04-11-2016, 11:24 AM
1464403695-COINBASEDMOBILECHARGERPROJECTREPORT.doc (Size: 3.18 MB / Downloads: 6)
INTRODUCTION
1.1.1 COIN INSERTION MOBILE CHARGER
This is the smart coin based mobile charging system that charges your mobile for particular amount of time on inserting a coin. The system is to be used by shop owners, public places like railway stations to provide mobile charging facility. So the system consists of a coin recognition module that recognizes valid coin is found it signals the microcontroller for further action. if a valid coin is found it signals the microcontroller and microcontroller then starts the mobile charging mechanism providing a 5v supply through a power supply through a power supply section to the mobile phone, now systems also needs to monitor the amount of charging to be provided .So the system can be used for smart mobile charging at public places.
The objective of this project is inserting the coin using charge for your mobile phone in public places. This project is very useful to people who are all using mobile phone without charging condition in public places. In this project, who are all using mobile phones in outside of home are office without charging condition. The coin based mobile phone charger is very useful to that person for using coin to charge for that mobile. A sensor system is used to detect the presence of coin. It may be of different type (IR sensor, Using LDR etc...). The coin is inserted between the transmitted and received signal.
When a signal came from sensor unit, the microcontroller activates the charger unit for a predefined time. After that it will reset to normal case. Driver circuit is used for provide the sufficient input voltage of relay. The relay will on to activate the 230v charger, we will use charger to charge for our mobile phone.
The major action in this system is controlled by transmitter section; this section consists of IR transmitter and IR receiver. Here we need to generate IR frequency continuously. So that by using a small tiny microcontroller frequency is produced and is connected IR receiver continuously receives the signals from the transmitter. Whenever the light path in between IR transmitter and IR receiver cuts by an obstacle receiver signal gives low to high pulse. By
to the IR led to generate IR light rays of 38 KHz frequency.
Connecting the receiver output to the micro controller interrupt pin, it gives interrupt to the micro controller immediately the system gives the buzzer and sends the message to the display on LCD display to the micro controller.
8051 Microcontroller
The microcontroller memory is divided into Program Memory and Data Memory. Program Memory (ROM) is used for permanent saving program being executed, while Data Memory (RAM) is used for temporarily storing and keeping intermediate results and variables. Depending on the model in use (still referring to the whole 8051 microcontroller family) at most a few Kb of ROM and 128 or 256 bytes of RAM can be used. However--
All 8051 microcontrollers have 16-bit addressing bus and can address 64 kb memory. It is neither a mistake nor a big ambition of engineers who were working on basic core development. It is a matter of very clever memory organization which makes these controllers a real “programmer’s tidbit“.
PIN Description:
Pins 1-8: Port 1 Each of these pins can be configured as input or output.
Pin 9: RS Logical one on this pin stops microcontroller’s operating and erases the contents of most registers. By applying logical zero to this pin, the program starts execution from the beginning. In other words, a positive voltage pulse on this pin resets the microcontroller.
Pins10-17: Port 3 Similar to port 1, each of these pins can serve as universal input or output. Besides, all of them have alternative functions:
Pin 10: RXD Serial asynchronous communication input or Serial synchronous communication
output.
Pin 11: TXD Serial asynchronous communication output or Serial synchronous communication
output.
Pin 12: INT0 Interrupt 0 input
Pin 13: INT1 Interrupt 1 input
Pin 14: T0 Counter 0 clock input
Pin 15: T1 Counter 1 clock input
Pin 16: WR Signal for writing to external (additional) RAM
Pin 17: RD Signal for reading from external RAM
Pin 18, 19: X2 X1 Internal oscillator input and output. A quartz crystal which determines operating frequency is usually connected to these pins. Instead of quartz crystal, the miniature ceramics resonators can be also used for frequency stabilization. Later versions of the microcontrollers operate at a frequency of 0 Hz up to over 50 Hz.
Pin 20: GND Ground
Pin 21-28: Port 2 If there is no intention to use external memory then these port pins are configured as universal inputs/outputs. In case external memory is used then the higher address byte, i.e. addresses A8-A15 will appear on this port. It is important to know that even memory with capacity of 64Kb is not used (i.e. note all bits on port are used for memory addressing) the rest of bits are not available as inputs or outputs.
Pin 29: PSEN If external ROM is used for storing program then it has a logic-0 value every time the microcontroller reads a byte from memory.
Pin 30: ALE Prior to each reading from external memory, the microcontroller will set the lower address byte (A0-A7) on P0 and immediately after that activates the output ALE. Upon receiving signal from the ALE pin, the external register (74HCT373 or 74HCT375 circuit is usually embedded) memorizes the state of P0 and uses it as an address for memory chip. In the second part of the microcontroller’s machine cycle, a signal on this pin stops being emitted and P0 is used
for data transmission (Data Bus). In this way, by means of only one additional (and cheap) integrated circuit, data multiplexing from the port is performed. This port at the same time used for data and address transmission.
Pin 31: EA By applying logic zero to this pin, P2 and P3 are used for data and address transmission with no regard to whether there is internal memory or not. That means that even there is a program written to the microcontroller, it will not be executed, the program written to external ROM will be used instead. Otherwise, by applying logic one to the EA pin, the microcontroller will use both memories, first internal and afterwards external (if it exists), up to end of address space.
Pin 32-39: Port 0 Similar to port 2, if external memory is not used, these pins can be used as universal inputs or outputs. Otherwise, P0 is configured as address output (A0-A7) when the ALE pin is at high level (1) and as data output (Data Bus), when logic zero (0) is applied to the ALE pin.
Micro Controller-AT89S52
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry- standard 80C51 instruction set and pin out.
2.2.6 Features
8K Bytes of In-System Programmable (ISP) Flash Memory
Endurance: 1000 Write/Erase Cycles
4.0V to 5.5V Operating Range
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Full Duplex UART Serial Channel
Fully Static Operation: 0 Hz to 33 MHz
2.3 LCD (Liquid Crystal Display)
LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images which can be displayed or hidden, such as preset words, digits, and 7-segment displays as in a digital clock. They use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements.
LCDs are used in a wide range of applications including computer monitors, televisions, instrument panels, aircraft cockpit displays, and signage. They are common in consumer devices such as video players, gaming devices, clocks watches, calculators, and telephones, and have replaced cathode ray tube (CRT) displays in most applications. They are available in a wider range of screen sizes than CRT and plasma displays, and since they do not use phosphors, they do not suffer image burn-in.
LCDs are, however, susceptible to image persistence.
The LCD screen is more energy efficient and can be disposed of more safely than a CRT. Its low electrical power consumption enables it to be used in battery-powered electronic equipment. It is an electronically modulated optical device made up of any number of segments filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or monochrome. Liquid crystals were first discovered in 1888. By 2008, annual sales of televisions with LCD screens exceeded sales of CRT units worldwide, and the CRT became obsolete for most purposes.
An LCD is made with either a passive matrix or an active matrix display grid. The active matrix LCD is also known as a thin film transistor (TFT) display. The passive matrix LCD has a grid of conductors with pixels located at each intersection in the grid. A current is sent across two conductors on the grid to control the light for any pixel. An active matrix has a transistor located at each pixel intersection, requiring less current to control the luminance of a pixel. For this reason, the current in an active matrix display can be switched on and off more frequently, improving the screen refresh time.
Crystal Oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize.
Frequencies far radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.
Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.
Besides quartz, the other substances that exhibit the piezo-electric effect are Rochelle salt and tourmaline. Rochelle salt exhibits the greatest piezoelectric effect, but its applications are limited to manufacture of microphones, headsets and loudspeakers. It is because the Rochelle salt is mechanically the weakest and strongly affected by moisture and heat. Tourmaline is most rugged but shows the least piezo-electric effect. Quartz is a compromise between the piezoelectric effect of Rochelle salt and the mechanical strength of tourmaline. It is inexpensive and readily available in nature. It is mainly the quartz crystal that is used in radio-frequency (RF) oscillators.
A crystal oscillator is an electronic oscillator circuit which uses inverse piezoelectric effect, i.e. when electric field is applied across certain materials it produces mechanical deformation. Thus it uses mechanical resonance of a vibrating crystal of piezoelectric materiel to create an electric signal with very precise frequency. They have high stability, quality factor, small size and low cost and this makes them superior over other resonators like LC circuit, ceramic resonator, turning forks.
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminal.
Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits. The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its development in the early 1950s the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other thing.