LCD based sound operated display using 8051 microcontroller (AT89C51)

Summary
Description
Circuit Diagram
Code
Components

Summary

This is an interesting idea in which a message is displayed on an LCD screen whenever a sound is produced. The message remains on LCD for a short duration of time and then disappears. This topic demonstrates the interfacing of a sound operated circuit and LCD display with the 8051 microcontroller (AT89C51). The circuit can be used to display welcome message at entrance; or warning messages at public places. It can also be used to aid communication for deaf and dumb people.

Description

The circuit consists of four major modules, namely, a sound sensor, an amplifying circuit, a control circuit and a display module. A switching circuit is also employed after the amplifier.

Any sound, say clap, is detected by a microphone (condenser mic) which acts as the sound sensor. This mic is connected to a two stage transistor amplifier. The mic output is thus amplified to a suitable level so that it can be detected at the TTL logic.

The output of the amplifier is coupled with a transistor switch. Whenever a high voltage output is received from the amplifier, it generates a pulse. The transistor switching circuit also ensures that a high TTL logic is not received at the microcontroller due to noise signals.

The pulses, from the switching circuit, are fed to the microcontroller AT89C51's pin which is programmed to detect the pulses. Whenever a high pulse at microcontroller input is detected, a message ‘HELLO WORLD’ is sent to a 16x2 LCD. The message remains on the LCD display for a short duration after which it is cleared again. The message is repeated whenever a high pulse (due to clap sound) is received by the controller.

The data pins of the LCD are connected to port P2, while the control pins (RS, R/W & EN) are connected to pins 1-3 of port P1, respectively. The microcontroller receives sound pulses through the first pin of port P0.

Circuit Diagram

Code

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Components


38,446-Reads	Preset A preset is a three legged electronic component which can be made to offer varying resistance in a circuit. The resistance is varied by adjusting the rotary control over it. The adjustment can be done by using a small screw driver or...
65,543-Reads	Transistor BC547 BC547 is an NPN bi-polar junction transistor. A transistor, stands for transfer of resistance, is commonly used to amplify current. A small current at its base controls a larger current...
38,378-Reads	Transistor BC548 BC548 is general purpose silicon, NPN, bipolar junction transistor. It is used for amplification and switching purposes. The current gain may vary between 110 and 800. The maximum DC current gain is 800. ...
7,617-Reads	Condenser Microphone Condenser microphone (mic) is a transducer that uses a capacitor (or condenser) to convert acoustical energy into electrical energy. The sound waves result into electric...
132,476-Reads	AT89C51 Microcontroller AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051 family. ATMEL 89C51 has 4KB of Flash programmable and erasable read only memory (...
132,015-Reads	LCD LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segments...