation. The basic idea of home automation is to employ sensors and control systems to monitor a dwelling, and accordingly adjust the various mechanisms that provide heat, ventilation, lighting, and other services. In Figure 2-1 shows a house is in the concept of Smart Home where every system is control and monitoring. By definition, a dwelling incorporating a communications network that connects the key electrical appliances and services, and allows them to be remotely controlled, monitored or accessed.

This can provide more control and security in different home applications. It provides services in six main areas environmental, security, home entertainment, domestic appliances, information and communication and health care. The assistive people can be monitored 24 hours basis in homely environment. Smart home system provides medication reminder, health monitoring, indication of any emergency situations like fallen.

Smart home technology is real, and it's becoming increasingly sophisticated. The idea of Smart Homes carries a vital role in the planning of future housing-based models of care.


InterHome, an existing smart home concept which has been designed to test and demonstrate how much greener and secure our homes could be if they incorporated intelligent technologies that adapt to our daily routine. The design of this project demonstrates the interoperability of the unit in a smart home environment. Smart Home which is based on Meridian CPU is known as InterHome. [20]


In this project all the sensors are only connected with microcontroller (Meridian/P) by using I2C bus. This bus is designed from the manufactures of the component. It is multi-master bus. So more than one device can be connected with this bus shows in Figure 2-2. The I2C translates into "Inter IC” can be called as IIC or I2C Bus. The bus I2C as designed by Philipsin the early '80s to allow easy communication between components which reside on the same circuit board. Philips Semiconductors migrated toNXP Semiconductor in 2006.

I2C -Bus requires two bus lines; a serial data line (SDA) and a serial clock line (SCL). It is a multi-master bus including collision detection and arbitration to prevent data corruption if two or more masters simultaneously initiate data transfer. It is serial and 8-bit oriented, bidirectional data transfers can be made at up to100 kbit/s in the standard mode or up to 400kbit/s in the fast mode. But now ahigh speed 3.4 Mbit/savailable. This bus can be connected by wires. The serial data (SDA) and serial clock (SCL) carry information between the devices connected to the bus. Every single device is recognized by a unique address. TheSDAandSCLlines are pulled up to the supply voltage (3.3V to 5V) with a pull-up resistor. As well as the number of devices connected to the bus is only limited by the total allowed bus capacitance of400pF. This bus is low power consumption and flexible to use.

Here the sensors are connected with microcontroller by using I2C bus. The device can operate as either a transmitter or receiver, depending on the function of the device. In addition to transmitters and receivers, devices can also be considered as masters or slaves when performing data transfers. A master is the device which initiates a data transfer on the bus and generates the clock signals to permit that transfer. At that time, any device addressed is considered a slave. Summery of the I2C bus is shown in Table 2-1.




The device which sends data to the bus


The device which receives data from the bus


The device which initiates a transfer. Generates clock signals and terminates a transfer.


The device addressed by master

Table 2-1: I2C bus Terminology


For this project work, build a wireless network by using XBee Modules. The XBee and XBee-PRO OME RF Modules were engineered to meet IEEE 802.15.4 standards and support the unique needs of low-cost, low-power wireless sensor networks. IEEE 802.15.4 provides a physical layer of low-rate wireless personal area networks (LR-WPAN). This is used due to the lower cost than other wireless communication system. XBee or XBee-PRO RF Modules has ISM (Industrial, Scientific & Medical) frequency band of 2.4GHz. It operates in low operating voltage. It provides more security by using Direct Sequence Spread Spectrum (DSSS). Spread Spectrums transmit much larger bandwidth than the information bandwidth through the channel.Each direct sequence channels has over 65,000 unique network addresses available.

Here for wrist belt, using XBee modules of Series1. The device is designed with XBee. So it will transmit data to another XBee of the exiting Smart Home system. The key difference between the XBee and XBee-PRO is distance of data transmission. XBee-Pro has long distance of data transmission. XBee Module of Series 2 needs configuration so this will provide more security than Series 1. For this project work XBee-PRO can be connected on the belt when requires more range and Series 2 for more security. In Table 2-2 shows the specification between XBee and XBee-PRO.


XBee 802.15.4 (Series 1)

XBee-PRO 802.15.4(Series1)

Indoor Range

Up to 30m

Up to 100m

Outdoor Range

Up to 100m

Up to 1500m

Transmit Power Output



Receive Current



Operating Temperature

-40°C to 85°C

-40°C to 85°C

Serial Interface Data Rate

1200 - 115200 bps

1200 - 115200 bps

RF Data Rate

250 000 bps

250 000 bps

Number of Channels

16 Direct Sequence

12 Direct Sequence

Operating Voltage



Table 2-2: Specification difference between XBee and XBee-PRO

XBee/XBee PRO is interfaced to a host device through a logic-level asynchronous serial port. Here XBee is connected with the UARTS pin of the microcontroller (Meridian/P). So the data which is send from Meridian/P that will be received by XBee. As well as it will again operate like vice versa. The details connection between Meridian/P and XBee as well as information of CTS and RTS is given in section 3.2.3. Through its serial port, the module can communicate with any logic and voltage compatible UART shows in Figure 2-3.


This project is based on the exiting Smart home system called InterHome. Here design a device for assisted living people of the InterHome to provide 24 hours health monitoring service. In section 3.1 have explored the architecture by developing a collection of applications and implementing them in a prototype system. Also describes regarding designed wrist belt. In section 3.2 focuses on only wrist belt. There also demonstrates design of each part of wrist belt like sensor unit, communication unit, power management unit and microcontroller unit. Every unit connects and works altogether. The schematic diagram of the designed system is given in section 3.2.


Main theme of this project is to design a device for assistive residences to monitor their health in 24 hours basis. This is a home automation system. Here propose a wearable wrist belt which is designed with XBee and sensors. LIS302DL and DS1624 are picked as accelerometer and temperature sensor. Additionally a panic button is added in the design for the people who have problems in speech. So they can call for assistance by pressing that button. The detail is explained in section 3.2.2. All components are connected and controlled by Meridian/P microcontroller. An XBee is connected with the wrist belt and another one is connected with existing Smart Home system (InterHome). Both XBee will make a wireless mesh network for data transmission. The whole operation of the system is

Figure 3-1 shows that an assistive residence of existing InterHome wearing the designed wrist-belt. The belt is build with XBee Module. It communicates with another XBee Module which is connected with InterHome. The wrist-belt sends data to the InterHome system. The InterHome device will send data toward Main Server and Database. The main server sends data again to the assistive living monitoring centre and emergency service. So monitoring centre can monitor the assisted residence on 24 hours basis. If any problem occurs then they can provide quick emergency service. On other hand, the main server can be connected with GSM or GPRS system. For any occurrence it will inform to the PDA or mobile phone. As well as the assistive person's data can be send 24 hours to the PDA or cell phone. This system is also applicable for care home service. By using this system care home service providers can monitor multiple patients at a time.

In Figure 3-2 shows the internal combination of the proposed wrist-belt. The accelerometer LIS302DL and temperature sensors DS1624 are connected with Meridian/P by using I2C bus. The explanation of this bus is given above in section 2.4. A panic button is connected with the GPIO (General Purpose Input /Output) pin of the Meridian/P. The connections between the sensors and panic button are described in sensor unit section 3.2.2. The collected data will send through the XBee Module which connected with the UATRS pin of the Meridian/P. The microcontroller can receive or transmit data through XBee Modules. For this project the microcontroller can only send data to the XBee. The wrist-belt works wireless. So the person is independence to move. That's why here using light weight rechargeable Li-ion battery. So a battery rechargeable system is designed in the wrist-belt. The Power management unit is designed with the battery rechargeable IC MCP73837 and DC-DC convertor. The design and operation of this unit is shown in section 3.2.4. All the components work altogether in the wrist-belt.



For this project Meridian/P Micro Development Board is used as microcontroller. This is the nucleus of this project. Sensors, XBee, Power Management Unit are connected with this. The whole device is designed on the base of Meridian/P. Meridian/P is combined with a 100MHz Freescale i.MXS ARM920T based processor, 8MByte of SDRAM (running at 96MHz), LCD controller, USB function, GPIO, SPI and I2C bus and serial port.The operating voltage is 5V. It runs on .NET Micro Framework. So for programming use C# in .NET Micro Framework.

Meridian/P has total 27 pins available for use as general purpose input/output pins but 19 of those pins are labelled as GPIO pins, remaining pin are not supported by .NET Micro Framework.

For this project, design the device by using only expansion 2 (EXP2). Other connections like LCD Expansion are not used. The pin identification of EXP2 is shown in Figure 3-3. The pins are notified with blue colour those are used for designing. Rest of the pins are in black colour those are not used so left open.

Powered 4.3V to 5V DC input voltage through USB port (J1) to run Meridian/P. Maximum voltage of Input/ Output pin is 3.3V. The typical power consumption of Meridian/P is only 80mA and operating temperature ratio is 0°C to 70°C. Pin-3 gives +3.3V. So this pin works as supply voltage for all devices. Pin 4 is 0V. So in this design makes it universal ground for all connections.

Meridian/P supports interfacing to device through the internal I2C bus master or SPI (Serial Peripheral Interface). But here choose I2C bus to connect with devices. More information regarding I2C bus is given in section 2.4. So the sensors LIS302DL and DS1624 are connected with I2C bus. To connect with this bus the device has to configurable with this bus by manufacture. The base input frequency to the I2C bus is 96MHz. In EXP2, Pin-20 and Pin-22 are signalled as I2C-SDA and I2C-SCL. Serial Clock line (SCL) is used to clock data to the bus and Serial Data line for controller send or receive data on this line.

If any of I2C or SPI bus does not use then that can be worked as input/output pin. In this design SDA and SCL both are pulled up with 47KΩ resistors.

XBee is connected with UART (Universal Asynchronous Receive/Transmitters) pins for data communication. Meridian/P has two UART pins. Here using UART1 of EXP2. Both UART 1 and UART2 are available serial ports (COM1 and COM2) under the .NET Micro Framework. In this design using all the UART pins of EXP2. The connections between URAT pins and XBee are given in details in Section 3.2.3. There are four UART pins are available in Meridian/P EXP2. A brief description and pin location is given in Table 3-1.


Pin Location



EXP2- Pin 24

This is transmitting data line for UART.


EXP2- Pin 26

This is an input line to the Meridian/P.


EXP2- Pin 28

This is receiving data line for the UART.


EXP2- Pin 30

This is an output line from the Meridian/P.

Table 3-1: UART pins description of Meridian/p


Sensor Unit is combined with two sensors and panic button. This device is designed with DS1624 temperature sensor and LIS302DL accelerometer. LIS302DL is three-axis accelerometer and DS1624 is digital temperature sensor. Both are enable to connect with I2C serial interface. In this section has explained the connections of both sensors as well as the panic button. Both are using supply voltage and I2C bus from Meridian/P.

Here using DS1624 of 8-pin DIP (Dual In-line Package). DS1624 consists of two seperate functional units. Those are 256-byte non-volatile E2 memory and direct-to-digital temperature sensor. E2 Memory are able to store any information depends on the user desires such as frequency compensation coefficients and direct to digital temperature sensor allows the DS1624 to measure the ambient temperature value in a 13-bit word, with 0.03125°C resolution. For this project using direct to digital function. So the temperature sensor and its related registers are accessed through the 2-wire serial interface (I2C bus).

Figure 3-4 shows that Pin-1and Pin-2 is notified SDA and SCL. Both pins are used for I2C bus. So Pin-1 is connected with Pin-20 of Meridian/P and Pin-2 is connected with Pin-22 of Meridian/P. Those are pulled up with 47KΩ resistor. Pin-8 is used for supply voltage so it is connected with Pin-3 of Meridian/P. The output voltage Pin-3 of Meridian/P is 3.3V. DS1624 operates in 2.8V to 5.5V. Pin-3 of this sensor is not connected and Pin-4is connected with universal ground. Pin-5 to Pin-7, those three pins are called address input pin. In this design all those pins are connected to ground. The input/output capacitance is 10pF and standby supply current is maximum 3µA. Operation of I2C bus and register operations for this sensor is given in section 4.2.1 and section 4.2.3.

In Figure 3-5 shows the view, pins outline and connection of LIS302DL.To monitor the movement of the assisted residence, the wrist-belt is designed with LIS302DL accelerometer. It is an ultra compact low-power (less than 1mW) three axis linear accelerometer. It is designed with sensing element which is capable of detecting the acceleration and an IC interface able to provide the measured acceleration through I2C/SPI serial interface. LIS302DL has dynamically user selectable full scales of ± 2g/± 8g and it is capable of measuring accelerations with an output data rate of 100 Hz or 400 Hz as well as the operating voltage range is 2.16V to 3.6V and temperature range is -40°C to 85°C.

‘g' defines the g-forces or gravitational force which is worked with accelerometer [33] It is applicable of the earth, it has two remarkable features: (1) it always directed toward the centre of the earth, and helps in defining the vertical. (2) It is directly proportional to the mass of the body. [32] When stationary, the force felt by earth's gravity is 1G, when a body undergoes a change in speed and direction, then the force increases in proportion to the rate of change. [34] Here ‘g' is defined as the acceleration due to gravity, gives feeling of weight for instance a heavier body has less acceleration. [32] The measurement information of ‘g' and analysis of acceleration due to movement is given in detail in Chapter 5 section 5.2.

It has 8 pins. Pin-1 is connected with 3.3V of supply voltage which is provided from Pin-3 of Meridian/P. Pin-2 is connected with ground. Pin-3 is SCL. Pin-4 and Pin-5 is notified is as MOSI and MISO. Both pins are used for SPI. MISO (Master Output/Slave Input) and MISO (Master Input/ Slave Output) is used as SDA (Serial Data Address) and SDO (Serial Data Output). [31] Pin-3 and Pin-4 is connected with SCL and SDA. Pin-5 leaves open. Pin-5 is CS. This is I2C or SPI mode selection. The value is 1 for I2C mode and 0 for SPI enabled. So due to using I2C bus connected with supply voltage (3.3V). Pin-7 and Pin-8, both is interrupt pin. Both are connected with GPIO pin of Meridian/P. So Pin-7 and Pin-8 connects with Pin-17 (GPIO6) and Pin-13 (GPIO2) of Meridian/P. The registers mode and bus interface operation is given in Section 4.2.5 and Section 4.2.1.

Panic button works like as switch. When panic button is pressed then it makes interruption in the whole system and notified to the InterHome by sending data that assistance is required. It has two pins. One pin is connected with ground and another pin is connected with Pin13- GPIO11 of Meridian/P pull up with 47KΩ resistor. The programming of this panic button given in Section 4.2.5 and the output of panic button is shown in Chapter 5 in Section 5.2.


This unit works only in data transmission operations. The wrist-belt is designed with XBee Module for communicating with InterHome. It is connected directly with Meridian/P microcontroller. The sensor unit sends data to the Meridian/P and it sends data to Smart Home device through XBee. The XBee communication system has been explained earlier in Section 2.6. Figure 3-7 shows the schematic and pin outlines of XBee as well as the connections with Meridian/P. The pins are notified with blue colour means those pins are used for design. Rest of unused pins are connected in a separate hole. So those pins can be used again for different and future applications.

XBee Module of Series1 is used in this device. So it was configured from manufacture. Series 2 needs manually configuration for operation but it provides more security. Some specifications of XBee Modules are given in Table 2-2.

The operation of this unit is based on data receiving and transmitting. So both components are operating as a transmitter and a receiver. The data out from XBee directly enters to Meridian/P. Similarly the data out from Meridian/P directly goes to XBee. Again the data sends towards XBee Module of InterHome. XBee is connected is with Meriden/P through UART pins. Table 3-1 provides information regarding UART pins of Meridian/P.

Pin-1 is connected with the supply voltage 3.3V of Pin-3 in Meridian/P. Pin-10 is connected with ground. Pin-2 is UART data output pin for XBee. So it is connected with Pin-28 of Meridian/P. Pin-28 of Meridian/P is UART1-RXD. This is UART data input pin for Meridian/P. Data received in this pin is processed by internal UART.

In other way, Pin-2 of XBee is UART data input pin. So here makes a connection of this pin with Pin-24 of Meridian/P. Pin-24 of Meridian/P is notified as UART1-TXD. This is transmitting data line for UART. So data is transmitted form Meridian/P to XBee.

Pin-9 and Pin-13, both are connected with GPIO pins of Meridian/P. Pin-9 is an input pin for sleep control line and Pin-13 is an output pin for ON/Sleep mode indicator. Pin-9 is connected with Pin-21of Meridian/P (GPIO7) and Pin-13 is connected with Pin-23 of Meridian/P (GPIO8).

CTS and RTS, Both pins are common in Meridian/P and XBee. CTS means Clear-To-Send and RTS means Ready-To-Send. In Meridian/P, Pin-30 is identified as UART1-CTS which is an OUTPUT signal from Meridian/P and Pin-26 is notified as UART1-RST that is an INPUT line to the Meridian/P.

So CTS-pin of XBee is connected with the RTS-pin of Meridian/P. That means data is flowing from XBee to Meridian/P. In other hand, RTS-pin of XBee is connected with CTS-pin of Meridian/P. Now the data is moving from Meridian/P towards XBee. This operation is shown in Figure 2-3.

Here Pin-12 is a digital input/output pin for XBee; notified as CTS. It is connected with Pin-26 of Meridian/P (UART1-RTS). Pin-16 (RTS) of XBee is connected with Pin-30 of Meridian/P

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