09-10-2015, 02:36 PM
fastest finger first using 89c51 with its ckt diagram
The quiz buzzer systems are widely used in school, colleges and TV programs. The team which presses the buzzer earliest is entitled to give the answer. At times it becomes very difficult to identify which team has pressed the button when two teams press the buzzer within a very small time gap. In such cases the decision can be biased due to human intervention. The quiz buzzer presented here takes care of the aforesaid problem. This quiz buzzer disables the other inputs as soon as the first buzzer is pressed. This quiz buzzer can be used for a maximum of eight teams. It is build around 8051 microcontroller (AT89C51).
Introduction:
Now a days quiz-type game shows are increasingly becoming popular on television. In such quiz games , fastest finger first indicators (FFFIs) are used to test the contestants reaction time. The player’s designated number is displayed with an audio alarm when the player presses his entry button.
Objective:
The fastest finger first circuit presented here determines as to which of the four contestants first pressed the button and locks out the remaining three entries of other three members. Simultaneously, an audio alarm (buzzer) and the correct decimal number display of the corresponding contestant are activated.
INTRODUCTION
Useful for quiz games,dumb charades etc.This fastest-finger-first circuit displays the player number along with beep sound when a specific player presses the button before others.It is designed for seven players and can be constructed easily using minimal hardware and software. When a microcontroller receives an input from any of seven tactile switches (S1 through S7),it disables the inputs from the rest of the switches assigned to other players.A master reset control (switch 0) has to be pressed to enable all the inputs for the next round of the quiz.
Details
CIRCUIT DESCRIPTION
A 9V DC supply from either a dry cell or a battery eliminator circuit is regulated by IC 7805.The regulated 5V DC obtained is used to power the circuit.The glowing of LED1 indicates the presence of power in the circuit.The circuit for the Fastest-Finger-First using microcontroller AT89C51.
MICROCONTROLLER AT89C51
At the heart of the circuit is flash-based microcontroller IC AT89C51.It is a low-power ,high performance CMOS 8-bit microcomputer with 4KB of flash programmable and erasable read-only memory(PEROM).It is manufactured using Atmel's high-density,non-volatile memory technology and is compatible with the industry-standard MCS-51 instruction set.The on-chip flash allows the program memory to be reprogrammed in-system or by a conventional non-volatile memory programmer. Combining a versatile 8-bit CPU with flash on a monolithic chip,the Atmel AT89C51 is a powerful microcontrollerthat provides a highly flexible and cost-effective solution to many embedded control applications. The AT89C51 provides the following standard features:
4KB flash
2. 128 bytes of RAM 3. 32 I/O lines 4. Two 16-bit timers/counters 5. A 5-vector,two-level interrupt architecture 6. A full duplex serial port 7. On-chip oscillator and clock circuitry.
Here port0 and port1 are used as input and output ports respectively.
Port-0
![Tongue Tongue](https://studentbank.in/images/smilies/tongue.gif)
![Tongue Tongue](https://studentbank.in/images/smilies/tongue.gif)