“Automatic bidirectional visitor counter for controlling using 8051 microcontroller (AT89S52)”

 “Automatic bidirectional visitor counter for controlling  using 8051 microcontroller (AT89S52)”

A counter that can change its state in either direction, under control of an up–down selector input, is known as an up–down counter. The circuit given here can count numbers from 0 to 9999 in up and down modes depending upon the state of the selector. It can be used to count the number of persons entering a hall in the up mode at entrance gate. In the down mode, it can count the number of persons leaving the hall by decrementing the count at exit gate. It can also be used at gates of parking areas and other public places.

This circuit divided in three parts: sensor, controller and counter display. The sensor would observe an interruption and provide an input to the controller which would run the counter in up/down mode depending upon the selector setting. The same count is displayed on a set of 7-segment displays through the controller.

This is very wonderful project to control the working of IR birectional Visitor counter. These sensor are equipped with the CPU which control the counter. 1. 8051 Microcontroller 2. ULN2003 3. LCD . 4.LM358 5.Relay 6.IR TRANSMITTER-RECEVER 

APPLICATIONS

Telecom 

• Mobile phone systems (handsets and base stations), modems, routers 

• Automotive application 

• Braking system, Traction control, Airbag release system, Management units, and Steer-by-wire systems. Domestic application 

• Dishwasher, television, washing machines, microwave ovens, Video recorders, Security system, Garage door controllers, Calculators, Digital watches, VCRs, Digital cameras, Remote Controls, Treadmills

 Robotic 

• Fire fighting robot, Automatic floor cleaner, robotic arm

 Aerospace application 

• Flight control system, Engine controllers, Autopilots, Passenger entertainment system 

Medical equipment 

• Anesthesia monitoring system, ECG monitors, Pacemakers, Drug delivery systems, MRI scanners 

 Defense system 

• Radar systems, Fighter aircraft flight control system, Radio system, Missile guidance systems 

Office automation 

• Laser printers, Fax machines, Pagers, Cash registers, Gas pumps, Credit /Debit card readers, Thermostats, Grain analyzers.  

COMPONENT DESCRIPTION

1)MICRO-CONTROLLER 8051  DESCRIPTION

The IC 8051 is a low-power; high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel IC 8051 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications. The IC 8051 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, full duplex serial port, on-chip oscillator and clock circuitry. In addition, the IC 8051 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning.

Pin Description of the 8051

PROCESSOR

A processor is an electronic device capable of manipulating data in a way specified by a sequence of instructions.

INSTRUCTIONS

Instructions in a computer are binary numbers just like data. Different numbers, when read and executed by a processor, cause different things to happen. The instructions are also called opcodes or machine codes.

Different bit patterns activate or deactivate different parts of the processing core. Every processor has its own instruction set varying in number, bit pattern and functionality.

PROGRAM

The sequence of instructions is what constitutes a program. The sequence of instructions may be altered to suit the application.

ASSEMBLY LANGUAGE

Writing and understanding such programs in binary or hexadecimal form is very difficult ,so each instructions is given a symbolic notation in English language called as mnemonics. A program written in mnemonics Form is called an assembly language program. But it must be converted into machine language for execution by processor.

ASSEMBLER

An assembly language program should be converted to machine language for execution by processor. Special software called ASSEMBLER converts a program written in mnemonics to its equivalent machine opcodes.

HIGH LEVEL LANGUAGE

A high level language like C may be used to write programs for processors. Software called compiler converts this high level language program down to machine code. Ease of programming and portability.

PIN DESCRIPTION

VCC (Pin 40)

Provides voltage to the chip . +5V GND (Pin 20)

Ground

XTAL1 (Pin 19) and XTAL2 (Pin 18)

Crystal Oscillator connected to pins 18, 19.Two capacitors of 30pF value. Time for one machine cycle:11.0592/12=1.085 µ secs

 RST (Pin 9) RESET pin

1.Active high. On applying a high pulse to this pin, microcontroller will reset and terminate all activities.

2.INPUT pin

3.Minimum 2 machine cycles required to make RESET 4.Value of registers after RESET

External Access: EA 31

•Connected to VCC for on chip ROM

•Connected to Ground for external ROM containing th e code Input Pin

Program Store Enable: PSEN 29

•Output Pin

•In case of external ROM with code it is connected to the OE pin of the ROM

Address Latch Enable: ALE 30

• Output Pin. Active high

•In case of external ROM ,ALE is used to de multipl ex (PORT 0) the address and data bus by connecting to the G pin of 74LS373 chip

I/O Port Pins and their Functions:

•Four ports P0,P1,P2,P3 with 8 pins each, making a total of 32 input/output pins

•On RESET all ports are configured as output. They need to be programmed to make them function as inputs

PORT 0

•Pins 32-39

•Can be used as both Input or Output

•External pull up resistors of 10K need to be connected

•Dual role: 8051 multiplexes address and data throu gh port 0 to save pins .AD0-AD7 •ALE is used to de multiplex data and address bus

PORT 1

•Pins 1 through 8 •Both input or output •No dual function

•Internal pull up registers

•On RESET configured as output

PORT 2

•Pins  21 through 28

•No external pull up resistor required •Both input or output

•Dual Function: Along with Port 0 used to provide t he 16-Bit address for external memory. It provides higher address A8-A16

PORT 3

•Pins 10 through 17

•No external pull up resistors required

PROCESSOR ARCHITECTURE