04-01-2013, 04:01 PM
Vehicle Speed Control System Using RF Communication
1Vehicle Speed Control.pdf (Size: 1.29 MB / Downloads: 71)
INTRODUCTION
The project is mainly used to control the speed of a moving vehicle according signal received by the receiver from transmitter.
The Main Components of Project
Microcontroller
Vehicle or Robot
DC Motors, to run the Vehicle
RF Transmitter
RF Receiver
LCD, to display the status of Vehicle and alert about the ZONE.
Power Supply
Working:
This project is developed based on EMBEDDED and RF Technology. When a vehicle enters a Danger Zone then the signal will be detected by the Rx which was transmitted by the Tx already placed in the Zone. The Signal received will be decoded by the microcontroller and alert the driver through a LCD Screen. According to signal received by Microcontroller controls the DC Motor Speed after a few seconds from the time it received the signal.
EMBEDDED SYSTEMS
An Embedded System is a special-purpose computer system designed to perform one or a few dedicated functions often with real-time computing constraints. It is usually embedded as part of a complete device including hardware and mechanical parts..
Embedded system controls many of the common devices. Physically, embedded systems range from portable devices such as digital watches and MP4 players. Now it ranges to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. Complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure.
Embedded processors can be broken into two broad categories: ordinary microprocessors (μP) and microcontrollers (μC), which have many more peripherals on chip, reducing cost and size.
Embedded systems are designed to do some specific task, rather than be a general-purpose computer for multiple tasks. Some also have real-time performance constraints that must be met, for reason such as safety and usability; others may have low or no performance requirements, allowing the system hardware to be simplified to reduce costs.
User Interfaces
Embedded systems range from no user interface at all - dedicated only to one task - to full user interfaces similar to desktop operating systems in devices such as PDAs.
A full graphical screen, with touch sensing or screen-edge buttons provides flexibility while minimizing space used the meaning of the buttons can change with the screen, and selection involves the natural behavior of pointing at what's desired.
The rise of the World Wide Web has given embedded designers another quite different option providing a web page interface over a network connection. This avoids the cost of a sophisticated display, yet provides complex input and display capabilities when needed, on another computer. This is successful for remote, permanently installed equipment. In particular, routers take advantage of this ability.
BRIDGE WAVE RECTIFIER
A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification. The term rectifier describes a diode that is being used to convert AC to DC.
A bridge-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Bridge-wave rectifier converts both polarities of the input waveform to DC (direct current), and is more efficient. However, in a circuit with a center tapped transformer (9-0-9) is used.
VOLTAGE REGULATOR
This is most common voltage regulator that is still used in embedded designs. LM7805 voltage regulator is a linear regulator. With proper heat sink these LM78xx types can handle even more than 1A current. They also have Thermal overload protection, Short circuit protection.
TCON (Timer Control, Addresses 88h, Bit-Addressable)
The Timer Control SFR is used to configure and modify the way in which the 8051's two timers operate. This SFR controls whether each of the two timers is running or stopped and contains a flag to indicate that each timer has overflowed. Additionally, some non-timer related bits are located in the TCON SFR. These bits are used to configure the way in which the external interrupts are activated and also contain the external interrupt flags which are set when an external interrupt has occurred.
TMOD (Timer Mode, Addresses 89h)
The Timer Mode SFR is used to configure the mode of operation of each of the two timers. Using this SFR your program may configure each timer to be a 16-bit timer, an 8-bit auto reload timer, a 13-bit timer, or two separate timers. Additionally, you may configure the timers to only count when an external pin is activated or to count "events" that are indicated on an external pin.
TIMER 0 AND TIMER 1
The "timer” or "counter "function is selected by control bits C/T in the special function register TMOD. These two timer/counters have for operating modes, which are selected by bit-pairs (M1/M0) in TMOD. Modes 0, 1, and 2 are the same for both timers/counters. Mode 3 is different.
RS232 STANDARD
RS denotes “Recommended Standard” and refers to official standards of Electronics Industries Association. RS-232 is the most known serial port used in transmitting the data in communication and interface. Even though serial port is harder to program than the parallel port, this is the most effective method in which the data transmission requires less that yields to the less cost. Serial RS-232 communication works with voltages (-15V ... -3V for high [sic]) and +3V ... +15V for low [sic]) which are not compatible with normal computer logic voltages.
The maximum RS-232 signal levels are far too high for computer logic electronics, and the negative RS-232 voltage for high cant be applicable at all by computer logic. Therefore, to receive serial data from an RS-232 interface the voltage has to be reduced, and the low and high voltage level inverted. In the other direction (sending data from some logic over RS-232) the low logic voltage has to be bumped up”, and a negative voltage has to be generated, too.
Independent channels are established for two-way (full-duplex) communications. The RS232 signals are represented by voltage levels with respect to a system common (power I logic ground). The “idle” state (MARK) has the signal level negative with respect to common, and the “active” state (SPACE) has the signal level positive with respect to common. RS232 has numerous handshaking lines (primarily used with modems), and also specifies a communications protocol.
SWITCH
In electronics, a switch is an electronic electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts. Each set of contacts can be in one of two states: either 'closed' meaning the contacts are touching and electricity can flow between them, or 'open', meaning the contacts are separated and non conducting.In this at the time of switch pressed(supply applied) the voltage across resister 8.2Kohms is VCC as capacitor is short circuit. And this switches are connected to LEDs by using microcontroller program. When we release the switch the capacitor get charges to VCC.
CONCLUSION
The project VEHICLE SPEED CONTROL SYSTEM USING RF COMMUNICATION has been successfully designed and tested.
It has been developed by integrating features of all the hardware components used. Presence of every module has been reasoned out and placed carefully thus contributing to the best working of the unit. Thus the data to be sent is encoded within the transmitted signal so that a well designed receiver can separate the data from the signal upon reception of this signal. The decoded data can then be used to perform specified tasks.
Secondly, using highly advanced IC‟s and with the help of growing technology the project has been successfully implemented.