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ABSTRACT
High intensity discharge lamp (HID) presently used for urban street light are based on principle of gas discharge, thus the intensity is not controllable by any voltage reduction method as the discharge path is broken. White Light Emitting Diode (LED) based lamps are soon replacing the HID lamps in street light. Thus intensity control is now possible by pulse width modulation based on sensing the movement and density of vehicles. The pulse width becomes very narrow on sensing no movement of vehicles. As the vehicle moves forward, the intensity goes on increasing for few lights ahead, and as it passes away the intensity goes on falling. Thus this way of dynamically changing intensity helps in saving a lot of energy. A programmable microcontroller is engaged to provide different duty cycle for different intensities at different density conditions.
1. INTRODUCTION
The main objective of this project is to reduce the power consumption in the streets. According to the existing system, power consumption is more due to the irregular functionalities of the street lights. By using our proposed system, we can control the consumption of power. initially, the light will be in dim condition, whenever the vehicle crosses the sensor(controller),light starts to increase .brightness of the light is depends on the number of vehicles which crosses the sensor. if one vehicle crosses the sensor, the light will be in minimum bright. More than 3 vehicles crosses the sensor, the light will be in maximum bright. by this proposed system we can control the power consumption of the street light.

We have two modes in this project for saving power
1. General mode (For vehicles only)
2. Dim mode (both for vehicles and pedestrians)
In general mode we can save more power than dim mode. In this mode the LED glows only based on the vehicle movement but for pedestrians this mode cannot be useful but the advantage of this mode is to save more power. In this mode we can save up to 50% of power.
In dim mode we can save less power, but this mode is useful for pedestrians as the LED glows with less intensity but based on the vehicle movement intensity increases. The advantage of this mode is, it is useful for pedestrians but it saves less power. In this mode we can save upto 35% of power
2. EMBEDDED SYSTEMS
Embedded system
An Embedded System is a combination of computer hardware and software, and perhaps additional mechanical part designed to perform a specific function. An embedded system is a microcontroller-based, software driven, reliable, real-time control system, autonomous, or human or network interactive, operating on diverse physical variables and in diverse environments and sold into a competitive and cost conscious market.
An embedded system is not a computer system that is used primarily for processing, not a software system on PC or UNIX, not a traditional business or scientific application. High-end embedded & lower end embedded systems. High-end embedded system - Generally 32, 64 Bit Controllers used with OS. Examples Personal Digital Assistant and Mobile phones etc .Lower end embedded systems - Generally 8,16 Bit Controllers used with an minimal operating systems and hardware layout designed for the specific purpose. Examples Small controllers and devices in our everyday life like Washing Machine, Microwave Ovens, where they are embedded in.
SYSTEM DESIGN CALLS:
Fig:2.1 System Design Calls
EMBEDDED SYSTEM DESIGN CYCLE
Fig:2.2 “V Diagram”
Characteristics of Embedded System
• An embedded system is any computer system hidden inside a product other than a computer.
• They will encounter a number of difficulties when writing embedded system software in addition to those we encounter when we write applications
– Throughput – Our system may need to handle a lot of data in a short period of time.
– Response–Our system may need to react to events quickly.
– Testability–Setting up equipment to test embedded software can be difficult.