14-04-2011, 11:23 AM
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ABSTRACT
Automotive vehicles are increasingly being equipped with collision avoidance and warning systems for predicting the potential collision with an external object, such as another vehicle or a pedestrian. Upon detecting a potential collision, such systems typically initiate an action to avoid the collision and/or provide a warning to the vehicle operator.
This system consist of a distance-measuring system based on ultrasonic sound utilizing the PIC 16f877A microcontroller and transmits a burst of ultrasonic sound waves towards the target and then receives the corresponding echo. An ultrasonic sound sensor is used to detect the arrival of the echo to the system. The time taken for the ultrasonic burst to travel the distance from the system to the subject and back to the system is accurately measured by the microcontroller. It also provides a warning signal to the driver if the distance between vehicle and obstacle crosses a particular limit. It also monitors the speed of the vehicle and if the speed limit is exceeded it is informed to the driver. The speed limit for different class of vehicles is set by authorities at different.
1. INTRODUCTION
This report describes a distance-measuring system based on ultrasonic sound utilizing the PIC 16f877A microcontroller. With the help of the distance measured, the micro-controller will make the vehicle stop suddenly if the vehicle is about to hit any obstacle or any other vehicle. With the help of this technology accidents are avoided. The system transmits a burst of ultrasonic sound waves towards the target and then receives the corresponding echo. An ultrasonic sound sensor is used to detect the arrival of the echo to the system. The time taken for the ultrasonic burst to travel the distance from the system to the subject and back to the system is accurately measured by the microcontroller.
Different types of vehicle speed limiters are in current use for regulating traffic especially across roads near populated areas such as hospitals, malls and schools. This project “DYNAMIC SPEED GOVERNER” is a new method by which vehicle speed is controlled externally rather than internally. The speed measurement and control is accomplished via two PIC16F877As with a RF transmitter and a receiver.
SOFTWARE SPECIFICATION
MPLAB IDE
MPLAB Integrated Development Environment (IDE) is a free, integrated toolset for the development of embedded applications employing Microchip’s PIC and dsPIC microcontrollers. MPLAB IDE runs as a 32-bit application on MS Windows, is easy to use and includes a host of free software components for fast application development and supercharged debugging. MPLAB IDE also serves as a single, unified graphical user interface for additional Microchip and third party software and hardware development tools. Moving between tools is a snap, and upgrading from the free software simulator to hardware debug and programming tools is done in a flash because MPLAB IDE has the same user interface for all tools.
A development system for embedded controllers is a system of programs running on a desktop PC to help write, edit, debug and program code- the intelligence of embedded systems applications in to a microcontroller. MPLAB IDE, runs on a PC and contains all the components needed to design and deploy embedded systems applications.
MPLAB IDE Programmer’s Editor helps write correct code with the language tools of choice. The editor is aware of the assembler and compiler programming constructs and automatically “color-keys” the source code to help ensure it is syntactically correct. The Project Manager enables you to organize the various files used in your application source files,processor description header files and library files.
Language tools run into errors when building the application, the offending line is shown and can be “double-clicked” to go to the corresponding source for immediate editing. After editing, press the “build” button to try again. Often this write-compile-fix loop is done many times for complex code, as the subsections are written and tested.
Once the code builds with no errors, it needs to be tested. MPLAB IDE has components called “debuggers” and free software simulators for all PICmicro and PIC devices to help test the code. Even if the hardware is not yet finished, you can begin testing the code with the simulator, a software program that simulates the execution of the microcontroller.
Once the hardware is in a prototype stage, a hardware debugger, such as MPLAB ICE or MPLAB ICD 2 can be used. These debuggers run the code in real time on your actual application. The MPLAB ICE physically replaces the microcontroller in the target using a high-speed probe to give you full control over the hardware in your design. The MPLAB ICD 2 uses special circuitry built into many Microchip MCUs with Flash program memory and can “see into” the target microcontrollers program and data memory. The MPLAB ICD 2 can stop and start program execution, allowing you to test the code with the microcontroller in place on the application. After the application is running correctly, you can program a microcontroller with one of Microchip’s device programmers, such as PICSTART Plus or MPLAB PM3. These programmers verify that the finished code will run as designed. MPLAB IDE supports most PICmicro MCUs and every PIC Digital Signal Controller.
How MPLAB IDE Helps
The organization of MPLAB IDE tools by function helps make pull-down menus and customizable quick keys easy to find and use. MPLAB IDE tools allow us to Assemble, compile, and page link source code. Debug the executable logic by watching program flow with the simulator, or in real time with the MPLAB-ICE emulator. Make timing measurements, view variables in watch windows, program firmware with PICSTART Plus or PRO MATE II, find quick answers to questions from the MPLAB IDE on-line Help and much more.
MPLAB IDE – An Integrated Development Environment
MPLAB IDE is an easy-to-learn and use Integrated Development Environment (IDE). The IDE provides firmware development engineers the flexibility to develop and debug firmware for Microchip’s PICmicro MCU families. The MPLAB IDE runs under Microsoft Windows 3.1x, Windows 95/98, Windows NT, or Windows 2000.
MPLAB IDE provides functions that allow you to:
1.Create and Edit Source Files
2.Group Files into Projects
3.Debug Source Code
4.Debug Executable Logic Using the Simulator or Emulator(s)
The MPLAB IDE allows you to create and edit source code by providing you with a full-featured text editor. Further, you can easily debug source code with the aid of a Build Results window that displays the errors found by the compiler, assembler, and linker when generating executable files. A Project Manager allows you to group source files, precompiled object files, libraries, and linker script files into a project format.
The MPLAB IDE also provides feature-rich simulator and emulator environments to debug the logic of executables. Some of the features are a variety of windows allowing you to view the contents of all data and program memory locations source code, program memory and absolute listing windows allowing you to view the source code and its assembly-level equivalent separately and together.
CCS C COMPILER
The compiler contains Standard C operators and built in libraries that are specific to the PIC registers. Access to hardware features from C. The compiler includes built-in functions to access the PIC microcontroller hardware such as READ_ADC to read a value from the A/D converter. Discrete I/O is handled by describing the port characteristics in a PRAGMA. Functions such as INPUT and OUTPUT_HIGH will properly maintain the tri-state registers. Variables including structures may be directly mapped to memory such as I/O ports to best represent the hardware structure in C.
The microcontroller clock speed may be specified in a PRAGMA to permit built in functions to delay for a given number of microseconds or milliseconds. Serial I/O functions allow standard functions such as GETC and PRINTF to be used for RS-232 like I/O.
The compiler runs under Windows 95, 98, ME, NT4, 2000, XP, Vista or Linux. It outputs hex and debug files that are selectable and compatible with popular emulators and programmers including the MPLAB IDE for source level debugging.
Functions may be implemented inline or separate, allowing to optimize for either ROM concerns or speed concerns. Function parameters are passed in reusable registers. Inline functions with reference parameters are implemented efficiently with no memory overhead. During the linking process the program structure, including the call tree, is analyzed. Functions that call one another frequently are grouped together in the same page segment. Functions may be implemented inline or separate. RAM is allocated efficiently by using the call tree to determine how locations can be re-used. Constant strings and tables are saved in the device ROM.
