Design And Construction Of An Auto Intensity Control Of Street Lights

ABSTRACT

Street lights are controlled manually in olden days. These days automation of street lights has emerged. But one can observe that there is no need of high intensity in peak hours i.e. when there is no traffic and even in early mornings. By reducing the intensity in these times, energy can be saved to some extent. This device automatically controls the intensity of street lights which is designed using microcontroller and LEDs.

The circuit consists of ATmega8 controller, Real time clock and LDR. Depending on the time and LDR value, micro controller automatically adjusts the intensity of the street lights using pulse width modulation. In this article, Pulse width modulation signal is generated in ATmega8 micro controller using timer/counter-2 at OCR2 i.e. PB3 pin.

Real time clock IC used is DS1307. It is compatible to I2C protocol. RTC acts as a slave. Time is read from RTC IC and micro controller automatically adjusts the intensity of light by generating PWM signal.

Light Dependent Resistor (LDR) is used in this project to check the intensity of light. Depending on the intensity, lights can be switched ON or OFF. Both light dependent resistor and real time clock are required for this project. Because, using Light dependent resistor alone may lead to wastage of energy. Using RTC alone may cause the lights to be switched on even when there is light.

0.1 Auto Intensity Control of Street Lights Circuit Principle:

• 1 Auto Intensity Control of Street Lights Circuit Diagram:
  • 1.1 Auto Intensity Control of Street Lights Circuit Design:
  • 1.2 Auto Intensity Control of Street Lights Circuit Simulation Video:
  • 1.3 How Auto Intensity Control of Street Lights Circuit Works?
  • 1.4 Auto Intensity Control of Street Lights Circuit Advantages:
  • 1.5 Limitations of this Circuit:

Street lights are controlled manually in olden days. These days automation of street lights has emerged. But one can observe that there is no need of high intensity in peak hours i.e. when there is no traffic and even in early mornings. By reducing the intensity in these times, energy can be saved to some extent. We have already published a post about Automatic Street Light Controller circuit which was designed using Relays and LDRs. This article explains the circuit that automatically controls the intensity of street lights which is designed using microcontroller and LEDs.

·         Auto Intensity Control of Street Lights Circuit Principle:

• The circuit consists of ATmega8 controller, Real time clock and LDR. Depending on the time and LDR value, micro controller automatically adjusts the intensity of the street lights using pulse width modulation. In this article, Pulse width modulation signal is generated in ATmega8 micro controller using timer/counter-2 at OCR2 i.e. PB3 pin.

Real time clock IC used is DS1307. It is compatible to I2C protocol. RTC acts as a slave. Time is read from RTC IC and micro controller automatically adjusts the intensity of light by generating PWM signal.

Light Dependent Resistor (LDR) is used in this project to check the intensity of light. Depending on the intensity, lights can be switched ON or OFF. Both light dependent resistor and real time clock are required for this project. Because, using Light dependent resistor alone may lead to wastage of energy. Using RTC alone may cause the lights to be switched on even when there is light.

Auto Intensity Control of Street Lights Circuit Diagram:

Circuit Diagram of Auto Intensity Control of Street Lights – Electronics Hub

Circuit Components:

• ATmega8 micro controller
• DS1307 IC
• Light Dependent Resistor
• LED array.
• LCD display

Related Post – Street Lights that Glow on Detecting Vehicle Movement

Auto Intensity Control of Street Lights Circuit Design:

The auto intensity control of street lights circuit is simple but it requires more coding part. This circuit consists of Atmega8 controller, DS1307, LDR, Relay and LEDs. The light dependent resistor is connected to ADC1 (PC1) pin of the micro controller. The analog light value is converted to digital value using ADC.

Real time clock has 8 pins out of which SCL and SDA are connected toPC5 and PC4 pins respectively. SCL is serial clock while SDA is serial data. As said before, RTC is I2C compatible, where I2C means inter integrated circuit. One bit of data is transmitted on data bus for each clock cycle. I2C protocol allows one to connect 128 devices. Data can be transferred between devices, using only two bi-directional buses. Each device can act as a slave or master. The slave devices will have one address and these devices can be accessed using this address.

LCD is the display used for displaying time which is read from RTC IC. Interfacing of LCD in 4bit mode is shown in circuit diagram. D4-D7 pins of LCD are connected to PD0-PD3 pins of microcontroller. RS pin of LCD is connected to PD4 pin of micro controller. RW and Enable pins are connected to PD5 and PD6 pins of controller.

LED array is number of high power LEDs connected in series. It is connected to PWM pin of the microcontroller.

I2C Protocol:

I2c is a communication protocol invented by Philips Company. This is well suited for communication between integrated circuits and pheripherals. This uses two lines to transfer data.

• Serial Data – SDA
• Serial Clock – SCL.

1. This can connect up to 128 devices using two wires. Each device connected will have an address. The device which initiates the data transfer is called Master.
2. Every device will have 7 bit address.
3.  Master initially sends the START bit on the data line.
4. Then it sends the address of the device with which wants to communicate and the mode of operation i.e. read or write.
5. The slave devices listen to the incoming data and checks if its address matches to the received data. The device whose address matches send an acknowledgement signal.
6. Then master starts transmitting or receiving the data from the slave.
7. After completion of the transmission, Master sends a STOP bit.
8. Data on SDA can be changed only if SCL pin is low.

Auto Intensity Control of Street Lights Circuit Simulation Video:

How Auto Intensity Control of Street Lights Circuit Works?

1. Initially power the circuit.
2. Time is displayed on the LCD display.
3. Place the LDR in darkness as the street lights switches on only when there is no light on LDR.
4. Now check the time if the time is between 9 pm to 2 am street light glows with full intensity.
5. Change the time by writing time to RTC and dump the code again.
6. Now switch on the circuit check the intensity. From 2pm intensity of the lights slowly starts decreasing and finally in early morning it glows with least intensity. When the light is sensed by the LDR lights are switched off automatically.

Code is written in such a way that up to 2 am lights will glow with full intensity. From then it slowly starts decreasing and finally it drops to zero in the morning.

Auto Intensity Control of Street Lights Circuit Advantages:

• Power wastage can be reduced.
• Using LED array reduces the cost.
• Using of RTC and LDR produces accurate results.

Limitations of this Circuit:

• Even though energy is saved if there are any vehicles after fixed time, intensity of the light is low.
• Maximum energy cannot be saved.