Digital Countdown Timer
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Transcript of Digital Countdown Timer
DIGITAL COUNTDOWN TIMER
Philip Gerald Jael
John Chamver Puno
Janelle Quianzon
3ITE
INTRODUCTION
An embedded system is a computer system designed for specific control functions within a
larger system, often with real-time computing constraints. It is embedded as part of a
complete device often including hardware and mechanical parts. By contrast, a general-
purpose computer, such as a personal computer (PC), is designed to be flexible and to meet
a wide range of end-user needs. Embedded systems control many devices in common use
today.
Embedded systems are a growing phenomenon in the technology world. Telephone and
communication devices were some the earliest innovators of embedded systems. Today,
governments and industries are putting major financing towards development of new
applications and devices for trains, planes, and automobiles. Embedded systems are also
found in smart cards and many consumer electronics.
The embedded system that the proponents will be making is a countdown timer.
OVERVIEW
A simple count-down LED timer that counts in minutes and seconds. Three buttons below
the LED provide control of the unit, allowing you set the desired countdown time in minutes
and seconds and a start/stop button. Completion of the countdown is indicated by an alarm
that starts when the countdown has finished and the display reads zero. The alarm is
stopped by pressing the start/stop button.
CIRCUIT DIGRAM
PROJECT COSTING
Resistor x 14 = 14
Led x 4 = 200
Breadboard x 2 = 120
Capacitor x 2 = 2
Switch x 3 = 75
AT89C2051 x 1 = 100
Transistor x 4 = 8
Total = 519
IMPLEMENTATION
The proponents will use the following:
The Embedded System would provide a countdown timer which has 3
switches (Reset, Stop and Start).
AT89C2051 IC to store the countdown program.
Breadboard for testing purposes and connection of wires.
Led will be used to show the generated numbers by the IC.
Wires will be used for the connections.
Resistors are used to regulate the voltage in every connection.
SOURCE CODE
HEX CODE GENERATED
TOOLS AND EQUIPMENT USED
Atmel Programmer
Atmel Trainer
Keil uVision 4
AT89C2051
Low-voltage, high-performance CMOS 8-bit microcomputer with 2KB of flash programmable
and erasable read-only memory. The device is manufactured using Atmel high-density
nonvolatile memory technology and is compatible with the industry-standard MCS-51
instruction set. This versatile 8-bit CPU with flash provides a highly flexible and cost-effective
solution for many embedded control applications.
7 – Segment Led Display
A seven-segment display (SSD), or seven-segment indicator, is a form of electronic display
device for displaying decimal numerals that is an alternative to the more complex dot-
matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters,
and other electronic devices for displaying numerical information.
Resistor
A resistor is a linear, passive two-terminal electrical component that implements electrical
resistance as a circuit element. The current through a resistor is in direct proportion to the
voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a
resistor's terminals to the intensity of current through the circuit is called resistance. This
relation is represented by Ohm's law.
Rectifier
A rectifier is an electrical device that converts alternating current (AC), which periodically
reverses direction, to direct current (DC), which flows in only one direction. The process is
known as rectification. Physically, rectifiers take a number of forms, including vacuum tube
diodes, mercury-arc valves, solid-state diodes, silicon-controlled rectifiers and other silicon-
based semiconductor switches.
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and
power. It is composed of a semiconductor material with at least three terminals for
connection to an external circuit. A voltage or current applied to one pair of the transistor's
terminals changes the current flowing through another pair of terminals. Because the
controlled (output) power can be much more than the controlling (input) power, a transistor
can amplify a signal.
Capacitor
A capacitor (formerly known as condenser) is a passive two-terminal electrical component
used to store energy in an electric field. The forms of practical capacitors vary widely, but all
contain at least two electrical conductors separated by a dielectric (insulator); for example,
one common construction consists of metal foils separated by a thin layer of insulating film.
Capacitors are widely used as parts of electrical circuits in many common electrical devices.
OPERATING PROCEDURE
1. First put the 4 LED and place its connection.
2. Next is place important parts like capacitor and resistor follow the connection for the
LED.
3. After that put the rectifier connect it to the LED.
4. Make a power supply using a small transformer using wires and a plug.
5. Lastly add the switch to the circuit
6. Test the circuit in the breadboard.
7. If there is no error place it in a circuit board/PCB.
PROBLEMS ENCOUNTERED
Program mismatched
Lack of materials
Wrong placement of wires
Power not turning on
SUMMARY
The goal of this proposed project aims to design, build, and test a countdown timer using
Atmel IC. This project is motivated by the need to expand our knowledge in embedded
systems. To achieve this goal, this project will employ innovative and indigenous materials,
which will help us in our project like the Keil uVision4, Atmel Programmer and Atmel
Trainer. The anticipated outcome of this project will be a countdown timer which has 3
buttons that would be Start, Pause and Stop.
The project will also:
Make an embedded system using AT89C2051/AT89C4051.
Develop a prototype for testing purposes.
Make a countdown timer using AT89C2051.
Make a code for the IC to produce a countdown timer
REFERENCES
http:// www.8051projects.info/proj.asp?id=61
http://technorati.com/technology/embedded/article/embedded-systems-devices-for-
everyday-life/#ixzz1pEJejytX
AT89C2051 Datasheet