PROJECT- I I

MICROCONTROLLERBASED

TRAFFIC CONTROL EMBEDDED SYSTEM

INDEX• INTRODUCTION• MICROCONTROLLER UNIT• FLOW CHART• BLOCK DIAGRAM• CIRCUIT OPERATION• COMPONENTS• PROJECT SNAP SHOTS• CONCLUSION• REFERENCE

What are Embedded Systems?

Embedded Systems are computing systems with tightly coupled hardware and software integration, which are designed to perform a specific task.

• Any device that includes a programmable computer but is not itself a general-purpose computer is an embedded system

• In simple terms, any device using a Microprocessor for control and automation is an Embedded System

What are traffic signals ?

Traffic Signals, also known as traffic lights, traffic lamps, signal lights are signalling devices positioned at or near road intersections, pedestrian crossings and other locations to control competing flows of traffic.

Traffic lights provide the right way to road users by displaying lights of a standard colour (red, yellow/amber, and green) following a universal colour code.

Why is traffic light an Embedded System?

• Traffic Lights contain a controller.

• The controller is appointed to control the changing of the lights accordingy.

• It consists of small no. of integrated chips (IC’s) which are programmed to perform a specific task.

• It also contains a timer which helps the controller to indicate the change of light after a specific interval of time.

MICRO- CONTROLLER UNIT

A Microcontroller which is also known as a true computer on a single chip. It has a CPU which contain ALU, PC, SP, REGISTERS.

In addition with a fixed amount of RAM,ROM,I/O ports including serial communication, and timer are all embedded together on a single chip. In some microcontroller an ADC and DAC (PWM o/p) also embedded in a single chip.

CPU

General-

Purpose

Microprocessor

RAM ROM

I/OPORT

TimerSerialCOMPort

CPU RAM ROM

serial

I/O Timer COM Port

MCU’s Architecture

Memory (program +data)

CPU

Von Neumann

ADDRESS

DATA Memory(program)

Memory(data)

CPU

Harvard

ADDRESS

ADDRESS

DATA

DATA

FEATURES OF MICROCONTROLLER CHIP• 8 bit CPU with register A and B,• 16 bit Program Counter and Data Pointer,• 8 bit Program Status Word,• Internal ROM (256 Bytes)and Internal RAM (8K)• 4 Ports of each 8 bit, P0-P3,• 2 timers of each 16 bit, T0 and T1,• Full Duplex serial data Transmitter/ Receiver,• Control Registers: TCON,TMOD,SCON,PCON,IE,IP,• Oscillator and Clock circuit.

OVERVIEW

As per pin diagram out of 40 pins, 32 pins are assigned for ports P0,P1,P2 and P3, where each ports takes 8 pins.

The rest of the pins are Vcc, GND,XTAL1, XTAL2, RST, EA’/VPP,ALE/PROG’, AND PSEN’.

Vcc: Pin 40 provides supply Voltage. The voltage source is 5V.GND: Pin 20 is grounded.

XTAL1 & XTAL2 : 8051 needs external clock to run it. Most often a crystal is connected to XTAL1 (19) and XTAL2(18) for supplying operating frequency.

RST: Pin 9 is the Reset pin. It is an input pin and is active high. Upon applying a high pulse to this pin the 8051 will reset and terminate all the activities

PIN DESCRIPTION

EA’/VPP: Pin 31 is the External access pin.The VPP signal is used at the time of EPROM programming, where we supply a 12V through this pin.

ALE/PROG’: ALE (pin 30) stands for Address Latch Enable. This is an output pin and is active high.

PROG’ is used at the time of EPROM programming.

PSEN’: PSEN’ (pin 29) stands for Program Store Enable. This is an output pin and connected to the external ROM.

PIN DESCRIPTION

Oscillator and Clock

8052 has on chip oscillator but requires an external clock to run it. Most often a Quartz Crystal oscillator is connected to XTAL 1 and XTAL 2 pins with 2 nos of 30pf capacitors.

RESET CIRCUIT

FLOWCHART

BLOCK DIAGRAM

CIRCUIT DIAGRAM

COMPONENTS REQUIRED

I ATMEL89C52 microcontroller - 1pc II Voltage regulator (+5 volts) - 1 pc III Two pin connector (Male +Female) - 2 pc IV Eight pin connector (Male +Female) - 6 pc V Reset switch -1 pc VI Resistor (8.2kohm) - 1 pc VII Capacitor (10 microfarad*1, 33 picofarad*2) - 3 pc VIII Crystal oscillator (11.0592 MHz) - 1 pc IX Resistor network - 5pc X LEDs (Green Red) - 16 pc XI Wires - as required XII Battery (9v) - 1 pc

SNAP SHOTS !!

Here we have used 8052 microcontroller because the internal memory of 8052 is greater than that of 8051.

A voltage regulator 7805 is used here to prevent any kind of damage as it maintains a constant voltage of 5v.

The reset circuit is used so that we can start the total operation from the very first whenever we want.

CONCLUSION

1. The 8051 Micro controller and Embedded Systems - Muhammad Ali Mazidi & Janice Gillispie Mazidi 2. Micro controllers Theory and Applications - Ajay V. Deshmukh 3. www.wikipedia.org 4. www.8051.com 5. www.8052.com 6. www.microcontroller.com7. Engineers garage

REFERENCE