This project uses X Bee wireless modules to control devices remotely with feedback. The transmitter unit takes input from switches and sends commands via an X Bee module. The receiver unit receives the commands via its X Bee module and controls devices like relays. The status of devices is displayed on an LCD. X Bee modules allow bidirectional wireless communication and are configured using AT commands to control devices remotely over short ranges.

1. X BEE Based Device Control with Feedback:
Introduction:
Automation designates an emerging practice of increased automation of household
appliances and features in residential dwellings, particularly through electronic means that
allow for things impracticable, overly expensive or simply not possible in recent past decades.
The term may be used in contrast to the more mainstream "building automation" or “industrial
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, security and surveillance systems.
This project is based on the wireless popular module x bee. These devices have many
advantages over other wireless modules. They are easy to use and can be configured easily by
AT commands. If required they can take even analog signals. The data transfer takes in serial
mode and bidirectional that is this works like a transreceiver. Here we are implementing this
technology to control the appliances at the remote location with feedback that whether the
device is on or not.
BLOCK DIAGRAM:
Transmitter end:
Receiver end:
KEYPA MICR
OCON
TROLL
ERLCD
X BEE
MODUL
E
MICRO
CONTROLLE
R
DEVIC
E
INTER
FACIN
G
DEVICE
DEVICE
X BEE
MODUL
E

2. Blocks in brief:
a) Transmitter Unit:
Input unit:
1. Switch: This consists of the 4 switches for the control of the device
Processing Unit
1. Controller Unit: This consists of the controller ATMEGA168 which is being programmed
to take the input and generate the desired output.
Output unit
1. X-bee module: This is basically transreceiver which will transmit the data wirelessly
when from transmitter and will receive the data when sent from the receiver block.
2. LCD: This is a 16X2 B/W LCD used to display the data that is status of the devices.
b) Receiver Unit:
Input unit:
1. X-bee module: This is basically transreceiver which will transmit the data wirelessly
when data is to be sent form this unit and will receive the data when sent from the
transmitter block.
Processing Unit
1. Controller Unit: This consists of the controller ATMEGA168 which is being programmed
to take the input and generate the desired output.
Output unit
1. RELAY Driver: IC ULN2803 will be used which can drive the relay proper voltage and
current.
2. 4- Bit Relay Card: Automatic switch that will put on and off the devices.
Note: The X-bee module is blank module. To make it function we have to configure the
module that is as coordinator and router then it functions. For this AT commands are being
sent to the X-bee module. There is much software to configure the X-bee available.

3. Working:
With the help of following block diagram we can easily describe the project. Two
microcontrollers are required to control the two x bee modules. Using buttons on the
transmitter end we can on- off any device connected at the receiver end. The LCD will display
the current status of the devices. At any time we can check the status of the devices.
Components Used:
Hardware Components:
1. X BEE modules
2. LM117 Voltage regulator
3. Switch
4. Microcontrollers
5. LCD
6. Relay
7. ULN2803
8. Power supply block
 X BEE:
X Bee is the standards-based wireless technology designed to
address the unique needs of low-cost, low-power wireless
sensor and control networks in just about any market. ZigBee
can be used almost anywhere, is easy to implement and needs
little power to operate. With hundreds of members around the globe, ZigBee uses the 2.4 GHz
radio frequency to deliver a variety of reliable and easy-to-use standards anywhere in the
world. ZigBee is a specification for a suite of high level communication protocols using small,
low-power digital radios based on the IEEE 802.15.4-2003 standard for wireless home area
networks (WHANs), such as wireless light switches with lamps, electrical meters with in-home-
displays, consumer electronics equipment via short-range radio. The technology defined by the
ZigBee specification is intended to be simpler and less ex pensive than other WPANs, such as

4. Bluetooth. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate,
long battery life, and secure networking. This is basically a transreceiver module.
 ATMEGA 168/328:
The Atmel AVR core combines a rich instruction set with 32
general purpose working registers. All the 32 registers are
directly connected to the Arithmetic Logic Unit (ALU), allowing
two independent registers to be accessed in one single
instruction executed in one clock cycle. The resulting
architecture is more code efficient while achieving throughputs up to ten times faster than
conventional CISC microcontrollers. The Atmega168 provides the following features: 16 Kbytes
of In-System Programmable Flash with Read-While-Write capabilities, 512 bytes of EEPROM, 1
Kbyte of SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three
flexible Timer/Counters with compare modes, internal and external interrupts, a serial
programmable USART, a byte oriented Two wire Serial Interface, a 6-channel ADC (eight
channels in TQFP and QFN/MLF packages) with 10-bit accuracy, a programmable Watchdog
Timer with Internal Oscillator, an SPI serial port, and five software selectable power saving
modes. The Idle mode stops the CPU while allowing the SRAM; Timer/Counters, SPI port, and
interrupt system to continue functioning. The Power down mode saves the register contents
but freezes the Oscillator, disabling all other chip functions until the next Interrupt or Hardware
Reset. In Power-save mode, the asynchronous timer continues to run, allowing the user to
maintain a timer base while the rest of the device is sleeping. The ADC
Noise Reduction mode stops the CPU and all I/O modules except
asynchronous timer and ADC, to minimize switching noise during ADC
conversions. In Standby mode, the crystal/resonator Oscillator is running
while the rest of the device is sleeping. This allows very fast start-up
combined with low-power consumption.

5.  Liquid Crystal Display: This is 16x2 B/W LCD for the display of the data.
 Relay Driver: ULN2803 is a current driver IC which drives the relay. The eight NPN Darlington
connected transistors in this family of arrays are ideally suited for interfacing between low logic
level digital circuitry (such as TTL, CMOS or PMOS/NMOS) and the higher current/voltage
requirements of lamps, relays, printer hammers or other similar loads for a broad range of
computer, industrial, and consumer applications. All devices feature open–collector outputs
and freewheeling clamp diodes for transient Suppression. The ULN2803 is designed to be
compatible with standard TTL families while the ULN2804 is optimized for 6 to 15 volt high level
CMOS or PMOS.
 RELAY: A relay is an electrically operated switch. Many relays use an electromagnet to operate
a switching mechanism mechanically, but other operating principles are also used. Relays are
used where it is necessary to control a circuit by a low-power signal (with complete electrical
isolation between control and controlled circuits), or where several circuits must be controlled
by one sign. Here, relay is used to switch on the devices.
 LM117: This is special voltage regulator which gives 3.3 V as output used for the X-bee power
supply.

6.  Switches: The switches are simple micro-switch that mini push to on switch that
makes the point continuous while pressed and discontinuous when released.
 Power Supply Block: The power supply consists of a step down transformer 230/12V, which
steps down the voltage to 12V AC. This is converted to DC using a Bridge rectifier. The ripples
are removed using a capacitive filter and it is then regulated to +5V using a voltage regulator
7805 which is required for the operation of the microcontroller and other components.
Note: Transmitter unit is battery powered
SOFTWARE COMPONENT:
ARDUINO COMPILER:
The Arduino IDE is a cross-platform application written in Java, and is derived from the IDE for
the Processing programming language and
the Wiring project. It is designed to introduce programming
to artists and other newcomers unfamiliar with software
development. It includes a code editor with features such
as syntax highlighting, brace matching, and automatic
indentation, and is also capable of compiling and uploading
programs to the board with a single click. There is typically
no need to edit make files or run programs on a command-
line interface. Although building on command-line is
possible if required with some third-party tools such as Ino.
The Arduino IDE comes with a C/C++ library called "Wiring"
(from the project of the same name), which makes many
common input/output operations much easier. Arduino
programs are written in C/C++.
Advantages and applications:
 The primary advantage is that the X-Bee modules are ‘bi-
directional’. Most budget 433 systems only transmit in
one direction, so the transmitter has no idea whether the

7. receiver is actually getting the data! The X-Bee modules transmit and receive in both
directions, so you can easily test (at both ends) if the system is working correctly.
 The second advantage is that of unique addressing. Each X-Bee unit has a unique serial
number. This means two (or more) units can be set up to exclusively talk to each other,
ignoring all signals from other modules. This is not easily achieved with 433 modules.
 The third advantage is that the X-Bee module has in build ‘data-packet’ building and
error-checking to ensure reliable data transmission.
 Finally the X-Bee protocol allows for a number of ‘channels’. By setting different units on
different c0hannels additional interference can be avoided.
 X-bee can used to sort out any type of wireless applications in limited range like physical
parameter monitoring, PC to PC communication without net, develop LAN network
without internet, wireless control applications etc.