This research paper describes the design of a microcontroller-based remote locator system. The system consists of a base unit and multiple remote units that can be attached to objects. The base unit allows the user to enter codes for remote units and transmit a signal to make a selected remote unit beep, helping the user find a lost object. The remote locator allows lost items to be found without wires by using radio frequency transmissions between the base unit and remote units.

1. RESEARCH PAPER ON
MICRO CONTROLLER BASED
REMOTE LOCATOR
Dept of Electronics and Communication Engineering
NITTE MEENAKSHI INSTITUTE OF TECHNOLOGY
Yelahanka, BANGALORE-64

2. PAPER AUTHORED AND CO-AUTHORED BY:
 KAMAL LAMICHHANE
 ASHWIN CHAPTE
 AVANEE BHAT. M. V
 KIRAN. M
(B.E students of ECE, NMIT Bangalore)

3. INTRODUCTION:
 The main aim of this project is to develop a remote device
that is used to locate the lost things by sending a signal to
small remote units connected to various items in the
surroundings such as watches, remotes, keys, TV remotes,
purses, eyeglass cases, and cell phones.. Even emergency
lights in case of a black out !!
WHAT EXACTLY HAPPENS ??
 When the particular thing is lost, the user uses a display to
see the listed out objects, finds its predefined code and
sends it.
 The remote unit attached to the lost item receives the
transmitted digital code and produces an alarm to alert
the user to locate the thing.
 The user can turn the alarm off on the movable device or
use a button on the device.

4. WHY REMOTE LOCATOR SYSTEM ??
 Less expensive than wired solutions.
 Sophisticated remote locators can be used in
inaccessible areas
 Can be used in locations where wired
infrastructure doesn’t exist.
 (add more if you can think of anything !!)

5. HOW IS THIS REMOTE LOCATOR DOING WITH
RESPECT TO GLOBAL USERS??
Research has predicted that the users will almost
triple by 2015 globally !

6. HARDWARE REQUIREMENTS:
 Keypad
 Liquid Crystal Display (LCD) screen
 8051 Microcontroller
 UART cables
 RF transmitter and receiver
 Buttons or switches

7. SCHEMATIC BLOCK DIAGRAM OF THE
SUBSYSTEM:
This subsystem has basically got 2 units namely BASE UNIT and REMOTE UNIT.

8. BASE UNIT INPUTS AND OUTPUTS:
 INPUTS:
1. Vcc
2. Keypad
3. On/Off button
4. Alert Button
5. Audible Tone Off button
 OUTPUTS:
1. LCD
2. 8051 Microcontroller
3. RF Transmitter
REMOTE UNIT INPUTS:
1. Vcc
2. Off button
3. Remote signal

9. LET’S GET STARTED..
(On the base unit)
 When an item is lost, the user scrolls through a
LCD screen. The name of the lost item is found
in the locator menu and the locator button is
then pressed used the keypad.
 The locator or the user menu has three modes
of operation:
1. SAVE MODE
2. ALERT MODE
3. LOAD MODE

10. 1. SAVE MODE:
 This mode is used to designate a code of each thing to
be located and to assign each item to its remote device
and then saved in the menu. The codes are entered into
the list using KEYPAD.
2. ALERT MODE:
 The person is then able to scroll through the list of codes
and locate the desired thing, he can then select the item
and press the alert to transmit the signal (RF) to each
remote unit. The remote devices then receive the
transmitted signal and when the correct remote receives
the signal, it sounds the alarm on the remote on the
particular code.
3. LOAD MODE:
 When the person wants to add or replace a remote
device in the menu. The added remotes each have a
predefined code that is entered into the device and
stored so that the device knows what signal to send in
order to activate the remote for this new item.

11. MAIN MENU:
 The main menu allows the person to choose
which mode of operation to be used.
 The menu is displayed on the LCD and the user
uses the keypad to select the desired mode.
Diagram 4 shows the software flow chart for the
main menu.

12. SAVE MODE:
 The LCD prompts the user to choose which remote unit to save
a name to a location.
 Then the person uses the keypad to choose which remote to
be named and can then use the keypad to enter the desired
name.
 The 8051 microcontroller then saves the entered name in a
module and the LCD goes back to displaying the main menu.
 The device which is remote is not used during this mode of
operation.

13. ALERT MODE:
 The LCD prompts the user to choose which remote unit is
to be found.
 The input keypad is used to scroll through the list and
choose the name of the desired item to be found.
 The 8051 microprocessor repeatedly sends the saved ID
number to the RF transmitter.
 The circuit of transmitter transmits the RF remote signal to
the remote unit receiver circuit.
 The receiver circuit then demodulates the received signal
and outputs the signal to the decoding circuit.
 The decoding circuit determines the ID number and
compares it to the predefined number of each remote
device.
 The remote device that has the matching ID number
produces the alarm until the user turns it off on the device
or the remote unit itself, using the alarm off switch

15. LOAD MODE:
 The LCD prompts the user to choose which remote
unit is being added.
 The input device keypad is then used to choose the
proper remote unit for loading the data.
 After that the LCD prompts the user to enter the
new ID number for the remote device, with the
help of keypad.
 the microcontroller then saves the ID number in a
module.

16. UART CIRCUITRY: (BASE TO REMOTE UNIT)

17. 1. The UART is used to separate the ID number from the
packed serial bit-stream transmitted from the base unit of
the subsystem.
2. The UART finds the beginning and the end of the
transmitted signal and then chucks the start and stop bits
that were added to the ID number before the transmission
of the bits.
3. The UART then carries out the intended ID number (shown
below) to the digital decoding and compare circuitry of
the subsystem.

18. DIGITAL DECODING OR COMPARING CIRCUITRY

19. 1. The purpose of this circuitry is to determine the
transmitted ID code and to compare this code to
the predefined code of the remote device.
2. ID code is stored in each flip flop of an eight-bit
shift register in order to decode and determine the
ID number code. The output of each flip-flop will be
compared to the predefined number for each
remote device.
3. If each flip-flop output matches the predefined
number code, the circuit produces a high output
else it produces a low output to the tone generating
circuit.

20. TONE GENERATING CIRCUITRY:
 The speaker on the device produces an
audible alert tone when it receives a high input
from the comparator circuitry.

21. CONCLUSION:
 When the particular thing is lost, the user uses a
display to see where the object is.
 The code or an identity of the lost item is found
in a predefined list of the lost things.
 The remote unit attached to the desired thing
like display or watch receives the transmitted
digital code from the unit and produces an
alarm to alert the user to locate the thing.
 Its applications include using sophisticated,
long range remote locators in inaccessible
areas where humans can’t venture.
 (ASHWIN ADD MORE IF YOU HAVE ANY!)