Coin based mobile charging using solar tracking system

Coin Based Mobile Charger Using Solar Tracking System 2014-15
This project is done by
Shashidhara T S ,S.I.T
TUMKUR ,if you like
the project idea and you
want to implement it
then contact :
8892484273,
shashits69@gmail.com
Dept. of E&C, SIT, Tumkur 1

CHAPTER 1
INTRODUCTION
Mobile phones have become a major source of business/personal communication.
The mobile phone business is currently worth billions of dollars, and supports
millions of phones. The need to provide a public charging service is essential.
1.1 MOTIVATION
Now a days students and many other people use the public transportation , people
who are making very long journey in order attend business conventions, conferences,
or for any private purpose don’t know that their battery level is low and they often
forget their charger at home or in hotel rooms. In rural areas there is no continuous
power supply about 13-14 hours. Many times battery becomes flat in the middle of
conversation particularly at inconvenient times when access to a standard charger
isn't possible . Many critics argued that long distance traveling vehicles provides
power points. Even though one or two power points are provided at a particular place
in the vehicles it is not all sufficient for all the passengers, therefore need to provide a
public charging service is essential and coin-based mobile battery chargers are
designed to solve these problems.
1.2 OBJECTIVE

The main aim of the project is to build a coin based mobile battery charger which
provides a unique service to both urban/rural public where grid power is not available
for partial/full time and a source of revenue for site providers for installation. The
coin-based mobile battery charger can be quickly and easily installed outside any
business premises and Solar energy is one of the abundant source of energy which is
freely available in the nature in this project solar tracking system is mainly used to
harness that energy in order to use it as power supply for charging the mobile.
1.3 ORGANIZATION OF THE REPORT
The report is divided into 5 chapters
Chapter 1: Introduction: Briefly describes the Motivation and the objectives.
Chapter 2: Block diagram description: Presents the block diagram of coin based
mobile charger using solar tracking system with a brief description of
each component.
Chapter 3: Hardware description: It encloses description of all the components,
their features with specifications.
Chapter 4: Software implementation: It describes the algorithm using flowchart
and software used.
Chapter 5: Results: This chapter includes the execution part of the project and the
results obtained.
Chapter 6: Conclusion and Future enhancement: It Includes Conclusion,
advantages ,applications and future enhancement.

CHAPTER 2
BLOCK DIAGRAM DESCRIPTION
The block diagram of the project coin based mobile charger using solar tracking
system is shown in Figure 2.1.
Figure 2.1: Block diagram of coin based mobile charger using solar tracking system.

The mobile battery charger starts charging a mobile connected to it, when a coin is
inserted at the insertion slot at the input stage. The type of coin will be displayed at
the LCD display for the user, so as to ensure correct coin insertion, if the correct coin
is inserted, the proximity sensor detects the coin and coin detection system sends a
pulse to the control unit authorizing to start mobile battery charging by enabling relay
where it acts as switch, regulator is used to supply the required voltage and current for
charging mobile. Solar panel used to harness solar energy whereas five LDR and
stepper motor is used to track the Sun to attain the maximum efficiency.
CHAPTER 3
HARDWARE DESCRIPTION
3.1. HARDWARE IMPLEMENTATION
The hardware implementation mainly consists of three sections Coin detection, Solar
tracking and mobile charging system. The implementation is shown in Figure 3.1.

Figure 3.1: Hardware Implementation Of Coin Based Mobile Charger Using Solar
Tracking System.
3.2. DESCRIPTION OF SOLAR TRACKING SYSTEM WITH
BLOCK DIAGRAM
Solar energy is one of abudantly available renewable source of energy. Presently
this field is having more demand and is likely to become integrated into more and
more aspects of every day life.

Different mechanisms are applied to increase the efficiency of the solar cell. Solar
tracking system is most appropriate technology to increase the output power of solar
cell . The mechanical movement of the solar panel is controlled through the stepper
motor, as shown in the Figure 3.2
Figure 3.2: Block diagram for solar tracking system.
As shown in the Figure 3.2 LDRs will be placed on edges of the solar panel or on a
separate platform, so according to the Sun light intensity LDR resistance will be
varied. Whenever the Sun light intensity is more LDR offers less resistance the
voltage across each LDR is given to ADC. According to this ADC shows the
equivalent digital output. Based on the received values from ADC, microcontroller
makes the decisions in accordance with the algorithm designed and rotates the stepper
motor to required position.
3.2.1 SOLAR PANEL
A major component of the solar tracking device will be the photovoltaic solar
panel that collects the sunlight and translates that into useful form energy.
Polycrystalline solar panels are economically feasible and are moderately efficient,
so this project uses 5x5cm solar panel with voltage and current ratings of

4V,100mA respectively. A polycrystalline solar panel is as shown in Figure 3.3. This
panel is mounted on the shaft of the stepper motor.
Figure 3.3: Polycrystalline solar panel.
3.3 LIGHT DEPENDENT RESISTOR (LDR)
It is an electronic component whose resistance decreases with increasing incident
light intensity. This project uses LDR as the sensor to sense the position of the Sun.
LDRs will be placed on edges of the solar panel or on a separate platform. A typical
LDR is as shown in Figure 3.4.
Figure 3.4: Light Dependent Resistor (LDR).
3.3.1 DESIGN OF LDR SENSOR CIRCUIT
As the sunlight falls on the LDR, the resistance of LDR falls. This allows
the current to easily pass through LDR thus voltage across LDR drops. But when
no light falls on LDR, the resistance is maximum thus voltage drop across LDR is
more. Figure 3.5 shows the complete sensor circuit.

Figure 3.5: Sensor circuit diagram.
3.3.2. LDR SENSOR CIRCUIT ARRANGMENT
LDR Sensor circuit consists of five LDR sensors and each LDR is covered using
hollow tubes as shown in Figure 3.6. It can either fixed on the panel or on a separate
platform.
Figure 3.6: LDR arrangement.
3.4 STEPPER MOTOR DRIVER CIRCUIT
ULN2803 is a stepper motor driver. It is mainly used for interfacing between low
logic level digital circuitry (such as TTL, CMOS or PMOS/NMOS) and the higher
current/voltage requirements of Stepper motors.

The phase inputs given to stepper motor from the microcontroller is in TTL logic
(0 to 3.5V) which is not sufficient to drive the stepper motor, so ULN2803 is used as
driver for stepper motor.
3.5 STEPPER MOTOR
A stepper motor is an electromechanical device which converts electrical pulses
into discrete mechanical movements. The stepper motor is used for position
controlling in the applications like disk drives, robotics and tracking systems.
This project makes use of 12 volt,1A,1.8degree-per-step, 4 phase bipolar stepper
motor since it provides heavy torque and commonly used to drive larger loads
such as solar panels etc.
Solar panel is mounted on shaft of the stepper motor where the direction and steps
for rotation is received from microcontroller through ULN2803.
3.6 COIN DETECTION SYSTEM
Figure 3.7: Coin detection system.
Coin accepted is based on the Proximity sensor, where diameter of the coin and
whether it is a coin or not is checked by proximity sensor as shown in the Figure 3.7.
If the inserted coin doesn’t match required specification, microcontroller will not
enable the charging system. If correct coin is inserted, invokes microcontroller along
with LCD interface and initiates mobile charging system.

3.6.1 PROXIMITY SENSOR
A proximity sensor is a sensor able to detect the presence of nearby objects
without any physical contact as shown in the Figure3.8.
Figure 3.8: Proximity Sensor.
A proximity sensor often emits an electromagnetic or electrostatic field, or a beam
of electromagnetic radiation (infrared, for instance), and looks for changes in the
field or return signal. The object being sensed is often referred to as the proximity
sensor's target.
Different proximity sensor targets demand different sensors. For example, a
capacitive or photoelectric sensor might be suitable for a plastic target; an
inductiveproximity sensor requires a metal target. As shown in the Figure 3.8. This
project uses 6 - 36V,200mA proximity sensor.
3.7 ANALOG TO DIGITAL CONVERTER (ADC)
It is an analog to digital converter. In this project ADC0809 with 8-channel single-
ended analog signal multiplexer with three select lines is used. A particular input
channel is selected by using the address decoder. Table 3.1 shows the input states for
the address lines to select any channel. The address is latched into the decoder on the
low-to-high transition of the address latch enable signal.
Table 3.1: Address for input selection.

The converter is designed to give fast, accurate, and repeatable conversions over a
wide range of analog voltage levels. The converter is partitioned into 3 major
sections: the 256R ladder network, the successive approximation register and the
comparator. The converter’s digital outputs are positive true.
Here IN0, IN1, IN2, IN3 and IN4 are used as input pins where inputs are given
from five LDRs respectively. The outputs of ADC i.e. D0 to D7 is connected to Port2
of microcontroller as shown in Figure 3.1.
3.8. LIQUID CRYSTAL DISPLAY (LCD)
Figure 3.9: Pin diagram of 16X2 LCD.
The Figure 3.9 shows the pin diagram of 16X2 LCD display. In this LCD each
character is displayed in 5X7 pixel matrix. While Vcc and GND (Vss) are connected
to +5V and ground respectively, Vee is used for controlling contrast. In this project
LCD is used to display message for coin insertion and detection, mobile charging
initiation and completion.
RS ( Register select)

The register select pin of LCD is connected to P3.6 pin of microcontroller. The RS
pin is used for selecting the registers. If RS is low, command register is selected,
allowing the user to send commands such as clear display, cursor at home etc. If RS is
high, data register is selected, allowing the user to send data to be displayed on the
LCD.
R/W (read/write)
R/W input allows the user to write information to the LCD or read information
from it. When reading R/W=1; when writing R/W = 0.
EN (enable)
The enable pin is used by the LCD to latch information present on its data pins.
When data is supplied to data pins, a high to low pulse must be applied to this pin in
order for the LCD to latch the data present at the data pins. This pulse must have a
minimum width of 450ns. EN pin of LCD is connected to P3.7 pin of microcontroller.
DB0-DB7
The 8-bit data pins DB0-DB7, are used to send information to the LCD or read the
contents of the LCD’s internal registers. To display letters and numbers, ASCII codes
for the letters A-Z, a-z and numbers 0-9 are sent to these pins while making RS as
high. Here DB0 to DB7 pins of LCD are connected P1.0 to P1.7 of microcontroller.
3.9 RELAY
Relay is an electrically operated switch. Many relays use an electromagnet to
operate a switching mechanism mechanically. In this project HEJQC3FC relay with
maximum current and voltage rating of 7.5A,14V is used, to supply +5V to multi
charger connector when it receives enable signal from microcontroller.
3.10 REGULATOR( LM317 )
The LM317 series of adjustable 3-terminal positive voltage regulators is capable of
supplying in excess of 1.5A over 1.2V to 37V output range. The Figure 3.11 Circuit
design using LM317.

In this project LM317 is used to attain 5V and 12V output voltages. Here input
voltage must be greater than required output voltage and it is given from the batterty
of 12V and 1.5A which is charged using solar panel.
Figure 3.11: Circuit design using LM317.
3.11 MICROCONTROLLER
The P89V51RD2 is 80C51 microcontroller with 64KB flash and 4KB of data
RAM.
The flash program memory supports both parallel programming and in serial ISP.
Parallel programming mode offers gang-programming at high speed, reducing
programming costs and time to market. ISP allows a device to be reprogrammed in
the end product under software control. The capability to field/update the application
firmware makes a wide range of applications possible.
The microcontroller[4] P89V51RD2 is used to give the control signals to the
stepper motor driver in order to generate the necessary sequence required to
energize the winding of the stepper motor and to give enable input to initiate
charging for certain interval of time.
Unique features of the microcontroller are as follows:
1. 8051 Central Processing Unit.
2. 5 V Operating voltage from 0 to 40 MHz.
3. 64 KB of on-chip Flash program memory with ISP (In-System Programming).
5. SPI (Serial Peripheral Interface) and enhanced UART.
6. Four 8-bit I/O ports with three high-current Port 1 pins (16mA each).
7. Three 16-bit timers/counters with Programmable Watchdog timer (WDT).
8. Eight interrupt sources with four priority levels.
9. TTL- and CMOS-compatible logic levels.

CHAPTER 4
SOFTWARE IMPLEMENTATION
4.1 SOFTWARE REQUIRED
The software implementation of the project is described in this chapter. The
programs for interfacing the LCD, Stepper motor and ADC is written in C language
and burnt in microcontroller with the help of Keil software.
4.1.1 Introduction to Keil
Keil was found in 1986 in order to market the add-on products for the
development tools provided by the silicon vendors. Keil implemented the first C
compiler designed for the group-up specifically for 8051 microcontroller. Keil
software development tools for the 8051 microcontroller family supports every level
developer from beginners to the professional applications engineer.
Creating HEX file:
• Open Keil and start a new project.
• Select device for target ‘Target 1’.
• P89V51RD2 will be selected as target device.
• Click on ‘Source Group’ and then click on ‘Add files to source group’.
• Choose the file and add it to ‘Source group’.
• Go to options for target ‘Target 1’, under output tab check the box ‘Generate
. Hex file’.
Dumping HEX file
• Connect the programmer to the microcontroller board.
• Select the device and choose the proper baud rate.
• Erase the previous program on the device.
• Select ‘Auto’ to dump the program.

4.2 FLOWCHART OF THE SYSTEM
The flowchart of the system is shown in Figure 4.1.
Figure 4.1: Flow chart of the system.

4.3 FLOW CHART OF ADC CALCULATION
The flowchart of ADC calculation is shown in Figure 4.2
Figure 4.2: Flow chart of ADC calculation.

4.4 FLOW CHART OF SOLAR TRACKING
The flowchart of Solar tracking system is shown in Figure 4.3.
Figure 4.3: Flow chart of Solar tracking

CHAPTER 5
RESULTS
This chapter includes the execution part of the project and the results obtained.
Figure 5.1 and 5.2 shows the snapshot of the project outer view and inner view
respectively.
Figure 5.1: Project Outer view.
Figure 5.2: Project inner view.

As soon as the system is switched on, the LCD displays to insert one rupee coin as
shown in Figure 5.3.
Figure 5.3: Indicates to insert one rupee coin.
After coin is inserted, LCD displays coin detected and mobile starts charging as
shown in Figure 5.4.
Figure 5.4: Indicates coin is detected.

As soon as the charging is initiated from microcontroller, LCD displays charging
started as shown in Figure 5.5.
Figure 5.5: Indicating the initiation of mobile charging.
If the light intensity on LDR0 is more, the stepper motor rotates to position as
shown in the Figure 5.6.
Figure 5.6: Indicating the Zeroth position of the solar system.

If the light intensity on LDR1 is more, the stepper motor rotates to position as shown
in the Figure 5.7.
Figure5.7: Indicating the First position of the solar system
in the Figure 5.8.
Figure5.8: Indicating the Second position of the solar system.

in the Figure 5.9.
Figure 5.9: Indicating the Third position of the solar system
in the Figure 5.10.
Figure 5.10: Indicating the Fourth position of the solar system

CHAPTER 6
CONCLUSION AND FUTURE ENHANCEMENT
6.1 CONCLUSION
In this project a novel method of charging mobile batteries of different
manufacturer using solar power has been designed for rural and remote areas
where the power supply is not at all available all the time. This project can be
implemented outside any premises where the user has to plug the mobile phone into
one of the suitable multi charge connector pin by inserting a coin in order to charge
the mobile. It is, of course, possible to continue charging by inserting more coins. In
the meanwhile continuous solar tracking is done.
6.2 ADVANTAGES:
1. The coin-based mobile battery charger can be quickly and easily installed
outside any business premises.
2. Low power consumption.
3. Simple and portable.
4. Cost effective.
5. Effectively receive maximum energy due to solar tracking system used.
6. No external source required.
7. Universal charger.
8. One time investment.
6.3 APPLICATIONS:
1. It can be installed in urban/rural areas where grid power is not
available for partial/full time.
2. It can be installed in public places like Hotels, conference centers, serviced
offices, leisure centers, retail outlets, in vehicles etc.
6.4 FUTURE ENHANCEMENT
This project can be enhanced by Implementing Image processing for coin
detection system.

BIBLIOGRAPHY
1. M.S. Varadarajan. “Coin Based Mobile Battery Charger” . Veltech Dr.RR and
Dr.SR Technical University Chennai, India Journal of Engineering
(IOSRJEN) ISSN: 2250-3021 Volume 2, Issue 6 (June 2012), PP 1433-1438.
2. David A. Bell, “Electronic Devices and Circuits”, 4th
edition, Prentice-Hall of
India Private Limited, 2013.
3. Robert L. Boylestad and Louis Nashelsky, “Electronic Devices and Circuit
Theory”, 9th
edition, Pearson Education, 2013.
4. Muhammed Ali Mazidi, Janice Gillispie Mazidi, Rolin.D.Mckinlay, “The
8051 microcontroller and embedded systems”, 2nd
edition, Prentice-Hall of
India Private Limited, 2012 reprint.
5. Millman And Halkias, ”Integrated circuits”, 5th
edition, Tata McGraw Hill
publications, Pune, 2012.

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Coin based mobile charging using solar tracking system

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