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CONTENTS

1 .INTRODUCTION

2 .DEVICES USED

3 .BLOCK DIAGRAM

4 .CIRCUIT DIGRAM

5 .AT MEGA 16 MICROCONTROLLER

6 .PIN DESCRIPTIONS

7 .32 BIT SERIAL IC BUS EEPROM

8 .FEATURES SUMMARY

9 .RTC(REAL TIME CLOCK)

10. PS/2KEYBOARD

11 .LED MATRIX DISPLAY

12 .BUZZER

13 .APPLICATION AND ADVANTAGE

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INTRODUCTION

This Project takes over the task of Ringing of the Bell in Colleges. It replaces the Manual

Switching of the Bell in the College. It has an Inbuilt Real Time Clock (DS1307 /DS 12c887)

which tracks over the Real Time. When this time equals to the Bell Ringing time, then the Relay

for the Bell is switched on.The Bell Ringing time can be edited at any Time, so that it can be

used at Normal Class Timings as well as Exam Times. The Real Time Clock is displayed on

LCDt display. The Microcontroller AT89S52 is used to control all the Functions, it get the time

through the keypad and store it in its Memory. And when the Real time and Bell time get equal

then the Bell is switched on for a predetermined time.

DEVICES USED

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BLOCK DIAGRAM

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A BRIEF INTRODUCTION TO AT MEGA 16 MICROCONTROLLER

Features

High-performance, Low-power Atmel AVR

8-bit Microcontroller

Advanced RISC Architecture

131 Powerful InstructionsMost Single-clock Cycle Execution

32 x 8 General Purpose Working Registers

Fully Static Operation

Up to 16 MIPS Throughput at 16 MHz

On-chip 2-cycle Multiplier

High Endurance Non-volatile Memory segments

16 Kbytes of In-System Self-programmable Flash program memory

512 Bytes EEPROM

1 Kbyte Internal SRAM

Write/Erase Cycles: 10,000 Flash/100,000 EEPROM

Data retention: 20 years at 85C/100 years at 25C(1)

Optional Boot Code Section with Independent Lock Bits

In-System Programming by On-chip Boot Program

True Read-While-Write Operation

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Programming Lock for Software Security

JTAG (IEEE std. 1149.1 Compliant) Interface

Boundary-scan Capabilities According to the JTAG Standard

Extensive On-chip Debug Support

Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG Interface

Peripheral Features

Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes

One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture

Mode

Real Time Counter with Separate Oscillator

Four PWM Channels

8-channel, 10-bit ADC

8 Single-ended Channels

7 Differential Channels in TQFP Package Only

2 Differential Channels with Programmable Gain at 1x, 10x, or 200x

Byte-oriented Two-wire Serial Interface

Programmable Serial USART

Master/Slave SPI Serial Interface

Programmable Watchdog Timer with Separate On-chip Oscillator

On-chip Analog Comparator

Special Microcontroller Features

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Power-on Reset and Programmable Brown-out Detection

Internal Calibrated RC Oscillator

External and Internal Interrupt Sources

Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, Standby

and Extended Standby

I/O and Packages

32 Programmable I/O Lines

40-pin PDIP, 44-lead TQFP, and 44-pad QFN/MLF

Operating Voltages

2.7V - 5.5V for ATmega16L

4.5V - 5.5V for ATmega16

Speed Grades

0 - 8 MHz for ATmega16L

0 - 16 MHz for ATmega16

Power Consumption @ 1 MHz, 3V, and 25C for ATmega16L

Active: 1.1 mA

Idle Mode: 0.35 mA

Power-down Mode: < 1 A

8-bit

Microcontroller

with 16K Bytes

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In-System

Programmable Flash

ATmega16(L)

Pin Configurations

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Pin Descriptions

VCC Digital supply voltage

.

GND Ground.

Port A (PA7..PA0) Port A serves as the analog inputs to the A/D Converter.

Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins

can provide internal pull-up resistors (selected for each bit). The Port A output buffers have

symmetrical

drive characteristics with both high sink and source capability. When pins PA0 to PA7

are used as inputs and are externally pulled low, they will source current if the internal pull-up

resistors are activated. The Port A pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

Port B (PB7..PB0) Port B is an 8-bit bi-directional I/O port with internal pull-up resistors

(selected for each bit). The

Port B output buffers have symmetrical drive characteristics with both high sink and source

capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up

resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

Port B also serves the functions of various special features of the ATmega16 as listed on

.

Port C (PC7..PC0) Port C is an 8-bit bi-directional I/O port with internal pull-up resistors

(selected for each bit). The

Port C output buffers have symmetrical drive characteristics with both high sink and source

capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up

resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,

even if the clock is not running. If the JTAG interface is enabled, the pull-up resistors on pins

PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.

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.

Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up resistors

(selected for each bit). The

Port D output buffers have symmetrical drive characteristics with both high sink and source

capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up

resistors are activated. The Port D pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

.

RESET Reset Input. A low level on this pin for longer than the minimum pulse length will

generate a

reset, even if the clock is not running.

.

XTAL1 Input to the inverting Oscillator amplifier and input to the internal clock operating

circuit.

XTAL2 Output from the inverting Oscillator amplifier.

AVCC AVCC is the supply voltage pin for Port A and the A/D Converter. It should be

externally connected

to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC

through a low-pass filter.

AREF AREF is the analog reference pin for the A/D Converter.

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64Kbit and 32Kbit Serial IC Bus EEPROM

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FEATURES SUMMARY

Two-Wire I

2

C Serial Interface

Supports 400kHz Protocol

Single Supply Voltage:

4.5 to 5.5V for M24Cxx

2.5 to 5.5V for M24Cxx-W

1.8 to 5.5V for M24Cxx-R

Write Control Input

BYTE and PAGE WRITE (up to 32 Bytes)

RANDOM and SEQUENTIAL READ Modes

Self-Timed Programming Cycle

Automatic Address Incrementing

Enhanced ESD/Latch-Up Protection

More than 1 Million Erase/Write Cycles

More than 40-Year Data Retention

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RTC(REAL TIME CLOCK)

RTCDS1307

A real time clock is basically just like a watch - it runs on a battery and keeps time for you even

when there is a power outage! Using an RTC, you can keep track of long timelines, even if you

reprogram your microcontroller or disconnect it from USB or a power plug.

Most microcontrollers, including the Arduino, have a built-in timekeeper called millis() and

there are also timers built into the chip that can keep track of longer time periods like minutes or

days. So why would you want to have a seperate RTC chip? Well, the biggest reason is

that millis() only keeps track of time since the Arduino was last powered- . That means that

when the power is turned on, the millisecond timer is set back to 0. The Arduino doesn't know

that it's 'Tuesday' or 'March 8th', all it can tell is 'It's been 14,000 milliseconds since I was last

turned on'.

OK so what if you wanted to set the time on the Arduino? You'd have to program in the date and

time and you could have it count from that point on. But if it lost power, you'd have to reset the

time. Much like very cheap alarm clocks: every time they lose power they blink12:00

While this sort of basic timekeeping is OK for some projects, some projects such as data-loggers,

clocks, etc will need to have consistent timekeeping that doesn't reset when the Arduino

battery dies or is reprogrammed. Thus, we include a seperate RTC! The RTC chip is a

specialized chip that just keeps track of time. It can count leap-years and knows how many days

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are in a month, but it doesn't take care of Daylight Savings Time (because it changes from place

to place)

-Time Clock (RTC) Counts Seconds,

Minutes, Hours, Date of the Month, Month, Day of

the week, and Year with Leap-Year

Compensation Valid Up to 2100

-Byte, Battery-Backed, General-Purpose RAM

with Unlimited Writes

2

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C Serial Interface

-Wave Output Signal

-Fail Detect and Switch Circuitry

-Backup

Mode with Oscillator Running

-40C to +85C

-Pin Plastic DIP or SO

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Ps/2keyboard

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Physical Interface

The physical PS/2 port is one of two styles of connectors: The 5-pin DIN or the 6-pin mini-

DIN. Both connectors are completely (electrically) similar; the only practical difference between

the two is the arrangement of pins. This means the two types of connectors can easily be

changed with simple hard-wired adaptors. These cost about $6 each or you can make your own

by matching the pins on any two connectors.

PC keyboards use either a 6-pin mini-DIN or a 5-pin DIN connector. If your keyboard has a 6-

pin mini-DIN and your computer has a 5-pin DIN (or visa versa), the two can be made

compatible with the adaptors described above. Keyboards with the 6-pin mini-DIN are often

referred to as "PS/2" keyboards, while those with the 5-pin DIN are called "AT" devices ("XT"

keyboards also used the 5-pin DIN, but they are quite old and haven't been made for many

years.) All modern keyboards built for the PC are either PS/2, AT, or USB. This document does

notapply to USB devices, which use a completely different interface.

Mice come in a number of shapes and sizes (and interfaces.) The most popular type is probably

the PS/2 mouse, with USB mice gaining popularity. Just a few years ago, serial mice were also

quite popular, but the computer industry is abandoning them in support of USB and PS/2devices. This document applies only to PS/2 mice. If you want to interface a serial or USB

mouse, there's plenty of information available elsewhere on the web.

The cable connecting the keyboard/mouse to the computer is usually about six feet long and

consists of four to six 26 AWG wires surrounded by a thin layer of mylar foil sheilding. If you

need a longer cable, you can buy PS/2 extenstion cables from most consumer electronics

stores. You should not connect multiple extension cables together. If you need a 30-foot

keyboard cable, buy a 30-foot keyboard cable. Do not simply connect five 6-foot cables

together. Doing so could result in poor communication between the keyboard/mouse and the

host.

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As a side note, there is one other type of connector you may run into on keyboards. While most

keyboard cables are hard-wired to the keyboard, there are some whose cable is not permanently

attached and come as a separate component. These cables have a DIN connector on one end (the

end that connects to the computer) and a SDL (Sheilded Data Link) connector on the keyboard

end. SDL was created by a company called "AMP." This connector is somewhat similar to a

telephone connector in that it has wires and springs rather than pins, and a clip holds it in

place. If you need more information on this connector, you might be able to find it on AM.Don't

confuse the SDL connector with the USB connector--they probably both look similar in my

diagram below, but they are actually very different. Keep in mind that the SDL connector has

springs and moving parts, while the USB connector does not.

The pinouts for each connector are shown below:

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LED MATRIX DISPLAY

It is made up of number of led's connected together

To display a static message or running display. Now a days it has become Most favorable

because it can show alphanumeric characters as well as any shape. It can be of different sizes

(row x column)

We have used (7x40).

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BUZZER

A buzzer or beeper is an audio signalling device, which mabe mechanical, electromechanical, or

piezoelectric. Typical uses of buzzers and beepers include alarm devices, timers etc.

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Application and Advantage

It can be used in the college, school for bellingpurpose.

It can be used in the any type of examination for bellingbecause we can set the ringing time.

Automatic scheduling of college bell is possible. Compact in size so takes less space.

Time editable facility is available.